DE19725850A1 - Semiconductor component with thin film resistor - Google Patents

Abstract

The semiconductor device comprises a semiconductor substrate (1). On one surface of the substrate a region (4a) is formed with an inclined angle, with respect to the substrate thickness direction. On this substrate surface is deposited an insulating film (2). The inclined angular region reflects laser light for equalising a thin-film resistor (3) deposited on the insulating film over the angular region, with the laser light passing through the resistor. Thus the laser light, reflected by the inclined angular region, reaches the resistor. The inclined region is adjusted at an angle exceeding 45 degrees, but less than 90 degrees.

Description

The present invention relates to a half conductor device that has a thin film resistor points with which a fine f same or trimming can be performed.

In general, a conventional laser fine is known method in which a resistance material, such as CrSi on a semiconductor substrate deposited an insulating material or the like and patterned into a predetermined pattern where followed by a laser on the resulting thin layer resistance is directed, making part of it Structure melted and its resistance to a ge desired value is set.

During the laser fine adjustment or trimming process, the La beam directed at the thin film resistor, through the thin film resistor. Through this kicking laser light is at an interface between an underlying oxide layer and the semiconductor substrate reflects and overlaps with the idea emit laser light or generate interference. Because of the This interference creates a problem in that a stable fine adjustment of the thin film resistance impossible is to be carried out.

To solve this problem are described in US 4,594,265 and U.S. 4,708747 discloses various methods. Each this method relates to a semiconductor device in of the respective semiconductor layers by providing an iso  insulating layer within a semiconductor substrate are electrically isolated. Furthermore, at the Surface of the semiconductor substrate from an insulating layer formed and a thin film resistor formed thereon. In the former method, etching or the like on the surface of the semiconductor layer, the itself at the interface between the insulating iso layer within the semiconductor substrate and the Semiconductor layer is made of depressions or V-grooves formed, causing light reflection at the interface is prevented that between the insulating insulation layer within the semiconductor substrate and the semi-lead layer lies. In the latter procedure, the Reflection of the laser light also prevents that the thickness of the formed within the semiconductor substrate th insulating layer to a value which is related to the insulating insulation layer makes the laser light appear "transparent".

The methods described in these U.S. patents in no way take into account the reflection of the penetrated laser light at the interface between the insulation layer just below the thin layer stands between the semiconductor substrate and the upper surface of the semiconductor substrate is formed.

From the reference "The Journal of Nippondenso Technical Disclosure No. 87-023" (published on November 15, 1992) a method is disclosed which shows countermeasures in this regard and is shown in FIG. 16. According to this conventional method, a thin film resistor 3 is formed on a Si substrate 1 with an insulation layer 2 therebetween. Furthermore, a level difference section A with a 1/4 of the laser wavelength corresponding height is provided at an interface between the Si substrate 1 and the insulation layer 2 just below the thin film resistor 3 , thereby causing mutual extinction of the laser light, which is caused by the Upper portions and lower portions of the concave and convex portions are reflected in the level difference portion A. Consequently, interference between the incident laser light and the reflected laser light in the vicinity of the thin film resistor is prevented, which is why a laser fine adjustment can be performed in an excellent manner.

However, there is a problem with this method going that the height of the top section and the bottom Section through the concave and convex sections of the level difference section can be set highly precisely to avoid interference due to the reflected La extinguish serlichts.

The invention is therefore based on the object Semiconductor device and a method for its manufacture to create a thin film resistor in outstandingly fine adjustment by a laser holds, with no precise control of an upper level Section and a lower section of a level dif border section is necessary.

To solve the problems described above according to the invention in a semiconductor device with a thin film resistor formed therein, which is a fine adjustment required by a laser at an interface between one immediately below the thin layer resistance insulation layer and a Semiconductor substrate an oblique or oblique ge constituted area that is related to a thickness direction of a semiconductor substrate so inclined is that what falls on it and through the thin film wi the laser light passed through from the inclined position  Area is reflected so that it is the thin layer resistance reached.

Due to the reflected laser light from the obliquely ge posed or oblique area results in a com interference between the reflected laser light and the incident laser light as opposed to the case where the interface between the insulation layer and the semiconductor substrate is flat. Because of the the interfering light received there is a zone where the laser energy is more forced to a greater extent in an area where the Thin film resistance is. As a result, the fine be carried out in an excellent manner. This means that the present invention fine tunes of thin film resistance not by preventing Re flexion of the laser light at the interface between the Isolation layer and the semiconductor substrate as in the stand prevents technology, but reflection on it Consciously uses the interface.

As a result, the reflected laser light does not like must be extinguished in the prior art, must also Height of the upper section and the lower section of the Level difference section, which consists of the concavities or round cavities and convexities or bulges for Extinguishing the reflected laser light does not result can be set or controlled with high precision. It's enough if by the at the interface between the Insulation layer and the semiconductor substrate formed inclined area an interference state between the incident laser light and the one in between Interface reflected laser light changed or vari is. According to the invention can be an excellent Fine adjustment can be made, depending on the thickness of the Insulation layer is not affected.  

Preferably, the slanted area is set to an angle that is greater than 45 ° and less than 90 ° with respect to a thickness direction
of the semiconductor substrate. As a result, the laser light that has passed through the thin film resistor is reflected from the oblique-angled area, which is why it reliably reaches the thin film resistor.

The oblique area can also be curvilinear be. This means that the thin layer resistance penetrated laser light with ver different angles reflected on the oblique area which is curvilinear. As a result it is expected that near the surface of the semi-lead device alternately a zone in which this occurs lende laser light and the reflected laser light cooperate that their two energies due to their tw Interference are strengthened, and a zone trained Det on which the incident laser light and the reflec tated laser light interact so that their Weaken energies due to interference.

Even if an upper section and a lower Ab intersection (i.e. a level difference section) each between between the inclined or oblique areas is caused by the thin film laser light passed through the reflection the upper / lower sections of the level difference cut as well as in the obliquely angled areas changes described in the interference laser light.

At least one of the connecting sections between the oblique areas and the adjacent upper ab cut the level difference section or the verb sections between the oblique areas and the adjacent lower portions of the level difference cuts are preferably curved and smooth  det. In this case, this is resisted by the thin film stood through laser light with different win reel at the smooth curvilinear connecting sections inflected. As a result, one can again expect that in near the surface of the semiconductor device selsel the zone in which due to the interaction of the incident laser light and reflected laser light their energies are amplified and the zone is created where the incident laser light and the reflected La interact so that their respective energy gien be weakened.

When the oblique areas are arranged like this are that a multitude of oblique areas inside are half the spot size of the radiating laser, is also the zone where the incident La serlicht with the reflected laser light for amplification their energies work together with a higher truth probability or reliability in the area in which the thin film resistor is formed. Hence can a fine adjustment of the thin film resistance in reliable eng manner.

The oblique area can be created by using a selective oxidation layer are formed. Through the Formation of the oblique area using egg A selective oxidation layer can have a smooth surface che are trained in the oblique area, which for the reflection of a laser light is suitable. Because the out formation of the oblique-angled area is also the same early on with the formation of the selective oxidation layer to isolate a component area, such as egg a transistor region formed in the semiconductor substrate, can be done, the oblique area be formed without losing the number of manufacturing steps to enlarge.  

Furthermore, the oblique-angled areas can be in shape applied by strips or in the form of stitches are formed, the strips crossing each other Zen. In the event that the obliquely angled areas mesh are arranged in a shape, the upper and lower are from Sections of the level difference section alternate between the oblique areas.

At this point, the inventors of the experimental results carried out according to the invention grasslands. Comparing a case where a laser light in relation to the stripe-shaped oblique angles areas is irradiated in such a way that it strips crosses vertically, with a case where a laser light is irradiated in such a way that it is parallel to the strips lies, it is found that when the laser is irradiated an excellent fine light in parallel can be carried out immediately, while on the other hand the Irradiation with a laser light in the vertical direction led to that only a moderate fine adjustment was carried out could be.

As a result, if the oblique area and the pe Alternate gel difference section in the form of stripes can be applied by irradiation with a Laser light parallel to the stripes of the oblique Ge offers and the level difference section an excellent Fine adjustment can be carried out.

When fine-tuning the thin-film resistance, fer Sometimes a method of performing fine tuning also used in which the scanning direction of a laser is not set to one of the directions, but at whose scanning direction is bent like the letter "L" or changed (hereinafter referred to as "L-letter cut" designated). In the event that the oblique areas are formed in strips, can accordingly  Situation arise in which the "L-letter cut" does not can be done in an excellent way.

According to those of the inventors of the present invention carried out test results could be that a stable fine adjustment by can be performed if the between the oblique Areas formed level difference section mesh mig is arranged. So if the top and bottom Sections of the level difference section alternately indicated are arranged, the "L-letter cut" can emerge in gender-wise.

The invention is based on execution examples with reference to the drawing be wrote.

Show it:

Fig. 1 is a sectional view illustrating a semiconductor device according to a first embodiment of the Invention;

Fig. 2 is an illustration showing a test measurement for measuring the fine balance energy;

FIG. 3A is a sectional view showing a conventional sample, as used in a test;

Fig. 3B is a sectional view illustrating a sample according to the first embodiment, as used in the experiment;

Fig. 4 is a graph showing the measurement results for the fine balance energy;

5A is a sectional view showing a semiconductor device illustrating a conventional structure.

FIG. 5B occurs a view illustrating a state of interference of the laser light, the semiconductor device in the half with the construction of FIG. 5A;

Fig. 6A he is a sectional view, the device comprises a semiconductor having a structure according to the first exemplary embodiment;

FIG. 6B is a view illustrating an interference state of the laser light as it occurs in the semiconductor device with the structure of FIG. 6A;

Fig. 7 is a view illustrating an image of a portion of a semiconductor device after carrying out the fine adjustment as it is received by the transmission type of an electronic microscope;

Fig. 8 is a view showing a picture of a cut Ab represents a semiconductor device according to the first embodiment, as it is received from the transmission type of an electronic microscope;

9A is a sectional view illustrating a sample having ei nem conventional structure as used for an experiment.

Fig. 9B as it was used for the test is a sectional view which illustrates a sample according to a second embodiment; Fig

Fig. 10 is a graphical representation of the measurement results for the fine adjustment energy;

Figure 11 is a view illustrating the relationship between the scanning of a laser and a level-difference portion. 4;

Fig. 12 is a view showing the level difference section 4 , in which the level differences are arranged in the form of meshes;

Fig. 13 is a graphical representation of the measurement results for the fine adjustment energy when the level differences of the level difference section 4 have been arranged in a mesh shape;

FIG. 14A-14C are views illustrating the manufacturing steps for manufacturing a semiconductor device;

FIG. 15A-15C are views illustrating the manufacturing steps for manufacturing a semiconductor device; and

Fig. 16 is a sectional view illustrating a conventional semiconductor device.

First embodiment

Fig. 1 shows a sectional view illustrating a semiconductor device according to a first exemplary embodiment from the invention.

In the semiconductor device shown in FIG. 1, a level difference section 4 (trapezoidal level difference section) is formed in a surface of a semiconductor substrate 1 made of silicon. An insulation layer 2 , such as a BPSG layer, which contains boron (B) or phosphorus (P), is deposited on the semiconductor substrate 1 . Furthermore, on the insulation layer 2 , the surface of which is flattened or smoothed, a thin-film resistor 3 of, for example, CrSi is formed. Furthermore, Al electrodes 5 a and 5 b are formed from ge at both end sections of the thin film resistor 3 , an insulation layer 6 , such as an oxide layer, and a protective layer 7 , such as a nitride layer (SiN), being formed in this way that they cover the surfaces of the Al electrodes 5 a and 5 b and the thin film resistor 3 .

The level-difference portion 4 has tapered portions 4 a (also known as "oblique regions" or "obliquely ge turned pages" hereinafter), the lower From sections 4 b to the upper portions 4 c of the level-Diffe Renz portion 4 to connect. Each of these cone sections 4 a is designed such that it forms an angle α with respect to the thickness direction of the semiconductor substrate 1 , which is indicated by an arrow A in FIG. 1. When performing the fine adjustment, a laser light that has passed through the thin film resistor is reflected at the cone sections 4 a, again reaching the thin film resistor 3 . It should be noted that the angle α is set to 45 ° <α <90 °, so that the laser light which has passed through the thin film resistor 3 is reflected back upwards. The angle α is preferably set to 50 ° α 70 °. It should also be noted that the surface orientation of the semiconductor substrate shows a (100) plane.

If one compares a case in which the fine adjustment was carried out with respect to this semiconductor device with a case in which the fine adjustment was carried out with respect to a conventional semiconductor device which has no level difference section 4 , the effects of the level Difference sections 4 on the fine adjustment operation based on the test results.

In the experiment, a large number of samples were prepared, the thicknesses of the insulation layer 2 being formed differently immediately below half of the thin-film resistor 3 . Referring to FIG. 2 was inserted between the Al electrode 5 a and 5 b a measuring device for measuring the resistance value between the electrodes 5 a and 5 b is closed. While the laser corresponds to the arrows (a), (b), (c),. . . - As shown in the figure - is deflected, the laser irradiation is carried out, and its output signal changes. The laser output signal is detected when the resistance value recorded by the measuring device 51 becomes infinite, ie when the thin-film resistor 3 is melted due to the laser radiation, with the result that there is an open state between the Al electrodes 5 a and 5 b . It should be noted that Fig. 2 is a plan view of the semiconductor device with the thin film resistor 3 formed therein as shown in a top view.

Incidentally, it should be noted that the one used in the experiment Device represents a fine adjustment device, which by the ESi Company is manufactured; the laser used was a YLF laser with a wavelength λ of 1.048 µm; in which a pulsed laser with an irradiation pulse width of approx. 50 ns and a pulse interval of 1.3 ms has been. Furthermore, the spot size of the CrSi layer irradiating laser set to 10 microns.  

FIGS. 3A and 3B show detailed views Schnittan which len, the samples used in the experiment depicting. Referring to FIGS. 3A and 3B, in each of the samples used in the experiment, the insulation point of view 2, which befin det immediately below the thin film resistor 3 made of a BPSG layer 2 a, a P-SiN layer 2 b, by plasma chemical vapor deposition (CVD) was formed, a TEOS layer 2 c, which was formed using a tetraethyloxylsilane gas, an SOG layer 2 d (spin-on-glass) and a TEOS layer 2 e. The insulation layer 6 , which is located immediately above the thin-film resistor 3 , consists of a TEOS layer 6 a, a P-SiN layer 6 b and a TEOS layer 6 c.

FIG. 3A shows the conventional semiconductor device, the interface between the semiconductor substrate 1 and the insulation layer 2 located immediately below the thin-film resistor 3 being flat, while FIG. 3B shows a semiconductor device in which at the interface between the semiconductor substrate 1 and the insulation layer 2 immediately below half of the thin film resistor 3, the level difference section 4 with cone sections 4 a according to FIG. 1 is provided.

Further, in the semiconductor device used in the experiment according to the first embodiment, the upper portions of the level difference portion 4 as shown in FIG. 3B were formed at a distance W which was set to 2 µm.

In the experiment, the laser output power (laser energy) was checked, which made it possible to carry out a fine adjustment if the thicknesses of the BPSG layer 2 a according to FIGS. 3A and 3B were changed between 4000 Å to 7000 Å (400 nm to 700 nm).

The test results are shown in FIG. 4. In the figure, the marking denotes the measured values that are obtained using the conventional semiconductor device according to FIG. 3A, while the marking O indicates the measured values that are obtained using the semiconductor device according to the first exemplary embodiment according to FIG. 3B. It should be pointed out that the marking ⚫ is described below.

As is apparent from FIG. 4, in the herkömmli chen semiconductor device for fine adjustment preferential laser output Benö greater when the thickness of the BPSG layer 2 a at about 4000 Å (400 nm) and at about 7000 Å (700 nm) than the required laser output power if this thickness is at a respective one of the remaining values, exceeding 0.8 mW, which represents the laser output power which causes a breakdown or damage to the protective layer 7 . On the other hand, be understood that a in the semiconductor device accelerator as the first embodiment, the laser output required for the fine adjustment stable at about 0.3 mW, the fine adjustment is thus particularly geeigne even when changing the thickness of the BPSG layer 2 ter way can be carried out. This is described in detail based on the results obtained by simulation.

In FIGS. 5A and 5B and Figs. 6A and 6B are the results obtained by simulation shown with respect to the interference states of the laser light, which occurs in a conventional case in which the interface between the insulation layer 2 and the semiconductor substrate 1, flat or is flat, and for a case in which the interface lying between has inclined regions 4 a.

FIGS. 5A and 6A indicate corresponding parts of the sections of the semiconductor devices, each having the semiconductor substrate 1 made of Si and on in consecutive order the insulating layer 2, which consists of CrSi thin-film resistor 3, the insulating layer 6 and the protective layer 7 are trained. It should be noted that in FIG. 6A, the lateral width W of the simulation model is 2 μm, which corresponds to the same distance between the level difference section 4 according to FIG. 3B. The interference state or state of mutual interference of the laser light, which occurs when laser light with a wavelength of 1.048 μm is irradiated on each of these semiconductor devices, is shown in FIGS . 5B and 6B.

In FIGS. 5B and 6B, the surfaces each having the same laser energy due to the mutual Beeinflus solution of the laser light by contour lines or outlines designated, while the reference numerals in the figures represents the intensity of the laser energy that occurs as a result of such mutual interaction.

In Fig. 5B, due to the planar surface of the semiconductor substrate 1 are parallel to the surface of the semiconducting generated tersubstrats 1 lying interference fringes. This means that, in the thickness direction of the device according to FIG. 5A, the zones appear alternately at which the incident laser light and the reflected laser light mutually influence one another in such a way that their energies increase or weaken ver. In this case, if the zone in which the laser energy is weakened by the mutual influence is generated at the position of the thin film resistor 3 , then the fine adjustment of the thin film resistor 3 can not be carried out. Accordingly, in this case, the possibility for performing the fine adjustment is unsuitably influenced by the thickness of the insulation layer 2 , which is immediately below the thin film resistor 3 . Even if the output power of the laser is increased sufficiently at this time so that a fine adjustment would be possible, however, this increase in the laser output power is limited, since an excessive increase in the laser output power causes a breakdown or destruction of the insulation layer and the like .

On the other hand, according to FIG. 6B, interference fringes are generated which differ from the interference fringes according to FIG. 5B. More specifically, zones appear alternately in which the incident laser light and the reflected laser light intensify and weaken with respect to their energies, these zones extending in a direction perpendicular to the thickness direction of the semiconductor device according to FIG. 6A, ie in the lateral direction according to FIG . 6A. At the point or position of the thin-film resistor 3 , the zones in which the laser energy is amplified by the mutual influencing of the laser light are consequently generated in this case. As a result, fine adjustment of the thin film resistor 3 can be performed reliably.

Accordingly, contact of the semiconductor device shown in FIG. 5A and 5B with the conventional structure falls on in which layer depending on the thickness of the insulation 2, which is located immediately below the thin film resistor 3, a fine adjustment performed not who the can or this fine adjustment can be performed since zones in which the laser energy is amplified by the mutual influence of the laser light and zones in which the laser light is weakened alternate in the thickness direction (designated as direction A in FIG. 1) of the semiconductor device. In the semiconductor device according to this first embodiment, however, due to the cone sections 4 a shown in FIG. 1, which are formed at the interface between the semiconductor substrate 1 and the insulation layer 2 , not only in the thickness direction of the semiconductor device, but also in its lateral direction Direction, which extends perpendicular to the thickness direction, creates zones in which the laser energy is amplified and weakened by the mutual influence of the incident laser light and the reflected laser light. Within the area in which the thin-film resistor 3 is formed, the zones with increased laser energy therefore necessarily exist, which is why fine adjustment can be carried out in a reliable manner.

Next, 7 is a sectional view in Fig. Darge provides showing an image of a cross-sectional view of the semiconducting tervorrichtung as electron microscope of an electronic Mi is received by the transmission type (TEM) after a fine adjustment was made on thin film resistor 3 by.

According to Fig. 7, the fine adjustment of the Dünnschichtwi derstands was performed using a laser energy of about 0.2 microjoules 3, which represents a minimum energy or about one minimum energy for implementing the equalization on the thin film resistor Feinab 3. The areas designated by M in the figure each show areas in which the thin-film resistor 3 has melted. This figure shows that the thin film resistor 3 is actually melted in the lateral direction at certain intervals. It is assumed that the laser energy according to FIG. 6B is amplified in the areas denoted by M in FIG. 7, which is why the thin-film resistor 3 has melted.

Next, 8 is a sectional view in Fig. Darge provides showing an image of the cross-sectional view of the semiconducting tervorrichtung as electron microscope of an electronic scanning type Mi (SEM) is added. According to this embodiment, the level difference section 4 is produced by forming the LOCOS oxide layer 2 L. In FIG. 8, the cone portion 4 is a curvilinear configured, wherein a connecting portion 4 d, which the conical portion 4a having a lower portion 4b of the level-Differenzab section 4 connects, as well as smooth and curvilinear ausgebil det. The lower portion 4 b is also curved such that it merges smoothly into the connecting portion 4 d. This means that a (formed by the cone section 4 a, the lower section 4 b and the connecting section 4 d) recess section is formed by the LOCOS oxide layer 2 L such that it has a curved shape. A connecting portion 4 e, c of the Ke gel section 4 a with an upper portion 4 of the level-difference portion connects 4, is as smooth and curvilinear formed.

It is believed that the distribution of energy Laserener, as shown in Fig. 6B, as well as from the Ke gel section 4 a, 4 b and lower portion of the upper portion 4 c of the level-difference portion 4 arises. According to Fig. 8, moreover, the passed through the thin film resistor 3 at the laser light cone portion 4 a Reflectors advantage which is formed curvilinearly in the directions different from each other piece by piece accordingly their reflecting positions. Hence, it is believed that such reflection makes a further contribution to maintaining the distribution of laser energy. In the same way, it is assumed that the connecting section 4 d between the conical section 4 a and the lower section 4 b or the connecting section 4 e between the conical section 4 a and the upper section 4 c also contributes to maintaining the distribution of the laser energy. In other words, the distribution of the laser energy is obtained through the recessed section, which results from the curved shape of the LOCOS oxide layer 2 L.

As described above, in the half lead device according to the first embodiment of In state of interference or the state of mutual leg flow between the incident laser light and the right reflected laser light changed so that a fine equal to the thin film resistance is enabled, and not a reflected beam of light from a laser at the Interface between the insulation layer and the half conductor substrate removed as in the prior art, son by using the reflected light from a laser the interference state changed at this interface.

Accordingly, since the reflected laser light does not need to be eliminated as in the prior art, there is consequently no need to control or adjust the height (Ts in Fig. 1) of the Pe gel differential portion 4 highly precisely and very sharply in order to generate the to prevent reflected laser light. According to this first embodiment, it is sufficient to vary or change the state of the interference between the incident laser light and the reflected laser light that is reflected at the interface by means of the cone sections 4 a that are at the interface between the insulation layer and the Semiconductor substrate are formed.

Second embodiment

A second exemplary embodiment is described below, in which a laser fine adjustment is carried out with respect to a semiconductor device which uses a so-called “SOI substrate (silicon on insulator)” as the semiconductor substrate 11 , as is shown, for example, in FIGS. 9a and 9b, in which an oxide layer (SiO₂ layer 11 b) is formed.

In the event that the semiconductor substrate 11 is used according to FIG. 9A, in performing the fine adjustment is light interference or interference between the incident laser light and the reflected laser that of the overlying interfaces between a SiO₂ layer 11b and an Si layer 11 c is reflected (where the surface orientation corresponds to a (100) plane), and the underlying interfaces between the SiO₂ layer 11 b and a semiconductor substrate 11 a problematic.

The Fig. 9A shows the conventional Halbleitervorrich tung, wherein the surface of the semiconductor substrate 11 flat or planar. FIG. 9B shows the semiconductor device according to the second exemplary embodiment, the surface of the semiconductor substrate 11 having a level difference section 4 formed therein. It should be noted that a detailed structure of an insulation layer 2 , an insulation layer 6 and a protective layer 7 in FIGS. 9A and 9B has the same structure as the respective layers according to FIGS . 3A and 3B. The thickness of the SiO₂ layer 11 b within the semiconductor substrate 11 is set to 0.9 μm. A YAG laser with a wavelength of 1.06 μm (as manufactured by the Teradyue Company) is used as the laser for carrying out the fine adjustment.

The experiment was carried out using the same method as shown in Fig. 2, wherein a check of the laser output power (laser energy per pulse) was carried out, in which a fine adjustment of the thin film resistor 3 was made possible if the thickness of the above the SiO₂ layer 11 b lying Si layer 11 c varied in the semiconductor substrate 11 and has been changed. The test results are shown in FIG. 10.

In FIG. 10, the mark denotes the measured values obtained with respect to the conventional semiconductor device shown in FIG. 9A, while the mark represents the measured values obtained with respect to the semiconductor device according to the second embodiment, as shown in FIG. 9B .

As is apparent from FIG. 10, in the conventional semiconductor device in which the surface of the semiconductor substrate 11 is flat, the fine adjustment energy is also changed greatly when the thickness of the Si layer 11 c changes. On the other hand, in the semiconductor device according to the second embodiment, the fine balance energy is stable at about 0.09 µJ even if the thickness of the Si layer 11 c is changed.

In addition to the reflection of the laser light at the Ke gelabschnitten 4 a, the laser light when passing through the tapered portions 4 a is refracted in the second embodiment, wherein the by the taper portions 4a which has passed the laser light according to its change of direction to the radiation direction of the laser, the interface between the Si -Layer 11 c and the SiO₂ layer 11 b reached with different angles that differ from the angle of the radiation direction of the laser. For this reason, the laser light reaching the interface is also reflected in a direction that differs from the incident direction of the laser light, this reflected laser light being refracted again as it passes through the cone sections 4 a. Accordingly, the mutually influenced light, which is composed of the incident light rays and the reflected light rays, even in comparison to the case of the semiconductor substrate 1 shown in FIG. 3B by a larger number of reflected laser beams that propagate in different directions and intermingle, more complicated or more complicated. Consequently, one can also carry out an excellent fine adjustment in the same way as in the second embodiment described in the second embodiment.

Third embodiment

Next, as a third embodiment, the relationship between the level difference section 4 and the radiation direction of a laser will be described with reference to FIGS. 1 to 11.

Fig. 11 shows the level difference section 4 with the cone sections 4 a of FIG. 1, which is formed under the thin film resistor 3 and is arranged in strips in parallel to a respective straight line connecting the Al electrodes 5 a and 5 b. The level difference section 4 is designed such that its cross section when cutting the figure in the direction B corresponds to the structure of the pe gel difference section 4 according to FIG. 1. Further, the dotted areas in accordance with 11 denote Fig. Mas a kenmuster a nitride layer when the level-Differenzab section 4 by means of a LOCOS oxidation method of forming ge is the det USAGE the nitride layer as a mask. Accordingly, the cone portions 4 a, which are formed by so-called "bird's beaks", which are formed at the end portions of the LOCOS oxide layers, are formed at the borders between the dashed areas and the non-dashed areas.

If a laser scan is produced with respect to the semiconductor device in the direction A parallel to the strips and in the direction B perpendicular to the strips, the same test can be carried out as the test described with reference to FIGS . 3 and 4 has been. That is, a check of the fine adjustment energy takes place while the thicknesses of the BPSG layer 2 a have been changed. The test results are shown in FIG. 4.

In Fig. 4, the mark ○ denotes the fine adjustment energy when a laser scan in the direction A follows, while the mark ⚫ represents the fine adjustment energy for a laser scan in the direction B.

From Fig. 4 it follows that a laser scan in the direction B causes a large change in the fine adjustment energy corresponding to the thickness of the BPSG layer 2 a, whether the fine adjustment energy regardless of the thickness of the BPSG in a laser scan in the direction A Layer 2 a remains stable. Consequently, it follows that with a laser scanning and radiation with respect to the strip-shaped cone sections 4 a parallel to the direction in which the strips extend, an excellent fine adjustment can be carried out. On the other hand, if a laser scanning and irradiation with respect to the stripe-shaped cone sections 4 a in the direction B perpendicular to the direction A, in which the stripes extend, then the fine adjustment energy unfavorably changes according to the thickness of the insulation layer 2 , which is immediately below of the thin film resistor 3 is located. In comparison to the conventional case, without the level difference section 4 , which is indicated in FIG. 4 by the mark ∎, this deflection and radiation enables the fine adjustment energy to be suppressed to a lower value. This means that, according to FIG. 4, a fine energy of 0.8 mW or above can occur in the conventional semiconductor device, in which the protective layer is destroyed in accordance with the thickness of the BPSG layer 2 a, whereas in the case of a laser scan, the voltage is perpendicular to the stripes do not exceed the value of 0.8 mW of the fine adjustment energy and so a fine adjustment can be carried out.

In this case, the so-called "L-letter cut" method is sometimes used in the fine adjustment of the thin-film resistor 3 , in which the fine adjustment is carried out not only by laser scanning in one direction, but also by changing the scanning direction of a laser is carried out in a direction perpendicular thereto. In the event that this "L-letter cut" fine adjustment is carried out, there is a possibility that the fine adjustment cannot be carried out with the stabilized fine adjustment energy described above if the thickness of the insulation layer 2 located below the thin-film resistor 3 changes If the fine adjustment is carried out in a direction perpendicular to the strips of the level difference section 4 in the semiconductor device, in which the level difference section 4 is strip-shaped and the thin-film resistor 3 is formed above it.

The inventors of the present invention have carried out related experiments. Consequently Festge could provide be that a stable fine adjustment can be performed when the lying at the interface between the insulating layer and the semiconductor substrate 1 Pe gel-difference portion 4 is formed in accordance with a mesh pattern, wherein the lower portions 4b and the upper portions 4 c , which are connected to each other via the cone sections 4 a, appear alternately in a plan view.

An example of this pattern is shown in Fig. 12 Darge. In the pattern shown in FIG. 12, the dashed areas denote a mask pattern of a nitride layer, which was used in a LOCOS oxidation process and essentially corresponds to the upper sections 4 c of the level difference section 4 . The structure of the level difference portion 4 , which was formed using such a mask pattern, is shown on the sides of the mask pattern in the form of sectional views along directions A and B in FIG. 12.

The experimental results, which give the fine adjustment energy required to perform fine adjustment of the thin film resistor 3 of the semiconductor device, are shown in FIG. 13, wherein the insulation layer 2 above the level difference section 4 is formed from below Use of the mask pattern was formed according to FIG. 12, wherein the thin film resistor 3 was also formed above. It should be noted that the dimensions of a respective dashed area according to FIG. 12 are dimensioned such that the long side is 2 μm and the short side is 1 μm, while the irradiating laser is a YLF laser with a light spot size of 10 μm . In addition, the laser scanning took place in the direction of the arrow shown in FIG. 12.

As is apparent from Fig. 13 and Fig. 4, ver changes in the semiconductor device with the stripe-shaped level difference section 4 and in the semiconductor device with the mesh-shaped level difference section 4, the fine adjustment energy in the semiconductor device with the mesh-shaped Level difference section 4 something if the scanning direction of the laser runs parallel to the strips of the level difference section 4 . If, however, the scanning direction of the laser is perpendicular to the strips of the level difference section 4 , the result is that the change in the fine adjustment energy with respect to the semiconductor device with the mesh-shaped level difference section 4 can be suppressed.

Accordingly, in the semiconductor device having the thin film resistor 3 to which the "L-letter cut" fine adjustment must be applied, due to the level difference portion 4 , the cone portions of which are arranged in a mesh shape as shown in FIG. 12, stable fine adjustment can be performed. which is not influenced by the thickness of the insulation layer 2 located below the thin film resistor 3 .

Fourth embodiment

Next, as a fourth embodiment, an example of a manufacturing method for manufacturing the above-described semiconductor device having the level difference portion 4 and the thin film resistor 3 will be described with reference to FIGS. 14 and 15.

It should be noted that the corresponding construction subareas using known PN transitions electrically from can be isolated and separated from each other while in the respective semiconductor device described here Component areas or element areas using insulating material were electrically isolated from each other.

As shown in Fig. 14A, a semiconductor substrate 11 is first prepared. As for example in JP No. 6-196550, this semiconductor substrate 11 is bonded with a P-single-crystalline Si substrate 11 a with a silicon oxide layer 11 b formed thereon and an n-single-crystalline Si substrate 11 c at a temperature of approximately 1100 ° C. after carrying out the previously described pretreatments. Subsequently, the single-crystalline Si substrate 11 c is ground to a desired thickness and grooves 11 d referred to therein as "trenches" are formed using a dry etching method or the like. Furthermore, oxide layers 20 are formed on the side surfaces of a respective groove and polysilicon 30 or the like is introduced into the grooves. With the method described above, the semiconductor substrate 11 is completed.

Consequently, the adjoining components or elements are Ele by the oxide layers 11 b and the trenches electrically isolated from each other.

Next, as shown in FIG. 14B, an antioxidant mask 12 is formed on the surface of the semiconductor substrate 11 . This antioxidant mask 12 can be formed by depositing a nitride layer (SiN) using a vapor phase epitaxy method, such as CVD, for example, and subsequent patterning using a photolithographic method.

Subsequently, using an oxidation process called “LOCOS oxidation”, selective oxide layers 13 are formed over the trenches and the areas where the level difference section 4 is to be formed. It should be noted that these selective oxide layers 13 are formed on the surface of the semiconductor substrate 11 for the purpose of isolating the contiguous elements or semiconductor regions.

The LOCOS oxidation is carried out, for example, by introducing the semiconductor substrate 11 with the anti-oxidation masks 12 thereon into a thermal oxidation furnace (not shown), which is then carried out in an oxygen (O₂) and hydrogen (H₂) atmosphere at a temperature of 1000 ° C or the like, thermal oxidation is carried out for about 5 to 6 hours or the like.

At the time of this LOCOS oxidation, the oxidation proceeds from the end sections of the antioxidant masks 12 , the so-called "bird's beak" regions being cut off at the end sections of the selective oxide layers 13 , which means that the cone sections 4 a shown in FIG. 1 a Level difference section 4 can be designed by these bird beaks. It should be noted that the pattern of the selective oxide layers 13 for forming the level difference portion 4 is the same pattern as that shown in FIGS. 11 or 12. Further, since the Ke gel sections 4a are formed by thermal oxidation, the surface of the tapered portions 4 is formed as a smooth surface that is suitable for the reflection of a laser light that has passed through the thin film resistor 3 toward. This means that due to the design of the surface of the semiconductor substrate 1 as a mirror surface, the same state as for this mirror surface also results for the upper surface of the cone section 4 a.

Next, a semiconductor device such as a transistor is formed in the element area of the semiconductor substrate 11 , which is electrically isolated from the other area by the trench. FIG. 14 c shows an example in which a biopolar transistor is formed, which is composed of an N emitter 14 , a P base 15 and an N collector 16 . Subsequently, as shown in FIG. 15A, the insulation layer 2 is deposited using a BPSG layer, an SOG layer or the like, thereby leveling the surface of the substrate. This insulation layer 2 can consist of a multilayer structure, which in example has the same structure as the insulation layer 2 according to FIG. 3.

Next, as shown in FIG. 15B, the thin film resistor 3 is formed on the insulation film 2 above the area with the level difference section 4 . This thin-film resistor 3 is formed, for example, by inserting the semiconductor device according to FIG. 15A into a sputtering device in which a CrSi material used as target material on the insulation layer 2 in an atmosphere of a protective gas, such as Ar gas (Argon + Nitrogen (N₂) gas), deposited by means of a sputtering process and the CrSi material is then brought into a desired pattern. It should be noted that if a nitrogen gas is mixed into the protective gas atmosphere during the sputtering process, nitrogen is taken up in the thin-film resistor 3 .

Next, as shown in Fig. 15C, contact holes are formed in the insulation layer 2 , and then the electrode wiring material such as Al is deposited in the contact holes and brought to the desired pattern 5 a to 5 d. It should be noted that in FIG. 15C the thin film resistor 3 is connected to the collector 16 by means of the wiring pattern 5 a.

Next, the insulation layer 6 , such as an oxide layer, and the protective layer 7 , such as a nitride layer, are formed, which serve to protect the semiconductor device. The insulation layer 6 and the protective layer 7 can have the same structure as, for example, the TEOS layer 6 a according to FIG. 3 and the protective layer 7 shown in FIG. 1.

With regard to the semiconductor device constructed as described above, laser fine adjustment of the thin film resistor 3 is carried out in such a way that its resistance value is set. According to the fourth embodiment described above, the Kegelab sections 4 a can be formed without a subsequent increase in the number of manufacturing steps, since the formation of the level difference section 4 takes place simultaneously with the formation of the selective oxidation layer 13 .

It should be noted that other processes can be used as manufacturing processes for the cone sections 4 a instead of the selective oxidation process, such as, for example, isotropic etching using a wet etching process, dry etching using CF₄ gas or CCL₄ gas, etc. For the In case that the Kegelab sections 4 a are formed by means of a dry etching process, however, the etched surface must be thermally oxidized after performing the dry etching process, whereby its surface is smoothed.

It should be noted that an anisotropic etching process can also be used. This anisotropic etching process using an etching solution such as a potassium hydroxide (KOH) solution causes a (111) plane to appear because the Si substrate usually has a surface whose surface orientation is the same as in the fourth embodiment which is (100) level. Since the angle defined between the (100) plane and the (111) plane is almost 54 °, the angle α shown in FIG. 1 unsuitably receives the value of approximately 36 °.

The cone sections 4 a can also be formed by lightly pre-etching the surface of the silicon substrate and after forming the selective oxidation layer. In this case, a dry etching process can also be used.

The invention described above discloses one Level difference section with a thickness direction of a semiconductor substrate inclined Ke Gel section, which on a surface of the semiconductor is formed substrate. An insulation layer will formed above and leveled its surface, whereby then a thin film resistor is formed. Thereupon, regarding the thin film resistance Laser fine adjustment carried out. As a result, a Zu stood for the mutual influence between the ideas laser light and at the interface between the  Semiconductor substrate and the insulation layer reflected Laser light varies, creating a zone, where the laser energy increases, and a zone where the laser energy is weakened is made possible. The Laser tuning is preferably enhanced by the Laser energy performed.

Claims (19)

1. Semiconductor device with:
a semiconductor substrate ( 1 ; 11 );
an oblique-angled region ( 4 a), which is formed on a surface of the semiconductor substrate ( 1 ; 11 ) and is configured obliquely angled with respect to a thickness direction of the semiconductor substrate;
an insulation layer ( 2 ) which is formed on the surface of the semiconductor substrate ( 1 ; 11 ), which has the oblique-angled region ( 4 a); and
a thin-film resistor ( 3 ), which lies above the insulation layer ( 2 ) and is formed above the oblique-angled area ( 4 a),
whereby the oblique-angled area ( 4 a) for fine adjustment of the thin-film resistor ( 3 ) reflects a laser light that has passed through the thin-film resistor ( 3 ), so that the laser light reflected from the obliquely angled area ( 4 a) stood the thin-film resistor ( 3 ) reached. 2. Semiconductor device according to claim 1, characterized in that the oblique-angled region ( 4 a) is set to an angle which is greater than 45 ° and less than 90 ° with respect to the thickness direction of the semiconductor substrate ( 1 ; 11 ). 3. Semiconductor device according to claim 1 or 2, characterized in that the oblique-angled area ( 4 a) is curvilinear. 4. Semiconductor device according to one of the claims 1 to 3, characterized in that the oblique-angled area ( 4 a) between an upper section ( 4 c) and a lower section ( 4 b) of a level-Differenzab section ( 4 ) is such that the level difference section ( 4 ) from the oblique-angled area ( 4 a) is formed. 5. Semiconductor device according to claim 4, characterized in that at least one connecting section ( 4 e) between the oblique-angled area ( 4 a) and the upper section ( 4 c) of the level difference section ( 4 ) and a connecting section ( 4 d) between the obliquely angled area ( 4 a) and the lower section ( 4 b) of the level difference section ( 4 ) is shaped such that it is curved and smoothly shaped. 6. Semiconductor device according to one of claims 1 to 5, characterized in that a plurality of oblique-angled areas ( 4 a) is formed within a light spot size of the laser beam which is radiated onto the thin film resistor ( 3 ). 7. Semiconductor device according to one of the claims 1 to 6, characterized in that the oblique-angled region ( 4 a) is formed by a selective oxidation process in which oxidation is carried out using an antioxidant mask ( 12 ). 8. Semiconductor device according to one of the claims 1 to 7, characterized in that the oblique-angled region ( 4 a) is arranged in a plan view in the form of strips. 9. Semiconductor device according to one of claims 1 to 8, characterized in that the oblique-angled region ( 4 a) between an upper section ( 4 d) and a lower section ( 4 b) of a level-Differenzab section ( 4 ) is such that the level difference section ( 4 ) through the oblique-angled area ( 4 a) is formed and the upper section ( 4 c) and the lower section ( 4 b) of the level difference section ( 4 ) in a plan view alternately in the form of Stitches are arranged. 10. The semiconductor device according to any one of the claims 1 to 9, characterized in that the semiconductor to the substrate (11) made of a first semiconductor layer (11 a), an insulation layer (11 b), which is conductor layer on the first half is formed, and a second Semiconductor layer ( 11 c), which is formed on the insulation layer ( 11 b), the oblique-angled region ( 4 a) being formed on a surface of the second semiconductor layer ( 11 c). 11. Semiconductor device with:
a semiconductor substrate ( 1 ; 11 );
an insulation layer ( 2 ) which is formed on the semiconductor substrate ( 1 ; 11 );
a thin film resistor ( 3 ) formed on the insulation layer ( 2 ); and
a level difference section ( 4 ), the section of which is trapezoidal in structure, and which is formed at an interface between the semiconductor substrate ( 1 ; 11 ) and the insulation layer ( 2 ), which is located below the thin-film resistor ( 3 ),
wherein an oblique-angled side ( 4 a) of the trapezoidal level difference section ( 4 ) for fine adjustment of the thin-film resistor ( 3 ) reflects a laser light which has passed through the thin-film resistor ( 3 ) so that the laser light reflected from the obliquely angled side Thin film resistance ( 3 ) reached. 12. A method of manufacturing a semiconductor device comprising the steps of:
Forming an oblique-angled region ( 4 a) on a surface of a semiconductor substrate ( 1 ; 11 ), the oblique-angled region having an oblique angle with respect to the thickness direction of the semiconductor substrate;
Forming an insulation layer ( 2 ) on the semiconductor substrate ( 1 ; 11 );
Forming a thin film resistor ( 3 ) at a location that is on the insulation layer ( 2 ) and above the oblique region ( 4 a); and
Irradiating a laser light on the thin film resistor ( 3 ), whereby a resistance value of the thin film resistor ( 3 ) is set,
wherein the oblique-angled area ( 4 a) is designed such that during the step of irradiation by the laser, the laser light passing through the thin-film resistor ( 3 ) is reflected from the oblique-angled area ( 4 a) and reaches the thin-film resistor ( 3 ). 13. A method for producing a semiconductor device according to claim 12, characterized in that the oblique-angled region ( 4 a) is designed with an angle that is greater than 45 ° and less than 90 ° in relation to the thickness direction of the semiconductor substrate. 14. A method for producing a semiconductor device according to one of the claims 12 or 13, characterized in that the oblique-angled region ( 4 a) is formed with a curved line. 15. A method for producing a semiconductor device according to one of the claims 12 to 14, characterized in that the step of forming the obliquely angled region ( 4 a) is a step of forming a level difference section ( 4 ) on the surface of the semiconductor substrate ( 1 ; 11 ) and after performing this step, an upper section ( 4 c) and a lower section ( 4 b) of the level difference section ( 4 ) are formed and the upper section ( 4 c) and the lower section ( 4 b) is connected by the oblique area ( 4 a). 16. A method for producing a semiconductor device according to one of the claims 12 to 15, characterized in that at least one connecting section ( 4 e) between the oblique-angled area ( 4 a) and the upper section ( 4 c) of the level difference section ( 4 ) and a connecting portion ( 4 d) between the oblique-angled area ( 4 a) and the lower portion ( 4 b) of the level difference portion ( 4 ) in the step of forming the oblique-angled area is formed so that it is curvilinear and smooth in shape having. 17. A method for producing a semiconductor device according to one of claims 12 or 17, characterized in that the step of forming the obliquely angled region ( 4 a) is carried out by a selective oxidation process which is carried out on the surface of the semiconductor substrate ( 1 ; 11 ) Forms antioxidant masks ( 12 ) and selectively oxidizes the surface of the semiconductor substrate ( 1 ; 11 ), which is not covered by the antioxidant mask ( 12 ). 18. A method of manufacturing a semiconductor device according to any one of claims 12 to 17, characterized in that the step of forming the oblique-angled area ( 4 a) forms the oblique-angled area visually a plan view in the form of strips and the step of irradiating with the laser, the laser light is emitted by scanning parallel to the strips. 19. A method for producing a semiconductor device according to one of claims 12 to 18, characterized in that the oblique-angled region ( 4 a) is formed as a result of the formation of a level difference section ( 4 ) on the surface of the semiconductor substrate ( 1 ; 11 ) , and an upper portion ( 4 c) and a lower portion ( 4 b) of the level difference portion ( 4 ) with respect to a plan view are alternately arranged in the form of stitches.