US20170117151A1

US20170117151A1 - Integrated circuit and process thereof

Info

Publication number: US20170117151A1
Application number: US14/945,443
Authority: US
Inventors: En-Chiuan Liou; Chih-Wei Yang; Kuei-Chun Hung
Original assignee: United Microelectronics Corp
Current assignee: United Microelectronics Corp
Priority date: 2015-10-22
Filing date: 2015-11-19
Publication date: 2017-04-27
Also published as: US11482517B2; TWI704647B; US20180261589A1; TW201715649A

Abstract

An integrated circuit process includes the following steps. A substrate including a first area and a second area is provided. A plurality of line patterns cover the substrate of the first area, and a sacrificial line pattern covers the substrate of the second area, wherein these line patterns separate from and are orthogonal to the sacrificial line pattern. The present invention also provides an integrated circuit formed by said process. A substrate includes a first area and a second area; a plurality of line patterns cover the substrate of the first area; a slot pattern is in the substrate of the second area, wherein these line patterns are orthogonal to the slot pattern. Additionally, a plurality of line patterns cover the substrate; a sacrificial line pattern is at ends of the line patterns, wherein these line patterns separate from and are orthogonal to the sacrificial line pattern.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to an integrated circuit and a process thereof, and more specifically to an integrated circuit and a process thereof that applies orthogonal sacrificial line patterns.
2. Description of the Prior Art
For containing as many semiconductor components in a chip area as possible and for reducing process costs, various semiconductor methods are presented to shrink components' sizes and increase components' density in a chip. In one aspect, operating speed can be fastened as components' sizes shrink; in another aspect, energy costs while operating can be reduced as components' sizes shrink. Thus, it becomes an important issue in current industry to shrink integrated circuit layouts. In integrated circuit processes, field effect transistors are extremely important electronic devices. The processing steps of the field effect transistors are improved to get small volume and high quality transistors as components' sizes shrink.
Ideal critical dimensions (CD) of photoresist layers used for forming integrated circuit layouts including transistors are hard to maintain as components' sizes shrink due to many factors such as the non-uniformity while coating the photoresist layers, pattern collapse and decreasing critical dimensions (CD). Thus, anew solution for overcoming said problems is required in the industry.

SUMMARY OF THE INVENTION

The present invention provides an integrated circuit and a process thereof, that forms sacrificial line patterns orthogonal to and separate from ends of line patterns to improve photoresist uniformity, enhance density of line patterns and end profiles of the line patterns.
The present invention provides an integrated circuit process including the following steps. A substrate including a first area and a second area is provided. A plurality of line patterns are formed to cover the substrate of the first area, and a sacrificial line pattern is formed to cover the substrate of the second area, wherein the line patterns separate from the sacrificial line pattern, and the line patterns are orthogonal to the sacrificial line pattern.
The present invention provides an integrated circuit including a substrate, a plurality of line patterns and a slot pattern. The substrate includes a first area and a second area. The line patterns cover the substrate of the first area. The slot pattern is located in the substrate of the second area, wherein the line patterns are orthogonal to the slot pattern.
The present invention provides an integrated circuit including a substrate, a plurality of line patterns and a sacrificial line pattern. The line patterns cover the substrate. The sacrificial line pattern is located at ends of the line patterns, wherein the line patterns are orthogonal to and separate from the sacrificial line pattern.
According to the above, the present invention provides an integrated circuit and a process thereof, which forms a plurality of line patterns covering a substrate of a first area and a sacrificial line pattern covering a substrate of a second area. The sacrificial line pattern is orthogonal to and separates from ends of the line patterns. In this way, the density of the line patterns approaching processing limitation is increased. Liquid coating materials such as photoresists are prevented from over-flowing into other areas, thereby enhancing photoresist uniformity and improving profiles of ends of the line patterns.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a layout of an integrated circuit process according to one embodiment of the present invention.

FIG. 2 schematically depicts a layout of an integrated circuit process according to one embodiment of the present invention.

FIG. 3 schematically depicts a layout of an integrated circuit process according to one embodiment of the present invention.

FIG. 4 schematically depicts a layout of an integrated circuit process according to another embodiment of the present invention.

FIG. 5 schematically depicts a layout of an integrated circuit process according to another embodiment of the present invention.

FIG. 6 schematically depicts a cross-sectional view of an integrated circuit process according to an embodiment of the present invention.

FIG. 7 schematically depicts a cross-sectional view of an integrated circuit process according to an embodiment of the present invention.

FIG. 8 schematically depicts a cross-sectional view of an integrated circuit process according to an embodiment of the present invention.

FIG. 9 schematically depicts a cross-sectional view of an integrated circuit process according to an embodiment of the present invention.

DETAILED DESCRIPTION

FIGS. 1-3 schematically depict layouts of an integrated circuit process according to one embodiment of the present invention. As shown in FIG. 1, a substrate 110 is provided. The substrate 110 may be a semiconductor substrate such as a silicon substrate, a silicon containing substrate, a III-V group-on-silicon (such as GaN-on-silicon) substrate, a graphene-on-silicon substrate, a silicon-on-insulator (SOI) substrate or a substrate containing epitaxial layers. The substrate 110 may include a first area A and a second area B. In this embodiment, the first area A is a dense area while the second area B is an isolated area, thereby the dense area being right next to the isolated area. A plurality of line patterns 120 cover the substrate 110 of the first area A. Two sacrificial line patterns 130 cover the substrate 110 of the second area B. It is emphasized that the line patterns 120 of the present invention must be orthogonal to and separate from the sacrificial line patterns 130. That is, all of the line patterns 120 have one same direction. As the line patterns 120 are all along x-direction, the sacrificial line patterns 130 are along y-direction. Six line patterns 120 and two sacrificial line patterns 130 are depicted in this embodiment, but the number of the line patterns 120 and the sacrificial line patterns 130 is not limited thereto. A length L1 of the sacrificial line patterns 130 preferably correspond to and contain six of the line patterns 120.
The line patterns 120 and the sacrificial line patterns 130 are formed by one same process. For example, single material layer or multi-material layers may cover the substrate 110, and then the material layer or the material layers may be patterned to form the line patterns 120 and the sacrificial line patterns 130 on the substrate 110 at the same time. In this way, the line patterns 120 and the sacrificial line patterns 130 all have common materials, but it is not limited thereto.
Due to process limitations, current lithography and etching processes have a critical dimension (CD) at one direction larger than a critical dimension (CD) at another direction. For instance, due to process limitations, a current lithography and etching process may have a critical dimension (CD) at x-direction less than a critical dimension (CD) at y-direction. Thereby, the line patterns 120 may be along x-direction while the sacrificial line patterns 130 may be along y-direction to increases the density of the line patterns 120. The sacrificial line patterns 130 are located in the isolated area, and can be removed selectively in later processes, thereby the density of sacrificial line patterns 130 less than the density of the line patterns 120 is allowed. Therefore, the sacrificial line patterns 130 have the minimum size larger than the minimum size of the line patterns 120, but it is not limited thereto. In one case, a width w1 of one single line patterns 120 is a critical dimension under exposure limitation, and a width w2 of one single sacrificial line patterns 130 is larger than the critical dimension w1 under exposure limitation.
As shown in FIG. 2, a pattern cutting process P1 is performed to remove end parts 120 e of the line patterns 120 and the sacrificial line patterns 130. In this embodiment, the sacrificial line patterns 130 are removed completely. In other embodiments, only parts of the sacrificial line patterns 130 are removed. For example, only one of the two sacrificial line patterns 130 is removed. The dashed-line in FIG. 2 is a cutting range of the pattern cutting process P1. The cutting range of the pattern cutting process P1 contains and is larger than the end parts 120 e of the line patterns 120 and the sacrificial line patterns 130 to ensure removing the end parts 120 e and the sacrificial line patterns 130 completely. As shown in FIG. 3, slot patterns 120 a/130 a (depicted as slashed-line areas) are formed in the substrate 110 surrounding the edges of the end parts 120 e of the line patterns 120 and the sacrificial line patterns 130 due to etching twice. This means one etching process is performed to pattern the line patterns 120 and the sacrificial line patterns 130, and then the second etching process is performed as the pattern cutting process P1. Therefore, the slot patterns 120 a/130 a are formed in the substrate 110 surrounding the edges of the end parts 120 e of the line patterns 120 and the sacrificial line patterns 130 as the end parts 120 e of the line patterns 120 and the sacrificial line patterns 130 are removed.
In this embodiment, due to the sacrificial line patterns 130 being in the isolated area, the slot patterns 130 a are also in the isolated area; due to the sacrificial line patterns 130 having the minimum size larger than the minimum size of the line patterns 120, the slot patterns 130 a having the minimum size larger than the minimum size of the line patterns 120; due to the line patterns 120 needing to be orthogonal to and separating from the sacrificial line patterns 130, the line patterns 120 b are all orthogonal to and separate from the slot patterns 130 a, but it is not limited thereto. In other embodiments, the cutting range of the pattern cutting process P1 may be the whole second area B extending to the end parts 120 e, depending upon practical requirements. In addition, the cutting range of the pattern cutting process P1 may be a cutting range including at least one of the sacrificial line patterns 130.
Furthermore, FIGS. 1-3 depict six individual line patterns 120, but it is not limited thereto. The present invention may be applied to a sidewall image transfer (SIT) process, a self-aligned double patterning (SADP) process, or others. FIGS. 4-5 schematically depict layouts of an integrated circuit process according to another embodiment of the present invention. As shown in FIG. 4, two adjacent line patterns 222/223/224/225/226/227 are connected by connecting parts 222 a/223 a/224 a/225 a/226 a/227 a. That is, the line patterns 222/223 are connected by the connecting parts 222 a/223 a to constitute a closed pattern 220 a; the line patterns 224/225 are connected by the connecting parts 224 a/225 a to constitute a closed pattern 220 b; the line patterns 226/227 are connected by the connecting parts 226 a/227 a to constitute a closed pattern 220 c. As shown in FIG. 5, a pattern cutting process P2 is performed to remove end parts 222 e/223 e/224 e/225 e/226 e/227 e of the line patterns 222/223/224/225/226/227 and the sacrificial line patterns 230 completely and to remove the connecting parts 222 a/223 a/224 a/225 a/226 a/227 a completely. The cutting range of the pattern cutting process P2 is depicted as the dashed-lines of FIG. 5, but it is not limited thereto. A length L2 of the sacrificial line patterns 230 preferably corresponds to the three closed patterns 220 a/220 b/220 c at x-direction. In one case, a width w3 of the closed patterns 220 a/220 b/220 c is a critical dimension under exposure limitations (which may be a width of removed sacrificial patterns), and a width w4 of one single sacrificial line patterns 230 is larger than the critical dimension under exposure limitations, but it is not limited thereto.
According to the above, the line patterns 120/222/223/224/225/226/227 of the present invention may include gate patterns, fin patterns, spacer patterns or mask patterns, but it is not restricted thereto. The gate patterns may include polysilicon patterns or amorphous silicon patterns, and the mask patterns may include multilayer patterns, and the multilayer patterns may include nitride/oxide layer patterns or others, depending upon practical requirements.
FIGS. 6-9 schematically depict cross-sectional views of an integrated circuit process according to an embodiment of the present invention. FIGS. 6-9 are cross-sectional views along CC′ line of FIGS. 1-3. In this embodiment, the line patterns 120 are gate patterns, but it is not restricted thereto. Please refer to FIGS. 1-3 and FIGS. 6-9.
As shown in FIG. 6 along with FIG. 1, the substrate 110 may include an isolation structure 10 located in the second area B, meaning located in the substrate of the isolated area. The isolation structure 10 may be a shallow trench isolation (STI) structure, which may be formed by a shallow trench isolation (STI) process, but it is not limited thereto. A gate layer 120′ may blanketly cover the substrate 110, wherein the gate layer 120′ includes an electrode layer 122′ and a cap layer 124′ from bottom to top. In this embodiment, the electrode layer 122′ maybe a polysilicon layer or an amorphous silicon layer; the cap layer 124′ may be a dual layer composed of an oxide layer and a nitride layer from bottom to top, but it is not limited thereto.
A lithography and etching process maybe performed to pattern the electrode layer 122′ and the cap layer 124′ to form a plurality of line patterns 120 including an electrode layer 122 and a cap layer 124, and two sacrificial line patterns 130 including an electrode layer 132 and a cap layer 134 as well, as shown in FIG. 7 along with FIG. 1. In this embodiment, the line patterns 120 and the sacrificial line patterns 130 are formed simultaneously from the gate layer 120′ atone same process, thereby the line patterns 120 and the sacrificial line patterns 130 having common materials, but it is not limited thereto. The line patterns 120 must be orthogonal to and separate from the sacrificial line patterns 130. The sacrificial line patterns 130 have a minimum size larger than a minimum size of the line patterns 120.
As shown in FIGS. 8-9 along with FIGS. 2-3, a pattern cutting process P1 is performed to remove end parts 120 e of the line patterns 120 and the sacrificial line patterns 130. More precisely, as shown in FIG. 8, an optical dispersive layer (ODL) 20 and a silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30 may blanketly cover the line patterns 120, the sacrificial line patterns 130 and the substrate 110. In this embodiment, the optical dispersive layer (ODL) 20 and the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30 may be formed blanketly from bottom to top, but it is not limited thereto. Instead, the optical dispersive layer (ODL) 20 or/and the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30 may be formed selectively. A photoresist may be coated and patterned to form a patterned photoresist Q on the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30. It is noted, since the sacrificial line patterns 130 orthogonal to the line patterns 120 have a capability like retaining walls, over-flowing into the second area B (meaning the isolated area in this embodiment) of the optical dispersive layer (ODL) 20, the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30 and the patterned photoresist Q, which causes thickness non-uniformity and etching non-uniformity of the optical dispersive layer (ODL) 20, the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30 and the patterned photoresist Q, can be avoided. Thereby, profiles of ends of the line patterns 20 can be improved. Since the sacrificial line patterns 130 have a minimum size larger than a minimum size of the line patterns 120, the present invention can be applied to current lithography and etching processes such as off-axis illumination, which has a critical dimension (CD) at one direction larger than a critical dimension (CD) at another direction, hence increasing the density of the line patterns 120.
The end parts 120 e of the line patterns 120 and the sacrificial line patterns 130 may thus be removed by transferring patterns of the patterned photoresist Q, as shown in FIG. 9 along with FIG. 3. More precisely, the patterns of the patterned photoresist Q may be transferred into the optical dispersive layer (ODL) 20 and the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30, and then the patterns of the optical dispersive layer (ODL) and the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30 are transferred to remove the end parts 120 e of the line patterns 120 and the sacrificial line patterns 130. Therefore, line patterns 120 b including an electrode layer 122 b and a cap layer 124 b and an optical dispersive layer (ODL) 20′ and a silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30′ remain, but it is not limited thereto. Thereafter, the patterned photoresist Q, the optical dispersive layer (ODL) 20′ and the silicon-containing hard mask bottom anti-reflection coating (SHB) layer 30′ may be removed. It is noted, as the end parts 120 e of the line patterns 120 and the sacrificial line patterns 130 are removed, the edges of the end parts 120 e and the sacrificial line patterns 130 are etched twice. Therefore, slot patterns 120 a in the substrate 110 and slot pattern 130 a in the isolation structure 10 are formed at the edges of the end parts 120 e and the sacrificial line patterns 130.
Moreover, the line patterns 120 and the sacrificial line patterns 130 are in the bulk substrate 110 in this embodiment. In addition, the substrate 110 may include a plurality of fin structures in a silicon substrate, and an oxide structure between the fin structures, wherein the line patterns 120 are disposed across the fin structures and on the oxide structure, and the sacrificial line patterns 130 are disposed on the oxide structure, or slot patterns are disposed in the oxide structure, thereby a multi-gate field effect transistor can be formed, depending upon practical requirements.
To summarize, the present invention provides an integrated circuit and a process thereof, which forms a plurality of line patterns covering a substrate of a first area and at least a sacrificial line pattern covering a substrate of a second area. The sacrificial line pattern is orthogonal to and separates from ends of the line patterns. The sacrificial line pattern has a minimum size larger than a minimum size of the line patterns, thereby increasing the density of the line patterns.
A pattern cutting process is performed to remove end parts of the line patterns and the sacrificial line patterns at the same time, wherein the pattern cutting process may include forming and transferring the patterned photoresist and other coating materials.
Since the sacrificial line pattern is orthogonal to the line patterns, the uniformity of the photoresist can be enhanced, the profiles of ends of the line patterns can be improved. For instance, as the line patterns are in a dense area while the sacrificial line patterns are in an isolated area, the sacrificial line pattern orthogonal to the line patterns can prevent coating materials such as the photoresist from over-flowing into the isolated area, and thus degrading uniformity can be avoided.
Furthermore, after the pattern cutting process is performed, slot patterns may be formed in the substrate surrounding the end parts of the line patterns and the sacrificial line pattern, thereby constituting a specific structure of the present invention. The line patterns and the sacrificial line pattern can be formed by one same process from common material layers, thus the line patterns and the sacrificial line pattern may have common materials. The line patterns may be gate patterns, fin patterns, spacer patterns or mask patterns, depending upon practical requirements.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

1. An integrated circuit process, comprising:

providing a substrate comprising a first area and a second area; and

forming a plurality of line patterns covering the substrate of the first area, and a sacrificial line pattern covering the substrate of the second area, wherein the line patterns are separated from the sacrificial line pattern, the line patterns are orthogonal to the sacrificial line pattern, and the sacrificial line pattern has a minimum width larger than a minimum width of the line patterns.

2. The integrated circuit process according to claim 1, wherein the first area comprises a dense area, the second area comprises an isolated area, and the dense area is right next to the isolated area.

3. (canceled)

4. The integrated circuit process according to claim 1, wherein the line patterns and the sacrificial line pattern comprise common material.

5. The integrated circuit process according to claim 4, wherein the line patterns and the sacrificial line pattern are formed by one same process.

6. The integrated circuit process according to claim 1, further comprising:

performing a pattern cutting process to remove the sacrificial line pattern and end parts of the line patterns after the line patterns and the sacrificial line pattern are formed.

7. The integrated circuit process according to claim 6, wherein the step of performing the pattern cutting process comprises:

forming a patterned photoresist to cover the line patterns, the sacrificial line pattern and the substrate;

transferring the pattern of the patterned photoresist to remove the sacrificial line pattern and the end parts of the line patterns; and

removing the patterned photoresist.

8. The integrated circuit process according to claim 7, further comprising:

entirely covering an optical dispersive layer (ODL) or/and a silicon-containing hard mask bottom anti-reflection coating (SHB) layer on the line patterns, the sacrificial line pattern and the substrate before the patterned photoresist is formed.

9. The integrated circuit process according to claim 7, wherein the integrated circuit process comprises: entirely covering an optical dispersive layer (ODL) and a silicon-containing hard mask bottom anti-reflection coating (SHB) layer on the line patterns, the sacrificial line pattern and the substrate before the patterned photoresist is formed, and the step of performing the pattern cutting process comprises:

transferring the pattern of the patterned photoresist to the optical dispersive layer (ODL) and the silicon-containing hard mask bottom anti-reflection coating (SHB) layer; and

transferring the pattern of the optical dispersive layer (ODL) and the silicon-containing hard mask bottom anti-reflection coating (SHB) layer to remove the sacrificial line pattern and the end parts of the line patterns.

10. The integrated circuit process according to claim 1, wherein the line patterns comprise gate patterns, fin patterns, spacer patterns or mask patterns.

11. The integrated circuit process according to claim 10, wherein the line patterns are gate patterns comprising polysilicon patterns or amorphous silicon patterns.

12. The integrated circuit process according to claim 10, wherein the line patterns are mask patterns comprising nitride over oxide layer patterns.

13-20. (canceled)

21. An integrated circuit process, comprising:

providing a substrate comprising a first area and a second area; and

forming a plurality of line patterns covering the substrate of the first area, and a sacrificial line pattern being a rectangular line pattern covering the substrate of the second area, wherein the line patterns separate from the sacrificial line pattern, and the line patterns are orthogonal to the whole sacrificial line pattern.

22. An integrated circuit process, comprising:

providing a substrate comprising a first area and a second area; and

forming a plurality of line patterns along at x-direction covering the substrate of the first area, and a sacrificial line pattern along at y-direction covering the substrate of the second area, wherein the sacrificial line pattern exceeds from the line patterns at y-direction, the line patterns separate from the sacrificial line pattern, and the line patterns are orthogonal to the sacrificial line pattern.