US2753458A

US2753458A - Electron microscope

Info

Publication number: US2753458A
Application number: US446126A
Authority: US
Inventors: Kazato Kenji; Ito Kazuo
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-04-12
Filing date: 1954-07-27
Publication date: 1956-07-03
Anticipated expiration: 1973-07-03
Also published as: GB772621A; DE1039153B; FR1113365A; CH325279A

Description

y 1956 KENJI KAZATO ETAL 2,753,458

ELECTRON MICROSCOPE Filed July 27, 1954 INVENTORJ: hE/VJ/ hi4 ZA To /fAZUO I70 ATTOAAMFY ELECTRON MICROSCOPE Kenji Kazato, Musashino-shi, Tokyo, and Kazuo Ito, Nalranodru, Tokyo, Japan Application July 27, 1954, Serial No. 446,126

Claims priority, application Japan April 12, 1954 6 Claims. (Cl. 250 495) This invention relates to an electron microscope, and more particularly to an electron microscope in which changing conditions of a specimen which is continuously subjected to heating or gas reaction can be observed or photographed.

In a heretofore known electron microscope, if it is desired to observe how a specimen is changed when subjected to heating or chemical reaction of gas, such for example as oxidizing or deoxidizing gas, by which the specimen is affected, it is necessary that, first, the specimen is taken out of the vacuum to heat or effect a chemical reaction, next, the specimen thus treated is readjusted in the passage of the electron beam and thereafter the vacuuming operation is taken.

' This invention intends to remove the above troublesome handling and operation.

The chief object of this invention is to provide an electron microscope in which changing conditions of a specimen which has been held in the passage of the electron beam during heating or gas reaction treatment can be observed or photographed.

Another object of this invention is to provide an electron microscope which enables to observe changing conditions of the same region or the region adjacent thereto of a specimen being held in the same observation field.

Further object of this invention is to provide an electron microscopic arrangement in which a heating element of the specimen and a gas feeding device can easily be attached to a ready made electron microscope, if needed.

According to this invention, a heating element is entirely enclosed in a microscopic column and a specimen holder is combined with the heating element, a specimen being so attached thereto that it is held in the passage of the electron beam during the condition changing treatment. The heating element, as well as the specimen holder is associated with an adjusting means which can be operated out of the vacuum to set the specimen at any desired position. That is, the above arrangement is so made that continuous changing conditions of the specimen region laid in the same observation field can be investigated during heat treatment.

Heat shielding means are provided for preventing the objective pole pieces which are to be positioned near by the specimen from being excessively heated. For this purpose, it is preferable to use a cylinder which is transversely arranged with respect to the lens axis and into which the heatin" element and the specimen holder in tegrally and detachably fit through one end thereof, the upper and lower side walls of the cylinder forming little holes through which the electron beam can be passed. it is also preferable to provide an auxiliary heat shielding plate which is disposed out of the cylinder and has a little hole just large enough to pass the electron beam therelhrough, for aiding prevention of overheating to the objeclive pole pieces. This shielding plate plays also the part of preventing granules which will fly in all directions from the specimen in operation from choking the holes of the objective pole pieces. if the hole of the shielding plate nite States Patent Eatented July 3, 1956 2 has been clogged with the granules to prevent the advance of the electron beam, this shielding plate can be substituted by a new one.

There are also provided means for feeding desired gas on the specimen surface to which the electron beam impacts. The gas feeding means comprise a pipe inserted into the microscope from a gas source equipment which is arranged out of the vacuum and a nozzle connected to the pipe. A gas exhaust passage is also provided for removing the exhaust and excessive gases out of the column. This exhaust passage is composed of a connection pipe the inlet of which is near to the specimen position and an outlet tube secured to the column.

The above mentioned cylinder can also be used as a member for enclosing the specimen so as to prevent the fed gas from diffusing all over the vacuum. The construction is such that the nozzle is opened into the cylinder from the other end opposite to the attaching end of the heating element and the same end of the cylinder is in communication with one end of a bellows, the other end thereof being connected to an outlet tube.

Above the cylinder is arranged a wall having a little electron beam passing hole so that the cylinder is enclosed in a narrow chamber formed between the objective pole pieces and the wall, the narrow chamber communicating with an exhaust pipe which is led to a vacuum pump. By this arrangement, the vacuum in the column is scarcely reduced by gas leakage, although such gas leakage might be taking place through the electron beam passing hole formed in the cylinder wall. Experiments show that no obstruction preventing the advance of the electron beam by the fed gas can be recognized during operation.

Adjusting means are also provided for adjusting the specimen to and fro and for inclining the same to the advance direction of the electron beam. The means are constructed to be operated manually out of the vacuum, the inner end thereof being connected to the heating element. As above described, in the case where the nozzle and the heating element are connected together by means of the cylinder, the bellows connected to the cylinder enables to operate freely the specimen adjusting means. Although the specimen adjusting means can be constructed in any preferable manner, an example thereof will easily be understood from the detailed explanation hereinafter described referring to the accompanying drawing.

This invention will be more clearly understood by reference to the attached drawing, showing by way of example, one embodiment thereof, in which:

Fig. l is a vertical sectional view of main parts of an electron microscope according to this invention, showing the relative arrangement of a specimen heating element and specimen adjusting means; and

Fig. 2 is a sectional view along the line A-A of Fig. 1, showing the relation between a specimen attached to a heating element and gas feeding means.

Referring to the drawing, 1 represents one column of a microscope forming a vacuum chamber 2 therein. 3 is a wall having an electron passing hole 4, which divides the column chamber into the vacuum chamber 2 and an upper vacuum chamber 5. An electron beam producing device will be arranged in the upper part of the column, but the explanation and illustration in connection therewith are omitted for the sake of simplicity, as this invention has no direct relation thereto. 6 is a pair of electron beam defleeting devices having coils 7 and iron cores 7 which latter are detachably inserted into the former. 8 is an objective lens and 9 its pole pieces having electron passing holes Ill in the centre thereof.

According to this invention, in the vacuum chamber 2, slightly above the objective pole pieces 9 is provided a specimen heating element 11 which is composed of a heating body 12 as the axial part and an electric heater 13 Wound thereon, these parts being supported in a cylindrical insulator 14, made of porcelain, which has an arm 17 formed integrally therewith and extended perpendicularly thereto. A specimen holder 15 is secured to the heating body 12 or formed integrally therewith and a specimen 16 attached thereto is maintained in the position where it is exposed to the electron beam. The cylindrical insulator 14 is detachably fitted into a cylinder 37 which is arranged transversely to the lens axis. This cylinder serves as a heat shield which prevents overheatng of the objective pole pieces 9 by heat from the heating element. Between the cylinder 37 and the objective pole pieces 9 is arranged an auxiliary heat shielding plate 50 which prevents excessive heat from arriving at the objective pole pieces 9. The auxiliary shielding plate and the pole pieces are also provided with little holes 49 and respectively through which the electron beam can be passed.

In order to adjust the specimen position, there is also provided a mechanism for moving the heating element 141 to and fro and for rotating the same. To this end, the heat proof arm 17 is secured to the inner end of an ax1s 18, the outer end of which is extended through the column. The axis 18 is inserted into and coaxially with a sleeve 19 and the outer end extended from the latter has a knob 20, the inner surface of which is rotatbly engaged with the outer head 21 of the sleeve 19. To a threaded neck 22 of the sleeve is screwed a nut 23, the inner face of which contacts the outer end of a guiding member 24 mounted on the column. A sliding member 25 is fitted into the guiding member 24 so as to be guided thereby in the direction perpendicular to the paper. To this sliding member are attached pins 26 which mesh with longitudinal guiding slots 27 formed so as to guide the sleeve 19 along its axis only. The inner end of the sleeve 19 and the base of the guiding member 24 are connected by means of a bellows 28 which serves to hold the vacuum in the column and enables to operate freely the adjusting mechanism above ment1oned. 29 are the terminals of the electric heater; and 30 terminals of a thermo-couple 31 attached to the specimen holder 15.

Lead wires

32 and 33 connected respectively to these terminals pass through the axis 18, led to the outside of the vacuum.

By the above described adjusting mechanism, the heating element, accordingly the specimen position can be adjusted as follows:

The inclined angle of the specimen to the advance direction of the electron beam can be adjusted by rotating the knob 2G. The sleeve 19 accompanied by the axis 18 slides along its axis by rotating the nut 23, so that the specimen can be displaced to the right and the left. During these adjustments, the sleeve 19 is biased inwardly by elasticity of the bellows 28. In order to move the heating element, accordingly the specimen forwardly and backwardly or perpendicularly to the paper, any adequate adjusting mechanism for moving the sliding mernber 25 in the guiding member 24 will be also provided. Adjusting screws (not shown) may be used for pushing the sliding member 25 in the reverse direction.

In order to investigate gas reaction to the specimen, a gas feeding passage is preferably formed for supplying gas to the specimen surface being exposed to the electron beam. That is, the passage is so constructed that a flexible pipe 35 one end of which is in communication with any desired gas supply source 34 is led into the column therethrough and the other end of which is in communication with a nozzle 36 from which gas is supplied to the specimen surface. A connector is also provided for arranging the specimen 16 and the nozzle 36 in such relation that the fed gas is prevented from diffusing to all other vacuum chamber 3. The cylinder 37 serves also as such a connector in this example. The heating element 11 is detachably fitted to one end of the cylinder 37 as already described and to the other end thereof is secured a cover 38 through which the nozzle 36 is inserted. Thus, the specimen and the exit of the nozzle are enclosed in a chamber 39 restricted by the cylinder 37, into which gas is poured.

An exhaust passage is provided for removing exhaust and excessive gases out of the column, which passage has a bellows 43 formed as a connection pipe, the inlet of which is in communication with the cylinder 37, the other end of the bellows being in communication with an outlet tube 42 hermetically secured to the column wall. It is preferable to arrange the flexible pipe 35 in the bellows 43, one end of the flexible pipe communicating with a gas pipe 44 which is secured to the tube 42 and the other end thereof to the nozzle 36.

in the assembly, first, the gas inlet pipe and outlet tube 42, with the bellows, to which one end of the cylinder 37 is previously attached, are secured to the column and thereafter the sleeve 19 accompanied by all parts associated therewith including the element 11 is inserted through the column to fit the heating element into the other end of the cylinder 37. In adjustment, the cylinder 37 can be freely moved owing to flexibility of the pipe 35 and elasticity of the

bellows

23 and 43.

According to this invention, changing conditions of the specimen which is subjected to a desired constant or variable temperature caused by the heating element can be observed. We can also observe how the conditions of a specimen are changed, when subjected to heating and simultaneously to gas reaction caused by gas blowing against the observation surface of the specimen. In this case, one part of the gas which is fed into the vacuum chamber 39 will be diffused in other part of the column through the little hole 40 of the cylinder 37, but it is recognized that the amount of the diffused gas is too small to have an effect upon the vacuum in the column. With the intention of further reducing this effect of gas diffusion, however, it is preferable to provide a wall 45 in the vacuum chamber 2 to form a comparatively narrow chamber 46 which contains the cylinder 37, the chamber thus formed being continuously vacuumed through a vacuum pipe 47 communicating therewith. It is of course seen that the Wall 45 has a little hole 43 through which the electron beam can be passed. The auxiliary heat shielding plate 54 also serves to prevent granules which will fly in all directions from the specimen in operation from arriving at the holes 10 of the objective pole pieces 9. According to the inventors experiments, it was found that reaction gas which is fed into the vacuum chamber neither substantially prevents the advance of the electron beam nor influences upon the vacuum. However, in consideration of fear of preventing the advance of the electron beam according to kind of gas or its thickness, it will be preferable to carry out the gas feeding operation from the nozzle intermittently.

According to this invention, changing conditions of the same region or the region adjacent thereto of a specimen which is subjected to heating and gas reaction can be continuously observed or photographed in the same observation field.

A lens system comprising a plurality of lenses and observation and photographing parts which are to be arranged under the objective lens is well known by those skilled in the art, so that explanation and illustration in connection with these well known parts are omitted for the sake of simplicity.

Although the foregoing description has been made in connection with one embodiment of this invention, it is to be understood that various modifications may be made in the specific construction and arrangement disclosed therein without departing from the scope and spirit of this invention.

What is claimed is:

1. An electron microscope comprising in combination heating means which are arranged in the column of a microscope for heating a specimen, a specimen holder for holding said specimen in the passage of the electron beam during heat treatment and heat shielding means located adjacent said heating means for preventing objective pole pieces from being overheated by said heating means, thereby enabling that continuous heating conditions of said specimen is observed.

2. An electron microscope comprising in combination a heating element having a heating body and an electric heater Wound thereon which are arranged in the column of a microscope, a specimen holder which is secured to said heating body for holding a specimen in the passage of electron beam during heat treatment, and a heat shielding member which is disposed between said heating element and objective pole pieces for preventing said objective pole pieces from being overheated by said heating element.

3. An electron microscope comprising in combination a heating element having a heating body and an electric heater wound thereon which are arranged slightly above on objective pole pieces, a specimen holder Which is formed integrally with said heating body for holding a specimen in the passage of the electron beam during heat treatment, and a heat shielding cylinder which is arranged transversely to the lens axis and which surrounds said heating element and said specimen holder, for preventing objective pole pieces from being overheated by said heating element, said heat shielding cylinder having little holes just large enough to pass the electron beam.

4. An electron microscope comprising in combination a heating element having a heating body and an electric heater wound thereon which are arranged slightly above the objective pole pieces, a specimen holder which is formed integrally with said heating body for holding a specimen in the passage of the electron beam during heat treatment, a heat shielding cylinder which is arranged transversely to the lens axis and which surrounds said heating element and said specimen holder, said heat shielding cylinder having little holes just enough to pass the electron beam, a heat proof arm attached to said heat element, and adjusting means which is connected to said heat proof arm for adjusting the position of said specimen from the outside of the microscopic column.

5. An electron microscope comprising in combination a heating element having a heating body and an electric heater wound thereon which are arranged slightly above the objective pole pieces, a specimen holder which is formed integrally with said heating body for holding a specimen in the passage of the electron beam during heat treatment under gas feeding, a heat shielding cylinder which is arranged transversely to the lens axis and in which said heating element with said specimen holder is enclosed through one end thereof, said heat shielding cylinder having little holes just large enough to pass the electron beam, a gas feeding device for introducing reaction gas into said heat shielding cylinder through a cover attached to the other end thereof, thereby preventing said objective pole pieces from being overheated by said heat element and simultaneously preventing reaction gas from diffusing through said little holes out of said heat shielding cylinder, and a gas exhaust passage communicated with said heat shielding cylinder for leading out exhaust and excessive gases.

6. An electron microscope comprising in combination a heating element having a heating body and an electric heater wound thereon which are arranged slightly above the objective pole pieces, a specimen holder which is formed integrally with said heating body for holding a specimen in the passage of the electron beam during heat treatment, a heat shielding cylinder which is arranged transversely to the lens axis and which surrounds said heating element and said specimen holder for preventing objective pole pieces from being overheated by said heating element, said heat shielding cylinder having little holes just large enough to pass the electron beam, and an auxiliary shielding plate which is disposed between said heat shielding cylinder and said objective pole pieces for reducing heating of said objective pole pieces by said heating element and further serving to prevent granules which will fly in all directions from said specimen under treatment from arriving at holes of said objective pole pieces, said auxiliary heat shielding plate having a little hole just large enough to pass the electron beam.

References Cited in the file of this patent UNITED STATES PATENTS 2,266,082 Ruska Dec. 16, 1941 2,417,213 Picard Mar. 11, 1947 2,467,224 Picard Apr. 12, 1949 2,467,225 Hillier Apr. 12, 1949