JPS61294320A - Method and instrument for measuring substrate temperature - Google Patents

Abstract

PURPOSE:To measure accurately and quickly the temperature and the temperature distribution of the upper face of a substrate independently of the shape and the thickness of the substrate by bringing directly a thermocouple into contact with the surface of the substrate, on which a thin film should be formed, to measure the substrate temperature. CONSTITUTION:In preparation for depositing a thin film having a prescribed film composition on a substrate 3 in a growing chamber 1, a high vacuum flange 11 is pulled to stretch bellows 12, and a thermocouple 6 is prevented from intercepting a molecular beam evaporated from an evaporation source cell 2. When the temperature of the substrate 3 is measured before deposition of the thin film, the flange 11 is compressed to the growing chamber side to bring the front end of the thermocouple 6 into contact with the surface of the substrate. If a substrate holder 15 is earthed to the wall face of the growing chamber, it is confirmed whether the thermocouple 6 is brought into contact with the surface of the substrate or not according as a thermocouple terminal 15 and an optional point on the wall face of the growing chamber are connected electrically or not, and the substrate temperature is measured by the output of the thermocouple terminal 15.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention is a method for depositing a thin film with a desired film composition on the upper surface of a substrate in a vacuum growth chamber by a method such as vacuum evaporation, chemical vapor deposition, or molecular beam epitaxy. The present invention relates to a method and apparatus for measuring substrate temperature when

<Conventional technology> For example, in the molecular beam epitaxy growth method, 9
Conventionally, when depositing an epitaxially grown film of 0αAs on the attached substrate, a high vacuum growth chamber 1 is used as shown in FIG.
The constituent element Ga that forms the epitaxially grown film,
As is stored in separate evaporation source cells 2 (for simplicity, 1
Only one evaporation source cell is shown. ) and place it in the evaporation source cell 2.
is heated, and the evaporated substance that comes out is converted into a heating group in the form of a molecular beam.
At the same time, an epitaxially grown film of GaAs was deposited on the substrate 3 by expelling evaporated molecules that did not contribute to the deposition V to the outside of the growth chamber. A incident on the substrate 3
If the intensity of s is made sufficiently larger than the incident intensity of In, G
As that has reacted with a to form GaAs remains on the substrate 3, but excess As that does not react can be detached from the substrate because of its high vapor pressure. The substrate 3 is normally attached to a manipulator (not shown) in the growth chamber 1 and rotated, so it is not directly heated, but is heated by radiant heat from the heater 5 in the recess on the back of the substrate holder 4 to which the substrate is bonded. Conventionally, the temperature of the substrate 3 is measured as shown in the book "Molecular Beam Epitaxy" published by Kogyo Kenkyukai, edited by Kiyoshi Takahashi, pages 72 to 73.
Thermocouple 6 (W -%%”) inserted into the center of the recess on the back side
(Re) was used.

In this method, GaAs is epitaxially grown without rotating the substrate, so the tip of the thermocouple 6 is not brought into direct contact with the substrate holder 4. In addition, a thermocouple is not used to measure the temperature of the substrate 3; As shown in FIG. 1, a method of measuring the temperature by receiving thermal radiation emitted from the substrate surface through a window 7 of the growth chamber 1 with a radiation thermometer 8 outside the growth chamber has also been used.

<Problem to be solved by the invention><However, by the above method, the back plate 1 of the substrate holder
When measuring the board temperature, there is a board holder with a different heat capacity between the thermocouple and the board, and the distance from the board to the thermocouple is also far, so the temperature detected by the thermocouple is different from the temperature on the top surface of the board. . Furthermore, if the thickness and shape of a substrate holder or substrate are changed, the heat capacity will change, and the difference between the temperature detected by the thermocouple and the temperature on the top surface of the substrate will not be constant, but will vary. Furthermore, when the thermocouple is replaced due to breakage of the thermocouple, etc., the position of the tip of the thermocouple changes, and the above-mentioned temperature difference also changes.

Nine, how to measure the temperature of the substrate surface with a radiation thermometer:
Normally, the top surface of the substrate is mirror-like, making it difficult to focus the radiation thermometer accurately and reproducibly, and the temperature reading will vary depending on how well the radiation thermometer is focused. Also,
Since the area of the board is large, approximately 1 cm x 1 cm, the temperature measured by a radiation thermometer is only averaged within the area, and the thermocouple installed on the back of the board holder measures only 9 temperatures within that area. Because it was fixed in the central recess on the back of the holder, it was difficult to measure the temperature distribution within the substrate surface.

This invention was made in order to eliminate the drawbacks of conventional methods for measuring the temperature of a substrate that forms a thin film using methods such as vacuum evaporation, chemical vapor deposition, and molecular beam epitaxy. It is an object of the present invention to provide a substrate temperature measuring method and apparatus that can accurately and quickly measure the temperature and temperature distribution on the upper surface of a substrate regardless of its thickness.

<Means for Solving the Problems> In order to solve the above-mentioned problems, the substrate temperature measurement method of the present invention measures the substrate temperature by bringing a hot air pair into direct contact with the substrate surface on which a thin film is to be formed. It is characterized by this.

First, the substrate temperature measuring device of the present invention is characterized in that the thermocouple is provided so that it can move forward and backward from outside the growth chamber and can move horizontally and vertically so that it can come into contact with the surface of the substrate on which the thin film is formed.

As described above, since the method for measuring the substrate temperature of the present invention brings the thermocouple into direct contact with the surface of the substrate on which the thin film is formed to heat it up, the surface temperature of the substrate on which the thin film is formed can be accurately measured.

Mayu, the thermocouple is installed so that it can move forward and backward, as well as left and right and up and down, so that it can be brought into contact with a predetermined position on the surface of the thin film forming substrate from outside the growth chamber, making it possible to accurately measure the temperature distribution on the surface of the substrate on which the thin film is to be formed. It is also possible to lose the item.

<Example> Next, one embodiment of the present invention will be described.

The substrate temperature measurement *e1o in the example is attached to a part of the wall surface of the growth chamber 1 via a high vacuum flange 11. This substrate temperature measuring device IO is shown in Figure 1 (a).
, As shown in (b), two sets of high vacuum 7-lunges 11
．． A bellows 12 is extendably attached between bellows 11 and a bellows 12 is inserted into the bellows 12, and the rear end is attached to a 7-lunge 1 for high vacuum outside the growth chamber.
1, the front end of which is attached so that it can protrude into the growth chamber through the opening 117L of the high vacuum flange 11 outside the growth chamber, and a thermocouple 6 inserted into the insulating hollow cylindrical tube 13. The rear end of the thermocouple 6 is insulated and vacuum sealed to the outer high vacuum 7 flange 11 of the growth chamber and connected to the specific heat electronic terminal 15, and the tip end is connected to the tip of the insulating hollow cylindrical tube 13. It has a structure that allows it to be protruded and measure the output generated by the thermocouple.

When depositing a thin film of a predetermined film composition on the substrate 3 in the growth chamber 1 equipped with such a substrate temperature measuring device 10, first, as shown in FIG. 1(a), the high vacuum flange 11 outside the growth chamber is The bellows 12 is stretched by pulling it to the opposite side of the growth chamber so that the thermocouple 6 does not block the molecular beam evaporating from the evaporation source cell 2.

When measuring the temperature of the substrate 3 before thin film deposition, use the Perot 1
2, the high vacuum flange 11 outside the growth chamber is compressed toward the growth chamber, and the tip of the thermocouple 6 is brought into contact with the substrate surface. Then, if the substrate holder 15 is grounded to the wall of the growth chamber, whether or not the thermocouple 4 is in contact with the surface of the substrate 3 is determined by the fact that there is electrical continuity between the thermocouple terminal 15 and any point on the wall of the growth chamber. On the other hand, the substrate temperature can be measured by the output taken out from the thermocouple terminal 15.

In this embodiment, the thermocouple 6 is moved forward and backward in the direction of the substrate surface. If a screw is provided that can move forward and backward, the insulating hollow cylindrical tube 13 is pushed by the tip of the screw, and the tip of the insulating hollow cylindrical tube 13 is directed toward any surface of the substrate.
The temperature can be measured at any point on the surface of the substrate 3.

In addition, the relative position between the top surface of the substrate and the tip of the thermocouple due to replacing the thermocouple is almost non-existent, and the curve iaK in Figure 3
As shown, the measured value of the substrate temperature is 400% using the conventional method.
There is variation between °±20 °C, but in the case of the present invention (
Curve b) was found to hardly occur at 4000±0.5°C.

<Effects of the Invention> As is clear from the above description, according to the substrate temperature measuring method and apparatus of the present invention, ■ the method of measuring temperature by directly contacting the surface of the thin film-formed substrate with a thermocouple; The temperature of the upper surface of the thin film forming substrate can be accurately measured.

■Also, due to the method of contacting the thermocouple to the top surface of the board,
The temperature difference between the tip of the thermocouple and the top surface of the board is significantly smaller than with conventional temperature measurement methods. can accurately measure the temperature of

(2) Since the contact area between the top surface of the substrate and the tip of the thermocouple is extremely small, less than 0.5, it becomes possible to measure the temperature distribution within the surface of the substrate, compared to the conventional method of measuring the substrate temperature from the back side of the substrate holder.

■Even if you replace the thermocouple, unlike the conventional method, since the thermocouple is in contact with the substrate surface, there is almost no change in the relative position between the thermocouple tip and the substrate surface. , the substrate temperature can be measured extremely accurately.

■Furthermore, this substrate temperature measuring method and device can be used not only for molecular beam epitaxy growth, but also for measuring the temperature of thin film forming substrates in organometallic epitaxy, chemical vapor deposition, cluster ion beam epitaxy, vacuum evaporation, etc. Available.

[Brief explanation of the drawing]

1(a) and 1(b) are cross-sectional views of an embodiment of the substrate temperature measuring device of the present invention, FIG. 2 is a cross-sectional view showing an example of a conventional substrate temperature measuring method, and FIG. 3 is a cross-sectional view of the substrate temperature measuring device of the present invention. Figure 4: Temperature measurement method and diagram of changes in substrate surface temperature measured by thermocouple exchange measured by conventional substrate temperature measurement method.
is a cross-sectional view of another example of the conventional substrate temperature measurement method. In the drawing, 1... Growth chamber, 2... Evaporation source cell, 3... Substrate, 4... Basic holder, 5... Heater, 6... Thermocouple, 10... Substrate Temperature measuring device, 11... Seven lunges for high vacuum, 12... Bellows, 13... Insulating hollow cylinder, 15... Thermionic terminal patent applicant Sumitomo Electric Industries Co., Ltd. Agent 8 Patent attorney Mitsuishi Shigeru Department (1 other person) Figure 1 (b) Figure 2 Figure 3

Claims (2)

[Claims] (1) A substrate temperature measuring method characterized by measuring the substrate temperature by bringing a thermocouple into direct contact with the thin film forming side surface of the substrate. (2) A substrate temperature measuring device characterized in that a thermocouple is provided so as to be able to move forward and backward from outside the growth chamber and move horizontally and vertically so as to be able to contact the side surface of the substrate on which the thin film is formed.