JPH0451538A - Temperature measuring instrument for plate like object - Google Patents

Abstract

PURPOSE:To enhance the accuracy of a temperature measuring instrument by using a support member that contacts with a platelike object at three points and a plurality of thin film like thermocouples that are installed on more than one insulated contact portions of the support member and that generate an electromotive force in response to a temperature of the platelike object. CONSTITUTION:A wafer 10 is carried inside a treating vessel by an arm and put on three supporting pins 20. After, the gate of the treating vessel is closed, the vessel of air is evacuated until a predetermined vacuum is reached, and an infrared ray lamp 22 is applied to continue to hear the wader 10 at a predetermined temperature, followed by introducing process gas to carry out geseous phase treatment on the wafer 10. Further, the temperature of the wafer 10 is measured by thermocouples 30 formed into thin film shape on contact portions 20a of three support pins. With these thermocouples 30, it is proved that a thermal current due to a temperature difference, called the Seeback effect, flows to generate a thermal electromotive force on the interface between metallic thin films 32 and 34. A pyrometer 40 connected to these thermocouples 30 measures the temperature of the wafer 10 based on the cancell current that cancells the thermal current. In this way, the temperature of a platelike object can be measured precisely and stably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a temperature measuring device for a plate-shaped object such as a semiconductor wafer.

(Prior Art and Problems to be Solved by the Invention) In recent years, semiconductors have made remarkable progress, and along with this, processing processes for manufacturing semiconductors are also required to be controlled with complexity and precision. In particular, the wafer temperature during the fabrication process has a significant impact on the outcome of the fabrication process.

For example, in CVD equipment, the surface temperature of a semiconductor wafer is closely related to the film formation conditions, and it is important to accurately measure the wafer temperature and control the temperature based on this in order to perform precise processing. It has become indispensable.

FIGS. 6 and 7 show a conventional method for measuring wafer temperature. In FIG. 6, a semiconductor wafer 10
is supported on the chuck 12, and this chuck 1
2 has a built-in temperature control mechanism. Also, this chuck 1
A thermocouple 14 for measuring the chuck temperature is provided on, for example, the side wall of the chuck.

According to the temperature measurement method shown in FIG. 6, the temperature of the chuck 12 is measured instead of the temperature of the semiconductor wafer 10. However, since the chuck 12 has a considerable volume, its heat capacity becomes large. Further, since this type of processing process is often performed in a vacuum, thermal convection due to gas between the wafer 10 and the chuck 12 cannot be expected;
There is often a large temperature difference between the two. Since this temperature difference changes depending on the magnitude of the contact pressure between the wafer 10 and the chuck 12, there is a problem in that temperature measurement varies.

FIG. 7 shows an example of measuring the temperature of the wafer 10 in a non-contact manner. In the same figure, semiconductor wafer 1
0 has three supporting pins 16 instead of the chuck 12.
Supported by contact. Further, the temperature of the wafer 10 is controlled by an infrared lamp (
(not shown). The temperature of the wafer 10 is measured in a non-contact manner by a radiation thermometer 18 installed at a position away from the wafer 10.

The radiation thermometer 18 calculates the temperature of a hot object from the wavelength distribution of heat rays emitted from the object. However, this type of non-contact temperature measurement method
It depends on the emissivity of the object surface (a number indicating the position from a perfect black body), and this emissivity differs depending on the type of wafer 10. Furthermore, if a thin film or the like is attached to the surface of an object, the diffraction phenomenon of light caused by the film causes measurement errors, resulting in the problem that correct temperature measurement cannot be achieved.

Therefore, an object of the present invention is to improve measurement accuracy by bringing a temperature measuring element into direct contact with a plate-shaped object to be measured, and by sufficiently reducing the heat capacity of this temperature measuring element. The object of the present invention is to provide a temperature measuring device that can realize stable temperature measurement without being influenced by various process conditions.

[Structure of the Invention (Means for Solving the Problems) The present invention includes a support member that supports a plate-shaped body in contact with it at three locations, and a thin film on at least one insulated contact portion of the support member. It is characterized by having a thermocouple which is formed in a shape of four and generates an electromotive force depending on the temperature of the plate-shaped body.

(Function) According to the present invention, the plate-like object to be measured is supported by the support member that contacts the plate-like object at three places, so even if the plate-like object is warped, etc. However, stable support can always be achieved.

Furthermore, at least one contact portion of the support member includes:
A thermocouple formed in the form of a thin film is provided. Since this thermocouple is in direct contact with the plate-shaped body and generates an electromotive force depending on the temperature of the plate-shaped body, the temperature of the plate-shaped body can be directly measured based on this electromotive force. Moreover, since this thermocouple is formed in the form of a thin film at the contact part, its heat capacity can be made sufficiently low, and the temperature of the plate-shaped body and the thermocouple become equal in a short time, making it possible to measure the temperature of the plate-shaped body. can be achieved with high precision.

(Example) Hereinafter, an example in which the present invention is applied to a CVD apparatus will be specifically described with reference to the drawings.

As shown in FIG. 3, a semiconductor wafer 10 is supported at three points by three support pins 20 inside a vacuum container (not shown). A plurality of infrared lamps 22 are provided below the semiconductor wafer 10, and the semiconductor wafer 10 is configured to be heated by infrared rays. Note that by evacuating the inside of this vacuum container and introducing a process gas, it is possible to vapor-phase grow a predetermined film on the semiconductor wafer 10.

FIG. 1 is an enlarged view of the upper end contact portion 20a of the support pin 2o. The support pin 2o is made of an insulator, preferably a material with poor thermal conductivity, such as quartz or ceramic. A thermocouple 30 as a temperature measuring element for measuring the temperature of the semiconductor wafer 10 is provided at the upper end contact portion 20a of the support pin 20. This thermocouple 30 includes a first metal thin film 32 made of, for example, platinum (Pt) and a first metal thin film 32 made of, for example, platinum rhodium (PtRd).
) and a second metal thin film 34 composed of
．． The second metal thin films 32 and 34 are formed so as to overlap each other. As shown in the plan view of FIG. The overlapping parts 32a, 34a of the second metal thin films 32, 34 are formed in a circular shape having a diameter smaller than the diameter of the support bottle 20, and the overlapping parts 32a.

The diameter of 34a can also be made as small as, for example, about 0.1+sm. The width of the pull-out portions 32b, 34b extending downward from the overlapping portions 32a, 34a of the support bottle 20 can be set to, for example, about 10 μm.

The first and second thin films are formed on the surface of the support bottle 20.
The metal thin films 32 and 34 can be preferably formed by plating, sputtering, vapor deposition, or the like. Further, a second metal thin film 3 that contacts the back surface of the semiconductor wafer 10
It is preferable that the apex portion of 4 is processed into a spherical shape with a predetermined curvature and brought into spherical contact with the back surface of the semiconductor wafer \10.

The first and second metal thin films 32 and 34 each have a thickness of 1 μm, for example.
It is formed to have a thickness of m, and output cables 36 and 38 are connected to the lead-out portions 32b and 34b, respectively. The output cables 36, 38 are made of the same material as the first metal thin film 32 or the second metal thin film 34 to which they are connected.

These two output cables 36 and 38 are input to the thermocouple thermometer 40, respectively. As is well known, the thermocouple thermometer 40 generates a current that cancels the thermal current generated by the thermoelectromotive force in the thermocouple 30, and displays the temperature based on the magnitude of this canceling current.

In this embodiment, the output of the thermocouple thermometer 40 is
The temperature is fed back to the second lamp drive circuit 42 to obtain a uniform temperature on the front surface of the semiconductor wafer 10. At this time, three thermocouples are attached to each of the three support bins 20.
0, the measured temperature is determined by three thermocouple thermometers 40. On the other hand, in order to obtain a uniform heating temperature of the semiconductor wafer 10, a plurality of infrared lamps 22, for example, several tens, are required.

In this way, when driving and controlling several dozen lamp drive circuits 42 using the outputs of three types of thermocouple thermometers 40, the fourth
It is possible to cite the feedback circuit shown in FIG.

In the system shown in FIG. 4, infrared lamps 22 are divided into three groups for each region adjacent to each support bin 20, and a plurality of infrared lamps 22 existing in this group are connected to one drive circuit 42. . The output lines of the three thermocouple thermometers 40 are connected to the lamp drive circuits 42 of each group, respectively. On the other hand, in the one shown in FIG. 5, the outputs of three thermocouple thermometers 40 are collectively connected to one lamp drive circuit 44, and all several dozen infrared lamps 22 are operated by this one lamp drive circuit 44. It is configured to perform drive control.

Next, the effect will be explained.

In this CVD apparatus, a wafer 1 is
0 is carried into the processing container and placed on the three support bins 20. During this reception, it is also possible to move the support bin 20 up and down.

After that, the gate of the processing container is closed and the vacuum is evacuated to a predetermined degree of vacuum, and then the wafer 10 is heated and maintained at a predetermined temperature using the infrared lamp 22, and a process gas is introduced to perform vapor phase growth processing on the wafer IO. Become.

The accuracy of film formation on the wafer 10 is closely related to the surface temperature of the wafer 10. Therefore, it is necessary to accurately measure the surface temperature of the wafer 10 and drive and control the infrared lamp 22 based on this measurement.

In this embodiment, the temperature of the wafer 10 is measured by thermocouples 30 formed in the form of a thin film on the contact portions 20a of the three support bottles 20. According to such a thermocouple 30, it is known that a thermal current due to a temperature difference flows due to the Seebeck effect. Second metal thin film 32.3
A thermoelectromotive force is generated at the joint surface (interface) of 4.

A thermocouple thermometer 40 connected to this thermocouple 30 measures the temperature of the wafer 10 based on a cancellation current that cancels the thermal current.

Therefore, the canceling current causes the first. Almost no current flows through the second metal thin film 32.34 and its output cable 36.38, and the first. The thickness of the second metal thin film 32°34 is set to 1, for example.
Sufficient durability can be obtained by forming the film as thin as about μm.

In this way, in this embodiment, since the thermocouple 30 is brought into direct contact with the Ueno X10, it is possible to accurately measure the temperature of the sea urchin/%10.

In addition, when measuring temperature by direct contact, the heat capacity of the temperature measurement element has traditionally been a problem.
According to the configuration of this embodiment, it is possible to sufficiently reduce the heat capacity. That is, the first and second metal thin films 32.
34 can be formed as thin as about 1 μm since almost no current flows therethrough, and its surface area can be configured to be extremely small as shown in FIG. In this way, the volume in which the temperature measuring element is formed becomes sufficiently small, so that its heat capacity can be significantly reduced compared to the conventional one. This effect can be achieved by making the material of the support pin 20 on which the thermocouple 30 is formed of quartz, ceramic, etc., which have poor thermal conductivity, thereby making it possible to significantly suppress heat radiation from the wafer 10. .

Moreover, in this embodiment, since the thermocouple 30 is in contact with the back surface of the wafer 10 at three points, the contact area is extremely small, and this also makes it possible to suppress heat radiation from the wafer 10.

In order to bring the thermocouple 30 into direct contact with the wafer 10 and perform accurate temperature measurements, it is essential to ensure sufficient contact pressure. In the case of this embodiment, wafer 1
0 is contacted at three points by thermocouples 30 at three locations, and
Since the contact portion of the thermocouple 30 with the wafer 10 is formed on a spherical surface with a predetermined curvature, the stress on the thermocouple 30 due to the weight of the wafer 10 becomes extremely large, and the thermocouple 30
It is possible to ensure sufficient contact by the elastic deformation of.

If the temperature of the wafer 10 can be accurately measured using the thermocouple thermometer 40, this can be fed back to the lamp drive circuits 42 and 44 that drive the infrared lamps 22.
0 uniform heating can be achieved. In particular, in the CVD apparatus like this embodiment, when forming a film on the wafer 10, it is necessary to suppress the temperature drop at the part where the support pins 20 come into contact. Since contact with the wafer 10 is ensured, it is possible to prevent the problem that the film thickness in the region corresponding to the support pin 20 is different from that in other regions.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible within the scope of the invention.

As a support member that supports a plate-shaped object such as the wafer 10, 3
It is essential that the members support the book, and stable support of the plate-like object cannot be achieved even if there are more or fewer members than this.

In this case, the thermocouple 30 is not necessarily formed on all three support members, but may be formed on at least one support member. Furthermore, thermocouple 30
The two types of metals constituting are not limited to the combination of platinum-platinum-rhodium as in the above embodiment, but it is also possible to employ a combination of other two types of metals that exhibit the Seebeck effect.

Furthermore, the present invention is not limited to application to CVD apparatuses such as those in the above-mentioned embodiments, but, for example, when a semiconductor wafer is used as a plate-shaped body, the present invention is applicable to a baking mechanism in a coating apparatus, or a plasma forming electrode is brought into direct contact with the wafer. It can be similarly applied to a sputtering device or the like placed in a position where the present invention is not used. Furthermore, the object to be processed is not limited to a semiconductor wafer, but may be a liquid crystal substrate, for example.

[Effects of the Invention] As explained above, according to the present invention, the thermocouple is brought into direct contact with the plate-shaped body whose temperature is to be measured, and the first . Since the heat capacity of the second metal thin film can be configured to be sufficiently small, it becomes possible to realize accurate temperature measurement of the plate-shaped body with good stability.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a wafer support part in a CVD apparatus to which the present invention is applied, FIG. 2 is a plan view of a thermocouple and support pins, and FIG. 3 is for explaining the wafer support state. 4 and 5 are block circuit diagrams of feedback control circuits using thermocouple thermometers, and FIGS. 6 and 7 are schematic diagrams of
FIG. 2 is a schematic perspective view for explaining a conventional temperature measurement method. DESCRIPTION OF SYMBOLS 10... Plate-shaped body, 20... Supporting member, 22... Infrared lamp, 30... Thermocouple, 32... First metal thin film, 34... Second metal thin film, 40...・Thermocouple thermometer. Agent Patent attorney Inoue - (1 other person) Figure ↑ 22 eta) 4 lamps

Claims (1)

[Claims] (1) A support member that contacts and supports the plate-shaped body at three locations, and a thin film formed on at least one insulated contact portion of the support member, which generates an electromotive force depending on the temperature of the plate-shaped body. 1. A temperature measuring device for a plate-shaped body, comprising: a thermocouple that generates a thermocouple;