JPH0498135A - Detection of temperature - Google Patents

Abstract

PURPOSE:To restrain the occurrence of a temperature difference between a temperature measuring terminal and a coating material by contacting a temperature sensor, in which a temperature measuring terminal is coated with material having large thermal conductivity, with an object to be continuously treated. CONSTITUTION:In the structure of a temperature sensor 13, a cap 23 having a spherical tip is fitted to a quartz fiber 22, in which phosphor 20 (e.g. phosphor to be excited by ultraviolet rays) is applied to a tip and the outer periphery is coated with fluororesin 21, so as to cover the phosphor 20. Then the pulse of the ultraviolet rays is irradiated to the phosphor 20 with a control device 14 in a condition where the cap 23 is contacted with e.g. a wafer 1 to detect the temperature of the wafer 1 by the attenuation time of reflected light from the phosphor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a temperature detection method, and particularly relates to a temperature detection method for detecting a temperature, and particularly for detecting an object to be continuously processed, such as a semiconductor element substrate to be etched (hereinafter abbreviated as wafer). This invention relates to a temperature detection method suitable for detecting the temperature of

[Prior Art] As a conventional temperature detection method, three methods are known, for example, as described in a catalog published by Lufstron.

One method is to apply a phosphor directly to an object, irradiate it with ultraviolet rays, and measure by utilizing the temperature dependence of the decay time of the reflected light.

The second method is to make a similar measurement by bringing the phosphor into direct contact with the object.

The third method is to make measurements by bringing a phosphor coated with PFA Deflon resin into contact with an object. This method is also described in the "Optical Fiber Contact Fluorescent Thermometer" catalog published by Astec Co., Ltd. on May 20, 1988.

[Problems to be Solved by the Invention] Assuming that the above-mentioned prior art is applied to detecting the temperature of an object that is continuously processed, such as a wafer that is being etched, the following solution is possible. There are tasks to be done.

First, in the above-mentioned prior art, the first method requires the direct coating of the k-1 phosphor on each wafer, which requires a large amount of time, and the phosphor is transported There is a problem that the inside of the apparatus is contaminated by peeling off, and the number of foreign substances adhering to the wafer increases, resulting in a decrease in the yield.

Next, in the second method, the phosphor peels off due to contact with the wafer, so the temperature of the wafer cannot be measured continuously, and also in this case, the amount of foreign matter adhering to the wafer increases. There is a problem that the yield is reduced.

Further, in the third method, since the thermal conductivity of the PFA Teflon resin is low, a temperature difference is generated between the wafer and the phosphor, and as a result, there is a problem that the temperature of the wafer cannot be accurately detected.

An object of the present invention is to provide a temperature detection method that can continuously and accurately measure the temperature of objects that are continuously processed.

1. Means for Solving the Problem] In order to achieve the above object, 1. a temperature sensor whose temperature measuring terminal is coated with a material having high thermal conductivity is brought into contact with an object to be continuously processed; It is designed to measure the temperature of

[Function] The temperature measuring terminal of the temperature sensor is coated with a material having high thermal conductivity, and the temperature sensor is brought into contact with an object to be continuously processed to measure the temperature of the object.

Therefore, the temperature difference caused by the thermal conductivity of the sheathing material is suppressed from occurring between the temperature measurement terminal and the sheathing material, and therefore the temperature of the continuously processed object can be accurately measured. Can be detected.

In addition, the temperature of the object can be continuously detected without peeling of the temperature measurement terminal due to contact of the temperature sensor with the object.

[Embodiment] Hereinafter, the configuration of a so-called magnetic field type microwave plasma etching apparatus to which an embodiment of the present invention is applied will be explained with reference to FIGS. 1 to 6.

FIG. 1 shows the overall configuration of the etching apparatus. Etching of a wafer 1 is performed by converting a process gas 3 introduced into a discharge tube 2 into plasma through the interaction of a microwave 4 and a magnetic field by a solenoid 5, and then This is performed while controlling the energy of ions incident on the wafer l by applying high frequency waves to the lower electrode 6 from a high frequency power supply 7. When the etching of the wafer 1 is completed, the etched wafer l is transferred from the lower electrode 6 to a transfer device (not shown) by the operation of a wafer push-up member (not shown), and then transferred to another location by the transfer device. Ru. Also, a new wafer is placed on the bottom electrode 6 and etched.

On the other hand, in order to cool the wafer l to be etched, in this case, a DC power supply 9 applies a voltage to the insulating film 8 of Al2203 or the like sprayed on the surface of the lower electrode 6 to electrostatically adsorb the wafer l, and then a mass flow controller is attached to the back surface. This is done by opening 10 and introducing He gas 11.

Further, the temperature of the lower electrode 6 is controlled by a refrigerant circulation machine 12, and the temperature of the wafer l being processed is detected by operating a temperature sensor 13 attached to the lower electrode 6 every - wafer by a control device 14. It is controlled by the control device 15 based on the value.

Next, a method for installing the temperature sensor 13 will be explained with reference to FIGS. 2 and 3.

The tip of the temperature sensor 13 is several tens of μm from the surface of the lower electrode 6.
It is attached to the lower electrode 6 via a vacuum introduction terminal 17 which has a rubber paragon 16 inside so as to protrude to some extent, and for this purpose the wafer pushing member 18 is provided with a notch 19. As a result, the temperature sensor 13 is displaced due to contact with the wafer l, that is, the temperature sensor 13 receives a downward force due to the electrostatic attraction force, and the downward displacement of the temperature sensor 13 due to this force and the He gas This prevents leaks.

Furthermore, if the protruding length of the temperature sensor 13 is large, the gap between the wafer 1 and the insulating film 8 will be large, and the electrostatic attraction force will be reduced or the electrostatic attraction will not occur. In order to prevent IJ2 from occurring, the protrusion length of the temperature sensor 13 needs to be several tens of μm (for example, about 50 μml).

Next, the structure of the temperature sensor 13 will be explained with reference to FIG.

A cap 23 having a spherical tip is attached to a quartz fiber 22 whose tip is coated with a phosphor (for example, a phosphor excited by ultraviolet rays) 20 and whose outer periphery is coated with a fluororesin 21 so as to cover the phosphor 20. It is installation. Then, with the cap 23 in contact with the wafer 1, the controller 14 irradiates the phosphor 20 with a pulse of ultraviolet light, and detects the temperature of the wafer 1 based on the decay time of the reflected light from the phosphor 20. Here, for example, the radius of the cap 23 is 0.5
It is about mm. Suitable materials for the cap 23 are Δ(2, Cu, W, SiC, etc.) with high thermal conductivity.In other words, the large amount of heat and the thickness of the cap 23 (distance between the wafer l and the phosphor 20) are constant. If so, the detection error is inversely proportional to the thermal conductivity of the cap 23. Here, Al2,
The thermal conductivities of Cu, W, and SiC are approximately 1,500 to 500 times higher than that of PFA Teflon, making it possible to extremely reduce detection errors.

Next, a method of controlling the wafer temperature during processing using the temperature sensor 13 will be explained with reference to FIG.

The temperature of the wafer l during the etching process is measured by the crushing sensor 13.
is detected by contacting the back surface of the wafer 1, and the output from the PID controller 26 according to the deviation 25 between this value and the preset target value 24 changes the opening degree of the mass flow controller IO, and the He gas The flow rate of 11 is adjusted and controlled.

FIG. 6 shows the measurement results of the detection accuracy of the wafer 1 temperature when the cap 23 made of aluminum is actually used.

The error between the wafer l temperature and the detected temperature was ±1° C., making it clear that the temperature of the wafer l during processing could be controlled with high accuracy.

For example, in low-temperature etching, in which the wafer is cooled to suppress lateral etching progress and etched with line widths on the order of submicrons or quarter microns, highly accurate control is required to control the temperature of the wafer during the etching process. In etching, it is extremely effective to be able to accurately detect the temperature of the wafer as described above.

Next, another method of controlling the wafer l temperature will be explained with reference to FIGS. 7 and 8.

The difference from the method described above is that a control device 27 is provided to control the refrigerant temperature in the refrigerant circulation machine 12 based on a signal from the temperature sensor 13.

Adjust the refrigerant temperature by operating the heater or refrigerator in the refrigerant circulation machine 12 according to the output from the PID controller 26 according to the deviation 25 between the detected value of the wafer 1 temperature and the preset target value 24, The temperature of the lower electrode 6 is controlled. Note that in FIGS. 7 and 8, other devices that are the same as those in FIGS. 1 and 5 are designated by the same reference numerals, and their explanations will be omitted.

Next, another method of controlling the wafer 1 temperature is shown in FIG.
This will be explained using Figure 0.

The difference from the two methods described above is that a heater 28 is provided inside the lower electrode 6, and a control device 29 is provided that operates the heater 28 based on a signal from the temperature sensor 13 to control the temperature of the lower electrode 6.

The input voltage to the heater 28 is changed by the output from the PID regulator 26 according to the deviation 25 between the detected value of the wafer 1 temperature and the preset target value 24, and the voltage applied to the lower electrode 6 is changed.
control the temperature. Note that in FIGS. 9 and 10, the same devices as in FIGS. 1 and 5 are designated by the same reference numerals, and their explanations will be omitted.

Next, another method for attaching the temperature sensor 13 will be explained with reference to FIG.

A plate spring 30 made of stainless steel spring steel and having a spring constant sufficient to be deformed by the weight of the wafer 1 is fixed to the lower electrode 6 with a screw 31, and a vacuum introduction terminal 17 is attached to the plate spring 30 with a nut 32 to adjust the temperature. The sensor 13 is fixed.

By doing so, even if the amount of protrusion of the temperature sensor 13 from the surface of the lower electrode 6 is large, the temperature sensor 13 can be reliably brought into contact with the electrostatically attracted wafer l, which has the effect of reducing variations in detection accuracy.

Although the temperature sensor is supported by a leaf spring in this case, other types of spring means can be used instead. In other words, at least the wafer is deformed (displaced) by its own weight.
Any spring constant is sufficient as long as it has a spring constant of a certain degree.

Next, another structure of the temperature sensor 13 will be explained with reference to FIG.

The difference from that shown in FIG. 3 is that a vapor deposited film 33 is formed on the surface of the phosphor 20 instead of the carab 23, and the same detection accuracy can be obtained. Suitable materials for the film include Ag, 'Au, 'A, and C. In addition, the heat resistance temperature of Shizui optical body and quartz fiber is 450℃ and 1
000° C., and if it is deposited at a temperature below the heat-resistant temperature of the phosphor, no particular problem will arise in its performance.

Next, another structure of the temperature sensor 13 will be explained with reference to FIG.

This is a sheath type thermocouple in which a stainless steel tube 34 is filled with magnesium oxide 35 and a thermocouple 36 is fixed.The tip of the sheathed thermocouple is covered with a cap 23 or a vapor deposited film 33.This occurs when the entire stainless steel tube 34 is covered with stainless steel and magnesium oxide. Measurement errors caused by these thermal conductivities can be suppressed to a small level, and detection accuracy for road gaps, etc., can be obtained compared to that using the phosphor 20 described above.

However, when applied to the above-mentioned etching apparatus, it is necessary to provide one robust filter in the circuit to cut off the high frequency waves from the high frequency power source.

The above description has been made regarding the case where it is applied to an etching apparatus, but it can also be applied to other applications where wafers are processed continuously.

The present invention can also be applied to film forming apparatuses such as a sputtering apparatus, a CVD apparatus, an MBE apparatus, and the like.

In any case, it is not limited to wafers that are continuously processed in this way, but also objects that are processed continuously, that is, objects that have multiple objects, and objects that cannot be directly attached to temperature measurement terminals. The present invention is extremely effective for detecting temperatures such as

Further, even if the object is cooled, heated, or neither cooled nor heated, no problem will arise in implementing the present invention.

[Effects of the Invention] According to the present invention, it is possible to continuously and accurately detect the temperature of objects that are continuously processed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a microwave etching apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of the temperature sensor mounting portion of FIG. 1, and FIG. Figure 4 is a detailed longitudinal section of the main part of the temperature sensor, Figure 5 is a wafer temperature control circuit diagram, Figure 6 is an experimental diagram for wafer temperature measurement, and Figure 7 is a detailed longitudinal cross-section of the main part of the temperature sensor.
The figure is a main part configuration diagram of a microwave etching apparatus showing other control methods for wafer temperature, FIG. 8 is a wafer temperature control circuit diagram, and Section 9 shows other control methods for controlling wafer temperature. Main part configuration diagram of the microwave etching apparatus shown in Fig. 10.
The figure also shows a wafer preparation control circuit diagram, Fig. 11 is a vertical sectional view of the temperature sensor mounting part showing another embodiment of the temperature sensor, and Fig. 12 shows another embodiment of the temperature sensor 1. FIG. 13 is a detailed vertical cross-sectional view of a main part of a temperature sensor showing still another embodiment of the temperature sensor. ], ------- Wafer, 6------ Lower electrode, 8--- Insulating film, 9----1--- DC power supply, 1
0---Mass flow controller. 12-------Refrigerant circulation machine, 13-----1 temperature sensor, 14.15.27.29-----Control device, 1
6------Packing, 17------Vacuum introduction terminal, 18---Wafer pushing member, 19------
--- Notch, 20 --- One phosphor, tube, evening, 30 Quartz fiber, PID controller, leaf spring, 33 Vapor-deposited film, Kyahi'sz Figure 43, 13-11, 4 18-1-Wafer push-up''); P-war 4th flash 5th closing O figure / 4 (s) '47 country 7 O darkness I figure y O l θ figure O l Flash 12th eye O 13 drunkenness

Claims (1)

[Claims] 1. In a method for detecting the temperature of an object that is continuously processed, a temperature sensor whose temperature measurement terminal is coated with a material having high thermal conductivity is brought into contact with the object; A temperature detection method characterized by measuring the temperature of. 2. The temperature detection method according to claim 1, wherein the temperature measurement terminal is a phosphor, the phosphor is covered with a cap made of a material with high thermal conductivity, and the cap is brought into contact with the object. . 3. The temperature detection method according to claim 2, wherein the phosphor is covered with a cap made of Al, Cu, W, or SiC. 4. The humidity detection method according to claim 1, wherein the temperature measuring terminal is a phosphor, the phosphor is covered with a vapor deposited film having high thermal conductivity, and the vapor deposited film is brought into contact with the object. 5. The temperature detection method according to claim 4, wherein the phosphor is coated with a deposited film made of Ag, Au, or Al. 6. The temperature detection method according to claim 1, wherein the temperature measuring terminal is a thermocouple, the thermocouple is covered with a cap made of a material with high thermal conductivity, and the cap is brought into contact with the object. 7. The temperature detection method according to claim 1, wherein the temperature measurement terminal is a thermocouple, the thermocouple is covered with a deposited film having high thermal conductivity, and the deposited film is brought into contact with the object. 8. The temperature detection method according to any one of claims 1 to 7, wherein the temperature sensor is brought into contact with the object by applying an external force. 9. The temperature detection method according to claim 8, wherein the temperature sensor is brought into contact with the object by electrostatic adsorption force. 10. The temperature detection method according to any one of claims 1 to 7, wherein the temperature sensor is supported by a spring force and brought into contact with the object. 11. Temperature detection according to any one of claims 1 to 7, in which the temperature sensor is brought into contact with the object by electrostatic adsorption force, and the temperature sensor is supported by a spring force and brought into contact with the object. Method.