JPH0621012A - Method and device for manufacturing semiconductor - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a technology for controlling a wafer temperature in a semiconductor manufacturing process, which enables in-process measurement of the temperature of the wafer during the process and causes contamination of the device by impurities. It is an object of the present invention to provide a wafer temperature measuring and controlling method, and its apparatus, which are free from the above problems. [Structure] To have a step of forming a resist film on a wafer and a step of measuring an infrared absorption spectrum line intensity specific to the resist film on the wafer in a processing step, The infrared thermometer output for measuring the infrared absorption spectrum line intensity of the wafer is configured to have a step of feeding back to the wafer temperature control mechanism, and the resist film temperature measuring device on the wafer in the processing step and the temperature measuring device According to the output, the temperature control unit for controlling the wafer temperature and the wafer temperature control mechanism controlled by the temperature control unit are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for controlling a wafer temperature in a semiconductor manufacturing process. In recent years, the miniaturization of VLSI has progressed, and control of the wafer temperature during processing has become an important technology in various wafer processing such as dry etching. Especially in dry etching, since the reaction rate on the wafer surface greatly depends on the wafer temperature, technology for controlling the wafer temperature is becoming indispensable.

[0002]

2. Description of the Related Art Conventionally, in plasma etching, there have been two methods for measuring the wafer temperature in plasma. One of them is a method in which a blackbody paint is applied on the surface of a measurement wafer and the blackbody radiation from it is measured by an infrared thermometer. The other is that when a fluorescent substance layer is formed by coating a fluorescent substance on the back surface of the measurement wafer and the fluorescent substance layer is irradiated with pulsed light through an optical fiber, the fluorescent light emitted is attenuated. It was a method of obtaining the temperature by measuring a constant.

[0003]

All of these conventional methods require a wafer for temperature measurement in order to measure the temperature. That is, this temperature measuring wafer is set in, for example, a plasma etching apparatus, the temperature in plasma is measured, and the obtained temperature is regarded as the actual temperature of the wafer in the plasma etching process.

Therefore, these conventional measuring methods do not measure the so-called in-process temperature. There is also a problem that the processing equipment is contaminated by impurities contained in the blackbody paint or fluorescent paint of the temperature measurement wafer.

Therefore, the present invention provides a method and apparatus for measuring and controlling a wafer temperature, which enables in-process measurement of the temperature of a wafer during a process and does not cause contamination of the apparatus by impurities. The purpose is to provide.

[0006]

The above problems can be solved by the following method and manufacturing apparatus. A method for measuring a wafer temperature, which comprises a step of forming a resist film on a wafer and a step of measuring an infrared absorption spectral line intensity specific to the resist film on the wafer in a processing step, and a method specific to the resist film A method for controlling the wafer temperature by feeding back the infrared thermometer output for measuring the infrared absorption spectrum line intensity to the wafer temperature control mechanism,
A wafer processing apparatus having a resist film temperature measuring device on a wafer in a processing step, a temperature control unit for controlling a wafer temperature by an output of the temperature measuring device, and a wafer temperature control mechanism controlled by the temperature control unit.

FIG. 1 illustrates the principle of the present invention. Figure 1
(a) is a schematic diagram of a semiconductor wafer temperature measuring device. In the figure, 1 is a semiconductor wafer, 2 is a resist film on a semiconductor wafer, 3 is a lens, 4 is a slit, 5 is an infrared filter, 6 is an infrared sensor, and 7 is an infrared thermometer. Further, FIG. 1 (b) is a diagram schematically showing the infrared absorption spectrum of the resist film and the transmission characteristics of the infrared filter 5. In the figure, 8 is the infrared absorption spectrum of the resist film,
9 indicates the transmission characteristics of the infrared filter 5. For example, by installing a bandpass filter 5 corresponding to the absorption wavelength of 8 μm in the resist film in front of the infrared sensor 6 of the infrared thermometer 7, radiation outside the absorption wavelength band of 8 μm is cut and the absorption spectrum of 8 μm is cut. The intensity is measured accurately. Since the absorption spectrum intensity of 8 μm depends on the temperature of the resist film, the temperature of the resist film 2 can be measured by measuring the absorption spectrum intensity of 8 μm. Since the resist film 2 is in close contact with the wafer 1 and the thickness of the resist film 2 is as thin as about 1 μm, the temperature of the resist film 2 is considered to be almost the same as the temperature of the wafer 1.

[0008]

FIG. 2 shows the infrared absorption spectrum of the resist film used in the present invention. Figure 2 (a) shows the i-line resist,
Figure 2 (b) shows the infrared absorption spectrum of what is called a g-ray resist, and these are all near 8 μm (exactly 7.95 μm).
m, the wave number is 1257 cm ^-1 ) and has an absorption line due to the benzene ring. There is an absorption line due to the OH group near 3 μm. The three vertical lines written near 1250 cm ^-1 are
It shows the filter performance with a width of ± 0.15 μm centered on 7.59 μm.

These absorption lines are common to all resists, and it is possible to use either the 8 μm absorption line intensity or the temperature dependence of the 3 μm absorption line intensity for measuring the temperature of the resist. However, the measurable temperature range is that the former is above room temperature and the latter is about 200 ° C.
The above temperature is reached. In the present invention, the 8 μm absorption line is used, and the temperature of the resist is measured using an infrared thermometer having a bandpass filter corresponding to this.

FIG. 3 is a diagram showing the accuracy of the infrared thermometer by comparing the reading of the infrared thermometer with the temperature reading of the thermocouple. Figure 3 (a) shows that the resist film has a thickness of 3.
The figure shows the case where the resist film has an emissivity of 1.00 when the thickness is 6 μm or more. In this case, the difference (ΔT) between the infrared thermometer reading and the thermocouple reading is 2 ° C.
In addition, Fig. 3 (b) shows the case where the resist film has a thickness of 1.2 µm and the correction is performed so that the resist film has an emissivity of 0.60. Even in this case, ΔT is 6 ° C or less.

Therefore, the semiconductor wafer temperature measurement by the infrared thermometer is practically equivalent to the temperature measurement by the thermocouple.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Two embodiments of the present invention will be described below with reference to the drawings. In the drawings and the previous drawings, the same reference numerals represent the same members. First Embodiment FIG. 4 is a schematic diagram showing a parallel plate dry etching apparatus according to the present invention. This device is a semiconductor wafer temperature measuring means (
This is an apparatus provided with an infrared camera 15), a temperature control unit 16, and an electrostatic chuck power supply 17. In the figure, 10 is a dry etching chamber, 11 is an RF application electrode, 12 is a counter electrode, 13 is an electrostatic chuck, 14 is an infrared transmission window, 15 is an infrared camera (for example, 004 type manufactured by Minolta Camera Co., Ltd.), 16
Is a temperature control unit, 17 is an electrostatic chuck power supply, 20 is a cooling water inlet, and 21 is a cooling water outlet.

Wafer to be dry-etched 1
Are held by the electrostatic chuck 13. Electrostatic chuck
The contact area of the wafer 1 attracted to the surface of 13 depends on the attraction force of the electrostatic chuck 13, and the attraction force of the electrostatic chuck 13 depends on the attraction voltage. Therefore, the thermal resistance of wafer 1 is controlled by the adsorption voltage. The radiation of the resist film 2 is guided to the infrared camera 15 through the infrared transmission window 14 and the resist film 2
By measuring the 8 μm absorption line intensity of 2, the temperature of wafer 1 can be determined in-process.

FIG. 5 is a block diagram showing a method for controlling the temperature of a semiconductor wafer by using the apparatus of the first embodiment. 3 is a block diagram showing the procedure of a temperature control method for the wafer 1 according to the present method. FIG.

First, the wafer 1 on which the patterned resist film 2 is formed is held by the electrostatic chuck 13 in the chamber 10 so that the resist film 2 faces the counter electrode 12.
A predetermined dry etching is started.

Radiant light from the resist film 2 is transmitted through an infrared transmitting window.
It leads to the infrared camera 14 through 14, and the infrared thermometer
The temperature of Wafer 1 is determined by measuring the 8 μm absorption line intensity of the radiant light. On the other hand, the output of the infrared thermometer is input to the temperature control unit 16.

In the temperature control unit 16, the difference is compared with the standard voltage corresponding to the set temperature, and the difference is determined by the electrostatic chuck power supply 17
Give feedback to. Second Embodiment FIG. 6 is a schematic view showing a parallel plate dry etching apparatus according to the present invention as in FIG. However, this apparatus is an apparatus in which a semiconductor wafer temperature measuring means 15, a temperature control unit 16, and a gas cooling pressure control mechanism 18 of the present invention are provided in a conventional parallel plate dry etching apparatus.

A gap is provided between the back surface of the wafer 1 supported by the electrostatic chuck 13 and the surface of the electrostatic chuck 13 to form a gas pool 19 into which the helium (He) gas flows. Be done. 10 SCCM of He gas is supplied as a whole, less than 1 SCCM of it is supplied to the gas reservoir 19 by the gas pressure control device 18, and the rest is needle valve 22.
Through the vacuum exhaust port 23. In this way, the pressure of He gas in the gas reservoir 19 is dynamically controlled by the balance of the flow rates. Wafer 1 is cooled by the heat conduction of He gas, but the heat conduction of He gas depends on the pressure of He gas.
The temperature of wafer 1 is controlled by controlling the pressure of He gas.

FIG. 7 is a block diagram showing a method of controlling the temperature of a wafer by using the apparatus of the second embodiment. First, the wafer 1 on which the pattern resist film 2 is formed is
With the electrostatic chuck 13 in the chamber 10, the resist film 2
Are held so as to face the counter electrode 12, and predetermined dry etching is started.

Radiant light from the resist film 2 is transmitted through an infrared transmitting window.
It leads to the infrared camera 14 through 14, and the infrared thermometer
The temperature of Wafer 1 is determined by measuring the 8 μm absorption line intensity of the radiant light. On the other hand, the output of the infrared thermometer is input to the temperature control unit 16.

In the temperature control unit 16, the temperature is compared with the standard voltage corresponding to the set temperature, and the difference is fed back to the gas cooling pressure control device 18. In the embodiment, the resist film is provided on the Si substrate, but the principle of the present invention is also applicable when an organic material film such as SOG (Spin On Glass) is formed instead of the resist film. Applies similarly.

[0022]

According to the present invention, there is provided a wafer temperature measuring / controlling method and apparatus capable of in-process measuring the temperature of a wafer in a process and preventing contamination of the apparatus by impurities. . As a result, it greatly contributes to the improvement of reliability in the manufacture of highly integrated circuits such as VLSI.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a diagram showing an infrared absorption spectrum of a resist film used in the present invention.

FIG. 3 Graph comparing infrared thermometer readings with thermocouple thermometer readings

FIG. 4 is a schematic diagram showing a parallel plate dry etching apparatus of a first embodiment.

FIG. 5 is a block diagram showing a method for controlling the temperature of a wafer by using the apparatus of the first embodiment.

FIG. 6 is a schematic diagram showing a parallel plate dry etching apparatus of a second embodiment.

FIG. 7 is a block diagram showing a method for controlling the temperature of a wafer by using the apparatus of the second embodiment.

[Explanation of symbols]

 1 Semiconductor wafer 2 Resist film 3 Lens 4 Slit 5 Infrared filter 6 Infrared sensor 7 Infrared thermometer 8 Infrared absorption spectrum of resist film 9 Transmission characteristics of infrared filter 5 Chamber 10 RF application electrode 12 Counter electrode 13 Electrostatic chuck 14 Infrared Transmission window 15 Infrared camera 16 Temperature control unit 17 Electrostatic chuck power supply 18 Gas cooling pressure control device 19 Heat transfer gas reservoir 20 Cooling water inlet 21 Cooling water outlet 22 Needle valve 23 Vacuum exhaust port

Claims (16)

[Claims] 1. A wafer temperature measuring method for measuring an in-process wafer temperature in a semiconductor wafer processing step, which comprises: forming a resist film on a semiconductor wafer; and measuring an infrared absorption spectral line intensity specific to the resist film. A method for measuring a temperature of a semiconductor wafer, comprising: 2. The step of measuring the infrared absorption spectrum line intensity specific to the resist film includes the step of providing a bandpass filter corresponding to the infrared absorption spectrum line wavelength. A method for measuring the temperature of a semiconductor wafer as described. 3. The semiconductor wafer temperature measuring method according to claim 1, wherein the infrared absorption spectrum line peculiar to the resist film is an absorption spectrum line near a wavelength of 8 μm due to a benzene ring. 4. A wafer temperature control method for controlling a wafer temperature in a semiconductor wafer processing step, comprising a step of forming a resist film on a semiconductor wafer, and an infrared absorption spectrum line intensity specific to the resist film by an infrared thermometer. A semiconductor wafer temperature control method comprising a step of measuring and a step of feeding back the infrared thermometer output to a wafer temperature control mechanism. 5. The step of measuring the infrared absorption spectrum line intensity peculiar to the resist film by an infrared thermometer comprises the step of providing a bandpass filter corresponding to the infrared absorption spectrum line wavelength. The method of controlling the temperature of a semiconductor wafer according to claim 4. 6. The semiconductor wafer temperature control method according to claim 4, wherein the infrared absorption spectrum line peculiar to the resist film is an absorption spectrum line near a wavelength of 8 μm due to a benzene ring. 7. The semiconductor wafer temperature control method according to claim 4, wherein a heat conduction cooling control means based on gas pressure is used for the wafer temperature control mechanism. 8. The semiconductor wafer temperature control method according to claim 4, wherein the semiconductor wafer temperature control method further comprises an electrostatic chuck mechanism for holding the semiconductor wafer. 9. The semiconductor wafer temperature control method according to claim 8, wherein the wafer temperature control mechanism uses a thermal resistance control means based on an adsorption voltage of an electrostatic chuck mechanism. 10. A semiconductor wafer temperature measuring device for measuring an in-process wafer temperature in a semiconductor wafer processing step, wherein a resist film formed on the semiconductor wafer and an infrared absorption spectral line intensity specific to the resist film are measured. And an infrared thermometer for controlling the temperature of a semiconductor wafer. 11. The infrared thermometer for measuring the infrared absorption spectrum line intensity specific to the resist film has a bandpass filter corresponding to the infrared absorption spectrum line wavelength. Semiconductor wafer temperature measuring device. 12. The semiconductor wafer temperature measuring device according to claim 10, wherein the infrared absorption spectrum line peculiar to the resist film is an absorption spectrum line near a wavelength of 8 μm due to a benzene ring. 13. A semiconductor manufacturing apparatus for processing a semiconductor wafer, a temperature measuring device for measuring an infrared absorption spectrum line intensity specific to a resist film on a wafer during a processing step by an infrared thermometer, and an output of the temperature measuring device. A semiconductor manufacturing apparatus, comprising: a temperature control unit for controlling the wafer temperature according to the above; and a wafer temperature control mechanism controlled by the temperature control unit. 14. The semiconductor manufacturing apparatus according to claim 13, wherein the wafer temperature control mechanism is a heat conduction cooling control mechanism based on gas pressure. 15. The semiconductor manufacturing apparatus according to claim 13, further comprising an electrostatic chuck mechanism that holds the semiconductor wafer. 16. A wafer temperature measuring method for measuring an in-process wafer temperature in a semiconductor wafer processing step, comprising a step of forming an organic material film on a semiconductor wafer, and an infrared absorption spectrum line intensity specific to the organic material film. And a step of measuring the temperature of the semiconductor wafer.