JP2001289714A - Temperature measurement method and measurement device of substrate and treating device of the substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately otain a temperature accurately in a temperature measuring method for measuring the temperature of a semiconductor wafer. SOLUTION: A thermal radiation light intensity distribution relative to each wavelength of thermal radiation light radiated from a heated semiconductor wafer is measured, and the wavelength, having maximum thermal radiation light intensity in the measured thermal radiation light intensity distribution is found. Thereafter, the temperature of a corresponding semiconductor substrate is found from the wavelength found. The wavelength, having the maximum thermal radiation light intensity, does not depend on the kind of a film deposited on the semiconductor wafer or the state of the wafer surface but is determined only by the temperature of the semiconductor substrate. Therefore, the temperature of the semiconductor wafer can be measured accurately, and heating treatment at the formation time of various films on the semiconductor wafer or the like can be excited satisfactorily, by heating and controlling the semiconductor wafer at a set temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the temperature of a semiconductor wafer during the processing of a semiconductor wafer, and an apparatus for processing a substrate using the temperature measuring apparatus. Alternatively, the present invention relates to a semiconductor wafer temperature measurement technique for a heating process such as resistance heating.

[0002]

2. Description of the Related Art Conventionally, a semiconductor wafer has been subjected to RTP (Rapid) using lamp heating or resistance heating.
Thermal Process), CVD (Ch)
Various heat treatments, such as forming various films on a semiconductor wafer, recovering crystal defects of a substrate, and annealing for removing substrate damage, are performed using an electronic vapor deposition (Evaporation) apparatus. The RTP apparatus heats a semiconductor wafer by utilizing the fact that the substance itself generates heat by absorbing the energy of lamp light. In the resistance heating, the semiconductor wafer is heated by using radiation or heat conduction emitted from the heater.

Although it is relatively easy to grasp the state of the heating source as described above, it is important to accurately measure the temperature of the semiconductor wafer itself during the semiconductor device manufacturing process. It was a difficult technique. Conventionally, the general method used to measure the temperature of the semiconductor wafer itself is whether it is lamp heating or resistance heating.
In general, a method is used in which infrared rays radiated from a semiconductor wafer are measured by a pyrometer, and the temperature is determined from the infrared ray intensity. That is, a calibration curve between the infrared intensity and the corresponding wafer temperature is determined in advance by experiments or the like, and then the infrared temperature of a specific wavelength is actually measured to determine the wafer temperature. However, a wide temperature range,
For example, when the wafer temperature is in the range of 500 to 1200 ° C., the temperature cannot be measured continuously.

FIG. 3 is a sectional view showing an example of a conventional RTP apparatus using lamp heating. In FIG. 1, a semiconductor wafer 11 arranged in a substantially sealed chamber 10 is
It is horizontally supported by the wafer support table 12 with its surface facing upward. The semiconductor wafer 11 is heated by a plurality of lamps 14 serving as a heating source of the RTP apparatus, particularly through a quartz plate 13 located above the semiconductor wafer 11. In order to increase the heating efficiency, a reflector 15 is provided on the side of the lamp 13 opposite to the semiconductor wafer 11, and the energy of light applied to the side opposite to the semiconductor wafer 11 is reflected by the reflector 15. Then, the semiconductor wafer 11 is configured to be reached.

To measure the temperature of the semiconductor wafer 11, heat radiation from the back surface of the semiconductor wafer 11 is transmitted through a quartz plate 13 to a heat radiation measuring device 16.
First, the intensity of the thermal radiation at a specific wavelength is measured.
The arithmetic unit 17 stores in advance data of a calibration curve between the infrared intensity obtained by an experiment or the like and the corresponding wafer temperature, and the intensity measured by the thermal radiation measuring device 16 is stored in the arithmetic unit 17. Is converted into a wafer temperature based on the data. Then, the arithmetic unit 17 sets the lamp 1 so that the temperature of the semiconductor wafer 11 becomes the set temperature.
4 is sent to the lamp control system 18 through the signal line 19. The lamp control system 18 is connected to the power supply line 2
By controlling the output of each lamp 14 through 0, the in-plane temperature distribution of the semiconductor wafer 11 is made uniform. In FIG. 3, the power supply line 20 is represented by one line.
Actually, it is connected to each lamp 14 from the lamp control system 18. The lamp control system 18 receives the power control signal from the arithmetic unit 17, controls the power of each lamp 14, and manages the semiconductor wafer 11 at a desired temperature.

[0006]

However, the method of determining the wafer temperature from the infrared intensity as in the above-mentioned conventional method has the following disadvantages. That is, the semiconductor wafer 11
Is not a perfect black body, the required temperature strongly depends on the infrared radiation efficiency of the semiconductor wafer. That is,
The temperature of the semiconductor wafer greatly varies depending on the state of the semiconductor wafer, for example, the state of formation of a single film or a laminated film such as a polysilicon, a nitride film, and an oxide film, and a measurement error of the wafer temperature occurs due to such factors. . Further, in the temperature measurement method using a pyrometer, even the infrared rays that are multiply scattered between the back surface of the semiconductor wafer 11 and the reflection plate (pyrometer mounting portion) 15 are measured, so that the measurement error of the wafer temperature is further increased. Problem, and furthermore,
In the low temperature range of about 500 ° C., the infrared radiation intensity itself is small, so that the wafer temperature cannot be measured accurately, and the temperature change is continuously measured over a wide range such as a range of 500 to 1200 ° C. There was a problem that could not be done.

[0007] For the above reasons, in order to improve the temperature measurement accuracy while using the above-mentioned conventional method, the first method is used.
In addition, it is necessary to frequently calibrate the wafer temperature in accordance with the element structure formed on the surface thereof, the type of the deposited film, and the like. However, this method causes a loss in the operation rate of the apparatus. . Secondly, it is necessary to keep the state of the back surface of the wafer constant, but this requires a redundant process that does not contribute to the original manufacturing process, such as removing the film deposited on the back surface, before the processing in the RTP apparatus. To increase the manufacturing cost.

As a measuring method other than the non-contact temperature measuring method described above, there is a method of measuring a wafer temperature by bringing a thermocouple into contact with a semiconductor wafer. This method does not depend on the surface condition of the semiconductor wafer, and can perform the thermometer side relatively accurately. However, since the heat capacity of the thermocouple is larger than that of the semiconductor wafer, rapid measurement of the semiconductor wafer such as an RTP device is possible. Poor measurement followability for manufacturing processes requiring a temperature rise or fall or short process steps. Therefore, if a thermocouple is used for the temperature measurement of the RTP apparatus accompanied by a rapid change in the wafer temperature, the thermocouple does not follow the rapid change in the wafer temperature.
Also in this case, a temperature error occurs.

Therefore, none of the conventional methods for measuring the temperature of a semiconductor wafer has sufficient accuracy and reproducibility of the temperature measurement, so that the temperature can be accurately measured during the semiconductor manufacturing process without affecting the manufacturing process such as cost. There is a problem that it is difficult to measure the wafer temperature.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a semiconductor device without depending on the state of a device structure, a film forming material, and the like formed on a semiconductor wafer.
It is an object of the present invention to provide a wafer temperature measuring method and a measuring device capable of accurately measuring a wafer temperature, and a substrate processing apparatus using the wafer temperature measuring device.

[0011]

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present inventors have conducted intensive studies. It has been found that the wavelength at which the thermal radiation light intensity becomes maximum does not depend on these states, and that this wavelength corresponds to the temperature of the substrate. Therefore, in the present invention, the wavelength at which the intensity of the heat radiation light from the substrate is maximized is determined, and the temperature of the substrate is calculated from this wavelength.

That is, a method of measuring the temperature of a substrate according to the present invention is a method of measuring the temperature of a semiconductor substrate heated by a heating means, wherein the temperature of the semiconductor substrate heated by the heating means is measured. A measurement step of measuring the intensity distribution of the heat radiation light for each wavelength, and the wavelength at which the heat radiation light intensity is maximum in the measured heat radiation light intensity distribution,
Calculating a temperature of the semiconductor substrate based on the obtained wavelength.

According to a second aspect of the present invention, in the method of measuring a temperature of a substrate according to the first aspect, the calculating step includes setting a wavelength at which the thermal radiation light intensity is maximum to λm, Where T is a constant determined by Planck's thermal radiation equation and C is a step of obtaining the absolute temperature T of the semiconductor substrate based on the following equation: λm · T = C.

Further, according to a third aspect of the present invention, there is provided a substrate temperature measuring device, wherein the heating means heats the semiconductor substrate, and the heat radiation light for each wavelength of the heat radiation light from the semiconductor substrate heated by the heating means. Measuring means for measuring the intensity distribution of, the wavelength calculating means for determining the wavelength at which the thermal radiation light intensity is maximum in the measured thermal radiation light intensity distribution, the said based on the wavelength determined by the wavelength calculating means Temperature calculating means for determining the temperature of the semiconductor substrate.

In addition, a substrate processing apparatus according to a fourth aspect of the present invention controls the substrate temperature measuring apparatus according to the third aspect and a heating means of the temperature measuring apparatus based on the obtained temperature of the semiconductor substrate. And a control unit for adjusting the semiconductor substrate to a set temperature.

According to a fifth aspect of the present invention, there is provided the substrate processing apparatus according to the fourth aspect, wherein the substrate processing apparatus includes an annealing apparatus using lamp heating or resistance heating.
It is an oxide film growth apparatus or a chemical vapor deposition apparatus.

As described above, according to the first to fifth aspects of the present invention, the thermal radiation light intensity distribution for each wavelength of thermal radiation from a heated substrate such as a semiconductor wafer is first measured, and the measured thermal radiation is measured. The wavelength at which the light intensity is maximum is determined, and the temperature of the substrate is determined based on the determined wavelength. Here, the wavelength at which the thermal radiation light intensity is maximum does not depend on the state of the film formed on the substrate or the state of the substrate surface, even if the state is different. Can be. As a result, the substrate can be appropriately heated, and the substrate temperature can be managed at the set temperature.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wafer temperature measuring method according to the present invention will be described.

The semiconductor wafer temperature measuring method of the present invention is based on the following concept. The energy of thermal radiation from a semiconductor wafer is proportional to Planck's thermal radiation equation (1) for various wavelengths. The proportionality constant is called an emission coefficient and depends on the surface condition of the semiconductor wafer.

Εdλ = 8πhc / λ ⁵ · dλ / (Exp (hc / λkT) −1) (1) ε: thermal radiation light intensity λ: wavelength T: absolute temperature h: Planck constant (6.622777 × 10 ⁻²⁷⁾ erg ・
sec) c: speed of light (2.99976 × 1010 cm · sec)
^-1 ) k: Boltzmann constant (1.38026 × 10 ^-16 er)
g · deg ⁻¹ ) FIG. 1 is a graph obtained by solving the equation (1) with respect to wavelength on the horizontal axis and thermal radiation intensity on the vertical axis. The graph in FIG.
This is an example solved for two cases of 00 ° C. and 1000 ° C. As can be seen from this graph, the wavelength λm of the thermal radiation when the thermal radiation intensity has a maximum value changes with the absolute temperature T of the substrate. The locus of the maximum value is shown by a broken line in the graph. In order to clarify the correlation between the wavelength λm and the absolute temperature T, the equation (1) is developed. Here, if x = hν / kT = hc / λkT ν: frequency, h · ν = c, the above equation (1) can be expressed as: ε = 8π / (hc) ⁴ · (kT) ⁵ · x ⁵ / (Exp
(X) -1). When the maximum value of the thermal radiation light intensity ε is obtained, x is determined as the root of d / dx · x ⁵ / (Exp (x) −1) = 0, so that xm = 4.96
It can be seen that there is a maximum at 51 ... That is, λm · T = hc / kxm = 0.2918 cm · deg≡C (2) (C is a constant determined from Planck's thermal radiation equation). FIG. 2 is a graph obtained by solving this equation for the temperature on the horizontal axis and the wavelength on the vertical axis. It can be seen that the wavelength λm is inversely proportional to the absolute temperature T, and has a long wavelength at a low temperature, but shifts to a shorter wavelength as the temperature rises. The wavelength λm of the heat radiation light which becomes the maximum value of the heat radiation light intensity distribution with respect to this wavelength
Is determined by the temperature of the object.

From the above, the method for measuring the temperature of a substrate according to the present embodiment measures the intensity distribution of heat radiation light for each wavelength of heat radiation light from a semiconductor wafer in the measurement step.
Thereafter, in the temperature calculation step of the semiconductor wafer, a wavelength λm of the heat radiation light at which the heat radiation light intensity is maximum in the measured heat radiation light intensity distribution is found, and the obtained wavelength λm
, The absolute temperature T of the substrate corresponding to the wavelength λm is obtained.

By performing such a temperature measurement, the temperature T of the semiconductor wafer is determined as apparent from the above equation.
Only the wavelength λm of the thermal radiation light is obtained, and the temperature of the semiconductor wafer can be measured if only this wavelength λm is obtained. Therefore, the influence of the back surface dependence of the wafer (such as the dependence of the film material deposited on the back surface) and the multiple scattering between the back surface of the semiconductor wafer 11 and the reflection plate 15 shown in FIG. The problem of occurrence of a temperature measurement error can be solved.

That is, in the measurement method for measuring the intensity of the thermal radiation at a specific wavelength and obtaining the wafer temperature corresponding to the thermal radiation intensity as in the conventional substrate temperature measuring method, the specific wavelength radiated from the semiconductor wafer is used. It has been difficult to accurately measure the temperature of the semiconductor wafer because the thermal radiation light intensity of the semiconductor wafer changes in accordance with the state of the wafer. Focusing on the fact that the wavelength at which the thermal radiation light intensity is maximum does not depend on this change in the wafer state, and from this point of view, the present invention uses the wavelength at which the thermal radiation light intensity from the semiconductor wafer becomes the maximum to obtain the wavelength of the semiconductor wafer. The feature is that the temperature is measured.

Since the attenuation of the radiation light intensity due to multiple scattering does not depend on the wavelength of the thermal radiation light, the attenuation coefficient based on this is constant. This attenuation coefficient is determined by physical factors such as the mounting position of the measuring instrument and the solid angle detected by the detector.

Next, a specific example of the semiconductor wafer temperature measuring method according to the present embodiment will be described with reference to the RTP apparatus shown in FIG. The temperature measurement method according to the present embodiment can basically employ a conventional RTP device.

In measuring the temperature of the wafer, a plurality of heat radiation light measuring instruments (measurement means) are arranged such that heat radiation from the back surface of the semiconductor wafer (semiconductor substrate) 11 is opposed to the semiconductor wafer 11 via the quartz plate 13. 1), the intensity distribution of the thermal radiation for each wavelength of the thermal radiation as illustrated in FIG. 1 is measured. In the example of the RTP apparatus in FIG. 3, the thermal radiation measurement devices 16 are arranged radially only on one side from the center of the semiconductor wafer 11. When one or both of the lamp 14 and the semiconductor wafer 11 are rotated in order to improve the uniformity of the in-plane temperature distribution of the semiconductor wafer 11, the entire surface of the semiconductor wafer 11 is arranged in such an arrangement. Temperature distribution can be measured. The intensity distribution signal of the thermal radiation measured at each position of the semiconductor wafer 11 by the individual thermal radiation measuring devices 16 is input to the arithmetic unit 17.

The arithmetic unit (wavelength calculating means and temperature calculating means) 17 performs an arithmetic process such as differentiation on the intensity distribution curve which has become the intensity distribution output signal of the measured thermal radiation, to calculate the thermal radiation intensity. The point at which the change becomes zero is determined, and the wavelength λm of the thermal radiation when the thermal radiation intensity reaches a maximum value is determined. The arithmetic unit 17 includes, for example, a relational expression (2) between the wavelength λm and the temperature T of the semiconductor wafer 11, or FIG.
The data as shown in the figure is built in, and the obtained wavelength λ
The absolute temperature T of the semiconductor wafer 11 can be measured from m. The apparatus shown in FIG. 3 includes a plurality of thermal radiation light measuring instruments 16.
Is installed, and the lamp 14 or the semiconductor wafer 11
Is rotated, it is also possible to obtain information on the in-plane temperature distribution of the semiconductor wafer 11, particularly the temperature distribution in the radial direction.

Further, the arithmetic unit 17 includes the semiconductor wafer 1
1 is stored, the measured temperature T on the semiconductor wafer 11 is compared with the set temperature, and based on the temperature difference, the temperature T of the semiconductor wafer 11 is set to the set temperature. Then, a command signal for controlling the power of the lamp (heating means) 14 is output from the arithmetic unit 17. This command signal is input to the lamp control system 18 through the signal line 19. Since the output of the lamp 14 is corrected by the lamp control system (adjustment control means) 18 through the power supply line 20, the uniformity of the in-plane temperature distribution of the semiconductor wafer 11 is improved. Although only one power supply line 20 is shown in FIG. 3 for simplicity, the power supply line 20 is actually connected to each of the lamps 14 from the lamp control system 18 so that power control can be performed independently. It has become.
Therefore, the in-plane temperature distribution of the semiconductor wafer 11 is measured by the plurality of thermal radiation light measuring devices 16, and the lamp 14
Can be controlled independently, and the temperature uniformity of the semiconductor wafer 11 can be improved. Semiconductor wafer 11
Examples of the processing include annealing for recovering the crystal result of the semiconductor wafer 11 using lamp heating or resistance heating, and growth of an oxide film or chemical vapor deposition on the semiconductor wafer 11.

In the above, an example of the wafer temperature measuring method in the RTP apparatus has been described in the case of the single-wafer heat treatment in which the semiconductor wafers 11 are heat-treated one by one using a lamp heating method. In the case where a resistance heating method is adopted, the same can be implemented. Further, it goes without saying that the principle of the temperature measuring method of the present invention is taken into consideration that the present invention can be applied to an apparatus other than the single-wafer heat treatment.

[0030]

As described above, according to the first to fifth aspects of the present invention, the substrate temperature of the semiconductor wafer can be accurately measured without depending on the state of film formation on the semiconductor wafer. It is possible to In the process of manufacturing a semiconductor device, the substrate temperature is accurately heated to a set temperature.
It is possible to appropriately perform various heat treatments such as formation of various films on a semiconductor wafer and recovery of a crystal defect of a substrate by management.

[Brief description of the drawings]

FIG. 1 is a diagram showing a correlation between a wavelength of heat radiation light and a heat radiation intensity.

FIG. 2 is a diagram showing a correlation between a wavelength at which the thermal radiation intensity is maximum and a temperature.

FIG. 3 is a diagram illustrating a configuration of an RTP device.

[Explanation of symbols]

 Reference Signs List 10 Chamber of RTP apparatus 11 Semiconductor wafer (semiconductor substrate) 12 Wafer support 13 Quartz plate 14 Lamp (heating means) 15 Reflector 16 Thermal radiation measuring instrument (measuring means) 17 Arithmetic apparatus (wavelength calculating means and temperature calculating means) 18 Lamp control system (adjustment control means) 19 Signal line 20 Power supply line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/31 H01L 21/31 E 21/26 T

Claims (5)

[Claims] 1. A substrate temperature measuring method for measuring the temperature of a semiconductor substrate heated by a heating means, comprising: measuring an intensity distribution of the heat radiation light with respect to each wavelength of the heat radiation light from the semiconductor substrate. And calculating a wavelength at which the thermal radiation light intensity is maximum in the measured thermal radiation intensity distribution, and calculating the temperature of the semiconductor substrate based on the determined wavelength. How to measure substrate temperature. 2. The calculation step is defined as follows: λm is a wavelength at which the thermal radiation light intensity is maximum, T is an absolute temperature of the semiconductor substrate, and C is a constant determined by Planck's thermal radiation equation. 2. The method according to claim 1, further comprising the step of obtaining an absolute temperature T of the semiconductor substrate based on T = C. Heating means for heating the semiconductor substrate; measuring means for measuring an intensity distribution of the heat radiation light with respect to each wavelength of the heat radiation light from the semiconductor substrate heated by the heating means; Wavelength calculating means for determining a wavelength at which the thermal radiation light intensity is maximum in the thermal radiation light intensity distribution; anda temperature calculating means for determining the temperature of the semiconductor substrate based on the wavelength determined by the wavelength calculating means. A substrate temperature measuring device, characterized in that: 4. A temperature measuring device for a substrate according to claim 3, further comprising: a control unit for controlling a heating unit of the temperature measuring device based on the obtained temperature of the semiconductor substrate to adjust the semiconductor substrate to a set temperature. A substrate processing apparatus. 5. The substrate processing apparatus according to claim 4, wherein the substrate processing apparatus is an annealing apparatus using lamp heating or resistance heating, an oxide film growth apparatus, or a chemical vapor deposition apparatus.