JPS63243826A - Optical device for temperature measurement - Google Patents

Abstract

PURPOSE:To detect the accurate temperature of even a wafer being heated by photoirradiation at all times by cooling the aperture stop of the objective in a light measurement optical system. CONSTITUTION:The temperature measurement optical system 10 provided below the center of a quartz chamber 2 consists of the objective 7 which forms an image of the wafer 5 through the aperture stop SA, the relay lens composed of two positive lens groups 8 and 9 for re-forming the wafer image obtained by the objective 7 on a detector 11, and a mirror 12 for two-dimensional scanning and a filter 13 which are arranged at a position S1 conjugate to the aperture stop. Then a cooling means 20 is provided at the periphery of the aperture stop SA and cooling water is supplied at all times by a circulation system to hold the aperture stop SA below constant temperature. Thus, the aperture stop SA of the objective is cooled to minimize heating emitted light incident directly on the temperature measurement optical system from a heating device and heating emitted light from a body to be heated by the aperture stop SA of the objective 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical device for temperature measurement, and particularly to a temperature measurement optical device for a lamp annealing apparatus used in the manufacturing process of semiconductor devices.

[Conventional technology]

2. Description of the Related Art In recent years, technology that utilizes the thermal and chemical effects of light has been adopted in the manufacturing process of semiconductor devices, and the development of light irradiation devices for this purpose has been progressing. This type of light irradiation device has high irradiation energy and
It is necessary to perform uniform heating in order to cause the chemical reaction to proceed uniformly over the entire surface of the wafer, which is the object to be irradiated. As such a light irradiation device, various configurations have been proposed, such as one in which heating bar-shaped halogen light sources of about 10 pieces each are arranged above and below the quartz chamber for the wafer to be processed in the quartz chamber.

[Problem that the invention seeks to solve]

However, regardless of the configuration of the heating device,
In order to maintain uniformity of the temperature of the wafer during heating, it is necessary to detect the temperature distribution over the entire surface of the wafer. As a special condition in the optical heating device, since the temperature measuring optical device itself is affected by optical heating, there is a problem in that it is difficult to always accurately detect the temperature during optical heating. For this reason, even if there is uneven temperature distribution on the wafer being heated, it cannot be corrected during heating, making it impossible to maintain temperature uniformity, and chemical processing by heating cannot be performed uniformly. The problem was that it was difficult.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical temperature measuring device that can always accurately detect the temperature of a wafer that is being heated by light irradiation.

[Means for Solving the Problems] The present invention provides a temperature measuring optical device having a temperature measuring optical system for measuring the temperature of a heated object heated by a heating means. An objective lens for forming an image of the object surface on the temperature detection means and an aperture stop for limiting the amount of light incident on the objective lens are provided, and a cooling means is provided for cooling the aperture stop of the temperature measuring optical system. It is something that

Further, the aperture stop can be arranged at the focal position of the objective lens on the heated object side, so that the objective lens can be configured as a telescopic link on the exit side thereof, and furthermore, the optical scanning member can be disposed within the temperature measuring optical system at the aperture position of the objective lens. It can be configured to be provided at a position conjugate with the diaphragm. It is possible to arrange a negative meniscus lens with a convex surface facing the heated object side on the heated object side of the aperture diaphragm, and in this case, this meniscus lens is also cooled by the cooling means of the aperture diaphragm. It can be done.

[Effect]

By cooling the aperture diaphragm of the objective lens in the temperature measurement optical system in this way, the heating radiation that enters the temperature measurement optical system directly from the heating device and the heating radiation from the object to be heated can be cooled to the aperture diaphragm of the objective lens. Because it is minimized by
It is possible to prevent the temperature measurement optical system itself from being heated and causing an abnormality in temperature measurement performance.

Further, by arranging the aperture stop at the focal position of the objective lens on the heated object side, the objective lens can be formed into a telescopic link on its exit side, so that the subsequent optical system can be configured in a compact size. Furthermore, if the temperature measurement optical system is configured to include a light scanning member placed at a conjugate position of the aperture stop, it becomes possible to successively measure the temperature at any position on the surface of the heated object. . The objective lens of the temperature measurement optical system is preferably placed behind the aperture diaphragm, but in order to expand the angle of view as an objective lens, the convex surface should be oriented toward the heated object side of the aperture diaphragm. By arranging a negative meniscus lens, it is possible to accurately detect a wider temperature range on the heated object. In this case, if this meniscus lens is also cooled by the cooling means of the aperture diaphragm, it is possible to prevent the meniscus lens from being heated.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a cross-sectional view showing a schematic configuration of a light irradiation device that employs a temperature measuring optical device according to a first embodiment of the present invention, and FIG. 2 shows a configuration of an annular light source used in this light irradiation device. FIG. The light irradiation device shown here is based on the configuration disclosed in Japanese Patent Application No. 61-211208 filed by the same applicant as the present application. That is, in the device disclosed in the previous application, a plurality of annular light sources are arranged concentrically around a predetermined axis corresponding to the center of the object to be irradiated, and the object is illuminated by the annular light sources arranged concentrically. It illuminates and heats a wafer as an irradiation object.

Now, in FIG. 1, a wafer 5 as an object to be irradiated is placed on a support table 6 in the center of a quartz chamber 2. As shown in FIG.

On the upper and lower surfaces of the chamber 2, a plurality of annular light sources 1a, lb, and lc are arranged concentrically about a straight line corresponding to the normal N on the center position of the wafer 5, respectively.

The three illustrated annular lights ala, 1b, and IC are arranged concentrically around a normal N corresponding to approximately the center of the wafer, as shown in FIG. In each annular light source in FIG. 2, the substantial light emitting part is indicated by a broken line.

An air supply port 4a for supplying a gas atmosphere is provided at the upper center of the chamber 2, and an exhaust port 4b is provided at the lower center. It is constructed so that a constant pressure can be maintained by the gas atmosphere.

The temperature measurement optical system IO installed at the lower center of the chamber is
An objective lens 7 forms an image of the wafer 5 through the aperture stop SA, and a detector 11 detects the wafer image formed by the objective lens.
A relay lens composed of two positive lens groups 8 and 9 for re-forming an image upward, and a two-dimensional scanning angle mirror 2 and filter 13 arranged at a conjugate position S1 with the aperture stop between the relay lenses. It is configured. Aperture diaphragm S,
is placed at the focal point of the objective lens 7 on the wafer 5 side, and the principal ray P from the wafer surface exiting the objective lens is parallel to the optical axis as shown by the broken line in the figure, forming a so-called telecenter link. A cooling means 20 is provided around the aperture stop SA, and cooling water is constantly supplied by a circulation system (not shown) to maintain the aperture stop SA below a certain temperature.

The black body radiation energy from the wafer 5 is guided to the detector 11 by the objective lens 7, two positive lenses 8°9 forming a relay lens, and the two-dimensional scanning mirror 12 disposed between them, and the two-dimensional scanning mirror 12 is rotated. By scanning the entire wafer surface, the temperature distribution over the entire wafer surface can be measured. A bandpass filter 13 is arranged between the two-dimensional scanning mirror 12 and the positive lens 9, which transmits only temperature measurement wavelengths in the wavelength range of 4 μm to 6 μm. Of the radiation directed toward the entire surface of the objective lens 7, the aperture diaphragm S
Light is blocked except for radiation reaching the opening of A, and heat generated by absorption is removed by cooling water, so the detector
This solves the problem of errors in the temperature measured on the wafer surface. Further, since the subsequent constituent members of the temperature measuring optical system are not heated, it is possible to prevent changes in the characteristics of the optical system and deterioration of performance.

As shown in the plan view of Fig. 2, annular lights arranged concentrically [
1a, lb, and lc are halogen lamps with a color temperature of about 3000°, and the emission spectrum has a distribution as shown by the solid line in FIG. 3 according to the blank radiation equation. However, since the wafer 5 is irradiated through the chamber 2 made of quartz, the wafer is irradiated with a light beam in a wavelength range of 0.3 μl to 3.5 μm, which overlaps the transmission range of quartz. Since the object to be irradiated, such as a silicon wafer, generally absorbs well up to the 0 wavelength of about 1.1 μm, it is efficiently heated by the light beam in the wavelength range that passes through the quartz chamber. 800゛～1
Similarly, a wafer heated to 500' K (500'C to 1200'C) exhibits a spectral distribution shown by the dashed line in FIG. 3 from the spectral distribution shown by the dashed line in FIG. By using the bandpass filter to set the wavelength range of 4 μm to 6 μm as the temperature measurement wavelength, it becomes possible to detect the temperature of the wafer without being affected by the irradiation light from the annular heating light source. Therefore, as optical members for the temperature measurement optical system, ZnS+Zn5e+CaFz, Ge, S+, etc., which have excellent transmittance in the above temperature measurement wavelength range, are recommended.
It is necessary to construct it from materials such as

Since the semiconductor wafer 5 as the object to be irradiated has different heat conversion and heat radiation conditions of light energy depending on the past process, lot, gas atmosphere, etc., in this embodiment, the semiconductor wafer 5 is constantly irradiated by the 1i11 temperature optical system 10 capable of two-dimensional scanning. The temperature of the entire surface of the irradiated object is measured, and the temperature before each annular light source is controlled in order to control the absolute value and uniformity of the temperature.

In the configuration of the above embodiment, since light is irradiated by concentrically arranged annular light sources, the shape of the light source is rotationally symmetrical with respect to the center of the irradiated object, and the wafer is approximately rotationally symmetrical. It is possible to uniformly illuminate the wafer, and it is possible to uniformly perform heating and chemical reactions by light irradiation over the entire surface of the wafer. By independently controlling the amount of light emitted from each annular light source, it becomes possible to heat the irradiated object while maintaining a uniform temperature over the entire surface.

Since the light source has a rotationally symmetrical shape consisting of an annular light source arranged concentrically facing the irradiated object, the temperature measuring optical system can be arranged at the center of the annular light source as in the above embodiment. By arranging the irradiated object on the central axis of the annular light source, it becomes possible to optically observe the surface of the irradiated object from the central axis of the irradiated object in a non-contact manner. When using a chamber for irradiating light while placing an object to be irradiated in a specific gas atmosphere, a supply/exhaust port for supplying and exhausting gas into the chamber can be provided through approximately the center of the annular light source. Since the gas can be supplied and exhausted from the center of the irradiated object, it is extremely advantageous in maintaining the uniformity of the chemical reaction caused by the gas. Furthermore, as an annular light source, it is difficult to realize a light source in which the light emitting part is continuous over the entire circumference as shown in Fig. It is preferable to form a light source, and it is also possible to combine a plurality of linear light sources into an annular shape.

FIG. 4 is a diagram showing a schematic configuration of a second embodiment of the temperature measuring optical device according to the present invention, and a light source for heating the wafer 5 is not shown. In this embodiment, the wafer image formed by the objective lens is transferred to the first relay lens R3 and the second relay lens R3.
2 to the detector 11. Fourth
In the figure, the lens group constituting the temperature measurement optical system 30 is shown as a thin-walled system, and members having substantially the same functions as those of the first embodiment shown in FIG. 1 are given the same reference numerals. The radiant infrared light from the wafer 5 passing through the aperture stop S is condensed by the objective lens 7 to form an image of the wafer on the image plane I0. Image surface ■. The light flux from is re-imaged onto the image plane [,
Furthermore, a second relay lens R consisting of positive lenses 14 and 15
2 on the detector 11.

In this second embodiment, since the distance from the objective lens 7 to the detector 11 can be increased by the two relay lenses R1 and R2, it is possible to install the detector further away from the heating device. Since the influence of the heating source on the detector can be prevented, temperature measurement accuracy can be improved, and the degree of freedom in configuring the heating device and the temperature measurement device can also be increased. Here, the first relay lens R,
A conjugate position S1 of the aperture stop SA is formed between the two positive lens groups 8.9, and a second conjugate position S2 with the aperture stop SA is formed between the two positive lenses 14.15 of the second relay lens R1. is formed, and a two-dimensional scanning mirror 12 is placed at this position. A field stop S is arranged on the image plane 11 formed by the first relay lens R3.
By forming the surface on the detector side of , into a mirror surface, it is possible to obtain a lucidus signal from the detector, and it is also possible to obtain a position detection signal of the two-dimensional scanning mirror 12.

FIG. 5 shows the temperature measuring optical system 30 of the second embodiment shown in FIG.
FIG. 2 is an optical path diagram showing a practical lens configuration having the configuration. As shown in the figure, the objective lens 7 has a negative meniscus lens 7a disposed on the wafer 5 side of the aperture stop S with a convex surface facing the wafer side, and a negative meniscus lens 7a disposed behind the aperture stop S with a concave surface facing the aperture stop side. A positive meniscus lens 7b and a biconvex positive lens 7c whose convex surface faces toward the aperture stop, a positive meniscus lens 7d whose convex surface faces toward the aperture stop, and a wafer image ■. It is constituted by a negative meniscus lens 7e with a convex surface facing the aperture stop side arranged on both sides of the lens. Since the objective lens 7 has a negative meniscus lens 7a on the wafer 5 side of the aperture stop SA, the objective lens 7 can be configured to have an extremely wide angle of view.
It is also possible to accurately detect the temperature in the periphery of the wafer 5. The positive lens 8 constituting the first relay lens R1 is composed of a positive meniscus lens convex toward the detector side, and the positive lens group 9 of the first relay lens R is composed of a positive lens 9a and a meniscus lens having a convex surface facing the wafer side. It is composed of a lens 9b. The positive lens group 14 constituting the second relay lens R2 includes a meniscus lens 14a convex toward the detector side and a positive lens 14b.
and a positive lens group 15.

Here, the rear positive lens group 9 of the first relay lens R and the front positive lens group 14 of the second relay lens R2 are configured symmetrically with respect to the field stop S, and the conjugate position S of the aperture stop SA, and S2 are formed in an imaging relationship of equal magnification. By two-dimensionally rotating the two-dimensional scanning mirror I2 placed at the conjugate position S2 of the aperture stop SA, infrared radiation from any position on the wafer 5 surface can be guided to the detector 11. It is possible to detect the temperature at each position. In FIG. Also, points Q and e on the periphery of the wafer
The state of the image-forming light rays is shown by broken lines. still,
It is also possible to scan the entire surface of the wafer along the orthogonal coordinates by using the two-dimensional scanning mirror 12 as a one-dimensional scanning mirror and by providing another one-dimensional scanning mirror at a position S that is conjugate with the aperture stop. . Further, by configuring one one-dimensional scanning mirror and the detector to be integrally rotatable about the optical axis of the objective lens, it is possible to scan the entire wafer surface along polar coordinates.

All of the lens members constituting the temperature measurement optical system 30 must be made of a +1 material that can sufficiently transmit infrared light in the temperature measurement wavelength range. In order to prevent the meniscus lens 7a located on the wafer side from being heated by the heating irradiation light, it needs to be made of a material that also transmits the heating irradiation light well. For this reason,
The meniscus lens 7a closest to the wafer is made of ZnS (zinc sulfide).

It is preferable to select Zn5e' (zinc selenium) and CaFz (calcium fluoride).
nS is used. The reason why we adopted a material with good thermal conductivity for the lens closest to the wafer is to facilitate heat exchange when this lens is also cooled by the aperture diaphragm cooling means described later, and to enhance the effect of preventing the lens from overheating. be. Further, the surface of the meniscus lens 7a is treated with a thin film that covers the temperature measurement wavelength range of 4 to 6 μm and reflects heating irradiation light of 1.1 μm or less. As for the meniscus lens 7a with 11 Vc, there is no need to take into account the influence of the heating irradiation light, so a material with a high refractive index is selected to improve the imaging performance, and a material with a high refractive index is selected for the positive lens.
(germanium), and ZnS is used for the negative lens 7b and meniscus lenses 9b and 14a.

6 is a cross-sectional view showing a specific configuration of the cooling means 20 for the aperture stop SA in the temperature measurement optical system 30 shown in FIG. 5, and FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG. It is. The cooling water supplied from the cooling water supply pipe 22a is passed through the aperture diaphragm S.
The water is injected into the hollow part 21a in the cooling tube 21 that supports the negative meniscus lens 7a closest to the wafer of the objective lens, as shown by the arrow in the figure, and is diverted around the aperture stop SA and passed through the drain pipe 22b. After being drained and cooled via a heat exchanger (not shown), the water is circulated to the water supply pipe 22a.

The cooling cylinder 21 is made of a metal such as copper that has excellent thermal conductivity, and can efficiently exchange heat using cooling water as a refrigerant. As shown in the figure, the aperture stop S is configured as a conical surface forming a hollow part 21a in the cooling cylinder 21, and the absorbed heat of the heating irradiation light shielded here is cooled by cooling water supplied to the hollow part 21a. and a constant temperature is maintained at all times. Further, the support portion of the negative meniscus lens 7a located closest to the wafer is also configured to serve as the side surface forming the hollow portion 21a of the cooling cylinder 21, and this meniscus lens 7a can also be sufficiently cooled.

In the configuration of the second embodiment described above, since the aberration of the pupil of the objective lens 7 is large, the luminous flux of all angles of view is restricted at the conjugate position S1 of the aperture diaphragm SA, and the aperture diaphragm SA of the objective lens is slightly large. Open aperture is set. Therefore, the diaphragm disposed at the conjugate position of the aperture diaphragm SA functions as a second aperture diaphragm to ultimately limit the heating irradiation light. For this reason, there is a possibility that the second aperture stop S also generates heat, and in the above embodiment, as shown in FIG. 6, the second aperture stop S1 is also configured to be cooled to some extent. That is, the cooling tube 21 is connected to the other lens element 7b of the objective lens.
, 7c, 7d, 7e, 1st L/-'v 7 (
7) The front positive lens 8 and the second aperture stop Sl are supported inside, and it is possible to cool them integrally. The cooling u-tube 2I has a fixed ring 23 that allows it to emit light! ! ((
It is fixed to the support plate 24 of the main body of the shooting device.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent the measurement optical system from being heated during heating by the heating irradiation light, so that accurate temperature detection of the wafer being heated is always possible.

In addition, by configuring the objective lens of the temperature measurement optical system as a telescopic link on the exit side, the configuration of the optical system can be made compact, and by installing a scanning mirror and widening the angle of the objective lens, a wide area can be seen on the wafer heating object surface. It becomes possible to measure temperatures over a wide range of areas.

Furthermore, in the configuration of the above embodiment, the entire surface of the wafer can be uniformly irradiated by a plurality of annular light sources arranged concentrically, and crystallinity can be detected in real time by the temperature measuring optical device according to the present invention. By controlling the light emitting side of each of the multiple annular light sources arranged concentrically according to the temperature distribution on the surface of the heated object, it is possible to maintain a uniform temperature distribution at all times and perform uniform heat treatment. A light irradiation device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the configuration of a light irradiation device employing the first embodiment of the temperature measuring optical device according to the present invention, and FIG.
FIG. 3 is a plan view showing the arrangement of the circular light source in the configuration shown in the figure; FIG. 3 is a diagram showing the characteristics of the radiation type of the blank; FIG. 5 is an optical path diagram showing a practical lens configuration of the temperature measuring optical device of the second embodiment shown in FIG. 4, and FIG. 6 is a sectional view showing the configuration of the cooling means of the second embodiment. Figure 7 is the ■− of Figure 6.
■It is an arrow sectional view. [Explanation of symbols of main parts] 5...Object to be heated (wafer) 7...Objective lens SA...Aperture stop 20...Cooling means 1
1...Infrared detector 12...Scanning mirrors la, lb, Ic, 1d-Annular light source N...Concentric center of annular light source (normal to the center of the wafer) Applicant: Agent of Nippon Kogaku Kogyo Co., Ltd. Patent Attorney Takashi Watanabe 0.2 to 4. OG, o 20. OElt
[(,um, Fig. 5 22q Fig. 7

Claims (1)

[Scope of Claims] 1) In a temperature measuring optical device having a temperature measuring optical system for measuring the temperature of a heated object heated by a heating means, the temperature measuring optical system is configured to generate an image of the surface of the heated object. It has an objective lens formed on the temperature measurement detection means, an aperture diaphragm for limiting the amount of light incident on the objective lens, and a cooling means for cooling the aperture diaphragm of the temperature measurement optical system. Temperature measurement optical device. 2) The temperature measuring optical device according to claim 1, wherein the aperture stop is arranged at a focal position of the objective lens on the side of the object to be heated. 3) The temperature measuring optical device according to claim 1, wherein the temperature measuring optical system includes a light scanning member disposed at a conjugate position of the aperture stop. 4) The objective lens of the temperature measuring optical system has a meniscus lens on the heated object side of the aperture stop with a convex surface facing the heated object side, and the cooling means also cools the meniscus lens. A temperature measuring optical device according to claim 1.