JPH0513355A - Lamp annealing device - Google Patents

Abstract

PURPOSE:To uniformize the temperature increase of a wafer by controlling the calorific power of a plurality of lamps provided on the rear plane of the wafer based on temperatures at the parts on the wafer surface, which are measured by a two-dimensionally arranged temperature detecting element. CONSTITUTION:A plurality of cylindrical lamps 1 are lined up in flat facing top and a wafer 4 is arranged on a supporting plate 6 placed above by permitting the pattern forming plane of the wafer to face top. The wafer 4 is heated by a water-cooling or air-cooling reflecting plane 2 having quartz windows 3 provided between the lamps 1 and the supporting plate 6. A radiation thermometer 9 is arranged outside of a transmitting window 8 provided on the wafer 4, the temperature is measured by the radiative infrared rays of the wafer 4 and based on the converted inner plane temperature distribution of the wafer 4, the size of an opening is adjusted by a restrictor 31 so as to balance the heat release quantity from the side plane 41 with the heating quantity. The uniform temperature increase from the rear plane to the front plane whose heat absorbing rates are almost fixed is allowed without a pattern and uniform heat treatment is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp annealing apparatus used for oxidation, diffusion of impurities, annealing, etc. in a semiconductor manufacturing process, and in particular, a lamp annealing apparatus having a structure suitable for uniformly treating the temperature within a wafer surface. Regarding the device.

[0002]

2. Description of the Related Art The process of heat-treating a silicon wafer in a semiconductor manufacturing process tends to shorten the processing time because of the necessity of fine processing due to high integration of LSI. Also,
As the diameter of the wafer to be processed increases, the demand for uniform wafer temperature becomes more severe. In response to this, a single-wafer processing apparatus that processes one wafer at a time is becoming mainstream, instead of a batch-type apparatus that processes a plurality of wafers at a time, which has been conventionally used. This is because the temperature difference between wafers in the batch type apparatus increases as the processing for a short time becomes necessary. However, although the temperature difference between the wafers is improved by using the single-wafer processing apparatus, the temperature distribution in the wafer surface must be reduced. A typical example of such a single-wafer type apparatus is a lamp annealing apparatus. Since the wafer is rapidly heated by using the halogen lamp or the arc lamp light source, the processing can be performed in a short time. However, introduction of the lamp annealing apparatus into a mass production line has problems such as poor temperature uniformity within the wafer surface and reproducibility of processing temperature, or occurrence of slip lines. In order to deal with these problems, the following improvements have been made in the lamp annealing apparatus.

(1) Optimization of lamp illuminance distribution Since the wafer radiates more heat from the periphery than from the center, if the amount of heat generated by the lamp is made uniform, the temperature in the periphery becomes lower than in the center. Generally, a plurality of lamps are divided into zones to increase the heat generation amount of the lamps for heating the peripheral portion of the wafer. Also,
In the invention described in Japanese Patent Laid-Open No. 1-319934, a ring-shaped auxiliary heating lamp having a variable heat generation amount is provided around the wafer. In the invention described in Japanese Patent Application Laid-Open No. 1-238116, a transmittance variable filter is installed between the lamp and the wafer to correct the illuminance distribution on the wafer.

Further, in the invention disclosed in Japanese Patent Laid-Open No. 61-237431, a wafer is placed on a single crystal silicon disk having a recess at the center, and the wafer is heated together with the silicon disk. Since the wafer is contained in the recess of the silicon disk, heat radiation from the outer peripheral side surface can be reduced. Furthermore, Japanese Patent Application Laid-Open No. 62-12 has aimed at achieving the same effect as the present invention.
There is an example in which a guard ring is provided on the outer periphery of a wafer as shown in Japanese Patent No. 8525. Also, JP-A-63-257221
The technique disclosed in JP-A No. 9-49 is to reversely utilize the temperature decrease due to the contact of the support tool described in the next section, to support only the central portion of the wafer to make the temperature uniform.

(2) When the wafer is rapidly heated by the wafer support lamp, the shape and material of the support greatly affect the in-plane temperature distribution of the wafer. For example, quartz, which is most commonly used as a material for a support, hardly transmits infrared rays having a wavelength of visible to 4 μm, and thus is harder to heat than a silicon wafer. In addition, if the supporting tool is made of another material that easily absorbs infrared rays, such as silicon or silicon carbide, the heat capacity becomes larger than that of the wafer, and therefore the temperature of the wafer in the portion in contact with the supporting tool is unlikely to rise. In order to prevent this, the shape of the support (a structure in which the wafer is supported by thin pin-shaped projections) has been devised so that the area in contact with the wafer is as small as possible.

[0006] Instead of that, Japanese Patent Laid-Open No. 1-2966
No. 18, which continuously supports the peripheral portion of the wafer as in the invention described in Japanese Patent Laid-Open No. 71120/1988, the wafer is mounted on a thin plate magnet as in the invention described in Japanese Patent Laid-Open No. 64-71120 and placed in a chamber. There are inventions such as magnetic levitation. As another example, there is a method in which a gas is blown to the back surface of the wafer to float the wafer.

(3) Wafer Temperature Measurement In order to make the temperature of the wafer uniform, it is necessary to precisely control the heating value of the lamp. The heating value distribution of the lamp that minimizes the temperature distribution within the wafer surface changes depending on many parameters such as the type of wafer, the processing temperature, the time from the start of processing, the control method, and the device structure. Therefore, it is necessary to control the heat generation amount while measuring the temperature of the wafer moment by moment (feedback control). For that purpose, a technique for accurately measuring the temperature of the wafer is important. For temperature measurement, non-contact measurement is desired to prevent contamination of the wafer, and in many cases a radiation thermometer is used. In order to measure the temperature of a wafer with an emissive thermometer, the two problems of "the lamp light is not detected by the emissive thermometer" and "correction of the measured value for wafers with different emissivities" are solved. There must be.

In the former, the temperature of the lamp is considerably higher than that of the wafer (for example, the temperature of the lamp is 1500 to 2000 ° C.,
The wafer is about 1000 ° C.), and the latter is necessary because the emissivity is different because the surface condition of the wafer is different in various processes. Conventional methods to solve these problems are
Electronic Materials March 1990 issue, or JP-A-1-296
No. 617 and JP-A-60-131430. That is, the wavelength emitted from the lamp is 4μ
In this method, infrared rays of m or more are removed by utilizing the absorption of a quartz window, and the temperature of the wafer is measured using a radiation thermometer that detects infrared rays of 4 μm or more in wavelength. When the temperature of the quartz window rises, infrared rays re-emitted from the quartz window have an influence, so that the quartz window is cooled to, for example, 500 ° C. or lower so as not to be re-emitted. The technique described in Japanese Patent Application Laid-Open No. 60-131430 is an invention characterized by exactly eliminating the influence of lamp light by this method. The invention described in Japanese Patent Application Laid-Open No. 1-296617 is devised so that the quartz window is doubled to facilitate cooling and to make the above-mentioned effect more remarkable.

In the example shown in the electronic material March 1990 issue,
Since an arc lamp is used for the lamp and the wavelength of 2 μm or more is hardly emitted, the measurement wavelength is set to 3 μm. As described above, conventionally, by using the radiation thermometer which basically detects a wavelength different from the light of the lamp, that is, a wavelength of 3 to 4 μm or more, the influence of the lamp light is prevented.

The problem with the wafer emissivity is that the electronic material 1
It is described in the March 990 issue. Since the measurement wavelength of the radiation thermometer is 3 μm, the emissivity of the wafer changes with temperature. Therefore, the relationship between the temperature and the emissivity is obtained using a reference wafer having a thermocouple embedded therein, and the measured value of the radiation thermometer is corrected based on this. Further, there is a problem that the emissivity of a wafer on which various films are formed changes due to interference of light in the films. In order to deal with this, the emissivity is estimated from the reflectance measured before the process using a black body radiation source and an infrared detector.

[0011]

SUMMARY OF THE INVENTION The present invention is to solve the following problems in the prior art described above.

(1) Nonuniformity of wafer surface temperature due to pattern This problem is caused by "LSI of 1988 No. 6".
Substrate thermal stress simulation ". The rate at which the light of the lamp is absorbed by the pattern of the LSI formed on the surface varies within the wafer surface. Further, during rapid heating with a lamp, since the thickness of the wafer is as thin as 1 mm or less, it is difficult to make the temperature uniform due to heat conduction. Therefore, the temperature of the portion that absorbs the lamp light well rises rapidly, and the temperature of the portion that does not absorb much heat rises slowly. For the above reasons, in a device that heats the wafer from the side where the pattern is formed, temperature distribution is likely to occur in the surface of the wafer, and it is not sufficient to divide the lamp into appropriate zones and adjust the heat generation amount.

(2) Local temperature nonuniformity in the vicinity of the outer peripheral portion of the wafer The temperature nonuniformity in the outermost peripheral portion of the wafer is mainly due to the fact that the heat transfer area increases by the side portion of the wafer. This will be described with reference to FIG. Looking at the in-plane temperature distribution of the wafer when the amount of heat generated by the lamp is made uniform, the heat dissipation due to radiation increases from the center to the outer periphery, so the temperature decreases toward the periphery of the wafer. In order to prevent the temperature from decreasing in the periphery, it is necessary to divide the lamp into a plurality of zones and increase the amount of heat generated in the periphery. However, since the outer circumference of the wafer has a large amount of heat transfer area corresponding to the side surface, increasing the heat generation amount in the peripheral zone makes the temperature distribution of the wafer approximately uniform, but the temperature rises only in the outermost circumference. Occurs.

(3) Wafer Support The local temperature decrease of the wafer by the support tool is caused mainly by the large heat capacity of the support tool and its local contact with the wafer. The problem is simple if the heat capacity of the support can be made small enough to be ignored, but it is not possible to make the support extremely small or to make the contact portion thin in consideration of the rigidity for supporting the wafer. Also, the material of the support tool should not contaminate the wafer, and is therefore limited to quartz, silicon, silicon carbide (SiC) and the like.

Among the above-mentioned prior arts, the one in which the wafer is placed on the thin disk and magnetically levitated in the chamber is essentially likely to contaminate the wafer because of the magnetic material. This is because most of them are metals, and it is considered that the metal element diffuses in the wafer when the wafer is placed on the wafer and heat-treated. Further, in the case of blowing a gas to levitate the wafer, the fact that the temperature of the portion where the gas is blown is lowered by convective heat transfer is not considered. The one that continuously supports the peripheral portion of the wafer can solve the problem that the temperature becomes locally low. However, if the diameter of the wafer is increased from φ150 mm to φ200 mm, there is a high possibility that problems such as deformation of the wafer during heat treatment due to stress due to its own weight will occur.

(4) Measurement of Wafer Temperature Distribution In the prior art, it is essentially difficult to measure the temperature of the wafer by using a radiation thermometer having a measurement wavelength of 1 μm or more. That is, the emissivity of the wafer changes with temperature at a wavelength of 1 μm or more. Therefore, it is necessary to obtain the relationship between the temperature and the emissivity using the reference wafer as shown in the literature of the electronic material March 1990 issue.
However, even if the relationship between temperature and emissivity is known for the reference wafer, that relationship does not always apply to wafers having various films formed on their surfaces. In many cases, this is not the case. This is because the emissivity of the film of polycrystalline silicon, SiO2, Si3N4, W, etc. formed on the surface does not always show the same temperature dependence as that of the silicon wafer as the base material. Therefore, it is difficult to accurately correct the temperature dependence of the emissivity by the method using the reference wafer. There is also a problem with the reflectance measurement method for correcting emissivity change due to film interference. That is, 1 μm
This is because no consideration is given to the fact that at the above wavelengths, the wafer at room temperature transmits infrared rays and the emissivity cannot be obtained even if the reflectance is measured. In order to use a radiation thermometer having a measurement wavelength of 1 μm or more, it is necessary to measure the wafer emissivity during processing (simultaneously with temperature measurement), not before processing. However, this is not possible due to the problems described below.

The wafer surface on which the reflectance is measured (that is, the surface on which the emissivity value needs to be known in order to measure the temperature with the radiation thermometer) is not always smooth. For example, when measuring the back surface of the wafer, it must be noted that the back surface is not polished unlike the side on which the pattern is formed and has a surface roughness of about 1 to 2 μm and is not a mirror surface. It is easy to measure the reflectivity of a specular surface, but it is difficult to measure the reflectivity of a surface that exhibits diffuse reflective properties. This is because the integrating sphere must be used. As the integrating sphere, a hemispherical mirror, a parabolic mirror, an ellipsoidal mirror or the like whose inner surface is coated with a metal having a high reflectance such as aluminum or gold is used. Therefore, the reflectance cannot be measured while the wafer is being heat-treated. The surface on which the pattern is formed (front side) has an initial surface roughness of 0.1 to 0.2 μ.
It can be regarded as a mirror surface at about m. However, when a complicated pattern is formed, the surface roughness increases, so that it cannot be called a mirror surface. Therefore, there is no choice but to use the integrating sphere for the reflectance measurement on the front side of the wafer.

Further, in order to make the temperature within the wafer uniform, it is necessary to control the heat generation amount of the lamp divided into a plurality of zones to be optimized on the spot. This requires a wafer temperature distribution, that is, two-dimensional temperature information.
However, in the conventional lamp annealing device,
I was just measuring the temperature of the spot. Instead of measuring the temperature distribution of the wafer during processing, a method is used in which the optimum heat generation distribution is determined by experimentally repeating heating and temperature measurement using a reference wafer in which a plurality of thermocouples are embedded. Alternatively, in the experiment, treatments such as oxidation and annealing are performed, and the optimum heat generation distribution is determined so as to minimize variations in the oxide film thickness and sheet resistance. However, this method is not suitable for mass production processes that have to process a wide variety of wafers. This is because it is necessary to obtain an appropriate heat generation distribution each time the type of wafer changes.

A first object of the present invention is to provide a lamp annealing apparatus having an apparatus structure in which it is easy to make the temperature within the wafer uniform.

A second object of the present invention is to easily uniformize the temperature within the wafer surface in the lamp annealing apparatus, and at the same time, to cope with the increase in the diameter of the wafer and reduce the stress applied to the wafer during processing. The purpose is to provide a holding structure.

Further, a third object of the present invention is to provide a temperature measuring means for accurately detecting the temperature within the wafer surface in the lamp annealing apparatus.

[0022]

In order to achieve the first object, a lamp annealing apparatus of the present invention comprises a plurality of lamps for heating a wafer placed on a support, and the lamps. In a lamp annealing apparatus comprising a temperature measuring means for measuring the temperature of the surface of the heated wafer on which the pattern is formed, and a control means for controlling the heat generation amount of the lamp based on the temperature measured by the temperature measuring means, The lamp is installed only on the back side of the wafer, and the temperature measuring means is a radiation thermometer in which temperature detecting elements are two-dimensionally arranged.

Further, in order to achieve the above second object,
Another lamp annealing apparatus of the present invention is a plurality of lamps for heating a wafer placed on a support, and a temperature measuring means for measuring the temperature of the surface of the wafer heated by the lamps on which the pattern is formed. And a control means for controlling the heating value of the lamp based on the temperature measured by the temperature measuring means, the lamp is installed only on the back surface side of the wafer, and the temperature measuring means is two-dimensional. The support is a support plate that transmits visible light or infrared light having a wavelength that mainly contributes to the heating of the wafer, and that contacts substantially uniformly over the entire back surface of the wafer. It is characterized by becoming.

In another lamp annealing apparatus of the present invention, it is preferable to use a flat plate or a flat plate having an upper surface and a peripheral portion whose thickness decreases toward the periphery. Further, in the lamp annealing apparatus and another lamp annealing apparatus of the present invention, a squeezing mechanism for adjusting the irradiation range of the light of the lamp is provided between the plurality of lamps and the supporting plate, and in addition, the wafer is provided inside the radiation thermometer. A similar field stop should be provided.

Further, in the lamp annealing apparatus and another lamp annealing apparatus of the present invention, the supporting plate has a substantially outer shape similar to that of the wafer, and a shielding means for shielding the light of the lamp from the field of view of the radiation thermometer around the supporting plate. May be provided.

Further, in order to achieve the above third object,
Still another lamp annealing apparatus is a control means of the lamp annealing apparatus and another lamp annealing apparatus of the present invention,
Correction for correcting the measurement value of the radiation thermometer based on the emissivity distribution data of the wafer created from the shape of the pattern of the wafer, the reflectance of the portion where the pattern is formed, and the reflectance of the base portion of the wafer It is characterized by the provision of a section.

[0027]

In the lamp annealing apparatus of the present invention, the plurality of lamps heat the wafer from the back surface side opposite to the surface on which the pattern is formed, and the temperature measuring means uses the two-dimensionally arranged temperature detection elements to form the wafer pattern. The temperature of each part of the formed surface is measured, and the control means increases the calorific value of the lamp corresponding to the part where the temperature rises slowly based on the temperature measurement value of each part of the wafer from the temperature measuring means, and the predetermined value of the wafer is obtained. Since the heating temperature is controlled so as to reach the above heating temperature, the temperature of the wafer rises uniformly from the back surface to the front surface where the heat absorption coefficient in which the pattern is not formed is substantially constant.

In addition, in another lamp annealing apparatus of the present invention, a plurality of lamps heat the wafer from the back surface side, and the temperature measuring means has a two-dimensionally arranged temperature detection means, as in the lamp annealing apparatus of the present invention. The element measures the temperature of each part of the surface of the wafer, and the control means controls the heating value of the lamp based on the measured temperature value of each part of the wafer to raise it to a predetermined temperature, and the support plate heats the wafer. Since it transmits visible light or infrared rays having a wavelength that mainly contributes to the back surface of the wafer and is placed in contact with the flat surface above the entire back surface of the wafer, the back surface of which the heat absorption rate is almost constant without pattern formation. From the surface to the surface, the temperature of the wafer rises uniformly, and the wafer is not locally deformed due to thermal stress or self-weight, so that no deformation occurs.

Further, in each of the above lamp annealing devices, when a supporting plate having a thin peripheral portion is used, the peripheral portion of the supporting plate has a smaller heat capacity than a thick central portion, and heat absorption from a heated wafer is reduced. It reduces the temperature drop in the peripheral area caused by heat radiation from the outer peripheral surface. Further, the squeezing mechanism can adjust the amount of heating to the outer peripheral side surface of the wafer by changing the size of the opening, thereby reducing local temperature nonuniformity near the outermost periphery of the wafer. You can Since the field stop provided inside the radiation thermometer is similar in shape to the wafer, the temperature measuring means can be adjusted to measure only the temperature of the wafer. Since the shielding means shields the light of the lamp, which wraps around the wafer from the outside from the outside, from the field of view of the radiation thermometer, the radiation thermometer is not affected by the light of the lamp, and the accuracy of the temperature measurement value of the wafer can be improved.

Further, in still another lamp annealing apparatus, the correction unit radiates the wafer created from the shape of the pattern of the wafer and the reflectance of the portion where the pattern is formed and the reflectance of the base portion of the wafer. Since the measured value of the radiation thermometer is corrected based on the rate distribution data, the temperature distribution of the wafer can be known accurately when processing any type of wafer, and the temperature of the wafer becomes more uniform during processing. It enables various feedback control.

[0031]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 is a sectional view of a lamp annealing apparatus showing a first embodiment of the present invention. Lamp 1, reflector 2, quartz window 3, wafer 4, chamber 5, support plate 6, support base 7,
It is composed of a transmission window 8 and a radiation thermometer 9. A plurality of cylindrical lamps 1 are arranged in a plane shape facing upward, and a wafer 4 is placed on a support plate 6 facing and placed above the wafer 4 with the back surface opposite to the surface on which the pattern is formed facing down. The wafer 4 is placed and heated through the quartz window 3 provided between the lamp 1 and the support plate 6. A water-cooled or air-cooled reflector 2 below the lamp 1.
Is provided, and in addition to the direct light of the lamp 1, the wafer 4 is irradiated with reflected light and used for heating. The reflector 2 has a semicircular, semielliptical, parabolic or flat cross section. The supporting plate 6 is preferably made of quartz which transmits visible light or infrared rays which mainly contributes to heating of the wafer, and the edge portion of the supporting plate 6 is also held by a supporting base 7 made of quartz, silicon or SiC. Although the support base 7 shown in FIG. 1 has a cylindrical shape, it may have any shape as long as it can support the peripheral portion of the support plate 6.

The entire back surface of the wafer 4 contacts the support plate 6,
The lamp is heated by infrared rays radiated from the lamp 1 and transmitted through the quartz window 3 and the support plate 6 to be visible to 4 μm. Since the heat radiation from the wafer 4 to the support plate 6 due to the heat conduction becomes substantially uniform over the entire surface of the wafer 4, the temperature rise of the wafer 4 is not locally delayed. Further, since the light from the lamp 1 is applied only to the back surface of the wafer 4, an LSI pattern is formed on the front surface side, and even if the absorption rate of that portion is low (or high), the temperature within the surface is Difference is unlikely to occur.

Next, the temperature measurement will be described. Wafer 4
A transmission window 8 is provided above and a radiation thermometer 9 is installed outside the transmission window 8 to measure infrared rays emitted from the wafer 4 to measure the temperature. The transmission window 8 is made of a material such as quartz or sapphire. The radiation thermometer 9 uses a CCD image sensor as a detector and can easily measure the temperature distribution of the wafer 4 two-dimensionally. CCD
There is an application in which a radiation thermometer having a detector is applied to a plasma processing apparatus (Japanese Patent Application No. 2-236712). In the present invention, in addition to the known radiation thermometer, a field stop is added so that the light from the lamp 1 does not enter.

FIG. 2 shows the internal structure of the radiation thermometer 9. This is composed of a condenser lens 91, a field stop 96, a relay lens 92, an interference filter 94, a relay lens 93, and a CCD image sensor 95 which are sequentially arranged on the optical axis. A field stop 96 having a hole similar to the wafer 4 is installed at a position where the condenser lens 91 forms an image of the wafer 4. The interference filter 94 is installed between the relay lens 92 and the relay lens 93, and collimates the emitted light of the wafer 4 that has been condensed, and then blocks infrared rays of 1 μm or more through the interference filter 94. Since infrared rays having a wavelength of 1 μm or less that have passed through the interference filter 94 do not pass through the wafer 4, the light of the lamp 1 is CCD.
It does not reach the image sensor 95. The hole similar to the wafer 4 formed in the field stop 96 is made slightly smaller than the image of the wafer 4 formed by the condenser lens 91. Therefore, it is possible to prevent the light of the lamp 1 sneaking from the outside of the wafer 4 from being blocked by the field stop 96 and entering the CCD image pickup device 95.

The emissivity distribution of the wafer 4 is obtained as described below and used as a correction unit to correct the measurement value of the radiation thermometer 9. 1
Since the radiation thermometer 9 that detects wavelengths of μm or less is used,
The wafer 4 which does not transmit a wavelength of 1 μm or less is opaque, and the reflectance may be measured to obtain the emissivity in this wavelength range. As shown in FIG. 1, the radiation thermometer 9 measures infrared rays radiated from the surface of the wafer 4 in a direction perpendicular to the central portion of the wafer 4, whereas the peripheral portion of the wafer 4 is measured.
Infrared rays emitted obliquely to the surface will be measured. Therefore, as the emissivity, it is necessary to know not only the directional emissivity in the perpendicular direction but also the value of the emissivity at an angle corresponding to the measurement position. Here, the directional emissivity ε has a relationship of ε + ρ = 1 with the directional incident-hemispherical reflectance ρ.
After all, the directional incident-hemispherical reflectance of the wafer 4 may be measured by changing the incident angle. Hereinafter, the emissivity refers to the directional emissivity, and the reflectivity refers to the directional incident-hemispherical reflectivity.

A procedure for measuring the reflectance and correcting the emissivity using the reflectance will be described. The surface of the wafer is irradiated with light from a light source and the reflected light is measured by a detector, and the reflectance is obtained from the ratio of the intensity of the reflected light to the intensity of the irradiated light.
The angle dependency of the reflectance is measured by changing the direction of irradiating the wafer 4 with light. Considering the measurement position (that is, the measurement angle) and the surface condition at that position based on the measured reflectance,
The distribution of the emissivity within the plane of the wafer 4 is calculated. Then, the infrared image measured by the radiation thermometer 9 during the heat treatment is corrected by this emissivity distribution. Specifically, a procedure of multiplying the signal of the CCD image pickup device 95 by the calculated emissivity distribution and then converting it into temperature may be adopted.

The surface of the wafer 4 has a part having a specular reflection property and a part having a diffuse reflection property. Hereinafter, a practical configuration for measuring these reflectances will be described with reference to the drawings. FIG. 3 shows the configuration of the light source section of the apparatus for measuring reflectance.
The light of the lamp 11 is taken in from one end of the optical fiber 14 through the lens 12 and the interference filter 13, and the light emitted from the other end is collimated by the lens 15 and irradiated onto the wafer 4.
The lens 15 is housed in the light irradiation head 18. The interference filter 13 has the same characteristics as those used for the radiation thermometer 9. When the surface of the wafer 4 is a mirror surface, the light irradiation head 1 is simply attached to the normal line of the surface of the wafer 4.
It suffices to install the detector 16 at a position symmetrical to the position 8. However, when the surface of the wafer 4 is a diffusing surface, the integrating sphere 17 covers the portion of the wafer 4 irradiated with light in order to capture all the reflected light in the detector 16 as shown in FIGS.
Need to be provided.

FIG. 4 shows an integrating sphere 17 used for measuring reflected light reflected in a direction perpendicular to the surface of the wafer 4.
FIG. 5 shows an integrating sphere 17 used for measuring reflected light in an oblique direction with respect to the surface of the wafer 4.

As the integrating sphere 17, a parabolic mirror or an ellipsoidal mirror may be used instead of the hemispherical mirror. Integrating sphere 17
Is provided with an opening 171 for irradiating the light from the light source and an opening 172 for attaching the detector 16 so as to be symmetrical with respect to the normal line of the wafer 4. For this reason,
The same measurement unit can be used for both specular reflection and diffuse reflection. The direction of irradiating the wafer 4 with light is made to coincide with the angle whose emissivity is to be known. Therefore, the openings 171, 17
A plurality of integrating spheres 17 having different numbers 2 are provided. The relationship between the intensity of the light with which the wafer 4 is irradiated and the intensity of the light captured by the detector 16 is obtained in advance using a sample having a known reflectance. Thereby, the reflectance can be accurately measured regardless of whether the surface of the wafer 4 is a mirror surface or a diffusion surface, and the value of the emissivity can be known.

FIG. 6 is a sectional view showing a lamp annealing apparatus of the second embodiment according to the present invention. In addition to the configuration shown in the first embodiment, a shielding plate 10 is provided so that the light of the lamp 1 does not go around to the front side of the wafer. This shield 10
Has a donut shape in which the wafer 4 enters the inside of the shielding plate 10 with almost no space. As the material, SiC having a high heat resistance and a high infrared absorption rate may be used. The shielding plate 10 can reduce the light of the lamp 1 that goes around to the front side of the wafer 4. Therefore, less light is reflected by the surface of the wafer 4 and is sensed by the radiation thermometer 9, and the accuracy of temperature measurement is improved. For the same purpose, the chamber 5 facing the front surface side of the wafer 4 is also used.
It is also effective to blacken the inner surface of the. The chamber 5 may be made of SiC having a high emissivity.

In addition, in the third embodiment of the present invention shown in FIG. 7, in addition to the structure of the lamp annealing apparatus of the first embodiment, a thin projection 51 having a sharp tip has no gap on the inner surface of the chamber 5. It was set up like this. Protrusion 51 and protrusion 51
Since the black body condition is satisfied during this period, the light of the lamp 1 is not reflected in the direction of the wafer 4 even if this portion is irradiated. Therefore, the influence of the light of the lamp 1 can be reduced.

As a support plate for supporting the wafer 4 in FIG.
The support plate having a different surface structure from that of the lamp annealing apparatus of the first embodiment is shown. In order to prevent a local temperature drop of the wafer 4, it is preferable that the entire back surface contact the quartz plate. However, in order to reduce the dust attached to the wafer 4, it is preferable that the contact area is small. Considering this, the support plate 6A of this embodiment
Are provided with concentric slits 61 at intervals of 1 to 5 mm on the surface which the back surface of the wafer 4 contacts. Further, the support plate 6B shown in FIG. 9 is a support plate whose purpose is to make the thickness of the central portion thicker than that of the periphery so as to increase heat radiation due to heat conduction and to correct heat radiation due to radiation in the periphery.

FIG. 10 shows a fourth embodiment of the present invention. In this embodiment, in addition to the lamp annealing of the first embodiment, in order to make the temperature of the outermost peripheral portion of the wafer 4 uniform, the lamp 1 of A mechanism for changing the size of the opening for irradiating the wafer 4 with light is provided. That is, the quartz window 3 is doubled, and the diaphragm 31 for adjusting the size of the opening is provided between them. Specifically, the structure for adjusting the size of the aperture may be the same as the diaphragm of the camera. The diaphragm 31 is water-cooled or air-cooled so that the temperature of the light from the lamp 1 does not rise. The amount of heat applied to the side surface 41 is minimized when the aperture is made substantially the same as that of the wafer 4 by the diaphragm 31 (if the amount is further decreased, the temperature around the wafer 4 decreases). When the diaphragm 31 is fully opened, the amount of heat from the side surface 41 is maximized. During this time, the size of the opening is adjusted so that the amount of heat radiated from the side surface 41 and the amount of heat are balanced. Also, this is performed during processing based on the result of measuring the in-plane temperature distribution of the wafer 4.

FIG. 11 shows a fifth embodiment for obtaining the same effect. A mechanism 101 for moving the shield plate 10 up and down is attached to the shield plate 10 shown in FIG. When the amount of heat applied to the side surface 41 of the wafer 4 is large, the shield plate 10 is moved below the wafer 4 so that the side surface is not irradiated with the light of the lamp 1. When the heating amount is small, the shield plate 10 is placed on the wafer 4
Move it higher so that the sides are also illuminated.
This operation is performed while the wafer 4 is being processed.

[0046]

According to the present invention, the lamp annealing apparatus is heated by the plurality of lamps only from the back surface side of the wafer, and the temperature measuring means two-dimensionally measures the temperature of each part on the front surface of the wafer, and the control means. Is configured to control the wafer to reach a predetermined heating temperature based on the temperature measurement values at various points of the wafer from the temperature measuring means, so that the heat absorption rate without pattern is almost constant from the back surface to the front surface. As a result, the temperature of the wafer rises uniformly, the in-plane temperature distribution of the wafer is reduced, and uniform heat treatment can be performed.

Further, in another lamp annealing apparatus of the present invention, as in the above lamp annealing apparatus, the plurality of lamps heat the wafer from the back surface side, and the temperature measuring means uses the temperature detecting elements arranged two-dimensionally. The temperature of each part of the surface of the wafer is measured, and the control means controls the heating value of the lamp based on the measured values of the temperature of each part of the wafer to raise it to a predetermined temperature, and the supporting plate mainly contributes to the heating of the wafer. Since it is configured to pass visible light or infrared rays having a wavelength of, and to be placed in contact with the entire surface of the backside of the wafer on a flat surface above it, there is no pattern formed. In addition, the temperature of the wafer rises uniformly, and the wafer is prevented from being deformed without being locally applied with an unbalanced load due to thermal stress or its own weight.

Further, in still another lamp annealing apparatus, the correction unit irradiates the wafer created from the shape of the pattern of the wafer and the reflectance of the portion where the pattern is formed and the reflectance of the base portion of the wafer. Since the measured value of the radiation thermometer is corrected based on the rate distribution data, the temperature distribution of the wafer can be known accurately when processing any type of wafer, and the temperature of the wafer becomes more uniform during processing. It enables various feedback control.

Thus, each lamp annealing apparatus of the present invention can reduce the thermal stress generated on the wafer during processing,
Even when processing a large-diameter wafer, the occurrence of slip lines can be prevented, and the yield of LSI production can be improved by improving the uniformity of oxide film thickness and the uniformity of sheet resistance.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a lamp annealing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an internal structure of a radiation thermometer.

FIG. 3 is a configuration diagram of a light source unit of the light reflectance measuring device.

FIG. 4 is a diagram showing an integrating sphere used for measuring reflected light in a direction perpendicular to the wafer surface.

FIG. 5 is a diagram showing an integrating sphere used for measuring reflected light in an oblique direction from the wafer surface.

FIG. 6 is a sectional view showing the structure of a lamp annealing apparatus according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing the structure of a lamp annealing apparatus according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view of a support plate in which a plurality of concentric circular grooves are provided in a plane. .

FIG. 9 is a cross-sectional view of a support plate having a thinned peripheral portion.

FIG. 10 is a sectional view showing the structure of a lamp annealing apparatus according to the fourth embodiment of the present invention.

FIG. 11 is a sectional view showing the structure of a lamp annealing apparatus according to a fifth embodiment of the present invention.

FIG. 12 is a temperature distribution diagram of the wafer when the amount of heat generated is uniform on the lamp surface.

FIG. 13 is a temperature distribution diagram of the wafer when the heating value of the lamp is increased in the outer peripheral portion of the wafer.

[Explanation of symbols]

1 lamp 2 reflector 3 Quartz window 4 wafers 5 chambers 6 Support plate 7 Support 8 infrared transparent window 9 Radiation thermometer 10 Shield 11 lamps 12 lenses 13 Interference filter 14 optical fiber 15 lenses 16 detector 17 integrating sphere 18 Light irradiation head 31 Aperture mechanism 61 slits 91 Condensing lens 92 relay lens 93 relay lens 94 Interference filter 95 Image sensor 96 Field stop 101 Shield moving mechanism

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Honma Mitsuru             502 Kintatemachi, Tsuchiura City, Ibaraki Japan             Tate Seisakusho Mechanical Research Center

Claims (7)

[Claims] 1. A plurality of lamps for heating a wafer mounted on a support, temperature measuring means for measuring the temperature of a surface of a wafer on which a pattern is formed, heated by the lamps, and the temperature measurement. In a lamp annealing apparatus provided with a control means for controlling the heat generation amount of the lamp based on the temperature measured by the means, the lamp is installed only on the back surface side of the wafer, and the temperature measuring means is two-dimensionally A lamp annealing apparatus comprising a radiation thermometer in which temperature detecting elements are arranged. 2. A plurality of lamps for heating a wafer placed on a support, temperature measuring means for measuring the temperature of the surface of the wafer heated by the lamps on which the pattern is formed, and the temperature measurement. In a lamp annealing apparatus provided with a control means for controlling the heat generation amount of the lamp based on the temperature measured by the means, the lamp is installed only on the back surface side of the wafer, and the temperature measuring means is two-dimensionally The support is a radiation thermometer in which temperature detection elements are arranged, the support is a support plate that transmits visible light or infrared light having a wavelength that mainly contributes to heating of the wafer, and that is substantially evenly contacted over the entire back surface of the wafer. The lamp annealing device is characterized in that 3. The lamp annealing apparatus according to claim 2, wherein the upper surface of the support plate is flat and the thickness of the peripheral portion decreases toward the periphery. 4. The lamp annealing apparatus according to claim 1, wherein a squeezing mechanism for adjusting a light irradiation range of the lamp is provided between the plurality of lamps and the support plate. 5. A field diaphragm similar to the wafer is provided inside the radiation thermometer.
The lamp annealing device according to any one of claims. 6. The support plate has an outer shape substantially the same as that of the wafer, and a shield means is provided around the support plate to shield the light of the lamp from the field of view of the radiation thermometer. The lamp annealing apparatus according to any one of 1 to 5. 7. The radiation temperature based on the emissivity distribution data of the wafer created from the shape of the pattern of the wafer, the reflectance of the portion where the pattern is formed and the reflectance of the portion where the pattern is not formed. The lamp annealing apparatus according to any one of claims 1 to 6, further comprising a correction unit that corrects a measurement value of the meter.