JPH08274146A - Wafer supporting member - Google Patents

Abstract

PURPOSE: To obtain a supporting member which can highly absorb light having the wavelength of a halogen lamp, can transmit absorbed heat throughout its entire body so that the member can uniformly heat a wafer, is hardly eroded by a halogenated gas, and has a long service life. CONSTITUTION: A wafer supporting member is formed of a sintered body of an aluminum nitride composed mainly of AIN containing Er2 O3 as a sintering auxiliary and Si within the range of 200-500ppm and having thermal conductivity of >=150W/mk. For example, a semiconductor wafer 20 is set on a susceptor 10 composed of a blacking purple sintered body of aluminum nitride and film forming gas is supplied to the wafer 20 while a high-frequency voltage is applied to an electrode 22 in a plasma section and upper electrode 23 for generating plasma. Then the wafer 20 is indirectly heated with a halogen lamp 30 provided below the susceptor 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a susceptor used for placing a wafer such as a semiconductor wafer or a glass substrate for LCD on the upper surface and indirectly heating it with a halogen lamp to form a film on the surface of the wafer. Etc. for a wafer support member.

[0002]

2. Description of the Related Art Conventionally, in the process of forming a film on the surface of a wafer such as a semiconductor wafer or a glass substrate for LCD, the wafer is placed on the upper surface of a disk-shaped susceptor, and a halogen lamp is indirectly used from below to form the wafer. There was one that was heated.

Further, in order to apply a film with high precision to the wafer, the wafer must be heated uniformly, and therefore,
Some of the above susceptors are made of aluminum having a high thermal conductivity.

However, the aluminum susceptor has a problem that the positional accuracy of the wafer cannot be maintained and the film deposition accuracy is impaired as the processing temperature rises because the difference in thermal expansion from the wafer is too large.

Therefore, the coefficient of thermal expansion of the wafer (4.2 × 1)
A susceptor formed of a silicon carbide based sintered body having a thermal expansion coefficient close to 0 ^-6 / ° C) and a high thermal conductivity among ceramics has been proposed.

[0006]

However, since the halide gas is used as the atmosphere gas in the film forming process, the susceptor made of the above-mentioned silicon carbide sintered body is corroded by the halide gas and is short-lived. However, there was a problem that it would end the life. Moreover, since the thermal conductivity of the silicon carbide sintered body is about 71 W / mk at the highest, the thermal conductivity is low for uniformly heating the wafer, and as a result,
There is a possibility that the film deposition accuracy of the wafer may be adversely affected.

On the other hand, today, an aluminum nitride sintered body is known as a ceramic which has a higher thermal conductivity than that of the silicon carbide sintered body and is not easily corroded by a halide gas. A susceptor formed of a body has also been proposed (Japanese Patent Laid-Open No. 5-25).
1365).

However, since the aluminum nitride sintered body generally has a milky white color, it reflects almost all of the wavelength light emitted from the halogen lamp, so that the absorptivity of the wavelength light is extremely high. It was bad. Therefore, there is a problem that the wafer cannot be heated to a temperature necessary for forming the film.

An object of the present invention is to improve the absorption of wavelength light (200 to 2000 nm) emitted from a halogen lamp by forming a wafer support member such as a susceptor from a blackened aluminum nitride sintered material, The wafer can be efficiently heated to a predetermined temperature, the absorbed heat can be transferred to the entire wafer support member to uniformly heat the wafer, and the long-life wafer support that is not easily corroded by halide gas It is to provide a member.

[0010]

In view of the above problems, the present invention provides a wafer supporting member containing AlN as a main component, Er ₂ O ₃ as a sintering aid, and Si 2
It is formed from an aluminum nitride sintered body having a thermal conductivity of 150 W / mk or more, which is contained in the range of more than 00 ppm and 500 ppm or less.

Originally, the aluminum nitride sintered body containing Er ₂ O ₃ had a pink color, but the present inventor turned black by adding Si to the aluminum nitride sintered body ( It has been found that black-purple to black) can be formed, and a wafer supporting member is formed from the blackened aluminum nitride sintered material.

Therefore, if this wafer support member is used,
The light of wavelength 200 to 2000 nm emitted from the halogen lamp can be absorbed at a high rate, and the wafer can be heated to a temperature necessary for forming a film. Moreover, since Si contained in the aluminum nitride sintered body is the same element as the material forming the semiconductor wafer and the glass substrate for LCD, there is no fear of adversely affecting the wafer.

Further, in order to form a film with high accuracy on the surface of the wafer, the wafer must be heated uniformly,
For that purpose, the thermal conductivity of the wafer support member is 150 W / m.
It must be k or more.

That is, since these wafer supporting members are heated by the halogen lamp in a state of being supported by the supporting base from below, the halogen lamp is not supported from the contact portion with the supporting base or the shaded portion formed by the supporting base. It cannot absorb wavelength light. Therefore, the thermal conductivity of the wafer support member is 1
If it is less than 50 W / mk, the heat absorbed from the other surface cannot be smoothly transferred to uniformly heat the entire wafer supporting member, and if a film is formed on a semiconductor wafer using the wafer supporting member. This is because it is not possible to form a uniform film because the film thickness of the surface of the semiconductor wafer located at the contact portion with the support base or the shaded portion formed by the support base becomes thin.

In order to set the thermal conductivity of the wafer supporting member within the above range, the content of Er ₂ O ₃ contained as a sintering aid in the aluminum nitride sintered body must be 5% by weight or more. I have to. This is because the thermal conductivity of the aluminum nitride sintered body is determined by the content of Er ₂ O ₃ which is a sintering aid, and when the content of Er ₂ O ₃ is less than 5% by weight, Er does not increase. The thermal conductivity of the aluminum nitride sintered body is 150 W / m because the content of ₂ O ₃ is too small.
This is because it cannot be set to k or more and the heat absorbed from the halogen lamp cannot be transferred to the entire wafer support member to uniformly heat the wafer. However, Er ₂ O ₃
When the content of Al exceeds 9% by weight, the thermal conductivity of the aluminum nitride sintered body can be set to 150 W / mk or more, but the amount of Er ₂ O ₃ becomes too large, so that it is eroded by the halide gas. There is a risk of receiving.

Therefore, the content of Er ₂ O ₃ contained in the aluminum nitride sintered body constituting the wafer supporting member must be in the range of 5 to 9% by weight.

20 emitted from a halogen lamp
In order to absorb the light having a wavelength of 0 to 2000 nm and efficiently heat the wafer to a predetermined temperature, it is preferable that the absorption rate of the light having the wavelength in the above range is 60% or more. It is important to set the brightness of the sintered body to 50 or less.

Here, the lightness means a standard light C as an illumination light source.
The value measured by a colorimeter (JIS Z 87
29), when the lightness is higher than 50, the aluminum nitride sintered body cannot be sufficiently blackened, so that the absorption rate of a part of the wavelength light of 200 to 2000 nm is 60% or less. This is because the wafer cannot be efficiently heated to the predetermined temperature.

Further, the content of Si contained in the sintered body is an important requirement in order to sufficiently blacken the aluminum nitride sintered body so that the brightness becomes 50 or less.

That is, if the Si content is 200 ppm or less, blackening cannot be sufficiently performed, so that the brightness is 5
This is because it cannot be set to 0 or less, and as a result, the absorptance of light having a wavelength of 200 to 2000 nm emitted from the halogen lamp cannot be set to 60% or more. However, if the Si content is more than 500 ppm, the brightness can be reduced to 50 or less, but the thermal conductivity of the aluminum nitride sintered material is significantly reduced to less than 150 W / mk, which is not preferable. . Moreover, since Si easily reacts with the halide gas as the atmospheric gas, if the content exceeds 500 ppm, Si precipitated in the grain boundary phase may react with the halide gas to promote erosion.

Therefore, the optimum range of Si contained in the aluminum nitride sintered body is preferably more than 200 ppm and not more than 500 ppm. Although it is possible to add Mo, W, or the like as a coloring agent in order to further blacken the aluminum nitride sintered body to increase the light absorptivity, if the addition amount of these coloring agents exceeds 50 ppm, nitriding will occur. Since the thermal conductivity of the aluminum-based sintered body decreases, it is desirable that the amount of the colorant added be within the range of 50 ppm or less.

Further, this aluminum nitride sintered body may contain CaO, MgO or the like as impurities, but the content of these impurities is 1% by weight based on the whole sintered body.
The following range is preferable. This is CaO or Mg
This is because if O is contained in an amount of more than 1% by weight because O easily reacts with a halide gas that is an atmospheric gas like Si, erosion of the aluminum nitride sintered body is promoted.

Further, in order to manufacture a wafer supporting member made of the above-mentioned aluminum nitride sintered body, the purity is 99% or more, the average particle diameter is 3 μm or less, preferably the average particle diameter is 1.
AlN powder having a Si content of about 5 μm and having a Si content of 100 ppm or less and Er ₂ O ₃ as a sintering aid were mixed at a weight ratio of 91: 9 to 95: 5, and a solvent was further added. And crush with Si ₃ N ₄ balls. At this time, Si ₃ N ₄ is mixed into the raw material due to abrasion of the balls, but the content of Si is adjusted to more than 200 ppm and 500 ppm or less by adjusting the crushing time. In addition, in order to make the color of the sintered body darker, Mo or W may be contained in the range of 50 ppm as a colorant.

Next, a binder is added to the above raw materials and mixed to prepare sludge, and a tape is formed by using a doctor blade method, and a laminated body of the tape is formed, which is then cut to a predetermined shape. Or the above slurry is dried by a spray dryer to prepare a granulated body, and the granulated body is filled in a predetermined mold and molded by a die press molding method or a rubber press molding method. Further, the obtained molded body is degreased in a vacuum atmosphere or an inert gas atmosphere, baked in the above atmosphere at a baking temperature of 1600 to 1800 ° C., and finally subjected to polishing or the like to be blackened and nitrided. A wafer supporting member made of an aluminum-based sintered body can be obtained.

As described above, since the wafer supporting member according to the present invention is formed of the blackened aluminum nitride sintered material, the 200 to 2 emitted from the halogen lamp is used.
The absorption rate of light having a wavelength of 000 nm can be set to 60% or more. Moreover, since the thermal conductivity is 150 W / mk or more, if a wafer such as a semiconductor wafer or a glass substrate for LCD is placed on the mounting surface and heated by a halogen lamp, it is necessary to perform film formation in a short time. The wafer can be heated up to the temperature and the entire wafer can be heated uniformly.

Further, in the wafer supporting member according to the present invention, in order to blacken the aluminum nitride sintered body, Er ₂ O ₃ is added as a sintering aid and Si is blackened, Since the amount is within a certain range, the erosion by the halide gas as the atmospheric gas can be significantly reduced, and the wafer supporting member can be used for a long period of time.

[0027]

EXAMPLE An example of the wafer support member according to the present invention will be described below.

FIG. 1 is a view showing a mode for forming a film on a semiconductor wafer using a susceptor 10 which is an example of a wafer supporting member according to the present invention, and FIG. 2 is a perspective view showing only the susceptor 10 of FIG. Then, the semiconductor wafer 20 is placed on the upper surface 11 of the susceptor 10 made of a disc-shaped black-purple aluminum nitride sintered body supported by the support 24, and the plasma lower electrode 22 provided below the susceptor 10 is provided. A high frequency voltage is applied to the plasma upper electrode 23 provided in the upper part of the susceptor 10 to generate plasma and supply a film forming gas, and the halogen lamp 30 disposed below the susceptor 10 indirectly heats the susceptor 10. The semiconductor wafer 20 arranged on the upper surface 11 is heated to form a film.

In order to manufacture this susceptor 10,
ErN as a sintering aid in AlN powder containing about 40 ppm of Si and having a purity of 99% or more and an average particle size of about 1.2 μm.
₂ O ₃ is mixed at a weight ratio of 94: 6, a solvent is further added, and the mixture is pulverized in a Si ₃ N ₄ ball for about 10 hours. Then, about 2% by weight of a binder is added to the above-mentioned pulverized raw material and dried by a spray dryer to prepare a granulated body, and then the granulated body is filled in a cylindrical rubber mold and a cylindrical body is formed by a rubber press molding method. Is molded and cut to have a diameter of 170 to 260 mm and a thickness of 7 to 12 mm.
Form a disc-shaped body of a degree. Then, after degreasing the molded disc-shaped body in a nitrogen atmosphere, it is fired in the atmosphere at a firing temperature of about 1700 ° C., and subjected to polishing to have a diameter of about 150 to 200 mm and a thickness of 6 to
A disk-shaped susceptor 10 of the present invention having a size of about 9 mm was obtained.

(Experimental Example 1) Here, an aluminum nitride-based sintered body was prepared in which the amount of Er ₂ O ₃ added was varied.
The value of the thermal conductivity with respect to the content of ₂ O ₃ was measured.

Each sample had a purity of 99%, an average particle size of about 1.5 μm, an AlN powder having a Si content of about 40 ppm, a purity of 99.9%, and an average particle size of 1.2 μm.
Er ₂ O ₃ powder of about m in a weight ratio of 91: 9 to 97:
Mix each in the ratio of 3 and add more solvent to add Si ₃
It was crushed for 10 hours with N ₄ ball. Then, 2% by weight of a binder was added to these and dried by a spray dryer to form a granulated body, and the obtained granulated body was filled in a mold, and a mechanical press machine had a diameter of 10 mm and a thickness of 3 mm.
A disc-shaped body of a certain degree was formed. Then, after degreasing the above disc-shaped body in a nitrogen atmosphere, it is removed in a nitrogen atmosphere.
Each sample was obtained by firing at a firing temperature of about 80 degrees.

By irradiating the sample with laser pulsed light and measuring the temperature rise of the surface opposite to the irradiation surface with a thermocouple, the maximum temperature reached during laser irradiation was compared with that of standard sapphire to determine the specific heat capacity. While calculating
The thermal diffusivity is calculated from the time when the temperature reaches half the maximum temperature, and the heat of each sample is calculated by the laser flash method, which is calculated by substituting the specific heat capacity value, the thermal diffusivity value and the density of each sample into the formula below. The conductivity was measured. Formula K = α ×
C _P × d K: Thermal conductivity α: Thermal diffusivity C _P : Specific heat capacity d: Density Further, in order to uniformly heat the wafer, the thermal conductivity of the wafer support member must be 150 W / mk or more. Therefore, in this experiment, those having a thermal conductivity of 150 W / mk or more were regarded as excellent.

The respective results are shown in Table 1.

[0034]

[Table 1]

First, it can be seen from Table 1 that the heat transfer coefficient of the sintered body can be improved as the content of Er ₂ O ₃ contained in the aluminum nitride sintered body increases.
However, in samples a and b, Er ₂ contained in the sintered body was
Since the content of O ₃ was less than 5% by weight, the heat transfer coefficient of the sintered body could not be set to 150 W / mk or more.

On the other hand, in the samples c to g according to the present invention, since the content of Er ₂ O ₃ contained in the sintered body is 5 wt% or more, the heat transfer coefficient of the sintered body is 150 W / mk. That's it.

(Experimental Example 2) Next, an aluminum nitride sintered body was prepared in which the contents of Si and Mo as a colorant were changed, and the thermal conductivity and brightness of each sample were measured.

Each sample had a purity of 99%, an average particle size of about 1.5 μm, and an Si content of 40 ppm.
1N powder and Er ₂ O ₃ powder having a purity of 99.9% and an average particle diameter of about 1.2 μm were mixed at a weight ratio of 94: 6, and MoO ₃ powder was further converted to Mo at 0, 25, 50. ,
It was added so as to be 100 and 500 ppm, and the mixture was pulverized with a solvent in a Si ₃ N ₄ ball for 10, 30, and 50 hours while changing the pulverization time. Then, 2% by weight of a binder was added to these and dried by a spray dryer to form a granulated body, the obtained granulated body was filled in a mold, and a disc having a diameter of 60 mm and a thickness of 6 mm was formed by a mechanical press machine. A plate-like body having a shape was formed. Then, after degreasing in a nitrogen atmosphere, baking is performed in a nitrogen atmosphere at a baking temperature of about 1700 ° C., and finally polishing is performed to obtain a thickness of 4
The plate-shaped body has a size of mm.

As another comparative example, an aluminum nitride sintered body having a Si content of 200 ppm or less crushed for about 1 hour with Si ₃ N ₄ balls and Er ₂ O ₃ as a sintering aid are included. High-purity aluminum nitride-based sintered bodies were also prepared.

Then, each sample is subjected to chemical quantitative analysis by the ICP method to measure the contents of Mo and Si contained in the aluminum nitride sintered body, and then the thermal conductivity is measured by the laser flash method. And standard light C
Was irradiated to each sample and the lightness was measured using a colorimeter (JI
S Z 8729).

As the evaluation in this experiment, those having a thermal conductivity of 150 W / mk or more and a brightness of 50 or less were considered excellent.

The respective results are shown in Table 2.

[0043]

[Table 2]

First, as can be seen from Table 2, the content of Si increases as the pulverization time with Si ₃ N ₄ balls increases, and the thermal conductivity of the aluminum nitride sintered body decreases accordingly. Was given. Then, in the samples K to P having the longest crushing time, the Si content was 610 to 612 p.
Since it was pm and 500 ppm or more, the thermal conductivity was 15
It was less than 0 W / mk.

Further, in the samples D, E, I and J, since the colorant Mo was contained in an amount of 50 ppm or more, the brightness could all be reduced to 50 or less.
Thermal conductivity of aluminum nitride sintered body is 150 W / mk
Was less than.

Further, in the samples A and P, since the Si content was 200 ppm or less, the thermal conductivity of the aluminum nitride sintered body could be 150 W / mk or more, but it should be sufficiently blackened. Therefore, the brightness could not be reduced to 50 or less.

In the high-purity aluminum nitride sintered body of sample Q, the brightness could not be set to 80 and 50 or less because Er ₂ O ₃ was not added, and the thermal conductivity was 8 as well.
It was as small as 0 W / mk.

On the other hand, in the aluminum nitride-based sintered bodies of Samples B to C and F to H according to the present invention, the Si content is in the range of more than 200 ppm and less than 500 ppm, and the content of Mo is contained. Since the amount is 50 ppm or less, the thermal conductivity is all 150 W / mk or more,
The brightness was also 50 or less.

(Experimental Example 3) Further, in order to see the relation between the lightness and the light absorption rate of the aluminum nitride sintered body, each of Samples A to C, P and Q in Table 2 was halogenated. Heat with a lamp and measure the reflectance and transmittance with a spectrophotometer in the region of light with a wavelength of 200 to 2000 nm,
The absorption rate was measured by substituting each value into the following formula.

Formula Absorption rate (%) = 100− (Reflectance + Transmittance) The respective results are shown in FIG.

As can be seen from FIG. 3, first, in the sample Q having the maximum lightness of 80, the absorptance of the wavelength light of 400 to 2000 nm out of the wavelength light of 200 to 2000 nm is 60%.
Was less than.

In the case of the sample A having a brightness of 58.3, 160
Regarding the absorptance of the light having the wavelength of 0 to 2000 nm, the absorptance of the light of the wavelength of 1800 to 2000 nm was less than 60% for the sample P having the lightness of 56.

On the other hand, in Samples B and C according to the present invention having a lightness of 50 or less, the absorptance was able to be 60% or more with respect to all wavelengths of 200 to 2000 nm. Particularly, in the case of the sample C having a brightness of 40 or less, 200 to 2
The absorptance for light of all wavelengths of 000 nm could be 80% or more.

Further, when the susceptor 10 was formed using the aluminum nitride sintered bodies of the samples B and C and film formation was performed as shown in FIG. 1, a film having a uniform thickness was formed on the semiconductor wafer 20. Could be formed.

[0055]

As described above, according to the present invention, the wafer supporting member contains AlN as a main component, Er ₂ O ₃ as a sintering agent, Si in an amount of more than 200 ppm, and 5% or less.
Thermal conductivity contained in the range of 00 ppm or less is 150 W /
Since the brightness of the sintered body can be set to 50 or less by forming the aluminum nitride sintered body of mk or more, 200 to 2000n emitted from the halogen lamp.
The absorptance for all wavelengths of m can be 60% or more. Therefore, when a wafer such as a semiconductor wafer or a glass substrate for LCD is placed on the upper surface of the wafer support member and heated by a halongen lamp, the wafer can be heated to a predetermined temperature in a short time and the wafer can be uniformly heated. Since it can be heated to a high temperature, highly accurate film formation can be performed. Moreover, since it is hardly corroded by the halide gas as the atmospheric gas, it can be used for a long period of time.

[Brief description of drawings]

FIG. 1 is an aspect diagram for forming a film on a semiconductor wafer using a susceptor which is an example of a wafer supporting member according to the present invention.

FIG. 2 is a perspective view showing only the susceptor of FIG.

FIG. 3 is a brightness of an aluminum nitride sintered body and 200 to 2
It is a graph which shows the relationship with the absorption rate of the wavelength light of 000 nm.

[Explanation on the sign]

 10 Susceptor 11 Upper Surface 20 Semiconductor Wafer 22 Plasma Lower Electrode 23 Plasma Upper Electrode 24 Support Stand 30 Halogen Lamp

Claims (1)

[Claims] 1. A main component is AlN, and Er is used as a sintering aid.
A wafer support member comprising an aluminum nitride sintered body containing ₂ O ₃ and containing Si in an amount of more than 200 ppm and 500 ppm or less and having a thermal conductivity of 150 W / mk or more.