JPH0786379A - Semiconductor manufacturing suscepter - Google Patents

Abstract

PURPOSE:To enable a semiconductor manufacturing suscepter to be enhanced in plasma resistance, improved in thermal uniformity, and elongated in service life by a method wherein an aluminum nitride sintered body is used as a base body, and an aluminum nitride thin film is deposited on the surface of the base body. CONSTITUTION:An aluminum nitride thin film 3 is formed as thick as 0.001 to 1.0mm on a sintered base body 2 whose main component is aluminum nitride. Furthermore, a heat releasing circuit 4 and/or a conductive circuit 5 are formed inside the base body 2. If the thin film 3 is smaller than 0.0001mm in thickness, it is lessened in service life, and if it exceeds 1.0 in thickness, it deteriorates in productivity due to that it is elongated in deposition time. The aluminum nitride sintered body is an excellent insulator which is above 10<13>OMEGA-cm in volume resistivity and 4X10<-6> to 5X10<-6>/ deg.C or small in thermal expansion coefficient and excellent in resistance to a thermal shock, so that it hardly cracks even if it changes suddenly in temperature. The aluminum nitride sintered body is also excellent in thermal conductivity. An aluminum nitride thin film is formed through a vapor method, so that it, is uniform in structure, high in impurity, and excellent in plasma resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a susceptor used in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus, a susceptor is for supporting a silicon wafer,
In general, a substrate surface made of graphite or a silicon carbide sintered body is coated with silicon carbide by a vapor phase method, or a high-purity silicon carbide sintered body formed by firing without adding a sintering aid is used. It is used.

Further, in the process of manufacturing a semiconductor, a pattern is formed on a silicon wafer by plasma etching. At this time, the susceptor is always exposed to a plasma atmosphere. However,
In such a plasma atmosphere, the silicon carbide itself constituting the susceptor is also etched, and there is a problem that the life of the susceptor is short.

Therefore, a susceptor used for plasma etching is formed of aluminum (Al) or alumina (Al ₂ O ₃ ) having excellent plasma resistance.

Further, as the integration of integrated circuits of semiconductor devices is improved, it is necessary to form a finer pattern. Therefore, a heating circuit may be formed inside the susceptor to perform plasma etching while heating the silicon wafer. I'm getting smashed.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Parts of semiconductor manufacturing equipment must be made of high-purity substances so that impurities such as silicon wafers will not be mixed. Needs to be plasma resistant in itself.

However, although the susceptor made of alumina (Al ₂ O ₃ ) has excellent plasma resistance, it has low thermal conductivity and thermal shock resistance, and lacks thermal uniformity, so that it is rapidly heated in the semiconductor manufacturing process. However, there was a problem that it could not be quenched.

Further, even if silicon carbide is used, the plasma resistance is not sufficient, and since the silicon carbide sintered body itself has conductivity, an electric circuit cannot be formed inside the susceptor.
Since it is necessary to separately provide a heating means, there is a drawback that the device becomes complicated and large.

[0009]

The inventors of the present invention have made extensive studies on the above problems from the viewpoint of the material forming the susceptor. As a result, the aluminum nitride sintered body has an insulating property and a heat resistance. By paying attention to its excellent conductivity, we further studied it, and by using an aluminum nitride sintered body as a substrate with a thin film of aluminum nitride formed on its surface as a susceptor, it has high plasma resistance and thermal uniformity. Therefore, the present invention has been accomplished, and the present invention has been completed, and the present invention has been completed.

That is, the semiconductor manufacturing susceptor of the present invention is
A thin film made of aluminum nitride is formed on the surface of a base body made of a sintered body containing aluminum nitride as a main component in the range of 0.001 to 1.
It is characterized by being formed with a thickness of 0 mm,
Further, a heat generating circuit and / or a conductive circuit are formed inside the base body.

The present invention will be described in detail below. A typical structure of the semiconductor manufacturing susceptor of the present invention is shown in FIG. According to FIG. 1, the susceptor 1 is composed of a base 2 made of an aluminum nitride sintered body and an aluminum nitride thin film 3 formed on the surface of the base 2. The thin film 3 is formed on the mounting surface of the silicon wafer or the entire surface exposed in the semiconductor manufacturing apparatus.

Specifically, the substrate 2 is mainly composed of aluminum nitride, and in addition, a compound of a Group 3a element of the periodic table such as Y, Er, Yb, or an alkaline earth element compound such as Ca. May be contained in a proportion of 20% by weight or less, but desirably, since these auxiliary components may exhibit impurity behavior with respect to the semiconductor in the semiconductor manufacturing apparatus,
It is preferable that the amount of the auxiliary component is as small as possible.
A highly purified product without adding an auxiliary component as proposed in No. 17038 is preferably used. In addition, the aluminum nitride sintered body has a thermal conductivity of 80 W / m · k or more, particularly 100% from the viewpoint of the uniform heating property and the rapid heating property of the susceptor.
W / m · k or more is desirable.

Such an aluminum nitride sintered body is obtained by adding and mixing the above-mentioned auxiliary components to aluminum nitride raw material powder, and shaping the mixture into a desired shape, and then 1600 to 1950 ° C. in a non-oxidizing atmosphere such as nitrogen. It is obtained by firing at the temperature of.

On the other hand, the aluminum nitride thin film 3 formed on the surface of the substrate 2 has a thickness of 0.001 to 1.0 mm, and particularly, a thickness of 0.
It is desirable to be formed with a thickness of 001 to 0.3 mm.
This is because if the thickness of the thin film is thinner than 0.001 mm, the life of the thin film becomes short, and if it exceeds 1.0 mm, the deposition time of the thin film becomes long and the productivity becomes poor. This aluminum nitride thin film is a well-known vapor phase method, for example, a PVD method such as sputtering or ion plating, plasma CVD, photo CVD, MO (Metal-organi).
c) It is easily formed by a CVD method such as CVD. The thin film formed by such a vapor phase method has a high purity of 99% or more. Although the film may contain AlON containing oxygen during the film formation process, the amount of oxygen is 20 atoms. If it exceeds 0.1%, the adhesion to the aluminum nitride sintered body that is the base may deteriorate, so it is desirable to control the oxygen content to 20 atomic% or less. Also,
It is desirable that the aluminum nitride thin film has a high purity and a thermal conductivity of 120 W / m · k or more.

Further, according to the present invention, the heat generating circuit 4 necessary for fixing the silicon wafer and keeping the temperature inside the substrate 2 and the conductive circuit 5 for electrostatically adsorbing the wafer are provided inside the substrate 2.
May be incorporated. These circuits 4 and 5 are
g, W, Mo, C, TiN, Pd, WC, Ni, etc. In particular, the heating circuit 4 is substantially uniform over the entire substrate 2 to prevent unevenness in heat retention of the silicon wafer. It is desirable to form so that. It is desirable that these circuits are formed of a material having a coefficient of thermal expansion similar to that of the base material, such as W, Mo and N.
i, etc.

Such a circuit can be formed, for example, by applying a metal paste as a metal paste in a predetermined pattern on a molded body mainly composed of aluminum nitride, and then simultaneously firing it under the above firing conditions. At this time, it is effective to add a small amount of aluminum nitride or an auxiliary component to the metal paste to enhance the adhesion between the circuit and the aluminum nitride sintered body.

[0017]

The aluminum nitride sintered body used as the base material in the present invention has a volume resistivity of 10 ¹³ Ω-cm.
It is a good insulator and has a thermal expansion coefficient of 4 x
Since it is as small as 10 ^{−6 to} 5 × 10 ⁻⁶ / ° C. and has excellent thermal shock resistance, it does not easily crack even when subjected to a rapid temperature change. In addition, since the thermal conductivity is also excellent, it is possible to reduce the temperature unevenness in the susceptor, so that it is possible to keep the temperature of the silicon wafer uniform.

Further, since the aluminum nitride thin film formed on the surface of the substrate is synthesized by the vapor phase method, it has a uniform structure and a very high purity, so that it is excellent in plasma resistance and is used for plasma etching. Also, it is possible to prevent generation of pinholes on the surface of the susceptor and deterioration due to etching. Moreover, since the surface of the base is covered with the high-purity aluminum nitride thin film, even if a slight amount of impurities is contained in the sintered body of the base, it is not released to the outside of the system, and the semiconductor manufacturing process In the above, it is possible to prevent the adverse effect of impurities. Furthermore, high-purity aluminum nitride has a thermal conductivity of 120 W / m.
-Because it is excellent as k or more, the soaking property can be further enhanced as compared with the case where the susceptor is composed of only the aluminum nitride sintered body.

Furthermore, many semiconductor manufacturing susceptors require heating, and the uniform heating is improved by using a substrate and a film containing aluminum nitride as a main component, but a heat generating circuit or an electric circuit such as an electrostatic chuck is used. By including in the susceptor, miniaturization can be achieved and reliability can be improved.

[0020]

The present invention will be described below with reference to the following examples. Example 1 A mixture obtained by adding 2% by weight of Y ₂ O ₃ to aluminum nitride powder was formed into a sheet, and then a W paste containing 2% by weight of aluminum nitride was formed on the surface of the sheet formed body by a screen printing method with a thickness of 25 μm. What was applied to the heating circuit pattern and electrostatic chuck pattern was sandwiched between other sheet moldings and laminated, and this was laminated at 1750 ° C in a nitrogen atmosphere.
Was fired to obtain an aluminum nitride sintered body disk having a thickness of 5 mm and having a heat generating circuit and an electrostatic chuck circuit incorporated therein. The thermal conductivity of the obtained aluminum nitride sintered body was measured by the laser flash method (thickness: 3 mm).
It was 2 W / m · k.

This sintered disk was put in a CVD processing furnace, and various thin films were formed by the thermal CVD method under the conditions of raw material gas and temperature as shown in Table 1 to manufacture a susceptor. Regarding the obtained thin film, the amount of oxygen in the film was measured by a combustion analysis method after the substrate was polished and removed.

Further, the adhesion of the thin film to the substrate was examined by cutting it together with the substrate and observing the cut surface with a stereoscopic microscope and a scanning electron microscope (SEM).
Neither film peeling nor cracking was observed.

Further, the obtained various susceptors are placed in a plasma etching apparatus to perform fluorine plasma,
The time until pinholes are generated on the surface of the susceptor after the start of etching is shown in Table 1 as the life.

Regarding the soaking property, the susceptor end portion (substrate diameter 210 mm) was measured while the heating circuit was energized and the center of the susceptor was heated to 200 ° C., and the temperature difference was shown.

[0025]

[Table 1]

As shown in Table 1, the sample No. 11 in which the SiC film was formed on the aluminum nitride substrate based on the conventional method had a certain degree of soaking property, but had low plasma resistance and a short life of 230 hours. It was a thing. Further, in sample No. 1 consisting of only the aluminum nitride sintered body, although the plasma resistance was relatively excellent, contamination was caused by impurities from the sintered body.

In contrast to these conventional examples, the invention products in which the aluminum nitride thin film was coated on the surface of the aluminum nitride sintered body exhibited high plasma resistance and a life of 500 hours or more.

Example 2 In the same manner as in Example 1, a thin film was formed on the produced aluminum nitride sintered body by the plasma CVD method under the conditions shown in Table 2 to manufacture a susceptor. The aluminum nitride thin film formed by the plasma CVD method is crystalline and has a purity of 99.99.
It was 9% or more. Example 1 for the manufactured susceptor
Various characteristics were evaluated in the same manner as in, and the results are shown in Table 2. For comparison, a high-purity SiC sintered body (purity 99.
The characteristics were similarly evaluated for a susceptor composed of 8%). According to Table 2, the product of the present invention showed about 4 times the life in plasma as compared with the high-purity SiC sintered body.

[0029]

[Table 2]

Example 3 A thin film was formed on the aluminum nitride sintered body produced in the same manner as in Example 1 under the conditions shown in Table 3 by using an alumina target in a mixed atmosphere of argon and nitrogen by a sputtering method. For comparison, Al ₂ O having a purity of 99% or more is used.
_The characteristics of the susceptor composed of _three sintered bodies were evaluated in the same manner. As a result, as shown in Table 3, high-purity Al ₂ O
_{3 Even} when compared with the sintered body, the product of the present invention has excellent plasma resistance,
It had a long life and was excellent in heat uniformity.

[0031]

[Table 3]

[0032]

As described above in detail, the semiconductor manufacturing susceptor of the present invention is excellent in plasma resistance and therefore prevents pinholes from being generated on the surface of the susceptor and deterioration due to etching even when plasma etching is performed. A longer life can be achieved. Further, since both the base and the thin film have high thermal conductivity, they have high thermal uniformity, and when a heat generating circuit or the like is built in, uniform heating of the semiconductor can be achieved. In addition, since the thin film has a high purity and is excellent in adhesion to the substrate, it has many advantages such as no inclusion of impurities in the semiconductor manufacturing process.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a susceptor for semiconductor manufacturing of the present invention.

[Explanation of symbols]

 1 Susceptor 2 Base 3 Thin film 4 Heating circuit 5 Conducting circuit

Claims (2)

[Claims] 1. A susceptor for semiconductor production, characterized in that a thin film made of aluminum nitride is formed in a thickness of 0.001 to 1.0 mm on a surface of a base body made of a sintered body containing aluminum nitride as a main component. . 2. The semiconductor manufacturing susceptor according to claim 1, wherein a heat generating circuit and / or a conductive circuit is formed inside the base.