JPH07153820A - Susceptor for semiconductor process and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a susceptor having high flatness and parallelism and uniform electrostatic attraction while ensuring plasma resistance, by forming a conducting circuit on the surface of a sintered body substrate whose main component is aluminum nitride, and forming a thin film composed of aluminum nitride so as to have a specified thickness on the circuit. CONSTITUTION:A substrate 2 consists of a sintered body whose main component is aluminum nitride, and the surface is flatly polished, fan which a conducting circuit 5 is formed. A heating circuit 4 is formed in the substrate 2. An aluminum nitride thin film 3 of 0.001-1.0mm in thickness is formed on the conducting circuit 5. Thereby the distance between the wafer mounting surface and the conducting circuit is not practically changed, so that the uniform attractive force can be obtained. Temperature irregularity in a susceptor can be reduced, and the temperature of a silicon wafer 1 can be kept uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a susceptor for a semiconductor manufacturing apparatus in which a conductive circuit is formed and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus, a susceptor has been used to support a silicon wafer, and generally has a substrate surface made of graphite or a silicon carbide sintered body coated with silicon carbide by a vapor phase method. Alternatively, a high-purity silicon carbide sintered body formed by firing without adding a sintering aid is used.

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 that constitutes 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 finer patterns. Therefore, a conductive circuit or a heat generating circuit for electrostatically adsorbing the wafer is formed inside the susceptor. It is also being heated.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention It is necessary that parts of a semiconductor manufacturing apparatus are made of a high-purity substance so that impurities are not mixed into a silicon wafer or the like.
Furthermore, the plasma etching component itself must have plasma resistance.

A susceptor made of alumina (Al ₂ O ₃ ) has excellent plasma resistance, but has low thermal conductivity and thermal shock resistance and lacks thermal uniformity, so that it is rapidly heated and rapidly cooled in the semiconductor manufacturing process. There was a problem that I could not do it.

Moreover, 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.

Therefore, a susceptor using an aluminum nitride sintered body having excellent plasma resistance and high thermal conductivity,
It has also been proposed to form an aluminum nitride thin film on a predetermined substrate surface. When a conductive circuit is formed in the aluminum nitride sintered body, the conductive paste is embedded in the aluminum nitride molded body and simultaneously fired. However, when such a conductive circuit is formed, since the sintering behavior and the thermal expansion behavior of the two are different, the susceptor is deformed, and the flatness and flatness of the silicon wafer mounting surface of the susceptor cannot be sufficiently obtained. . Since the wafer mounting surface of the susceptor is required to have high flatness, it is necessary to flatten the surface of the substrate. In that case, the distance between the wafer mounting surface and the conductive circuit differs depending on the location, and the electrostatic attraction force is increased. There were problems such as non-uniformity on the surface.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention can obtain a susceptor having high flatness and parallelism without deformation and uniform electrostatic attraction while utilizing the excellent plasma resistance of aluminum nitride. As a result of repeated studies for the purpose of, after the surface of the sintered compact base body mainly composed of aluminum nitride is planarly polished, a conductive circuit is formed on the surface of the base body, and a thin film made of aluminum nitride is formed on the conductive circuit. By doing so, they have found that the above objects can be achieved, and completed the present invention.

That is, the semiconductor manufacturing susceptor of the present invention is
The present invention is characterized in that a conductive circuit is formed on the surface of a base body made of a sintered body containing aluminum nitride as a main component, and an aluminum nitride thin film is further formed thereon to a thickness of 0.001 to 1.0 mm. As its manufacturing method, a step of producing a sintered body mainly composed of aluminum nitride,
A step of planarly polishing the surface of the aluminum nitride sintered body, a step of forming a conductive circuit on the surface after the polishing,
An aluminum nitride thin film is formed on the conductive circuit in an amount of 0.00
It is characterized by comprising a step of forming with a thickness of 1 to 1.0 mm.

The present invention will be described in detail below. The semiconductor manufacturing susceptor of the present invention comprises a structure mainly composed of aluminum nitride, and has a conductive circuit at least inside. Therefore, a specific structure of the susceptor of the present invention is shown in FIG. In FIG. 1, 2 is a substrate, 3 is an aluminum nitride thin film, and 5 is a conductive circuit. According to the present invention, the base body 2 is made of a sintered body mainly composed of aluminum nitride, and the conductive circuit 3 is formed on the surface of the base body 2 of the aluminum nitride sintered body. Further, a heating circuit 4 is formed inside the base 2 made of an aluminum nitride sintered body. The aluminum nitride 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 base body 2 is mainly composed of aluminum nitride, and in addition, Y, Er, Yb, etc. are included in the third periodic table.
There may be a case where the compound of the group a element or the compound of the alkaline earth element such as Ca is contained in an amount of 20% by weight or less, but preferably, these auxiliary components have an impurity behavior with respect to the semiconductor in the semiconductor manufacturing apparatus. Therefore, it is preferable that the amount of the auxiliary component is as small as possible. For example, JP-A-5-117038.
A highly purified product without the addition of an auxiliary component is preferably used as proposed in No. In addition, the aluminum nitride sintered body has a thermal conductivity of 80 W / m · k or more, particularly 100 W / m · k, from the viewpoints of the uniform heating property and rapid heating property of the susceptor.
The porosity is preferably 1 to 10% from the viewpoint of ease of forming a conductive circuit.

On the other hand, the conductive circuit formed on the surface of the substrate 2 has a coefficient of thermal expansion in the range of room temperature to 800 ° C. of 3 to 10 × 10.
It is formed of a conductive metal such as W, Mo, TiN, WC, and TiC at ^-6 / ° C., and is an auxiliary component of aluminum nitride or a sintered body that constitutes the substrate in order to improve the adhesion to the substrate. May contain a small amount. This conductive circuit is 0.5 ~
This is for electrostatically adsorbing the wafer by applying a voltage of 1.5 kV.

The aluminum nitride thin film 3 has a thickness of 0.001 to
It is desirable to be formed with a thickness of 1.0 mm, particularly 0.01 to 0.3 mm. This has a thin film thickness of 0.001 m.
When the thickness is less than m, it is difficult to obtain flatness because the unevenness of the conductive circuit pattern is reflected on the surface of the thin film, which depends on the thickness of the conductive circuit. This is because the deposition time is long and the productivity is poor.

In order to manufacture the susceptor for semiconductor production of the present invention, first, as described above, an aluminum nitride sintered body is produced, and in some cases, a susceptor substrate is produced by co-firing with a heating circuit. Specifically, aluminum nitride raw material powder is mixed with the above-mentioned auxiliary components and shaped into a desired shape, which is then subjected to 1600 in a non-oxidizing atmosphere such as nitrogen.
Although a sintered body can be obtained by firing at a temperature of ˜1950 ° C., when a heating circuit is built in, W, Mo, TiN, WC, Ti are contained in the aluminum nitride molded body.
A heating circuit pattern made of a conductor paste such as C may be internally provided and simultaneously fired under the above firing conditions.

At this time, the manufacturing process can be shortened by co-firing the conductive circuit similarly to the heating circuit. However, such co-firing tends to cause deformation of the substrate, etc. In order to manufacture a susceptor that requires flattening, it is necessary to flatten the substrate after firing by flattening. Therefore, since the distance between the silicon wafer mounting surface of the final susceptor and the conductive circuit varies depending on the location, a problem such as the inability to obtain a uniform suction force occurs.

Therefore, in the present invention, it is important that the conductive circuit is formed after the substrate made of the aluminum nitride sintered body is flat-polished. This conductive circuit was formed by printing a metal paste in a predetermined pattern on the surface of a sintered aluminum nitride-based sintered body as a main component, and then 1000-2.
It can be formed by baking at 000 ° C. At this time, it is effective to add a small amount of aluminum nitride or an auxiliary component together with the conductive metal to the metal paste to enhance the adhesion between the circuit and the aluminum nitride sintered body. In addition, it is also possible to pattern by a PVD method such as sputtering.

Then, an aluminum nitride thin film of 0.0015-1 ..
It is formed with a thickness of 0 mm. This aluminum nitride thin film is formed by a known vapor phase method, for example, a PVD method such as sputtering or ion plating, plasma CVD, or light C.
It is easily formed by a CVD method such as VD or MO (Metal-organic) CVD. The thin film formed by such a vapor phase method has a high purity of 99% or more, but oxygen is contained in the film during the film formation process and
Although it may contain ON, when the oxygen content exceeds 20 atomic%, the adhesion with the aluminum nitride sintered body as the base may decrease, so the oxygen content is controlled to 20 atomic% or less. Is desirable. Further, it is desirable that the aluminum nitride thin film has a high purity and a thermal conductivity of 120 W / m · K or more.

[0019]

According to the present invention, the conductive circuit for electrostatically adsorbing the silicon wafer is formed on the surface of the base of the aluminum nitride sintered body, so that even if the aluminum nitride thin film is formed on the upper surface of the base, the wafer can be mounted on the wafer. Since the distance between the placement surface and the conductive circuit is substantially unchanged, a uniform suction force can be obtained.

The aluminum nitride sintered body used as the base material of the susceptor has a volume resistivity of 10 ¹³ Ω.
-Since it is a good insulator of -cm or more, has a small coefficient of thermal expansion of 4 x 10 ^{-6 to} 5 x 10 ^-6 / ° C, and is excellent in thermal shock resistance, it cracks even when subjected to a sudden temperature change. Hateful. Further, 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, is very high in purity, is excellent in plasma resistance, and can be used for plasma etching. Generation of pinholes on the surface of the susceptor and deterioration due to etching can be prevented. 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 in the semiconductor manufacturing process. The adverse effect of impurities can be prevented. Furthermore, the thermal conductivity is 12
Compared to the case where the susceptor is made of only an aluminum nitride sintered body, it is excellent at 0 W / m · k or more,
Further, the soaking property can be improved.

[0022]

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 was laminated by sandwiching it between other sheet moldings, and this was fired at 1750 ° C. in a nitrogen atmosphere, and the heating circuit was incorporated inside and nitriding with a thickness of 5 mm and a porosity of 5.0%. An aluminum sintered body disk was obtained. This sintered disc was flat-polished and flattened, and then W containing 3% by weight of AlN on the surface of the sintered body was added.
The conductive paste was applied and baked at 1750 ° C. to form a conductive circuit of the electrostatic chuck.

This was placed in a thermal CVD treatment furnace and AlCl _{3
15sccm, NH 3 90sccm, N 2} 2500sc
cm gas was introduced at a furnace pressure of 40 torr and the substrate temperature was 9
The susceptor was manufactured by adjusting the film forming time at 50 ° C. and forming several kinds of aluminum nitride films having different film thicknesses. The oxygen amount in each of the formed aluminum nitride films was 0.5 atom% or less.

Regarding each of the obtained susceptors, regarding the adhesion between the aluminum nitride film and the substrate, the susceptor was
After heating to 0 ° C, cooling to room temperature, repeating this 5 times, cutting the susceptor and observing the cut surface with a stereoscopic microscope and a scanning electron microscope (SEM) to check the presence or absence of peeling or cracks in the thin film. It was Regarding the plasma resistance, the state of the susceptor surface after being kept in plasma for 100 hours in the semiconductor manufacturing apparatus was observed. Further, a voltage of 0.8 kV was applied to the conductive circuit, and the electrostatic attraction force of the silicon wafer was measured.

[0025]

[Table 1]

Comparative Example 1 A mixture containing 2% by weight of Y ₂ O ₃ added to aluminum nitride powder was formed into a sheet, and a W paste containing 2% by weight of aluminum nitride was formed in a thickness of 25 μm by a screen printing method to produce a heating circuit. And the conductive circuit pattern printed sheets are sandwiched and laminated, and this is 1750 in a nitrogen atmosphere.
It was fired at a temperature of ℃ to obtain an aluminum nitride sintered body disk having a thickness of 5 mm. After surface-polishing and flattening the surface of this sintered disk, an aluminum nitride film having a thickness of 300 μm was formed under the same film forming conditions as in Example 1 to manufacture a susceptor. As a result of performing various characteristic evaluations on the manufactured susceptor in the same manner as in Example 1, good results were obtained for film adhesion and plasma resistance, but when adsorption and desorption of silicon wafers were performed. It was found that the electrostatic attraction force on the surface of the susceptor varies because the silicon wafer is displaced from its original fixed position or the attraction force on the surface of the susceptor differs depending on the location.

[0027]

As described in detail above, the semiconductor manufacturing susceptor of the present invention has excellent plasma resistance, suppresses the mixing of impurities during semiconductor manufacturing, and has a uniform susceptor surface with respect to a silicon wafer. Adsorption force can be obtained. Further, when the heat generating circuit is formed inside the susceptor, it is possible to reduce unevenness in temperature inside the susceptor, so that the silicon wafer can be kept warm evenly.

[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 Silicon Wafer 2 Substrate 3 Thin Film 4 Heating Circuit 5 Conducting Circuit

Claims (2)

[Claims] 1. A conductive circuit is formed on the surface of a base body made of a sintered body containing aluminum nitride as a main component, and an aluminum nitride thin film having a thickness of 0.001 to 1.0 mm is formed on the conductive circuit. Susceptor for semiconductor manufacturing. 2. A step of producing a sintered body mainly composed of aluminum nitride, a step of planarly polishing the surface of the aluminum nitride sintered body, and a step of forming a conductive circuit on the polished surface. A method of manufacturing a susceptor for manufacturing a semiconductor, comprising a step of forming an aluminum nitride thin film with a thickness of 0.001 to 1.0 mm on the conductive circuit.