JP5527821B2 - Corrosion resistant material - Google Patents

Description

  The present invention relates to a corrosion-resistant member suitably used in a semiconductor device manufacturing process.

In the semiconductor manufacturing process, periodic self-cleaning is performed to remove film components adhering to components in the apparatus other than the wafer formed by the CVD apparatus that forms an oxide film or a metal film of wiring on the silicon wafer. In order to remove a film formed by thermal etching or plasma etching of an etching apparatus, highly corrosive NF ₃ , CF ₄ , C ₂ F ₆ , SF ₃ , ClF ₃ , COF ₂ , F _2, etc. A fluorine-based gas is used.

Components used in semiconductor devices such as a susceptor on which a wafer is placed, a focus ring installed on the outer periphery of the wafer, a shower plate for supplying gas, and the like, which are used under severe conditions in these highly corrosive gases, Conventionally, silicon (Si), quartz glass, silicon carbide, and the like have been appropriately used depending on the application.

However, these conventionally used materials have various problems. For example, quartz glass has a high vapor pressure of a reaction product compound such as silicon fluoride in the presence of a highly reactive fluorine-based gas, and vaporizes as a gas. Wear out.
Silicon carbide basically has better corrosion resistance than quartz glass, but silicon carbide used in semiconductor manufacturing equipment is mainly silicon-impregnated silicon carbide, so the silicon part is similar to quartz glass. It is worn out by reaction with the fluorine-based gas, and as a result, the structure is coarsened, and silicon carbide is easily detached from the constituent members, which causes generation of particles.

On the other hand, compared with quartz glass and silicon carbide, aluminum-based materials such as aluminum (metal), aluminum oxide (alumina), and aluminum nitride are vapor pressures of aluminum fluoride (AlF ₃ ) produced by reaction with fluorine-based gas. Has been attempted because of its extremely low.
Furthermore, a corrosion-resistant member has been proposed in which a coating film made of aluminum nitride and an aluminum fluoride is further provided thereon (see Patent Document 1). Moreover, although the object is different, an aluminum nitride sintered body having an aluminum nitride layer has been proposed in order to improve the smoothness of the surface (see Patent Document 2).

Japanese Patent No. 3078671 Japanese Patent Laid-Open No. 2-59474

However, when the aluminum nitride coating film is used for a long period of time by regular self-cleaning, it is highly corrosive NF ₃ , CF ₄ , C ₂ F ₆ , SF ₃ , ClF ₃ , COF ₂ , F _2. Since corrosion progressed from the surface by the fluorine-based gas such as, and fine particles were generated on the surface, it was not put into practical use.
In addition, the components used in the semiconductor device are expensive in terms of manufacturing method, and providing an aluminum fluoride further on the aluminum nitride coating film is very expensive as a consumable product. The current situation is that it is not commensurate with the manufacturing cost. Therefore, a component having a longer life has been desired.

In view of the above problems, the present invention can be used as various structural members against exposure to a halogen-based corrosive gas, and is particularly suitable as a constituent member of a semiconductor manufacturing apparatus and has corrosion resistance over a long period of time. It aims at providing a corrosion-resistant member.

The present inventor has intensively studied the aluminum nitride coating film, and the corrosion resistance to the fluorine-based gas varies greatly depending on the spin density of the coating film, and depending on the numerical value, many fine particles are generated on the film surface, It is found that cracks are generated in the coating film, and in particular, the corrosion resistance is improved by setting the spin density of the coating film to 5 × 10 ¹⁵ spins / g or more and 1 × 10 ¹⁹ spins / g or less. The present invention was completed by finding that it was greatly improved.

That is, the corrosion-resistant member of the present invention is a corrosion-resistant member in which the whole or a part of the heat-resistant member is covered with a coating film containing aluminum nitride as a main component, and the spin density of the coating film is 5 × It is characterized by being 10 ¹⁵ spins / g or more and 1 × 10 ¹⁹ spins / g or less.

The heat-resistant member is pyrolytic boron nitride, mixed sintered body of boron nitride and aluminum nitride, pyrolytic boron nitride coated graphite, aluminum nitride, rare earth oxide, aluminum oxide, silicon oxide, zirconia, sialon, graphite and high melting point One of the metals is the main component.
The said corrosion-resistant member is used suitably as a structural member of a semiconductor device manufacturing apparatus.

ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the fine particle by halogen type corrosive gas can be suppressed, a long-life corrosion-resistant member can be provided, and the structural member of the semiconductor manufacturing apparatus corresponding to the manufacturing cost of a semiconductor device It is possible to provide excellent effects such as

It is a schematic sectional drawing which shows the corrosion-resistant member which protected the surface of the electrostatic chuck with the heater which heats a wafer inside which is one Example of this invention with the aluminum nitride coating film. It is a schematic sectional drawing which shows the corrosion-resistant member which protected the surface of the sample holder (wafer holder) which is another Example of this invention with the aluminum nitride coating film. It is a schematic sectional drawing which shows the corrosion-resistant member which protected the surface of the ring component by the aluminum nitride coating film which is another Example of this invention. It is a figure explaining how to obtain | require the signal strength of a spin density by an electron spin resonance method (ESR). It is a figure which shows the measurement result by an electron spin resonance method (ESR).

The corrosion-resistant member of the present invention is aluminum nitride adjusted so that the spin density is 5 × 10 ¹⁵ spins / g or more and 1 × 10 ¹⁹ spins / g or less so as to cover all or part of the heat-resistant member. By using a member provided with a coating film, generation of fine particles can be suppressed, and the life of the member can be extended.

If the spin density is less than 5 × 10 ¹⁵ spins / g, many fine particles are generated on the surface, aluminum fluoride is generated on the surface of the coating film, and the fine powder is scattered on the wafer. On the other hand, if it exceeds 1 × 10 ¹⁹ spins / g, a large amount of fluorine is taken into the aluminum nitride structure and cracks occur in the aluminum nitride coating film, and even the heat-resistant member that is the base material of the coating film is corroded. The gas penetrates, corrodes the base material, peels off the coating film, and generates a large amount of particles. More preferably, it is 2 × 10 ¹⁶ spins / g or more and 3 × 10 ¹⁸ spins / g or less.

In order to form an aluminum nitride coating film on the heat-resistant member, chemical vapor deposition is used, from a tubular member having a double-pipe structure into the reactor, ammonia from one of the double tubes, and chlorination from the other. Aluminum or an organometallic compound of aluminum may be supplied in a gaseous state, and the spin density of the coating film can be easily adjusted to 5 × 10 ¹⁵ spins / g by variously adjusting the reaction temperature, the supply rate of raw materials, and the reaction pressure. As described above, it can be adjusted to 1 × 10 ¹⁹ spins / g or less.

The base heat resistant member is any one of pyrolytic boron nitride, mixed sintered body of boron nitride and aluminum nitride, aluminum nitride, rare earth oxide, aluminum oxide, silicon oxide, zirconia, sialon, graphite, and refractory metal By using as a main component, it can sufficiently handle processes at 500 ° C. or higher.
Examples of the rare earth oxide include zirconia and cerium oxide. Examples of the refractory metal include tungsten, tantalum, molybdenum, niobium, iron, nickel, and the like.

  Further, the corrosion-resistant member of the present invention includes an electrostatic chuck for mounting a semiconductor wafer, a heater for heating the semiconductor wafer, a mounting table for directly mounting the wafer, a ring disposed on the outer periphery of the wafer, and an insulation for a conductor device manufacturing apparatus. As a corrosion-resistant member used in parts and semiconductor device manufacturing apparatuses, it has an extremely beneficial effect, and it is possible to prevent generation of particles and contamination that cause semiconductor defects in the film forming process.

  By setting the thickness of the aluminum nitride coating film to 1 μm or more and 500 μm or less, sufficient corrosion resistance can be exhibited depending on use conditions. More preferably, it is 10 μm or more and 300 μm or less. If the thickness is less than 1 μm, there is a risk that the heat-resistant member is corroded and particles are generated if there is a partial defect. If the thickness exceeds 500 μm, the coating film may be separated at the boundary with the heat-resistant member. In addition, it takes an enormous amount of time for film formation and is not cost effective.

Next, specific examples of the corrosion-resistant member of the present invention will be described with reference to the drawings.
In the example shown in FIG. 1, a heater member 105 is built in to heat the wafer, and the surface of the electrostatic chuck, which is the heat-resistant member 101 including the electrostatic chuck electrodes 104a and 104b, is coated with aluminum nitride. The corrosion resistant member 100 (106 in the figure is a cooling gas hole) protected by the film 103. In the example shown in FIG. 2, the surface of the sample holder (wafer holder), which is the heat resistant member 101, is coated with the aluminum nitride coating film 103. Corrosion-resistant member 100 protected with The example shown in FIG. 3 is a corrosion-resistant member 100 in which the surface of a ring component, which is a heat-resistant member 101, is protected by an aluminum nitride coating film 103, both having equivalent corrosion resistance in an actual semiconductor manufacturing process. Long life and particle generation were suppressed.

In the present invention, the spin density (spins / g) is a value obtained by measuring the number of spins per gram of a single coating made of aluminum nitride by an electron spin resonance method (ESR method). In this measurement, the signal intensity is determined by the following [Equation 1] in comparison with the signal intensity of a polyethylene film into which ions are implanted.

The ESR method is a spectroscopic analysis that observes transitions between crystal levels that occur when unpaired electrons in a sample are placed in a magnetic field. The measurement is performed by sweeping the magnetic field under microwave irradiation. As the magnetic field (H) increases, the energy interval (ΔE) increases, and absorption is observed when this becomes equal to the microwave energy.
The ESR spectrum is usually obtained by a differential curve, and if it is integrated once, it becomes an absorption curve, and if it is integrated once more, the signal intensity is obtained (see FIG. 4).

Parameters obtained include g value, line width, and spin number. The g value is obtained by substituting the microwave frequency (ν) and the resonance magnetic field (H) into the resonance condition (hν = gβH). Here, h is a Planck constant and β is a Bohr magneton. Therefore, when each value is substituted, the following [Equation 2] is obtained.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited to these aspects, Various aspects are possible.
[Examples 1 to 8, Comparative Examples 1 and 2]
An aluminum nitride sintered body having a length of 30 mm, a width of 15 mm, and a thickness of 0.5 mm was set in the reactor, and an aluminum nitride coating film was provided on the entire surface by a thermal CVD method.
When forming the aluminum nitride coating film, trimethylaluminum (TMA) was supplied as a raw material as an organometallic compound of aluminum by a bubbler method, and ammonia was supplied after being evaporated by heating. In order to introduce the raw material gas into the reactor, ammonia was supplied from a tube outside the double tube, and trimethylaluminum was supplied from an inner tube. On the exhaust side, the gas inside the container was evacuated by an oil rotary vacuum pump, and the inside of the container was decompressed to form a film.

Corrosion-resistant members were prepared by changing the reaction temperature, the feed rate of trimethylaluminum as a raw material, and the reaction pressure in various ways to provide a coating film made of crystalline aluminum nitride (AlN) with a thickness of 100 μm and different spin densities. (Examples 1 to 8, Comparative Examples 1 and 2. See Table 1).
The obtained coating film was divided in half, and two 15 mm square samples were prepared, one for ESR measurement and the other for fluorine gas plasma etching test.

The ESR measurement was performed by polishing and removing a portion of the aluminum nitride sintered body from the produced corrosion-resistant member, using the aluminum nitride film alone as an ESR sample, and performing ESR measurement after weight measurement. The ESR apparatus was ESP350E manufactured by BRUKER, temperature was room temperature, microwave conditions were 9.46 GHz, 0.25 mW, and time constant was 327.68 ms.
The g value obtained from the ESR spectrum was 2.0030 (see FIG. 5). Judging from this value, it is considered that the observed ESR signal is caused by electrons trapped in the nitrogen vacancies (refer to Reference 3: Jpn.J.Appl.Phys.29, L652 (1990)).

On the other hand, a sample for a fluorine gas plasma etching test is mounted on an etching processing apparatus by masking a part of the surface of a coating film on a wafer with a polyimide tape, and a pressure of 10 Pa while flowing CF ₄ gas and oxygen at 50 sccm at a time. The plasma was generated, the RF power was adjusted to 500 W, and the etching test of the corrosion resistant member was continuously performed for 10 hours. Next, the corrosion-resistant member was taken out from the etching apparatus, the level difference between the masked part and the etched part was measured, the surface state change after etching was visually observed, and further, the scanning electron microscope (SEM) observation was performed. .

The results are summarized in Table 1. The surface state observed with a scanning electron microscope was indicated by “x” marks when cracks or surface roughness were observed in the film, and “◯” marks when there was no change.
As can be seen from Table 1, the spin density and the surface state after etching were found to be closely related.

In addition, when the spin density (spins / g) is 5.0 × 10 ¹⁵ or more and 1.0 × 10 ¹⁹ or less, fluorine ions having activity in the plasma enter into the nitrogen vacancies and are dissolved, and the aluminum nitride coating film Is considered to be a fluorine interstitial solid solution that increases the surface resistance. When the spin density is less than 5.0 × 10 ¹⁵ (spins / g), it is considered that the amount of solid solution of fluorine is small, and aluminum fluoride is precipitated on the surface, resulting in surface roughness. On the other hand, when the spin density exceeds 1.0 × 10 ¹⁹ (spins / g), the amount of solid solution increases, and it is considered that cracks were generated due to residual stress due to expansion accompanying structural change of the coating film surface.

DESCRIPTION OF SYMBOLS 100 Corrosion-resistant member 101 Heat-resistant member 103 Aluminum nitride coating film 104a, 104b Electrostatic chuck electrode 105 Heater member 106 Cooling gas hole

Claims (8)

A corrosion-resistant member in which all or part of the heat-resistant member is covered with a coating film mainly composed of aluminum nitride, having a reaction temperature of 600 to 1200 ° C., a trimethylaluminum supply rate of 0.10 to 0.20 mol / The spin density of the coating film formed by thermal CVD under the conditions of hr and reaction pressure of 100 to 120 Pa is 5 × 10 ¹⁵ spins / g or more and 1 × 10 ¹⁹ spins / g or less. A corrosion-resistant member characterized. The heat-resistant member is pyrolytic boron nitride, mixed sintered body of boron nitride and aluminum nitride, pyrolytic boron nitride coated graphite, aluminum nitride, rare earth oxide, aluminum oxide, silicon oxide, zirconia, sialon, graphite and high melting point The corrosion-resistant member according to claim 1, comprising any one of metals as a main component. The corrosion-resistant member according to claim 1, wherein the corrosion-resistant member is an electrostatic chuck. The corrosion-resistant member according to any one of claims 1 to 3, wherein the corrosion-resistant member includes a heating member. The corrosion-resistant member according to any one of claims 1 to 4, wherein the corrosion-resistant member is a mounting table on which a wafer is directly mounted. The corrosion-resistant member according to claim 1, wherein the corrosion-resistant member is a ring disposed on the outer periphery of the wafer. The corrosion-resistant member according to claim 1, wherein the corrosion-resistant member is an insulating component of a conductor device manufacturing apparatus. A semiconductor device manufacturing apparatus comprising the corrosion-resistant member according to claim 1 as a constituent member.

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