JP2007063069A - Light-transmissive yttria sintered compact and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an yttria sintered compact which is excellent in plasma resistance, corrosion resistance and light transmissivity and is usable suitably in a member for a semiconductor manufacturing apparatus or an optical member, particularly, in a light-transmissive member for an observation window, a lens, a discharge tube or the like to be exposed to corrosive gas in members for a plasma treatment apparatus and to provide a method for manufacturing the yttria sintered compact. <P>SOLUTION: The light-transmissive yttria sintered compact, which contains 0.02-5 wt.% zirconia and has 1-100 μm average crystal grain size and ≥70% linear transmissivity of visible light in 1 mm thickness, is obtained by adding zirconia to yttria raw material powder, which has ≥99% purity and the particle size of whose primary particle is ≤1.5 μm at D<SB>90</SB>, and sintering the zirconia-added powder in a reducing atmosphere or in vacuum at 1,700-2,000°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is excellent in translucency, plasma resistance, corrosion resistance, and the like, and is used for semiconductor manufacturing equipment and optical members, particularly in plasma processing equipment members such as observation windows, lenses, and discharge tubes that are exposed to corrosive gas. The present invention relates to a yttria sintered body that can be suitably used for an optical member and a method for producing the same.

  In the semiconductor manufacturing process, processing in a corrosive gas or plasma environment such as a wafer etching process is performed. In such a plasma processing apparatus, ceramics having excellent corrosion resistance such as quartz glass and high-purity alumina are used for peep windows, lenses, and discharge tubes that are exposed to plasma and corrosive gas and are required to have translucency. It is used a lot.

  However, even when using a member made of quartz glass, ceramics, or the like as described above, in the etching process, particularly in the plasma etching process, it is exposed to a harsh plasma environment. Etching of the member itself cannot be escaped, causing damage and deterioration of the member, and contamination of the wafer due to generation of particles accompanying these.

Recently, it has been studied to apply yttria, which is a material excellent in plasma resistance, to a member for a semiconductor manufacturing apparatus.
Conventionally, yttria sintered bodies have been manufactured by so-called atmospheric firing in which firing is performed at a high temperature of 2200 ° C. or higher in the atmosphere.
Further, for example, Patent Document 1 discloses a method of obtaining a yttria sintered body having excellent translucency by adding calcium oxide or zirconia powder to yttria powder.
JP-A-10-273364

However, the yttria sintered body obtained by the conventional atmospheric firing is colored or has minute pores of about 1 μm, and sufficient translucency is not obtained.
In addition, even with the manufacturing method described in Patent Document 1, it has been difficult to obtain a yttria sintered body with a visible light linear transmittance of 70% or more with a thickness of 1 mm and excellent in translucency.

  Therefore, in addition to excellent plasma resistance and corrosion resistance, the yttria sintered body is excellent in addition to excellent plasma resistance and corrosion resistance in order to be used for members such as a viewing window, a lens, and a discharge tube exposed to a corrosive gas in a member for a plasma processing apparatus. What was required to have translucency was demanded.

  The present invention has been made in order to solve the above technical problem, and is excellent in plasma resistance and corrosion resistance, and also has excellent translucency, and is a semiconductor manufacturing apparatus and optical member, particularly plasma processing. An object of the present invention is to provide a yttria sintered body that can be suitably used for a light-transmitting member such as a viewing window, a lens, and a discharge tube that is exposed to a corrosive gas in a device member, and a method for manufacturing the same. .

The translucent yttria sintered body according to the present invention contains 0.02% by weight or more and 5% by weight or less zirconia, has an average crystal grain size of 1 μm or more and 100 μm or less, and a visible light linear transmittance of 1 mm thick. 70% or more.
The yttria sintered body having such a structure has excellent translucency in addition to the excellent corrosion resistance against the corrosive gas, plasma and the like that the yttria itself has.

The method for producing a translucent yttria sintered body according to the present invention is a method for producing the translucent yttria sintered body, wherein the purity is 99% or more, and the particle size of the primary particles is 1 in _D90 . It is characterized in that zirconia is added to yttria raw material powder having a thickness of 0.5 μm or less and fired at 1700 ° C. or higher and 2000 ° C. or lower in a reducing atmosphere or vacuum.
Here, D ₉₀ means the particle size at 90% cumulative particle size.
The yttria raw material powder preferably has a primary particle diameter of D ₉₀ of 1.0 μm or less.
According to the above manufacturing method, it is possible to easily obtain a yttria sintered body having sufficient translucency to be used as an optical member such as a semiconductor manufacturing apparatus or a lens that requires translucency as described above.

As described above, the translucent yttria sintered body according to the present invention is excellent in corrosion resistance against corrosive gas, plasma, etc., and is also excellent in translucency. It can use suitably for translucent members, such as a sight glass, a lens, and a discharge tube, exposed to corrosive gas in the member for plasma processing apparatuses.
Moreover, according to the manufacturing method which concerns on this invention, the yttria sintered compact excellent in the above translucency can be obtained suitably.

Hereinafter, the present invention will be described in more detail.
The translucent yttria sintered body according to the present invention contains 0.02% by weight or more and 5% by weight or less zirconia, has an average crystal grain size of 1 μm or more and 100 μm or less, and a visible light linear transmittance of 1 mm thick. It is characterized by being 70% or more.
The yttria sintered body having such a structure has excellent translucency by adding a predetermined amount of zirconia in addition to the excellent corrosion resistance against the corrosive gas, plasma, etc. of yttria itself, and is used for a plasma processing apparatus. The member can be suitably used for a light-transmitting member such as a viewing window, a lens, or a discharge tube that is exposed to a corrosive gas.
When the linear transmittance of visible light is 1 mm thick and less than 70%, the yttria sintered body is not translucent to be used as an optical member such as a semiconductor manufacturing apparatus or a lens that requires translucency. It is enough.

As described above, the average crystal grain size of the yttria sintered body according to the present invention is 1 μm or more and 100 μm or less.
When the average particle diameter is less than 1 μm, it is difficult to obtain the above excellent translucency.
On the other hand, when the average particle diameter exceeds 100 μm, it is difficult to obtain a strength sufficient to withstand use as a member for a plasma processing apparatus.

In addition, the content of zirconia in the yttria sintered body is set to 0.02 wt% or more and 5 wt% or less.
When the content is less than 0.02% by weight, the effect of improving translucency by adding zirconia cannot be obtained.
Moreover, also when the said content exceeds 5 weight%, the zirconia addition effect which improves translucency reduces.

Translucent yttria sintered body according to the present invention as described above is at least 99% pure, yttria material powder the particle size of the primary particles is 1.5μm or less at D _90, the addition of zirconia, reduction It can be easily obtained by firing at 1700 ° C. or higher and 2000 ° C. or lower in an atmosphere or vacuum.

In the said manufacturing method, as a yttria raw material powder, a highly purified thing with a purity of 99% or more is used.
When the said purity is less than 99%, the plasma resistance and translucency of the sintered compact obtained will fall.

Further, as the yttria material powder, the particle size of the primary particles used as a 1.5μm or less at D _90.
When the particle size of the primary particles is greater than 1.5 μm at D ₉₀ , sufficient translucency is obtained for use as an optical member such as a semiconductor manufacturing apparatus or a lens that requires the above translucency. It is difficult.
The primary particles preferably have a D ₉₀ of 1.0 μm or less. Further, more preferably 0.5μm or less at D _50.
D ₅₀ means the particle size at a particle size accumulation of 50%.

A predetermined amount of zirconia powder is added to and mixed with the yttria raw material powder, molded into a predetermined shape, and then fired in a hydrogen atmosphere.
When the firing atmosphere is other than hydrogen, for example, the atmosphere or the like, the yttria purity of the obtained sintered base material is lowered, and it is difficult to obtain desired translucency.
In addition, the shaping | molding method of raw material powder is not specifically limited, For example, it can carry out by the pressure molding methods, such as a slip casting and CIP, etc. normally used.

The firing temperature is 1700 ° C. or higher and 2000 ° C. or lower.
When the firing temperature is less than 1700 ° C., many pores remain in the yttria sintered body, making it difficult to obtain the desired translucency, and when used as a member for a plasma processing apparatus, It becomes easy to corrode intensively.
On the other hand, when the firing temperature exceeds 2000 ° C., abnormal grain growth occurs and the strength of the sintered body is significantly reduced.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not restrict | limited by the following Example.
[Example 1]
100 g of yttria raw material powder having a purity of 99.5% was added to 200 g of water and stirred, and 3% by weight of zirconia powder was added and mixed therewith to prepare a slip.
The obtained slip was cast and dried, and then fired at 1800 ° C. in a hydrogen atmosphere to obtain a yttria sintered body.
With respect to the obtained sintered body, the average crystal grain size and the linear transmittance of visible light at a thickness of 1 mm were measured.
These results are shown in Table 1.

[Example 2]
3% by weight zirconia powder added to 99.5% pure yttria raw material powder, granulated with a spray dryer, and then pressure molded at 1.5 t / cm ² with CIP Was fired at 1800 ° C. in a hydrogen atmosphere to obtain a yttria sintered body.
With respect to the obtained sintered body, the average crystal grain size and the linear transmittance of visible light at a thickness of 1 mm were measured.
These results are shown in Table 1.

[Example 3 and Comparative Examples 1 to 5]
The production conditions shown in Example 3 of Table 1 and Comparative Examples 1 to 5 were the same as in Example 1, except that the yttria sintered body was produced. The linear transmittance of visible light at 1 mm thickness was measured.
These results are summarized in Table 1.

  As shown in Table 1, the yttria sintered bodies (Examples 1 to 3) obtained by the production method according to the present invention have an excellent light transmission with a visible light linear transmittance of 70% or more at a thickness of 1 mm. It was found to show sex.

Claims (3)

  Translucent characterized by containing zirconia in an amount of 0.02 wt% or more and 5 wt% or less, an average crystal grain size of 1 μm or more and 100 μm or less, and a linear transmittance of visible light of 1 mm thickness and 70% or more. Yttria sintered body. A method of manufacturing a light-transmitting yttria sintered body according to claim 1, wherein, and at least 99% pure, yttria material powder the particle size of the primary particles is 1.5μm or less at D _90, the addition of zirconia The method for producing a translucent yttria sintered body, comprising firing at 1700 ° C. or more and 2000 ° C. or less in a reducing atmosphere or in a vacuum. 3. The method for producing a translucent yttria sintered body according to claim 2, wherein the yttria raw material powder has a primary particle diameter of D ₉₀ of 1.0 μm or less.