JPH11236262A - Low thermal expansion ceramic structural member and member for semiconductor device producing apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low thermal expansion and high rigidity ceramic structural member suitable for a member for a semiconductor device producing apparatus capable of precisely producing a precise circuit board. SOLUTION: The ceramic structural member is based on a cordierite crystal phase, contains 0.5-10 wt.% (expressed in terms of oxide) at least one selected from the group of the groups IIa, IIIb and IVb elements of the Periodic Table with the exception of Mg, Al and Si, further contains a silicate compd. crystal phase contg. groups IIa and IIIb elements and an aluminum silicate crystal phase, optionally contains <=20 wt.% (expressed in terms of oxide) rare earth element and <=30 wt.% silicon nitride, silicon carbide, silicon oxynitride, etc., and has >=30 GPa relative density, <=0.5×10<-6> / deg.C coefft. of thermal expansion at room temp. and >=130 GPa Young's modulus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a vacuum device structure,
The present invention relates to a low thermal expansion ceramic structural member mainly composed of cordierite suitable for a member for a manufacturing apparatus in a semiconductor manufacturing process such as a susceptor, an electrostatic chuck, a vacuum chuck, or a stepper, and a member for a semiconductor element manufacturing apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, cordierite-based sintered bodies have been known as low thermal expansion ceramic structural members, and have been applied to filters, honeycombs, refractories, and the like. The cordierite-based sintered body is made of cordierite powder or MgO, Al ₂ O ₃ ,
By blending SiO ₂ powder, as a sintering aid thereto, and rare earth element oxides, SiO _2, CaO, MgO and the like were added, after molding into a predetermined shape and sintered at a temperature of 1000 ° C. to 1400 ° C. Created by things. (Special Publication 57-36
No. 29, JP-A-2-229760).

On the other hand, in a process of manufacturing a semiconductor integrated circuit device such as an LSI, in a process of forming fine wiring on a silicon wafer, a susceptor for supporting or holding the wafer, an electrostatic chuck or an insulating ring, and a circuit for forming a silicon wafer. Ceramics such as alumina and silicon nitride have been relatively inexpensive and chemically stable as jigs for XY tables of exposure equipment for forming or other various semiconductor manufacturing equipment. Widely used.

Recently, it has been proposed in Japanese Patent Application Laid-Open No. Hei 1-191422 and Japanese Patent Publication No. 6-97675 that a cordierite-based sintered body is applied as a semiconductor manufacturing device part by utilizing the low thermal expansion property of cordierite. Have been. According to Japanese Patent Application Laid-Open No. 1-191422, it is proposed that a reinforcing ring bonded to a mask substrate in an X-ray mask is formed of cordierite in addition to SiO ₂ , invar, and the like to control the stress of the membrane. Japanese Patent Publication No. Hei 6-97675 proposes using an alumina or cordierite-based sintered body as a substrate for an electrostatic chuck on which a wafer is mounted.

[0005]

In recent years, as the degree of integration in LSIs and the like has increased, the miniaturization of circuits has been rapidly advanced, and the line width of the circuits has been increasing to the level of the submicron order. A high precision is required for an exposure apparatus for forming a high-precision circuit on a silicon wafer.
At present, a positioning accuracy of 00 nm (0.1 μm) or less is required, and at present, an exposure alignment error has a great effect on the improvement of product quality and the yield.

[0006] Semiconductor manufacturing device generally alumina has been used for the ceramics such as silicon nitride, although the thermal expansion coefficient is smaller than that of the metal, each thermal expansion coefficient of 10~40 ℃, 5.2 × 10 ^{- 6} /℃,1.5×10 ^-6 /
° C, and several hundred n when the ambient temperature changes by 0.1 ° C
m (0.1 .mu.m), and this change becomes a serious problem in precision steps such as exposure, and the conventional ceramics have low accuracy and lower productivity.

On the other hand, the cordierite-based sintered body has a coefficient of thermal expansion of about 0.2 × 10 ⁻⁶ / ° C., which is lower than that of alumina or silicon nitride. The problem of exposure accuracy is solved to some extent.

However, like a stage for an exposure apparatus,
In the case where the support on which the silicon wafer is mounted moves at a high speed to the position where the exposure processing is performed, the support itself after the movement is still vibrating even after stopping at the predetermined position. However, there is a problem that the exposure accuracy decreases when the exposure process is performed. This becomes more remarkable as the wiring formed by exposure becomes thinner, and has become a fatal problem in forming a highly precise wiring circuit.

Since such vibrations are caused by the low rigidity of the members themselves, high rigidity, that is, high Young's modulus is required for these members.

Accordingly, an object of the present invention is to provide a low-thermal-expansion ceramic structural member which has low thermal expansion and high rigidity and low thermal expansion. Another object of the present invention is to provide a member for a semiconductor element manufacturing apparatus which is applied to an apparatus for manufacturing a semiconductor element such as a highly integrated circuit element and can manufacture a precise wiring circuit with high accuracy. is there.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies on the above problems and found that Mg, Al and Si were contained in ceramics having a cordierite crystal phase as a main phase.
It has been found that, by including at least one element selected from the group of elements of Groups 2a, 3b and 4b of the periodic table other than the above at a predetermined ratio, the coefficient of thermal expansion can be reduced and the Young's modulus can be further improved.

That is, the present invention mainly comprises a cordierite crystal phase and oxidizes at least one element selected from the group of elements of Groups 2a, 3b and 4b of the periodic table (excluding Mg, Al and Si). Containing 0.5 to 10% by weight in terms of material, having a relative density of 95% or more, and a thermal expansion coefficient of 0.5 at room temperature.
A low-thermal-expansion ceramic structural member having a temperature of × 10 ⁻⁶ / ° C. or less and a Young's modulus of 130 GPa or more. In particular, in the ceramics, at least one element selected from the group consisting of the elements in Groups 2a and 3b of the periodic table Containing a silicate compound crystal phase or an aluminum silicate crystal phase, containing a rare earth element in a proportion of 20% by weight or less in terms of oxide, and at least one selected from silicon nitride, silicon carbide, and silicon oxynitride. It is desirable to contain the seed in a proportion of 30% by weight or less.

According to the present invention, the above object is achieved by using the low thermal expansion ceramic structural member as a member for a semiconductor device manufacturing apparatus.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The ceramic sintered body according to the present invention has a cordierite crystal phase as a main phase and has a second phase in the periodic table.
At least one element selected from the group of elements a, 3b and 4b (excluding Mg, Al and Si) in a proportion of 0.5 to 10% by weight, preferably 2 to 8% by weight in terms of oxide. It is important to include.

By adding at least one element selected from the group of elements of groups 2a, 3b and 4b of the periodic table (excluding Mg, Al and Si), sintering of cordierite by itself is difficult to densify. Properties can be improved, and a higher Young's modulus and a lower thermal expansion can be promoted. Group of elements of groups 2a, 3b and 4b of the periodic table (provided that Mg,
Excluding Al and Si. )), At least one element selected from Ca, Sr, Ba, B, Ge, In,
Sn and the like are preferred.

The content of the above components is limited as described above because at least one element selected from the group of elements of Groups 2a, 3b and 4b of the periodic table (excluding Mg, Al and Si). If the oxide equivalent is less than 0.5% by weight, the effect of improving sinterability, high Young's modulus and lowering thermal expansion cannot be expected. If it exceeds 10% by weight, the coefficient of thermal expansion is 0.5 × 10 ^{−. 6}
/ ° C, which is not suitable for the purpose of the present invention.

The low thermal expansion ceramic structural member of the present invention has a cordierite crystal phase as a main phase.
In order to increase the Young's modulus, at least one type (M) selected from the group of elements of Groups 2a and 3b of the periodic table (excluding Mg, Al and Si) is composed of a silicate compound crystal phase or an aluminum silicate crystal. Desirably, a phase is formed. Specific examples of the silicate compound crystal phase include M ₂ Si ₂ O ₇ , and examples of the aluminum silicate crystal phase include MAl ₂ Si ₂ O ₈ .

In addition, the sinterability can be further improved by incorporating a rare earth element in an amount of 20% by weight or less, particularly 1 to 10% by weight, in terms of oxide in such ceramics, whereby the sinterability can be further improved, and Ceramics can be obtained. The rare earth elements used include Y, Yb, Er, S
m, Dy, etc., which are present as oxides in the sintered body at the grain boundaries of the crystal phase as an amorphous phase or a silicate crystal phase.

If the amount of the rare earth element in terms of oxide exceeds 20% by weight, the coefficient of thermal expansion of the ceramic exceeds 0.5 × 10 ⁻⁶ / ° C., which is not suitable for the purpose of the present invention. .

According to the present invention, at least one member selected from the group consisting of silicon nitride, silicon carbide and silicon oxynitride having a high Young's modulus is contained in the ceramic in an amount of 30% by weight.
In the following, it is possible to obtain a ceramic member having a higher Young's modulus while maintaining a low thermal expansion property, particularly by adding the component in a ratio of 10 to 20% by weight.

These components exist as crystal grains in the ceramic. Among them, silicon nitride is most effective. Note that the silicon oxynitride is a Si-N-O based compound, for example, Si ₂ N ₂ O. When the total amount of the silicon nitride, silicon carbide, and silicon oxynitride exceeds 30% by weight, the coefficient of thermal expansion of the ceramic is 0.5 × 1.
It exceeds 0 ^-6 / ° C, and is not suitable for the purpose of the present invention.

It is also important that the ceramic of the present invention has a relative density of 95% or more. This is because if the relative density is smaller than 95%, a high Young's modulus of 130 GPa or more cannot be achieved. The relative density is desirably higher, and is desirably 96% or more, and desirably 97% or more, in order to increase the Young's modulus.

In order to produce the low thermal expansion ceramic structural member as described above in the present invention, cordierite powder having an average particle size of 10 μm or less is mainly used, and the average particle size is 10 μm.
At least one compound selected from the group of elements of Groups 2a, 3b and 4b (excluding Mg, Al and Si) in the following periodic table is converted to oxide in an amount of 0.5 to 10% by weight. Add in proportions. The compound may be any of oxides, carbides, hydroxides, carbonates and the like.

Further, at least one of silicon nitride, silicon carbide, and silicon oxynitride having a rare earth element oxide having an average particle size of 10 μm or less at 20% by weight or less and an average particle size of 10 μm or less is selected.
The seeds are appropriately mixed at a ratio of 30% by weight or less, and then sufficiently mixed by a ball mill or the like, and formed into a predetermined shape by a desired forming means, for example, a die press, a cold isostatic press, an extrusion molding, a casting molding, and the like. I do.

Then, the molded body is put in a range of 1200 to 1500
C., especially at 1300-1400 ° C. for about 1-10 hours for densification. In addition, the reason why the firing temperature is limited as described above is that if the temperature is lower than 1200 ° C., a dense body cannot be obtained, and if the temperature exceeds 1500 ° C., the material is dissolved.

In the case of firing, when silicon nitride, silicon carbide, silicon oxynitride or the like is contained in the compact, it is preferable to fire in an inert gas such as nitrogen or argon so that these components are not oxidized.

In order to precipitate at least one silicate compound crystal phase or aluminum silicate crystal phase selected from the group of elements of Groups 2a and 3b of the periodic table (excluding Mg, Al and Si). The temperature decreasing process from the firing temperature to 1000 ° C. is performed at 300 ° C./hr.
By slowly cooling below, a crystalline phase can be positively precipitated.

It should be noted that the low thermal expansion ceramic structural member of the present invention has high rigidity, while maintaining excellent low thermal expansion characteristics.
That is, since it has a high Young's modulus, it is suitably used for structural members for various industrial machines that require low thermal expansion characteristics.
In particular, by using as a member for a semiconductor device manufacturing apparatus such as performing an exposure process on a wafer for forming a fine circuit, for example, a stage for an exposure apparatus, an optical system support, etc., it is possible to prevent a change in ambient temperature Also, there is no change in dimensions, excellent accuracy can be obtained, and a decrease in accuracy due to vibration can be prevented, so that the quality and mass productivity of semiconductor device manufacturing can be improved.

Further, the low thermal expansion ceramic structural member of the present invention can be used similarly as various structural members in a semiconductor device manufacturing process such as a vacuum device structure, a susceptor, an electrostatic chuck, a vacuum chuck or a stepper. The effect can be expected.

[0030]

EXAMPLES Cordierite powder (average particle size 2 μm, BE
T specific surface area 2 m ² / g) and various periodic table 2a, 3b and 4b group element compounds shown in Table 1 having an average particle diameter of 1 μm;
Using silicon nitride, silicon carbide, and silicon oxynitride powder having an average particle diameter of 0.6 μm and various rare earth element oxide powders having an average particle diameter of 1 μm, and blended to have the compositions shown in Tables 1 to 4. Molding was performed at 1 t / cm ² . Then, the compact was placed in a silicon carbide sagger and fired under the conditions shown in Tables 1 to 4. In addition, sample No. 3-6, 11, 15-20, 23, 32,
For 33, 35, and 38, 200 ° C /
The temperature was gradually cooled at a rate of 500 ° C./hr.

The obtained sintered body is polished and 3 × 4 × 14 m
m samples were prepared. Using this, the relative density was calculated based on the Archimedes method, and the coefficient of thermal expansion at room temperature was measured. The Young's modulus at room temperature was measured by the ultrasonic pulse method. Further, X-ray diffraction measurement was performed to identify a crystal phase other than cordierite.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

As is clear from the results of Tables 1 to 4, the elements of Groups 2a, 3b and 4b of the periodic table (however, Mg, Al
And Si. Samples Nos. 1, 2, and 41 in which no or no) is added have a low Young's modulus.
Samples Nos. 9 and 45 in which Group 2a, 3b and 4b elements are more than 10% by weight, Sample No. 14 in which the amount of rare earth oxide is more than 20% by weight, and Samples No. 14 in which the amount of silicon nitride is more than 30% by weight Sample No. 27 had a coefficient of thermal expansion of 0.5 ×
It exceeded 10 ^-6 / ° C. When the firing temperature is 1
Sample No. 21 having a temperature higher than 500 ° C. was melted, and densification was insufficient in sample No. 17 having a firing temperature lower than 1200 ° C.

In contrast to these comparative examples, the samples according to the present invention all exhibited low thermal expansion characteristics with a thermal expansion coefficient of 0.5 × 10 ⁻⁶ / ° C. or less, and further exhibited a Young's modulus of 130 GPa or more. Was. Among these, samples No. 24 to 26, 28 to 31, to which silicon nitride, silicon carbide and silicon oxynitride were added,
35, 36, 40, 48 and 54 have a Young's modulus of 160G.
Pa could be increased to Pa or more.

Samples Nos. 3 to 6, 11, 15 to 15 in which a silicate crystal phase containing an element from Groups 2a and 3b of the periodic table or an aluminum silicate crystal phase were precipitated.
6, 18-20, 23, 32, 33, 35, 37, 38
In any case, the Young's modulus could be increased to 140 GPa or more, and in Sample No. 35 in which these were combined, the Young's modulus could be increased to 170 GPa or more.

[0039]

As described in detail above, the low thermal expansion ceramic structural member of the present invention can increase rigidity, that is, Young's modulus, while maintaining excellent low thermal expansion characteristics of cordierite. As a result, by using this low thermal expansion ceramic structural member as a part for a semiconductor device manufacturing apparatus such as performing exposure processing on a wafer for forming a fine circuit, for example, a stage for an exposure apparatus, the temperature change of the atmosphere can be achieved. In this case, there is no change in dimensions, excellent accuracy can be obtained, and a decrease in accuracy due to vibration can be prevented, so that the quality and mass productivity of semiconductor device manufacturing can be improved.

Claims (5)

[Claims] 1. A group consisting of elements of Groups 2a, 3b and 4b of the Periodic Table (wherein Mg, A
Excluding l and Si. ) In an amount of 0.5 to 10% by weight in terms of oxide and a relative density of 95%.
A low-thermal-expansion ceramic structural member having a thermal expansion coefficient at room temperature of 0.5 × 10 ⁻⁶ / ° C. or lower and a Young's modulus of 130 GPa or higher. 2. The method according to claim 1, comprising a silicate compound crystal phase or an aluminum silicate crystal phase containing at least one element selected from the group consisting of Group 2a and 3b elements of the periodic table. Low thermal expansion ceramic structural member. 3. The low-thermal-expansion ceramic structural member according to claim 1, comprising a rare earth element in a proportion of 20% by weight or less in terms of oxide. 4. The low thermal expansion ceramic structural member according to claim 1, wherein at least one selected from silicon nitride, silicon carbide, and silicon oxynitride is contained in a proportion of 30% by weight or less. 5. A member for a semiconductor device manufacturing apparatus, comprising a low thermal expansion ceramic structural member according to any one of claims 1 to 4.