JP4897263B2 - Black low resistance ceramics and semiconductor manufacturing equipment components - Google Patents

Description

  The present invention relates to black low-resistance ceramics, and in particular, to ceramics exhibiting a black color suitable for use as a member for a semiconductor manufacturing apparatus such as an exposure apparatus, and having low resistance and low thermal expansion.

Conventionally, ceramics such as alumina, silicon nitride, silicon carbide, and aluminum nitride have been widely used for members such as a wafer support jig in a process of processing a silicon wafer in a semiconductor manufacturing process. (For example, see Patent Document 1.)

However, in recent years, with the miniaturization of devices, high accuracy is required to achieve the miniaturization. For example, in a semiconductor exposure apparatus, accuracy of less than 10 nm is required for stage positioning. Therefore, the reduction in alignment error has come to be regarded as a major element technology for future product quality improvement and yield improvement. However, a member using alumina, silicon nitride, silicon carbide, or aluminum nitride has a problem that since it has a high thermal expansion coefficient, it is easily affected by temperature, and such extremely fine positioning cannot be performed.

For this reason, low thermal expansion ceramics in which the thermal expansion coefficient is controlled by combining silicon carbide exhibiting a positive thermal expansion coefficient with eucryptite exhibiting a negative thermal expansion coefficient are required to be finely positioned. Application to semiconductor manufacturing equipment materials has been studied. (For example, see Patent Document 2.)

Furthermore, due to the demand for suppressing the reflectivity in the exposure process of semiconductor manufacturing equipment in recent years, the member is black, and from the demand for removing adverse effects due to static electricity when exposing fine circuits of semiconductor wafers. Studies are also underway to reduce the resistance of ceramics. (For example, see Patent Document 3.)
JP-A 53-96762 JP 2001-302338 A JP 2002-220277 A

However, the above-mentioned composite ceramics of eucryptite (theoretical chemical composition formula: LiAlSiO ₄ ) and silicon carbide are difficult to be densified, and in order to sinter at high density, hot isostatic pressing (HIP treatment) And a high temperature of 1360 ° C. or higher is required. Therefore, there has been a problem that a large sintered body cannot be obtained.

In addition, when carbon is added to exhibit a black color, there has been a problem that densification of ceramics is further inhibited.

  The present invention has been completed through intensive studies to solve these problems, and its purpose is to be dense and have a low thermal expansion, and is suitable as a member for a semiconductor manufacturing apparatus having a black color and a low resistance value. It is to provide ceramics.

The object of the present invention described above is a black low-resistance ceramic that exhibits black color, and the ceramic is selected from 70 to 85% by volume of eucryptite, TiB ₂ , ZrB ₂ , WC, TiC, ZrN, and β-SiC. 4.9-23% by volume of one or more conductive compounds, 0.1-3.9% by volume of silicon nitride, 3.1-10% by volume of carbon, and the volume resistivity of the ceramic A low black resistance characterized by a coefficient of 10 ⁵ Ω · cm or less, a coefficient of thermal expansion at 20 ° C. to 30 ° C. of −1 × 10 ⁻⁶ to 1 × 10 ⁻⁶ / ° C., and a relative density of 95% or more. Achieved with ceramics.

The object of the present invention is that the black low-resistance ceramic is obtained by sintering the raw material powder at a temperature of 1250 ° C. to 1400 ° C. in an inert gas atmosphere under a pressure of 50 kgf / cm ² or more. Achieved by the featured black low resistance ceramics.

The object of the present invention is also achieved by a member for a semiconductor manufacturing apparatus, characterized in that the black low-resistance ceramic described above is used as at least a part of a substrate.

According to the present invention, eucryptite that can be densified to a relative density of 95% or higher under a pressure of 50 kgf / cm ² or higher at a temperature of 1250 ° C. to 1400 ° C. in an inert gas atmosphere is a main component. It is possible to provide a low thermal expansion ceramic as a component, and there is an effect that a ceramic suitable as a member for a semiconductor manufacturing apparatus having a black color and a low resistance value can be obtained.

For example, the present inventors have proposed low thermal expansion ceramics made of various materials as materials used in semiconductor manufacturing equipment, precision equipment, measuring equipment, and the like.
In particular, since eucryptite exhibits a negative coefficient of thermal expansion, an extremely low coefficient of thermal expansion can be obtained by combining with a second material exhibiting a positive coefficient of thermal expansion. For this reason, the low thermal expansion ceramic which consists of a composite material which combined silicon carbide as a 2nd material has also earnestly examined.

Here, the ceramic of the present invention contains eucryptite in an amount of 70 to 85% by volume, and one or more conductive compounds selected from TiB ₂ , ZrB ₂ , WC, TiC, ZrN, and β-SiC 4.9 to 23. The reason for containing 0.1% to 3.9% by volume of silicon nitride, 0.1% to 3.9% by volume of silicon nitride, and 3.1% to 10% by volume of carbon is that the thermal expansion coefficient at 20 to 30 ° C. is −1 × by constituting in this range. This is because it has a low thermal expansion of 10 ⁻⁶ to 1 × 10 ⁻⁶ / ° C., can be made dense with a relative density of 95% or more, and can further increase rigidity. Therefore, the ceramic of the present invention is suitable as a semiconductor manufacturing apparatus member that can be adapted to miniaturization of semiconductor circuits.

Here, in the material composition constituting the low thermal expansion ceramic of the present invention, containing 0.1 to 3.9% by volume of silicon nitride is important for densifying the relative density to 95% or more. However, if silicon nitride is contained in an amount exceeding 3.9% by volume, the ceramic is cracked, which is not preferable.

Further, in the material composition constituting the low thermal expansion ceramic of the present invention, it is important to contain 3.1 to 10% by volume of carbon in order to obtain a black ceramic with uniform and no spots. Here, if the carbon content is less than 3.1% by volume, the blackness is not sufficient or color spots are not preferable, and if the carbon content exceeds 10% by volume, densification becomes difficult, which is not preferable. .

Further, in the material composition constituting the low thermal expansion ceramic of the present _{invention, TiB 2, ZrB 2, WC} , TiC, ZrN, 1 or more conductive compounds selected from beta-SiC containing 4.9 to 23 vol% This is very important.
As a result, the volume resistivity of the ceramic can be made 10 ⁵ Ω · cm or less, and it is possible to remove static electricity.
However, if the conductive compound is contained in an amount exceeding 23% by volume, densification becomes difficult, which is not preferable. If the conductive compound is less than 4.9% by volume, the volume resistivity of the ceramic cannot be made 10 ⁵ Ω · cm or less.
Here, when adjusting the thermal expansion coefficient at 20 ° C. to 30 ° C. to −1 × 10 ⁻⁶ to 1 × 10 ⁻⁶ / ° C. within the range of the present invention, β-SiC is particularly preferable as the conductive compound. The reason is that, as a constituent component other than eucryptite, the volume ratio of the conductive compound is the largest, and therefore β-SiC having the smallest thermal expansion coefficient among the conductive compounds is suitable for the thermal expansion control. Because there is.

Next, in the present invention, a black low resistance ceramic obtained by sintering raw material powder at a temperature of 1250 ° C. to 1400 ° C. in an inert gas atmosphere under a pressure of 50 kgf / cm ² or more is proposed. Yes.

Here, in the present invention, the reason why the raw material powder is sintered under the above-described conditions is that the thermal expansion coefficient of the ceramic at 20 to 30 ° C. is in the range of −1 × 10 ⁻⁶ to 1 × 10 ⁻⁶ / ° C. Further, since the relative density can be 95% or more, it is suitable as a semiconductor manufacturing apparatus member that can be adapted to refinement of a semiconductor circuit.
Here, nitrogen, argon, or the like can be used as the inert gas atmosphere.
In addition, in the pulverizing step of the raw material powder in the present invention, pulverization with a mortar, pulverization with a planetary ball mill, or the like can be applied in addition to known ball mill pulverization.
Further, in the case where a molding process is involved, uniaxial pressure molding, isostatic pressing, or the like can be applied.

Further, the present invention proposes a member for a semiconductor manufacturing apparatus characterized by using the above-described black low-resistance ceramic as at least a part of a base material.
That is, when the black low resistance ceramic of the present invention is used as a part of the base material of a member for a semiconductor manufacturing apparatus, it is possible to manufacture a fine circuit with a high yield due to low thermal expansion, and the member exhibits a black color. The reflectance in the semiconductor exposure process can be suppressed, and since it has low resistance, adverse effects on the formation of microcircuits on the semiconductor wafer due to static electricity can be eliminated. Therefore, a highly reliable semiconductor can be manufactured with a high yield.

Next, the present invention will be described with reference to specific examples and comparative examples.
(1) Mixing of raw material powder and pulverization As the raw material powder, commercially available β-eucryptite powder, conductive compound such as β-SiC, silicon nitride powder, and carbon powder are used. The content of each constituent component in the bonded body was set to the composition (volume%) shown in Table 1.
Next, each raw material powder having the composition ratio shown in Table 1 was put into a ball mill together with an ethanol solvent and an alumina ball, and mixed and pulverized by wet for 16 hours. The mixed and pulverized powder thus obtained was dried and crushed.

(2) Preparation of sintered body and measurement of relative density 50 to 200 kgf / cm ² of the mixed pulverized powder obtained as described above at a firing temperature shown in Table 1 in an inert gas atmosphere of nitrogen Sintering was performed under pressure to produce a ceramic sintered body.

The relative density of the ceramic sintered body obtained as described above was measured by the Archimedes method, and the measurement results are summarized in Table 1.
(3) Measurement of thermal expansion coefficient and volume resistivity With respect to the sintered bodies in Table 1, test bodies were separately prepared in the same manner for the sintered bodies in which no cracks occurred, and these test bodies were designated as JIS R3251 “ The coefficient of thermal expansion at 20 to 30 ° C. was measured by the method defined in “Method of measuring linear expansion coefficient by laser interferometer of low expansion glass”.
In addition, the volume resistivity was determined by forming a 1 mm wide electrode with a conductive paste at both ends and 10 mm from the end of a sample having a size of 4 × 3 × 30 mm, and using a four-terminal method (JIS K7194 “conductive plastic Measured according to “Resistivity test method by 4-probe method”). The obtained results are summarized in Table 1.

(4) Evaluation of degree of coloration of sintered body The sintered body in Table 1 was evaluated by visually observing the state of coloration of black and the degree of occurrence of color spots. The results are also summarized in Table 1.

(5) Evaluation result From the result of Table 1, it is No. which is an Example . 1-7, no. All of the specimens 9 to 12 have a low volume resistivity of 10 ⁵ Ω · cm or less and a thermal expansion coefficient at 20 ° C. to 30 ° C. of −1 × 10 ⁻⁶ to 1 × 10 ⁻⁶ / It was confirmed that the temperature was low and thermal expansion was low, and the relative density was 95% or higher. In addition, the coloration was uniform and black with no color spots. On the other hand, No. which is a comparative example. None of 13 to 22 could be used as a ceramic suitable as a member for a semiconductor manufacturing apparatus having a dense and black color and a low resistance value.

As described above, according to the present invention, eucryptite that can be densified to a relative density of 95% or higher under a pressure of 50 kgf / cm ² or higher at a temperature of 1250 ° C. to 1400 ° C. in an inert gas atmosphere. It is possible to provide a low thermal expansion ceramic as a main component, and there is an effect that a ceramic suitable as a member for a semiconductor manufacturing apparatus having a black color and a low resistance value can be obtained.

Claims (3)

A black low resistance ceramic exhibiting a black color, the ceramic, eucryptite the 70-85 _{vol%, TiB 2, ZrB 2,} WC, TiC, ZrN, 1 or more conductive compounds selected from beta-SiC 4.9-23 vol%, silicon nitride 0.1-3.9 vol%, carbon 3.1-10 vol%, and the volume resistivity of the ceramic is 10 ⁵ Ω · cm or less A black low-resistance ceramic having a thermal expansion coefficient of -1 × 10 ⁻⁶ to 1 × 10 ⁻⁶ / ° C. and a relative density of 95% or more at 20 ° C. to 30 ° C. The black low-resistance ceramic is obtained by sintering raw material powder at a temperature of 1250 ° C to 1400 ° C in an inert gas atmosphere under a pressure of 50 kgf / cm ² or more. The black low resistance ceramic described. A member for a semiconductor manufacturing apparatus, wherein the black low-resistance ceramic according to claim 1 or 2 is used as at least a part of a substrate.