JP3171664B2 - Substrate suction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate suction apparatus provided with a suction plate for sucking and moving or fixing a thin plate, and more particularly to a wafer hand or wafer holder for sucking and moving a thin plate such as a semiconductor wafer or for holding it by suction. The present invention relates to a substrate suction device according to the above.

[0002]

2. Description of the Related Art A wafer hand and a wafer holder incorporated in a semiconductor integrated circuit manufacturing apparatus are passed through a suction plate.
It is used to move a wafer by vacuum suction and to fix the wafer by vacuum suction. As the suction plate for the wafer hand and the wafer holder, a suction plate made of alumina, that is, a suction plate made of alumina, which is an insulator, is conventionally used.

[0003]

By the way, in the process of manufacturing an IC, dust is extremely hated, and such dust is taken into consideration. However, in the case of a conventional alumina suction plate, the electrostatic suction is applied to the suction plate. Have a disadvantage that they are easily charged and dust is easily absorbed by the static electricity. In order to solve this drawback, that is, to remove static electricity charged on the alumina suction plate, means for coating a conductor on the suction plate have been conventionally proposed.

[0004] However, the means for coating the conductor has many problems, such as the necessity of complicated steps. Therefore, a ceramic suction plate which does not require such means has been desired. That is, unlike a conventional suction plate made of alumina, which is an insulator, a ceramic suction plate which has a small specific resistance and is not charged with static electricity is demanded.

When a large number of pores are present on the surface of the suction plate, especially when a large number of pores (for example, pores having a diameter of 3 μm or more) are present, (a) dust and dirt adhere to the pores. However, this causes problems such as being mixed during the semiconductor manufacturing process.Furthermore, (b) a problem that gas or the like is adsorbed in the pores, thereby lowering the adsorbing ability and holding ability of a thin plate such as a semiconductor wafer. Occurs.

Therefore, in addition to the above-mentioned demands, an adsorption plate which also solves the above problems (a) and (b), that is, a ceramic adsorption plate having a small specific resistance and having very few pores on the surface of the adsorption plate. The emergence of is strongly desired today.

Accordingly, an object of the present invention is to provide a substrate suction device provided with a ceramic suction plate meeting the above demand. More specifically, an object of the present invention is to provide a substrate suction device provided with a ceramic suction plate having a low specific resistance and having very few pores on its surface. An object of the present invention is to provide a substrate suction device provided with a ceramic suction plate which can greatly contribute to integration and a high yield.

[0008]

According to the present invention, a titanium oxide adsorbing plate is used as a ceramic adsorbing plate, and the specific resistance of the adsorbing plate is 1.0 Ω · cm or less, and The present invention is characterized in that an adsorbing plate having a number of pores having a diameter of 3 μm or more and having a diameter of not more than 100 / mm ² existing on the surface thereof is used, thereby providing the above-mentioned substrate adsorbing apparatus.

That is, the present invention provides a substrate suction apparatus provided with a suction plate for sucking and moving or fixing a thin plate, wherein the specific resistance of the suction plate is 1.0 Ω · cm or less, and A substrate adsorption device comprising a titanium oxide adsorption plate having a number of pores having a diameter of 3 μm or more and not more than 100 per 1 mm ^2. "

Hereinafter, the present invention will be described in detail. The present inventors have made ceramics having a small specific resistance, and
As a result of diligent research on a method for producing a smooth ceramic having extremely few pores on the surface, it was found that the target ceramic adsorbing plate can be obtained by the following methods (1) to (3). The invention has been completed. (1) A method in which a high-purity titanium oxide fine powder is molded, and then the molded body is fired in air or an inert atmosphere, and further subjected to HIP treatment. (2) A method in which high-purity titanium oxide fine powder is molded and then fired in a reducing atmosphere. (3) A method in which high-purity titanium oxide fine powder is molded, fired in a reducing atmosphere, and further subjected to HIP treatment.

That is, the present invention has both the first property intended by the present invention that "the resistivity is extremely small" and the second property intended by the present invention that "there are very few pores on the surface". A technical object is to provide a ceramic suction plate. According to the production methods (1) to (3), the titanium oxide sintered body having both the first and second properties, that is, “the specific resistance is 1.0 Ω · cm or less, and And a titanium oxide sintered body having a number of pores having a diameter of not less than 3 μm and having a diameter of not more than 100 / mm ² existing on the surface thereof. ”This titanium oxide sintered body is used as an adsorption plate for a substrate adsorption device. The present invention to be used has been completed.

In the above production methods (1) to (3), the “high-purity titanium oxide fine powder” used as a raw material is 99%
It is preferable to use one having the above high purity. If it is less than 99%, the second property intended in the present invention, which is "a pore on the surface,
(A sintered body having a pore number of 3 μm or more and a pore number of 100 / mm ² or less) ”is not preferable (see Comparative Examples 6 and 7 described later).

Further, it is preferable to use the raw material fine powder having an average particle diameter of 1 μm or less. 1 μm
If a coarse powder is used, the second property, "sintered body having extremely few pores on the surface", which is also intended in the present invention, is difficult to obtain, which is not preferable (see Comparative Example 8 described later).

The “high-purity titanium oxide fine powder” used as a raw material will be further described.
If the purity is less than 99%, or if the average particle size is coarser than 1 μm, the properties of low-temperature easy sintering will be lost and the sintered density will not be sufficiently increased as described later. When sintering at a high temperature (a temperature exceeding 1300 ° C. defined in the present invention, for example, 1400 ° C., 1600 ° C.) to increase the sintering density, grain growth occurs and pores become coarse (comparative examples described later). 2-8
reference).

Therefore, in the present invention, as the “high-purity titanium oxide fine powder” to be used as a raw material, it is preferable to use a powder having a high purity of 99% or more and an average particle diameter of 1 μm or less. It is more preferable to use "high-purity titanium oxide fine powder having an average particle diameter of 0.5 μm or less".

In the present invention, the above raw material fine powder is formed by a usual CIP molding method or by a doctor blade method or an extrusion method, etc., and formed into a ceramic green sheet. Those molded by the doctor blade method or the extrusion method are then subjected to binder removal treatment as required.
Next, firing is performed by using any of the following methods (1) to (3) to produce a titanium oxide substrate having both the first and second properties intended in the present invention. (1) A method of firing in air or an inert atmosphere and further performing HIP treatment. (2) A method of firing in a reducing atmosphere. (3) A method of firing in a reducing atmosphere and further performing HIP treatment.

In the above methods (1) to (3), the firing temperature in the air or in a reducing atmosphere is preferably from 1100 to 1300 ° C., and more preferably around 1200 ° C. At a low temperature firing of less than 1100 ° C, it is difficult to obtain a titanium oxide sintered body because sintering itself does not proceed easily. On the other hand, at a firing temperature exceeding 1300 ° C, the second property, “porous surface -Sintered body with very few (100 / mm ² pores with a diameter of 3 μm or more)
The following sintered bodies) ”are not preferred because they are difficult to obtain (see Comparative Example 2 below).

The firing temperature will be further described. In the present invention, "1100 to 1300" which is lower than the firing temperature (about 1350 ° C.) usually used for titania ceramics.
° C ”in air, inert atmosphere or reducing atmosphere. At temperatures exceeding 1300 ° C, grain growth (crystal growth) is remarkable, and pores move to the grain boundary phase and pores accompanying grain growth. This is not preferable because coarsening of-occurs. And
In the present invention, in order to easily perform sintering at such a low temperature (to exhibit low-temperature sinterability), the aforementioned 99%
The above-mentioned “high-purity titanium oxide fine powder” having a high purity and an average particle diameter of 1 μm or less is used as a raw material.

In the above method (1), the sintering with a small specific resistance (specific resistance of 1.0 Ω · cm or less), which is the first property intended by the present invention, is achieved only by firing in the air or an inert atmosphere. Is not obtained (see Comparative Example 1 described later). Therefore, when the sintering method in the air or in an inert atmosphere is adopted, the obtained sintered body is further subjected to H in order to impart the first property described above, that is, the property of having a small specific resistance.
It is necessary to perform IP processing.

By this HIP treatment, for example, HIP treatment using carbon heater, the titanium oxide sintered body fired in the air or an inert atmosphere is converted into a semiconductor, and a desired 1.0% is obtained.
Those having a specific resistance of Ω · cm or less can be obtained. In addition,
In addition to the effect of reducing the specific resistance, the HIP treatment also has the effect of reducing the number of pores on the surface. The HIP treatment is performed at the firing temperature (1100) because the pores do not become coarse due to grain growth.
(1300 ° C.) or lower at 800 to 1100 ° C., and the pressure is preferably 500 kg / cm ² or more. More preferred HIP processing conditions are 1000 ° C. and 1500 k
g / cm ² .

In the method (2) of “calcining in a reducing atmosphere”, the titanium oxide is partially reduced by baking in a reducing atmosphere to be converted into a semiconductor, and a desired 1.0 Ω · c
Those having a specific resistance of not more than m are obtained. As this reducing atmosphere, firing can be performed in any reducing atmosphere as long as titanium oxide becomes a semiconductor during firing, but firing in a nitrogen atmosphere using, for example, a carbon heater is preferable. .

According to the method (2) of baking at 1100 to 1300 ° C. in a reducing atmosphere, the first property of the present invention that “specific resistance is extremely small” and “the surface has very few pores” Similarly, a titanium oxide sintered body having the second property intended in the present invention is obtained. Further, in the present invention, in order to further reduce the surface pores,
The titanium oxide sintered body obtained by the method (2) can be further subjected to HIP treatment using, for example, a carbon heater as described above. This HIP processing includes the H (1) described above.
As with IP treatment, at a firing temperature of 800 to 1100 ° C and a pressure of 500 kg /
cm ² or more, preferably 1000 ° C., 1500 kg / c
More preferably, it is performed at m ² .

In the present invention, the surface of the titanium oxide substrate obtained by the above methods (1) to (3) can be subjected to surface grinding and lapping as required. Then, a suction hole is formed in the titanium oxide substrate to obtain a titanium oxide adsorption plate.

[0024]

EXAMPLES Examples of the present invention will be described below together with comparative examples.
The present invention will be described in more detail. (Example 1) Polyvinyl butyral and ethyl alcohol were added to a titanium oxide powder having an average particle diameter of 0.25 µm and a purity of 99.8%, mixed and slurried, and then greened by a doctor blade method. Was prepared and fired at 1200 ° C. in the air after the binder removal treatment. Next, the sintered body is subjected to carraging in an argon atmosphere at a temperature of 1000 ° C. and a pressure of 1500 kg / cm ^2.
HIP treatment was performed in a HIP furnace having a bon heater.

The specific resistance and the number of pores of the obtained titanium oxide substrate were measured, and the results are shown in Table 1. No pores having a diameter of 30 μm or more were observed on the surface of the substrate. The above specific resistance was measured by a four-terminal method (1 V, 1 kHz). The diameter and number of pores on the substrate surface were observed with a scanning electron microscope, and measured using photographs of the obtained images. The specific resistance values in Table 1 are values measured at 25 ° C., and the number of pores is the number of particles having an average particle diameter of 3 μm or more / mm ² .

Example 2 Average particle size 0.25 μm, purity 99.8
% Titanium oxide powder, polyvinyl butyral and ethyl alcohol were added and mixed to form a slurry.
A green sheet is prepared by a blade method, debindered, and subjected to carbon heating in a nitrogen atmosphere.
It was fired at 00 ° C. About the obtained titanium oxide substrate,
As in Example 1, the specific resistance and the number of pores were measured, and the results are shown in Table 1. The surface of the substrate had no pores having a diameter of 30 μm or more.

(Example 3) A HIP having a carbon heater at a temperature of 1000 ° C and a pressure of 1500 kg / cm ^{2 in} an argon atmosphere was prepared in the same manner as in Example 1 except that the sintered body obtained in Example 2 was used. HIPed in the furnace. For the obtained titanium oxide substrate, the specific resistance and the number of pores were measured as in Example 1, and the results are shown in Table 1. The surface of this substrate
There were no pores having a diameter of 30 μm or more.

Example 4 Average particle size 0.7 μm, purity 99.2
% Of the titanium oxide powder of Example 1 except that
A substrate made of titanium oxide was obtained in the same manner as described above. For the obtained titanium oxide substrate, the specific resistance and the number of pores were measured as in Example 1, and the results are shown in Table 1. The surface of the substrate had no pores having a diameter of 30 μm or more.

(Comparative Examples 1 to 8) For comparison, Table 1
Using a titanium oxide powder having an average particle size and purity shown in Table 1, a green sheet was prepared in the same manner as in Example 1 and then debindered. (Comparative Examples 3, 5, 7, and 8 were further fired under the HIP processing conditions shown in Table 1) to obtain a titanium oxide substrate. For each of the obtained titanium oxide substrates, the specific resistance and the number of pores were measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 9 Further, for comparison, the average particle size was
A green sheet was prepared in the same manner as in Example 1 above, using aluminum oxide powder having a purity of 0.6 μm and a purity of 99.8%. After removing the binder, the green sheet was fired at 1600 ° C. in the air. About the obtained aluminum oxide sintered compact, the said Example 1
In the same manner as in Example 1, the specific resistance and the number of pores were measured.
It was shown to.

[0031]

[Table 1]

As is clear from Table 1, the average particle size is 0.25 μm.
m, 99.8% pure titanium oxide powder, molded, fired at 1200 ° C in air, and further reduced to 1000 ° C, 1500 ° C
In Example 1 in which the HIP treatment was performed at a pressure of kg / cm ² , a sample having a specific resistance of 0.7 Ω · cm and a pore number of 34 / mm ² was obtained. Further, in Example 2, which was fired at 1200 ° C. in a nitrogen atmosphere using the same raw material as in Example 1, the specific resistance was 0.3.
A sample having a pore number of 70 / mm ² at 9 Ω · cm was obtained.

The product obtained in Example 2 was further subjected to HIP
In Example 3 in which the treatment was performed, a specific resistance of 0.7 Ω · cm and a number of pores of 38 / mm ² was obtained, and it can be understood that both the specific resistance and the number of pores were improved by the HIP treatment ( Specific resistance: 0.9 → 0.7, number of pores: 70 → 38). Further, titanium oxide powder having an average particle size of 0.7 μm and a purity of 99.2% (Example 1)
Examples in which raw materials having a larger average particle size and a low purity were used, but all of which were within the scope of the present invention), were fired in the air in the same manner as in Example 1, and were further subjected to HIP treatment. in 4, the same 0.7Ω · cm resistivity as in example 1, the pore - the number, those of the examples 1 100 contemplated more but the present invention / mm ² within 92 amino / mm ² Obtained.

On the other hand, under the same conditions as in the first embodiment,
In Comparative Example 1 in which the P treatment was not performed, the number of pores was 70 / mm.
² , a product having a high specific resistance of 10 ¹² Ω · cm (0.7 Ω · cm in Example 1) was obtained. (A sintered body having specific resistance) "was not obtained. Further, in Example 1, the firing temperature in the atmosphere was set to 1600 ° C., and the HIP treatment was not performed.
In Comparative Example 3 subjected to IP treatment (1400 ° C., 1500 kg / cm ² ), not only the high specific resistance (10 ¹² Ω · cm) but also the number of pores was 840 / mm ² and 480 / mm ^2. Met.

Further, Comparative Example 4 in which the firing temperature in the nitrogen atmosphere in Example 2 was 1600 ° C. and the HIP treatment was not performed
And the product obtained in Comparative Example 4 was subjected to HIP treatment (1400
℃, 1500 kg / cm ² ) in Comparative Example 5
Although the resistivity is as low as Ω · cm, the number of pores is 920 /
It was mm ² and 770 pieces / mm ^2. The average particle size is
In Comparative Example 6, which was within the scope of the present invention and used the same 0.7 μm as in Example 4, but using a 92.0% raw material having a purity outside the scope of the present invention and calcined (1400 ° C.) in air. , 10 ¹² Ω
・ High specific resistance of cm and a pore number of 960 / mm ² were obtained.

The same raw material as in Comparative Example 6 was used, fired in the air, and further subjected to HIP treatment (1200 ° C., 1800 kg / cm
^In Comparative Example 7 in which ² ) was performed, the specific resistance was 0.8 Ω · cm due to the HIP treatment, but the low purity (92.0
%), And the temperature outside the range of the present invention (1400 ° C)
By baking in the air at, a pore number of 550 / mm ² was obtained.

Further, the purity of the raw material is within the scope of the present invention.
99.2%, but the average particle size is 2.1 μm outside the range of the present invention.
Baked in the air (1400 ° C)
In Comparative Example 8 in which the IP treatment (1200 ° C., 1800 kg / cm ² ) was performed, the specific resistance was 0.8 Ω · cm, but 310 pieces / mm.
A pore number of ² was obtained. In Comparative Example 9 which was an alumina sintered body (raw material purity: 99.8%, average particle diameter: 0.6 μm, fired in air), not only the high specific resistance of 10 ¹⁴ Ω · cm, but also the number of pores It was 1000 pieces / mm ² .

Examples 1 to 4 and Comparative Examples 1 to 9 shown in Table 1 above.
As is apparent from the above, the present invention uses high-purity titanium oxide fine powder having an average particle diameter of 1 μm or less and a purity of 99% or more, and is fired (sintered) at 1100 to 1300 ° C. in the air or a reducing atmosphere. In the case where the above-mentioned baking is performed in the air, HIP processing (for example, HIP processing in a HIP furnace having a carbon heater) is required. A titanium oxide substrate having very few pores, that is, a titanium oxide substrate having a specific resistance of 1.0 Ω · cm or less and a number of pores having a diameter of 3 μm or more existing on the surface of 100 or less per 1 mm ² is obtained. In the case of firing (sintering) in the reducing atmosphere, the specific resistance and the number of pores are further improved by performing the HIP treatment. Well - that the number is improved, it can understand.

[0039]

According to the present invention, as described in detail above, "1.0
Ω · cm or less ”and a very small specific resistance, and“ the number of pores with a diameter of 3 μm or more is 100 / mm ² or less ”.
Since the substrate adsorption device uses a titanium oxide adsorption plate, it is easy to take countermeasures against static electricity on the adsorption plate. Therefore, adsorption of dust and the like due to electrostatic charging does not occur, and the number of pores is extremely small. Since there is no pore having a diameter of 30 .mu.m or more, a remarkable effect is produced such that gas and the like are not adsorbed, and thus the adsorbing ability and holding ability of a thin plate such as a semiconductor wafer are not reduced. Further, the substrate suction apparatus of the present invention can be suitably applied to a wafer hand or a wafer holder incorporated in a semiconductor integrated circuit manufacturing apparatus,
This can greatly contribute to high yield and high integration of semiconductors.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65G 49/07 H01L 21/68 B25J 15/06

Claims (4)

(57) [Claims] 1. A substrate suction apparatus comprising a suction plate for suction-moving or fixing a thin plate, wherein said suction plate has a specific resistance.
1.0 Ω · cm or less and 3 present on the surface
A substrate adsorption apparatus comprising: a titanium oxide adsorption plate having a number of pores having a diameter of not less than 100 μm per 1 mm ² . 2. An adsorption plate made of titanium oxide having an average particle size of 1
After molding a titanium oxide powder having a purity of 99% or less at μm or less, firing at 1100 to 1300 ° C. in air or an inert atmosphere,
^2. The substrate suction device according to claim 1, further comprising a suction plate subjected to HIP processing under a pressure of 500 kg / cm ² or more. 3. An adsorption plate made of titanium oxide having an average particle size of 1
2. The substrate adsorption apparatus according to claim 1, wherein an adsorbing plate formed by molding a titanium oxide powder having a purity of 99% or less with a particle size of not more than [mu] m and firing at 1100 to 1300 [deg.] C. in a reducing atmosphere is used. 4. An adsorption plate made of titanium oxide having an average particle size of 1
After forming a titanium oxide powder having a purity of 99% or more with a particle size of less than μm, it is fired in a reducing atmosphere at 1100 to 1300 ° C.
^2. The substrate suction device according to claim 1, wherein a suction plate obtained by HIP processing under a pressure of not less than kg / cm ² is used.