JPH06236913A - Wafer fork - Google Patents

Abstract

PURPOSE:To provide a wafer fork little in pollution, strong, and accurate in dimension by constituting a placing part and a holding part for a fork for holding and carrying a water with pins and making the section in contact with the wafer out of ceramic on nonoxide line such as silicon nitride or the like. CONSTITUTION:A wafer fork body sintered body is manufactured by molding mixed powder, where 4wt.% Al2O3 powder, 3wt.%AlN powder, and 5wt.%Y2O3 powder are added uniformly to 100 pts.wt. of Si3N4 powder, under pressure of 800kg/cm<2> into an CIP, and cutting the obtained ceramic molded item by machining, and degreasing it for three hours at a temperature of 700 deg.C in nitrogen atmosphere, and sintering it successively for six hours at 1750 deg.C. Pins being obtained similarly are attached to it to complete a plating part 8 and a holding part 9. At this time, the contact area between a wafer fork 7 and a wafer 2 is 50.24mm<2>. Since it is made of material high in rigidity and tenacity, the reliability on carriage, and the availability and productivity of semiconductor devices improve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer fork used for transferring and transporting a wafer, and more particularly, a wafer fork having less contamination of the wafer due to impurities and less warpage, high strength and high dimensional accuracy. Regarding

[0002]

2. Description of the Related Art Conventionally, in a wafer heat treatment process or a transfer line in a semiconductor manufacturing process, various holders such as a wafer fork and a wafer chuck have been used in order to sequentially transfer and transfer a large number of sliced single crystal silicon wafers. It is used. The wafer fork is configured by forming a shallow recess into which a wafer is fitted in the central portion of a flat plate-shaped main body, while the wafer chuck is a holder that holds and holds the wafer by vacuum suction or electrostatic action.

The above-mentioned wafer fork is fixed to, for example, the tip of an arm of a transfer robot, is inserted through a minute gap into a gap between cartridges and carriers for accommodating wafers in multiple stages, and the wafer is picked up and held in a concave portion.
It is transported to the processing section of the next process.

Conventionally, as the above-mentioned wafer fork, one in which a stainless steel plate is cut and polished into a predetermined shape and then the processed surface is coated with a fluororesin coating or the like, or the entire fork is made of quartz glass is mainly used. .

[0005]

However, in a wafer fork whose surface is coated with resin on a stainless steel surface, the coating layer is broken in a short period of time, and impurities such as iron and alkali salts are likely to be transferred to the wafer side, which easily causes contamination. There is. In addition, the stainless steel forming the main body is likely to be plastically deformed, which often makes it difficult to carry out a highly accurate transfer operation. On the other hand, since the stainless steel itself has high toughness, if the transfer device itself malfunctions, the wafer fork may damage peripheral equipment such as an expensive robot and stop the manufacturing process.

On the other hand, a wafer fork made of quartz glass is less likely to be contaminated with impurities even when a coating layer is not formed, and is thermally stable, which is advantageous, while strength and rigidity are slightly low, so that it can be used repeatedly. There was a difficulty in using it as a structure that does. Especially in recent years
It is required to load more wafers in a cartridge or a carrier that stores a plurality of wafers, and the gap between adjacent wafers tends to be narrowed. Inevitably, a wafer fork inserted in the gap is also required. The demand for thinner products is increasing. However, as the device becomes thinner, its mechanical strength becomes smaller, so that it tends to bend in a short period of time, resulting in a problem of shortening the life.

As a means for solving the above problems, a purity of 9
A wafer fork formed by polishing an alumina (Al ₂ O ₃ ) sintered body of 9% or more is also used in part.
This Al ₂ O ₃ wafer fork is shown in FIGS.
As shown in FIG. 3, the peripheral circular step portion 3 is provided, and the wafer 2 is placed and held by the peripheral circular step portion 3. However, in the structure in which the wafer 2 is held by the circumferential step portion 3 as described above, the contact area with the wafer 2 is large and impurities are likely to adhere to the surface of the wafer 2. Since the wafer fork 1 and the wafer 2 have a so-called near net shape,
Particularly, a hard and brittle material such as ceramics is difficult and expensive to polish, and further improvement has been desired.

Further, in the Al ₂ O ₃ wafer fork,
The strength characteristics and durability vary greatly depending on the temperature conditions and atmospheric gas in the semiconductor manufacturing process, and there is a drawback that uniform reliability cannot be obtained. On the other hand, as the degree of integration of semiconductor substrates has rapidly increased from 1 Mbit to 4 Mbit, the allowable limit of impurities for wafers has become more stringent and the conventional Al ₂ O ₃
With wafer forks made by us, it is becoming impossible to handle.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a wafer fork having less contamination of the wafer with impurities, high strength and high dimensional accuracy.

[0010]

In order to achieve the above object, the wafer fork according to the first invention of the present application is a wafer fork that holds and sequentially conveys wafers,
It has a placing part for placing the wafer in contact with it from below, and a holding part for holding the wafer in a predetermined position by contacting the peripheral part of the wafer, and the placing part and the holding part consist of pins, and the placing part Further, at least a portion of the holding portion that is in contact with the wafer is made of at least one of Si ₃ N ₄ , Si—Al—O—N, and SiC.

Here, the mounting portion and the holding portion are formed of pins mainly to reduce the contact area between the wafer and the wafer fork, and the contact area is reduced, so that the contamination of the wafer is suppressed. Contact area is 20-100mm ²
It is preferable if it is 40 to 70 mm ^2. It is more preferable if

Further, at least the portions of the mounting portion and the holding portion that come into contact with the wafer are Si ₃ N ₄ , Si-Al-O-.
At least one of N and SiC is Si ₃ N ₄ ,
Si-Al-O-N and SiC have high strength values such as rigidity and toughness and environmental resistance characteristics as compared with other materials, especially ceramics, and are sufficient even when formed thin such as a wafer fork. While having durability,
This is because the thermal shock resistance is also excellent.

A wafer fork according to a second aspect of the present invention is a wafer fork that holds and sequentially conveys a wafer, and the area of the portion that contacts the wafer is 20 to 1
00 mm ² Is characterized in that.

Here, the area of the portion of the wafer fork that contacts the wafer is ²⁰ to 100 mm ^2. Was 20
mm ² If it is less than, the contact area is too small to support the wafer at the point, and if a wafer fork is manufactured with a material that does not have sufficient strength, too much force is applied to one point. Not preferable. Further, the holding of the wafer is likely to be unstable. On the other hand, 10
0 mm ² If it exceeds, the contact area is too large and the wafer is easily contaminated, which is not preferable. The preferred range is 40 to 70 mm ^2. Is. In this range, the wafer can be stably held, and the wafer is not contaminated much.

A more preferable range is 45 to 60 mm ^2. Is. In this case, since the wafer is supported by a certain area, a large force is not applied to one point, and the wafer is not contaminated too much.

In the second invention of the present application, the material of the wafer fork is not particularly limited, but it is preferably made of a material having excellent strength, such as Si ₃ N ₄ , Si-Al-O.
Non-oxidizing ceramics such as -N and SiC are suitable.

The contact area is 40 to 70 mm ^2. A preferable example of the means is to mount the wafer fork with a pin, but it is not particularly limited. As in the conventional case, the area of the peripheral circular step portion formed in a planar shape that comes into contact with the wafer may be made as small as possible.

Si ₃ N ₄ , Si-Al-O-N, S
A wafer fork made of a sintered body made of at least one kind of iC can be used as it is, but by further forming a contamination prevention layer such as a fluororesin coating on the surface of the sintered body, the contamination of the wafer is more effective. Can be prevented.

An example of the manufacturing method will be described below. In this example, the first and second inventions of the present application are simultaneously satisfied, that is, the material is at least one of Si ₃ N ₄ , Si—Al—O—N, and SiC, and the mounting portion and the holding portion are formed by pins, The contact area between the wafer and the wafer fork is 20 to 100 mm ²
The case will be described.

First, Si ₃ N ₄ , Si-Al-O-N,
A powder mixture of at least one kind of SiC is added with various sintering aids and uniformly mixed to prepare a raw material mixture, and the raw material mixture is subjected to a die press, a cold isostatic press (CI).
P) or the like is pressure-molded to obtain a rectangular ceramic molded body having a uniform thickness. Next, the obtained ceramic formed body is cut by machining to form a wafer fork formed body having a predetermined contour. The molded body is sintered and subjected to grinding / polishing to manufacture a wafer fork main body. On the other hand, similarly manufactured pins are attached to a predetermined position of the wafer fork as a mounting portion and a holding portion, and the wafer fork of the present invention is manufactured.

[0021]

According to the wafer fork of the first invention having the above structure, Si ₃ N ₄ , S having a high rigidity and toughness value is obtained.
Since it is formed of at least one of i-Al-O-N and SiC, a wafer fork having excellent durability and thermal shock resistance can be obtained. Further, since the portions of the wafer fork that come into contact with the wafer (the mounting portion and the holding portion) are made of pins, the contamination of the wafer can be suppressed.

Further, according to the wafer fork of the second aspect of the invention, since the contact area with the wafer is sufficient to keep the wafer from being contaminated, contamination of the wafer can be suppressed during the semiconductor manufacturing process.

[0023]

The present invention will now be described more specifically with reference to the following examples and drawings. Example 1 A mixed powder in which 4% by weight of Al ₂ O ₃ powder, 3% by weight of AlN powder and 5% by weight of Y ₂ O ₃ powder were uniformly added to 100 parts by weight of Si ₃ N ₄ powder. And mix 800
kg / cm ² 5m thickness obtained by CIP molding under the pressure of
The wafer fork body molded body is formed by cutting the ceramic molded body of m by machining to dewax the obtained wafer fork body molded body in a nitrogen gas atmosphere at a temperature of 700 ° C. for 3 hours, and subsequently in a nitrogen gas atmosphere. At temperature 1
Wafer fork main body sintered body 7a was manufactured by sintering at 750 ° C. for 6 hours.

The pins obtained in the same manner were attached to the above-mentioned sintered body of the wafer fork main body to form a mounting portion 8 and a holding portion 9 to manufacture a wafer fork 7. At this time, the contact area between the wafer fork 7 and the wafer 2 is 50.2.
4 mm ² Met. Example 2

100 parts by weight of Al ₂ O ₃ powder having a purity of 99.5% is added to 800 kg / cm ^2. Mold press molding with the pressure of
The obtained ceramic molded body having a thickness of 5 mm is cut by machining to form a wafer fork main body molded body, and the obtained wafer fork main body molded body is heated to a temperature of 70
Degrease at 0 ° C for 1 hour, and then in the air at a temperature of 170
Wafer fork main body sintered body 7a after sintering at 0 ° C for 2 hours
Was prepared.

The pins obtained in the same manner were attached to the above-mentioned wafer fork main body sintered body 7a to form a mounting portion 8 and a holding portion 9 to manufacture the wafer fork 7. At this time, the contact area between the wafer fork 7 and the wafer 2 is 5
0.24 mm ² Met. Comparative Example 1

Al based on 100 parts by weight of Si ₃ N ₄ powder
4% by weight of ₂ O ₃ powder, 3% by weight of AlN powder, Y
₂ O ₃ powder to prepare a mixed powder was uniformly added and 5 wt% to, 800 kg / cm ² Mold press molding with the pressure of
The obtained ceramic molded body having a thickness of 5 mm is cut by machining to form a fork main body molded body, and the obtained fork main body molded body is degreased at a temperature of 700 ° C. for 3 hours in a nitrogen gas atmosphere, followed by nitrogen. Temperature 1 in gas atmosphere
The integrated wafer fork sintered body 1a was prepared by sintering at 750 ° C. for 6 hours.

The peripheral circular stepped portion 3 is formed by grinding and polishing this.
Then, the recess 4 was formed, and the conventional wafer fork 1 was manufactured. The contact area between the wafer fork 1 and the wafer 2 at this time is 602.5 mm ² Met. Comparative example 2

100 parts by weight of Al ₂ O ₃ powder having a purity of 99.5% is added to 800 kg / cm ^2. Mold press molding with the pressure of
The obtained ceramic molded body having a thickness of 5 mm is cut by machining to form a wafer fork main body molded body, and the obtained wafer fork main body molded body is heated to a temperature of 70
Degrease at 0 ° C for 1 hour, and then in the air at a temperature of 170
Wafer fork main body sintered body 1a after sintering at 0 ° C for 2 hours
Was prepared.

By grinding / polishing this, the circumferential step 3
Then, the recess 4 was formed, and the conventional wafer fork 1 was manufactured. The contact area between the wafer fork 1 and the wafer 2 at this time is 602.5 mm ² Met.

Five wafer forks according to each of Examples 1 and 2 and Comparative Examples 1 and 2 were manufactured, and each wafer fork was subjected to a continuous operation for 3 months by a normal mounting method.
The contamination defect ratio of the wafer was measured. The results are shown in Table 1 below.

[0032]

[Table 1]

As is clear from the results shown in Table 1, the wafer forks according to Examples 1 and 2 are different from the wafer forks in which the peripheral circular step and the recess are formed by the conventional grinding / polishing process. As a result, impurities such as iron and alkali adhered to the wafer and the wafer could be made defective.

As described above, by adopting the wafer fork according to the first or second aspect of the present invention, the reliability of wafer transfer and the operation rate of the semiconductor manufacturing apparatus are greatly improved, and the productivity of the semiconductor apparatus is greatly improved. I was able to improve.

[0035]

As described above, according to the wafer fork according to the first aspect of the present invention, Si ₃ having a high rigidity and a high toughness value can be obtained.
Since it is formed of at least one kind of pin of N ₄ , Si-Al-O-N, and SiC, it has excellent durability and thermal shock resistance,
In addition, impurity contamination due to wafer contact is also greatly reduced. Further, according to the wafer fork according to the second aspect of the present invention, since the contact area with the wafer is small, the wafer is less contaminated.

Therefore, the wafer forks according to the first and second aspects of the present invention can improve the reliability of wafer transfer and the operation rate of the semiconductor manufacturing apparatus, and can greatly improve the productivity of the semiconductor apparatus.

[Brief description of drawings]

FIG. 1 is a plan view of a wafer fork according to a first aspect of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a plan view showing a structural example of a conventional wafer fork.

FIG. 4 is a sectional view taken along the line IV-IV in FIG.

[Explanation of Codes] 1, 1a Conventional wafer fork 2 Wafer 3 Circumferential circular step portion 4 Recessed portion 5 Robot arm 6 Tightening screw 7 Wafer fork of the present invention 7a Wafer fork main body of the present invention 8 pins (placement portion) 9 pins (Holding part) Reference number 9GA92800
11

Claims (2)

[Claims] 1. A wafer fork that holds and sequentially conveys a wafer, and has a mounting portion for mounting the wafer in contact therewith from below, and a holding portion for contacting the peripheral portion of the wafer and holding the wafer at a predetermined position. The mounting portion and the holding portion are made of pins, and at least the portions of the mounting portion and the holding portion that come into contact with the wafer are Si ₃ N ₄ , Si-Al.
A wafer fork comprising at least one of -ON and SiC. 2. In a wafer fork that holds and sequentially conveys a wafer, the area of the portion in contact with the wafer is 20 to 100 mm ^2. Wafer fork.