JP2005254412A - Vacuum suction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a step and a clearance in a joint portion between a placing portion and a supporting portion of a vacuum suction device, and to greatly improve flat machining accuracy of a wafer. <P>SOLUTION: The vacuum suction device comprises: the placing portion having a porous structure equipped with opening air holes and sucking/holding a machined article on a surface thereof; and the supporting portion supporting the placing portion, and equipped with suction holes communicating to the opening air hales in the placing portion. The placing portion and the supporting portion are directly joined with each other actually without a clearance, and a thin-wall portion bulging in a collar shape to the supporting portion side is formed on an upper edge of the placing portion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vacuum suction apparatus for sucking and holding an object to be processed such as a semiconductor wafer or a glass substrate in order to perform wet processing such as lapping.

In the manufacturing process of a semiconductor device, a vacuum suction device using a vacuum pressure is generally used when a semiconductor wafer is transported, processed, or inspected. As such a vacuum suction device, a device having a plurality of through holes opened in the suction surface is generally used. However, since the suction action is performed only with the through holes, the suction force in the suction surface is likely to be uneven. There has been a problem that the processing accuracy of the semiconductor wafer is lowered.

Therefore, in order to perform more uniform suction, a vacuum suction device in which a chuck body made of a porous member is attached to a holding metal has been studied. For example, as shown in FIG. 1, the mounting portion 1 made of a porous material is bonded to the support portion 2 with an adhesive such as resin or glass, and vacuum suction is performed from the lower suction hole 3 to A device for adsorbing the semiconductor wafer W to the adsorbing surface 1a of the placement unit has been proposed (see, for example, Patent Documents 1 and 2), and a vacuum adsorbing device as shown in FIG. 1 has been conventionally known.
JP-A-53-090871 JP 61-182738 A

In such a semiconductor wafer vacuum suction apparatus, since it is necessary to increase the flatness of the upper surface of the mounting portion, surface grinding of the upper surface of the mounting portion is performed using a diamond grindstone or the like. However, since the porous body constituting the placement portion and the dense body constituting the support portion are different in strength and hardness and in workability, the support portion and the placement portion are placed during grinding of the placement portion upper surface. The level | step difference as shown in FIG. 2 has arisen in the junction part with a part. If there is such a step, not only the flatness of the mounting surface cannot be obtained, but also air intake leakage tends to occur, so that uniform suction becomes difficult. As a result, there is a problem that the processing accuracy of the semiconductor wafer as the object to be processed is deteriorated.

Furthermore, in the conventional method of bonding a mounting member and a supporting member, which is a method for manufacturing a vacuum suction device, a gap generated at the interface between the side surface of the mounting portion and the side surface of the supporting portion surrounding it is unavoidable. As a result, the adsorption force on the mounting surface becomes non-uniform, leading to a reduction in wafer processing accuracy.
The present invention has been made in view of such circumstances, and an object of the present invention is to eliminate steps and gaps at the joint portion between the mounting portion and the support portion, and to greatly improve the wafer flat processing accuracy.

The object of the present invention described above is achieved by the following means.
(1) having a porous structure with open pores, a placement portion that holds the object to be treated by adsorption on its surface, and an intake air that supports the placement portion and communicates with the open pores of the placement portion A vacuum suction device comprising a support portion provided with a hole, wherein the placement portion and the support portion are directly joined substantially without a gap, and on the upper edge of the placement portion. Is a vacuum suction device characterized in that a thin-walled portion protruding in a hook shape is formed on the support portion side.
(2) The vacuum suction apparatus according to (1), wherein the outer edge of the object to be processed is sucked and held on the upper surface of the bowl-shaped thin portion of the mounting portion.

According to the present invention, in the vacuum suction device including the mounting portion made of the porous body and the support portion made of the dense body, the mounting portion projecting like a bowl on the support member side of the upper edge portion of the mounting portion. By forming the thin wall portion of the same quality as the above, it is possible to suppress the step generated due to the difference in workability between the mounting member and the support member during grinding of the mounting surface. In addition, since the object to be adsorbed can be adsorbed uniformly, it is possible to process the object to be processed such as a semiconductor wafer with extremely high accuracy.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 3 is a cross-sectional view showing a schematic configuration of a vacuum suction apparatus according to an embodiment of the present invention, and FIGS. A mounting part 4 made of a porous body, a support part 5 made of a dense body surrounding and supporting the outer edge of the mounting part, and a suction part 6 formed on the support part. On the mounting surface 4a, for example, a semiconductor wafer W is mounted as an object to be processed. The joint interface between the mounting portion 4 and the support portion 5 is directly joined with substantially no gap. Here, “substantially having no gap and being directly joined” means that the porous structure of the mounting portion is in contact with the interface of the support member. The suction part 6 has a hole shape provided so as to penetrate the support part 5 on the lower surface side of the placement part, and the placement part is sucked by a vacuum pump (not shown) through the suction part 6. The semiconductor wafer W is vacuum-sucked on the mounting surface 4a.

Here, the mounting surface 4a serving as the suction surface is formed by polishing together with the mounting portion 4 and the support portion 5 around the mounting portion. In the vacuum suction device according to the present invention, when the mounting surface is polished, by forming the thin portion 4b of the same quality as the mounting portion projecting like a bowl on the supporting member side of the mounting portion upper edge, The level difference caused by the strength and hardness difference between the mounting member and the support member can be suppressed to an extremely small level. However, since a step is generated between the bowl-shaped thin part 4b and the support part upper surface 5a not related to the thin part, the outer edge part of the object to be adsorbed such as a semiconductor wafer is held on the bowl-like thin part 4b. It is preferable to do so. (Constituent requirements relating to claim 2)

However, since the bowl-shaped thin part is a porous body of the same quality as the placement part, if the outer edge of the object to be adsorbed is held by the upper part, intake air leakage occurs. However, by reducing the thickness of the bowl-shaped portion, it is possible to suppress a decrease in the suction force due to intake air leakage. Even if air intake leakage occurs, the bowl-shaped part is a homogeneous porous body and is joined to the support member without any gaps, so that air intake leakage does not occur locally and the adsorption force varies. It does not occur. Therefore, a workpiece such as a semiconductor wafer can be adsorbed uniformly, and the grinding accuracy can be increased.

Here, the dimensional shape such as the thickness and width of the bowl-shaped thin portion is not particularly limited. However, if the width of the bowl-shaped portion 4b is too narrow or the thickness is too large, the effect of the step generated between the support portion 5a is increased. On the other hand, if the thickness of the bowl-shaped portion 4b is too small, the effect of providing the bowl-shaped portion 4b having the same quality as the placement portion is reduced, and a step is generated between the bowl-shaped portion 4b and the placement surface 4a. . Therefore, it is necessary to have an appropriate thickness and width. Specifically, it is determined in consideration of the pore diameter and particle diameter of the mounting member, the size of the object to be adsorbed, and the like so that a desired adsorption force can be obtained.

The vacuum adsorption apparatus according to the present invention includes a slurry adjustment step of adjusting a slurry by adding a solvent such as water to a ceramic powder such as alumina and a glass powder, and a placement portion for forming the slurry. It is produced by a manufacturing method comprising a slurry filling step for filling the voids of the support portion provided with the recesses and a firing step for firing the support portion filled with the slurry in the voids at a temperature equal to or higher than the softening point of the glass. Therefore, since the mating surfaces of the mounting member and the supporting member have a relatively complicated structure as in the vacuum suction device according to the present invention, the conventional method requires extremely high-precision processing. However, it can be easily manufactured without precision processing.

Next, in the vacuum suction device of the present invention, the support portion is made of one type of ceramics selected from alumina, silicon nitride, silicon carbide, and zirconia, and the mounting portion is made of alumina and glass, or silicon carbide and glass. It is characterized by becoming.

Here, the pores of the mounting portion made of a porous body are in communication, and the average pore diameter is preferably 10 to 150 μm and the porosity is preferably 20 to 40%, and such pore diameter and porosity are obtained. For this purpose, it is preferable to use an alumina powder or silicon carbide powder having an average particle size of 30 μm to 500 μm, which is another constituent material of the mounting portion.

Next, it is preferable to use a glass whose thermal expansion coefficient is smaller than that of the ceramic which is the other constituent component of the support portion and the mounting portion.
The reason for this is that by using low thermal expansion glass, it is possible to eliminate the gap at the interface between the porous body after sintering and the support member, and to the glass having a role as a binder in the porous body. This is because a state where compressive stress is applied is desirable.

In the present invention, it is preferable that the average particle diameter of the glass powder as the constituent material of the placement portion is smaller than the average particle diameter of the ceramic powder as the other constituent material of the placement portion.
The reason is that if the average particle size of the glass powder is larger than that of the ceramic powder, filling of the ceramic powder is hindered, and thus firing shrinkage occurs when sintering at a glass softening point or higher. The average particle size of the glass is preferably 1/3 or less, more preferably 1/5 or less, of the average particle size of the ceramic powder.
The amount of the glass powder to be added is not particularly limited, but a small amount is desirable because when it is added in a large amount as in the case where the particle size of the glass powder is large, filling of the ceramic powder is inhibited and firing shrinkage occurs. However, if the amount is too small, the bonding strength of the ceramic powder is lowered, and problems such as degranulation and chipping occur, so an amount that exhibits the bonding strength is required. Specifically, it is adjusted in consideration of the target porosity, the particle size of the ceramic powder, the firing temperature, the glass viscosity, etc., but it is generally desirable to add and mix about 5% to 30% by mass with respect to the ceramic powder. .

Next, the manufacturing method of the vacuum suction apparatus of this invention is demonstrated.
First, water or alcohol is added to and mixed with alumina powder and glass powder, or silicon carbide powder and glass powder, which are raw material powders of the porous body forming the mounting portion, to prepare a slurry. For mixing the raw materials, a known method such as a ball mill or a mixer can be applied. Here, the amount of water or alcohol is not particularly limited. In consideration of the particle size of the ceramic powder and the addition amount of the glass powder, the addition amount of water or alcohol is adjusted so as to obtain a desired fluidity.

Next, the obtained slurry is placed in the gap of the ceramic support portion made of alumina, zirconia, silicon carbide, or silicon nitride provided with a recess (not shown; the same shape as the placement portion) in which the placement portion is formed. Fill. At this time, it is advisable to apply vacuum defoaming for removing residual bubbles and vibration for enhancing filling as necessary. Further, the suction hole or suction groove is closed by a burned-out member such as wax or resin before pouring the mixture to be the placement portion.

Next, after sufficiently drying the support part in which the slurry is filled with the slurry, the support part is fired at a temperature equal to or higher than the softening point of the glass. At this time, if the firing temperature is lower than the softening point of the glass, sufficient integration cannot be achieved. On the other hand, if the firing temperature is too high, deformation or shrinkage occurs.

According to such a manufacturing method, the mounting portion and the supporting member can be integrally fired without separately manufacturing the mounting portion and the supporting portion, and the conventional joint surface between the mounting portion and the supporting portion can be formed. Since processing for matching is not necessary, a significant reduction in manufacturing cost can be realized. Furthermore, in the vacuum suction device according to the present invention, there is no gap between the joint interface between the mounting member and the support member seen in the vacuum suction device produced by joining the conventional mounting member and the support member. Grinding accuracy defects due to the gaps at the interface can be eliminated.

Hereinafter, the present invention will be described in detail by way of examples and comparative examples of the present invention. A vacuum suction device described in FIG. 3 as an example and FIG. 1 as a comparative example was prototyped.

(Example)
Alumina powder (average particle size 125 μm), glass powder (borosilicate glass, average particle size: 20 μm, thermal expansion coefficient 40 × 10 ⁻⁷ / ° C., softening point 800 ° C.) and distilled water in a mass ratio of 100: 20: 20 And kneading using a mixer, the slurry is then packed into a dense alumina support 5 (outer diameter 250 mm, inner diameter 200 mm, height 50 mm, depth 40 mm, thermal expansion coefficient 8.0 × 10 ⁻⁶ / ° C.) After vacuum defoaming, the mixture was shaken and settled and filled. After drying at 100 ° C., firing was performed at 1000 ° C. Next, the surface 4 was polished with a diamond grindstone to obtain a mounting surface 4a that becomes the suction surface of the vacuum suction device. When the bonding interface between the bowl-shaped thin portion 4b (thickness 2.0 mm, inner diameter 200 mm, outer diameter 220 mm) on the upper edge of the mounting portion and the support portion 5 was observed, no cracks or gaps were observed. The flatness of the 8-inch wafer contact surface (diameter 203.2 mm) and the amount of warpage during wafer (8 inch × 0.1 mm) suction were measured with a straightness measuring device, and the 8-inch wafer contact surface was measured. The flatness of the wafer was 0.3 μm, and the amount of warpage of the wafer showed the same value as the flatness.

(Comparative example)
After processing the porous alumina body into a predetermined shape to form the mounting portion 1, the mounting portion 1 is replaced with the alumina support portion 2 (outer diameter 250 mm, inner diameter 200 mm, height 50 mm, depth 40 mm, thermal expansion coefficient 8.0). × 10 ⁻⁶ / ° C.), and the support portion 2 and the placement portion 1 were glass-bonded at 800 ° C. As a result, a small gap was observed at the joint between the support portion 2 and the placement portion 1. And like Example, the mounting surface 1a used as an adsorption surface was formed by grinding | polishing with a diamond grindstone. When the flatness of the mounting surface and the amount of warpage during wafer suction were measured for the vacuum suction device produced in the same manner as in the example, the flatness of the mounting surface was 5 μm. Further, the amount of warpage of the wafer was 13 μm, and deformation exceeding the flatness of the mounting surface occurred.

  From the above results, according to the present invention, the level difference caused by the difference in workability between the mounting member and the support member during grinding of the mounting surface can be suppressed to an extremely low level. It was confirmed that extremely high precision machining is possible.

It is typical sectional drawing of the conventional vacuum suction apparatus. It is a partial expanded sectional view of the junction part vicinity of a support part and a mounting part. It is typical sectional drawing which shows schematic structure of the vacuum suction apparatus which concerns on this invention. It is a principal part expanded sectional view of the vacuum suction apparatus which concerns on this invention. It is a principal part expansion perspective sectional view of the vacuum suction device concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,4: Mounting part 1a, 4a: Suction surface 2,5: Support part 3,6: Suction hole 5b formed in support part: Saddle-shaped thin part W: Semiconductor wafer (to-be-processed object)

Claims (2)

It has a porous structure having open pores, and has a mounting portion that holds and holds the object to be processed on its surface, and an intake hole that supports the mounting portion and communicates with the open pores of the mounting portion. A vacuum suction device comprising the support portion, wherein the placement portion and the support portion are directly joined substantially without a gap, and the support portion is disposed on the upper edge of the placement portion. A vacuum suction device characterized in that a thin-walled portion protruding in a hook shape is formed on the side. 2. The vacuum suction device according to claim 1, wherein an outer edge of an object to be processed is held by suction on an upper surface of the bowl-shaped thin portion of the placement unit.

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