JPS629726Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a holding device used for surface processing of semiconductor wafers.

[Technical background of the invention and its problems] In general, a holding device for suctioning and fixing a semiconductor wafer (hereinafter simply referred to as a wafer) has a cylinder on the inner circumferential side, as shown in Fig. 1 and Fig. 2. The holding body 2 has a holding body 2 in which a shaped storage part 1 is bored, and a disc-shaped adsorbent body 3 made of a porous sintered body such as stainless steel, bronze, or ceramics is fitted into the storage part 1.
A suction hole 4 connected to a vacuum pump (not shown) is bored in the center of the storage section 1, and a plurality of annular grooves 5 are formed concentrically with the suction hole 4 on the inner bottom surface and radiate out. The grooves 6 are carved so as to communicate with each other. The top surface of the suction body 3 and the annular top surface 7 of the holding body 2 are set to be flush with each other, and the top surface of the suction body 3 and the bottom surface 8 of the holding body 2 are set to be parallel to each other. The holding body 2 is attached to the mounting base 10 by the alignment ring 9.
It is adapted to be fixed to the upper surface of the mounting base 10 coaxially with the rotation axis of the mounting base 10. By the way, Figure 3 shows the second
This is an enlarged cross-sectional view of part A in the figure, and as this figure shows, the sintered particles 12 in contact with the wafer 11
The surfaces of ... are ground so that they are on the same plane. The shapes of these ground sintered granules 12 range from those close to spheres to those of the sintered granules 1 before processing.
There are various kinds of particles, up to a fraction of the particle size of 2.
Among these, for particles that are a fraction of the particle size of the sintered granules 12 before processing, the bond with the surrounding sintered granules 12 becomes weak and the rigidity of the sintered granules 12 itself decreases. As a result, the wafer becomes weak and undergoes changes such as deformation, chipping, and falling off, which causes undesirable problems for the wafers held by suction. That is, FIG. 4a is
This shows a case where the sintered granules 12 are deformed, and a part of the deformed sintered granules 12 jumps out from the surface that contacts the wafer, applying local concentrated stress to the wafer, causing cracks and cracks in the wafer during processing. In addition to causing damage such as this, machining accuracy also deteriorates. Further, FIG. 4b shows a case where a part of the sintered granules 12 is missing, and the missing part is interposed between the wafer and the adsorbent 3, and the wafer is damaged as in FIG. 4a. Kratsk,
This not only causes damage such as cracks, but also degrades processing accuracy. Further, FIG. 4c shows that the sintered granules 12 have fallen off, and the fallen sintered granules 12 are attached to the wafer and the adsorbent 3.
By intervening between the sintered particles 12, problems similar to those shown in FIGS. 4a and 4b occur, and the support around the recessed part where the sintered particles 12 have fallen is weakened, making it easier for other sintered particles 12 to fall off.

[Purpose of the invention] The present invention has been made in consideration of the above circumstances, and provides a holding device that can perform high-precision processing of wafers by preventing depletion of the sintered particles constituting the adsorbent. There is a particular thing.

[Summary of the idea] As a sintered granule that comes into direct contact with the wafer, the grain size is several times larger than that of other sintered granules that do not come into contact with the wafer.
Sintered particles having a particle size 10 times larger are used, and the centers of the large-sized sintered particles are arranged parallel to the adsorption surface, and the adsorption surface is arranged so that the large-sized sintered particles It is formed by cutting the body flush.

[Embodiments of the invention] The present invention will be described in detail below based on embodiments with reference to the drawings.

5 and 6 respectively show a plan view and a sectional view including the axis of the holding device of this embodiment.
The holding body 14 has a holding body 14 with holes 3 formed therein, and a disk-shaped adsorbent 15 made of a porous sintered body such as stainless steel, bronze, or ceramic is fitted into the storage part 13. A suction hole 16 connected to a vacuum pump (not shown) is bored in the center of the storage section 1, and a plurality of annular grooves 17 are formed concentrically with the suction hole 16 on the inner bottom surface. The radial grooves 18 are carved so as to communicate with each other. The top surface of the suction body 15 and the annular top surface 19 of the holding body 14 are set to be flush with each other, and the top surface of the suction body 15 and the bottom surface 20 of the holding body 14 are set to be parallel to each other. The holding body 14 is fixed to the upper surface of the mount 22 coaxially with the rotation axis of the mount 22 by an alignment ring 21. By the way, FIG. 7 shows an enlarged view of section B in FIG. 5, and FIG. 8 shows an enlarged sectional view of section C in FIG. 6. As can be seen from these figures, the adsorbent 15 is It is composed of a porous coarse-grained sintered layer 23 that is in direct contact with the wafer, and a porous fine-grained sintered layer 24 that occupies most of the adsorbent 15. The coarse-grained sintered layer 23 has sintered particles 25 having a particle size of 0.05 mm to 1 mm on the upper surface of the adsorbent 15 so that their centers lie on the same plane parallel to the upper surface of the adsorbent 15. , are formed in a single layer by sintering in close contact with each other. The coarse grained sintered layer 23 is machined flush by grinding so that the amount of removal is less than 1/2 of the total volume of the grains before processing. on the other hand,
The fine grain sintered layer 24 is made of sintered grains of 0.01 mm to 0.2 mm, and the coarse and fine sintered layer 23 and the fine grain sintered layer 24 are firmly bonded by sintering.

Next, the method for manufacturing the holding device of this embodiment will be explained. First, as shown in FIG. 9a, 0.01
Primary sintering is performed using grains of mm to 0.2 mm to form a columnar fine grain sintered layer 24. . Next, the sintered granules 25 are placed on one end surface of the fine sintered layer 24 so that they are in contact with each other, and the center of each sintered granule 25 is the same parallel to the one end surface. The particles are densely laid on a flat surface and subjected to secondary sintering to form a coarse sintered layer 23 on the fine sintered layer 24 (see FIG. 9b). Then, the adsorbent 15 made in this way is placed in the storage part 13 of the holding main body 14.
Fit and fix by adhesion or press-fitting (see Figure 9c). Next, as shown in FIG. 9d, the adsorbent 1
5, the end surface on which the suction surface 27 is to be formed is supported by the support 26, and the bottom surface 28 of the holding body 14 is attached to the suction surface 27.
Grind it so that it is parallel to the end surface of the side to be formed. Furthermore, as shown in FIG. 9e, the holding body 1
Each spherical sintered granule 25 is supported by a support body 26 on the bottom surface 28 side of 4, and with the bottom surface 28 as a reference,
Grinding is performed so that the amount of scraping is less than 1/2 of the total volume of each sintered granule 25 before processing, thereby forming a suction surface 27 parallel to the bottom surface 28 (see FIG. 8).

Using the above holding device, vacuum adsorb the wafer,
When performing various processing such as wrapping, polishing, grinding, dicing, and honing, the wafer is supported by the coarse grain sintered layer 23 in which the size and shape of the sintered grains are uniform, so that the wafer is not arranged randomly. Compared to the case where the sintered particles are directly supported by the fine-grained sintered layer 24, the sintered particles are less likely to fall off, chip, or deform as shown in FIGS. 4a, b, and c. This is the coarse grain sintered layer 23
is adjusted so that the shape of the sintered particles 25 constituting this coarse-grained sintered layer 23 is uniform, so for example, the sintered particles 25 having a size of 1/2 or less of the total volume of the sphere This is because the bonding force between the sintered particles 25 is strong and the rigidity is also high.
Therefore, damage such as cracks and cracks on the wafer can be prevented from occurring, and processing accuracy such as parallelism, flatness, and thickness accuracy of the processed wafer can be improved. Furthermore, since the sintered particles forming the suction surface are less likely to fall off, break, or deform, the life of the holding device is also improved.

In addition, although the particle size of the fine grain sintered layer 24 is set to 0.01 mm to 0.2 mm in the above embodiment, it may be increased or decreased as appropriate depending on the situation.

[Effects of the invention] The holding device of the invention has an adsorbent layer made of porous sintered particles, a coarse sintered layer that directly supports the wafer, and a coarse sintered layer that supports the sintered particles in terms of particle size. It is composed of a fine sintered layer with small particles, and the shape and size of the sintered particles that come into direct contact with the wafer can be reliably controlled, so there is no possibility of the sintered particles falling off, chipping, or deforming. It becomes difficult. As a result, damage caused by sintered granules on the wafer is eliminated, and the processing accuracy of the wafer is improved. Furthermore, the life of the holding device is extended.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a conventional holding device, Fig. 2 is a sectional view taken along line M-M' in Fig. 1, Fig. 3 is an enlarged view of part A in Fig. 2, and Fig. 4 a, b, and c are 5 is a plan view of a holding device according to an embodiment of the present invention, FIG. 6 is a sectional view taken along line N-N' in FIG. 5, and FIG. Figure 5 is an enlarged view of part B of Figure 5, Figure 8 is an enlarged view of part C of Figure 6, Figure 9 a, b, c, d,
FIG. 5e is an explanatory diagram showing a method of manufacturing the holding device shown in FIGS. 5 and 6. FIG. 14... Holding body, 15... Adsorption body, 23...
Coarse grain sintered layer, 26...adsorption surface.

Claims (1)

[Claims for Utility Model Registration] (1) An adsorbent made of porous sintered particles that vacuum-adsorbs a workpiece, and a holding body that fits and holds the adsorbent, the adsorbent being , a single-layer coarse-grain sintered layer on which an adsorption surface for adsorbing and supporting the workpiece is formed, and sintered granules having a smaller grain size than the sintered granules constituting the coarse-grain sintered layer. and a fine grain sintered layer supporting and fixing the coarse grain sintered layer. (2) Practical use characterized in that the amount of scraping of the sintered granules constituting the coarse sintered layer to form an adsorption surface is less than 1/2 of the total volume of the sintered granules before processing. A holding device according to claim 1 of the patent registration claim.