JPS6218362Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an improvement of a vacuum chuck device for grinding, lapping, and honing a wafer.

[Technical background of the invention and its problems]

Generally, in the process of manufacturing semiconductor devices, semiconductors are cut into thin pieces to form so-called wafers, which are then subjected to processing such as grinding, wrapping, and honing. In these processes, the wafer is usually held and held by vacuum chuck equipment. To explain a conventional vacuum chuck device with reference to the drawings, in the first conventional example shown in FIGS. is embedded, and the suction body 3 is communicated with a vacuum source through a vacuum path 4, and the wafer 1 is suctioned and held on a flat suction surface 5 by reduced pressure. This is mainly used for grinding, etc. Next, as a second conventional example, the one shown in FIGS. 3 and 4 has an annular suction groove 7 concentrically on the chuck main body suction surface 5, and radial suction grooves 8, etc. communicating with these grooves, and vacuum The passages 9, . . . communicate with a vacuum source, and as in the case described above, the wafer 1 is attracted by reduced pressure.

In addition, instead of providing grooves on the suction surface, there is also a plate with a large number of holes as the suction surface. This type and the types shown in FIGS. 3 and 4 are mainly used for wrapping and honing.

However, with the above-mentioned vacuum chuck device, machining fluid and chips can enter between the suction body and the wafer during processing, corrode the back side of the wafer, make the wafer defective, and cause a decrease in precision. There was a drawback. Furthermore, the life of the adsorbent itself is shortened, the adsorption force is reduced, and accidents such as wafer scattering and cracking sometimes occur.

Various improved vacuum chucks have been devised to compensate for the above-mentioned disadvantages. In other words, an elastic seal is adhered to the suction surface of a vacuum chuck device as shown in FIGS. 3 and 4, except for the suction groove portion, to prevent processing fluid from entering between the suction surface and the wafer. There is. This format is
The elastic sheet is attracted to the suction surface via the elastic sheet, so the accuracy is poor, and the sheet cannot be processed by the processing equipment itself after the elastic sheet is pasted, so the elastic sheet must be installed with very high precision, and it also reduces wear. After that, it cannot be reused. Moreover, the sealing performance is not very good. In addition, what is shown in FIGS. 5 and 6, for example,
A porous member as shown in the figure is used as an adsorbent 3, a sealing groove 10 is provided surrounding the outer periphery, and a sealing member 11 made of an annular rubber having a V-shaped cross section is fitted into this. . The suction surface 5 has a diameter smaller than that of the wafer 1.
It protrudes slightly annularly from the outer peripheral portion 1a. The back surface 1b of the outer peripheral part 1a comes into contact with the sealing body 11, and when the wafer 1 is attracted by reduced pressure, the back surface 1b of the wafer 1 presses against the sealing member 11 against the elastic force of the sealing member 11, and the outer periphery of the wafer 1 The back surface 1b of the portion 1a is sealed. This vacuum chuck prevents processing fluid and chips from getting around to the back surface 1b, but the adjustment of the force that presses the wafer 1 is extremely delicate, and if the elastic force of the seal member 11 is too strong, the sealing performance is good, but the wafer 1 The outer periphery 1a is pushed upward and becomes thinner as a result of wrapping. On the other hand, if the elastic force is weak, contamination by the machining fluid is unavoidable, which makes it difficult to obtain a suitable sealing member 11 and prevents installation. The inconvenience of difficult adjustment is unavoidable.

[Purpose of invention]

The present invention was developed in view of the above-mentioned circumstances, and it is an object of the present invention to provide a vacuum chuck that allows easy attachment of wafers and reliably prevents contamination of the back surface.

[Summary of the idea]

The present invention includes a main body that adsorbs the inner back side of the wafer with an annular outer circumference left by vacuum, and a seal body that is slidably fitted on the outside of the main body.The wafer is suctioned and held by the main body by vacuum This is a vacuum chuck in which the seal body is attracted to the outer periphery of the wafer under reduced pressure to prevent processing fluids and the like from entering the back surface.

[Example of idea]

The details of the present invention will be explained below with reference to an embodiment shown in FIGS. 7 and 8. Reference numeral 21 is a chuck main body, and is constructed by integrally joining a mounting part 22 and a holding part 23, and the mounting part 22 is constructed by providing a flange (not shown) at the lower end of a cylindrical member. The entire vacuum chuck apparatus is fixed to the processing table. The upper holding part 23 has a base 23a which is a disk block member having an upper half 24 formed with a small diameter and a stepped part 25, and the outer diameter of the large diameter part is approximately the same as the outer diameter of the wafer 1. The outer diameter of the small diameter portion is formed to be slightly smaller than that of the wafer 1, and a concave portion 26 having an open top surface is provided concentrically. This recess 26 has a plurality of annular grooves 27, . . . similar to those shown in FIG. 3 on the bottom surface, and a plurality of radial grooves 28, . A vacuum line 29 is provided which communicates with a vacuum source (not shown) through. Above these annular grooves 26,..., a disc-shaped adsorbent 31 made of a porous material with air permeability is embedded so that its upper adsorption surface 31a is flush with the upper surface of the base body 23a, thereby forming the main body 21. has been done. Next, in the stepped portion 25, a seal body 32 made of an annular member having a rectangular cross section is slidably fitted into the upper half portion 24 having a small diameter. This seal body 32 has one end surface 33 of this.
A ring-shaped concentric suction groove 35 with an opening is provided at an appropriate depth, and this is communicated with a vacuum source through a second pressure reduction path 36 penetrating the side surface of the seal body 24, and is connected to a solenoid valve (not shown). By opening and closing, the suction groove 35 can be switched between reduced pressure and atmospheric pressure. The above is the explanation of the configuration.

Next, the operation of this embodiment will be described. When the wafer 1 is placed on the suction surface 31a, the upper half 24 has a smaller diameter than the wafer 1 as described above, so if the main body 21 and the wafer 1 are placed concentrically, 1b protrudes from the outer periphery of the upper surface of the main body 21. This is one end surface 33 of the seal body 32.
It will be in a state where it is facing. If necessary, an elastic sheet 37 made of a thin elastic material, such as polyester, is adhered to the end face of the sealing body 32. Next, when the pressure reduction device is operated, the pressure in the pressure reduction path 29, the annular groove 27, and the radial groove 28 is reduced, and the wafer 1 is firmly attracted to the attraction body 31. At the same time, the suction groove 35 of the sealing body 32 is also depressurized, and the sealing body 32 is attracted to the outer peripheral back surface 1b of the wafer 1 and brought into close contact with it. In this state, the attachment of the wafer 1 is completed, and the surface 1c of the wafer 1 is subjected to wrapping processing, for example, by a generally known method. At this time, the machining fluid containing abrasive grains is applied to the surface Ic.
However, since the sealing body 32 is in close contact with the entire circumference of the outer peripheral back surface 1b of the wafer 1, the machining liquid flows around the back surface 1b of the wafer 1,
There will be no intrusion.

[Effect of idea]

As described in detail above, the vacuum chuck device of the present invention is configured to hold the wafer with the suction body provided on the main body and to suction the annular seal body 32 over the entire circumference of the back surface of the periphery of the wafer. Processing fluid and chips do not enter the backside of the wafer and contaminate it, thereby preventing the production of defective products. In addition, since machining fluid and chips do not directly enter the adsorbent, the adsorbent is not damaged and has a long service life.
Furthermore, since the seal body does not push up and deform the outer peripheral part of the wafer from below, there is no need to adjust the relative positions of the body, seal body, etc. in order to seal the back surface. It is extremely easy to use, and has great benefits in improving work efficiency, quality, and yield.

In this embodiment, an adsorbent made of a porous member is used, but the present invention is not limited to this, and other conventional structures may be used.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the first conventional example, FIG. 2 is a sectional front view of the main part, FIG. 3 is a plan view of the second conventional example, FIG. 4 is a sectional front view of the main part, and FIG. The figure is a cross-sectional front view of the main part of the third conventional example, and Figure 6 is Figure 5A.
FIG. 7 is a sectional front view of a main part of an embodiment of the present invention, and FIG. 8 is an enlarged view of section A in FIG. 7. 1: Wafer, 1b: Back side of wafer outer periphery, 2
1: Chuck body, 31a: Adsorption surface, 32: Seal body, 33: One end surface, 35: Adsorption groove, 37: Elastic sheet.

Claims (1)

[Claims for Utility Model Registration] (1) A chuck body that has a flat suction surface that suctions the wafer by vacuum and holds the wafer by suction leaving an annular outer circumference, and an outer peripheral surface of the chuck body that is made of an annular member. an annular seal body which is slidably fitted into the wafer and whose one end face faces the back surface of the outer periphery of the wafer held by suction; 1. A vacuum chuck device comprising a suction groove that communicates with the seal member and adsorbs the seal member to the back surface of the outer circumferential portion through reduced pressure. (2) The vacuum chuck device according to claim 1, wherein the sealing body has an elastic sheet made of a film-like elastic member on one end surface.