JPS59169758A - Grinding device for wafer - Google Patents

Abstract

PURPOSE:To improve workability, by a method wherein wafer guides are located through the medium of wafer securing pads to the face and the back of each of a plurality of planetary gears, and rotary discs, having the top and the under surface whereto grinding cloths are bonded, are positioned concentrically with a solar gear. CONSTITUTION:A rotary upper disc 18 is moved above a rotary lower disc 20, planetrary gears 131 and 132 are lifted, wafer absorbing securing pads 142... on the back surface thereof are wet, and a wafer 27 is ground and secured as it is placed in an opening part 15 in a wafer guide 16. Thereafter, the wafer 27 is similarly secured to wafer absorbing securing pads 141... on the surface side. Then, the rotary upper disc 18 is lowered to a position allowing the gears 131 and 132 to turn, an outer periphery gear 12, the rotary lower disc 20, a solar gear 11 are turned counterclockwise, the rotary upper disc 18 is turned clockwise, and grinding is effected by the use of a grinding agent fed through a grinding agent feed port 19 and grinding cloths 171 and 172. After grinding, water is impregnated between the wafers 27 and the pads 141 and 142 to take out the wafers 27. This enables to enhance workability and to improve processing precision.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an improvement in a wafer polishing apparatus.

[Technical background of the invention]

As is well known, semiconductor elements such as transistors, IC1s, and LSIs are generally formed from mirror-surfaced wafers made of silicon.

Conventionally, as a polishing apparatus for obtaining such wafers, the one shown in FIG. 1 is known. Reference numeral 1 in the figure is a rotary disk with a polishing cloth 2 pasted on its upper surface. A rotary shaft 3 is attached to the rotary disk 1, and the rotary shaft 3 is rotated counterclockwise by driving a motor (not shown).
rotate in the same direction. For example, two pressure plates 5, which can be moved up and down by air cylinders 4, are provided above the rotary disk 1 at a predetermined distance. Note that a ball bearing is provided between the tip of the air cylinder 4 and the pressure plate 5. These pressure plates 5 have circular recesses 6 on their lower surfaces, and these recesses 6...
This is due to the fact that the wafer pasting grate 7 is fixed to the wafer pasting plate 7. The pressure plate 5... is the wafer pasting plate 7...
Move to apply pressure to the extent that it can rotate. Further, above the rotary disk 1, nozzles 8 are provided for discharging an abrasive mainly composed of 5102 or At205.

In a polishing apparatus having such a structure, first, each pressure plate 5 is raised and the wafer 10 is attached to the bottom surface of the wafer pasting plate 7 via a thermoplastic adhesive layer 9, respectively. Fix...

Next, the pressure plate 5 (by the cylinder)
... is lowered until the lower surface of the wafer 10 ... reaches the polishing cloth 2 on the rotary disk 1. Next, the rotary disk 1 is rotated counterclockwise while discharging the abrasive from the nozzles 8 . As a result, the wafer pasting plate 7 is rotated counterclockwise within the range where the wafer pasting plate 7 is located while being applied with pressure by the pressure plate 5, and the surface of the wafer 10 is rotated. is polished.

[Problems with background technology]

However, the above-described wafer polishing apparatus has the following drawbacks.

(1) The wafers 10... must be fixed to the wafer attachment grating 7... one by one via the adhesive layer 9..., and only one wafer 1o... needs to be fixed after polishing. Each wafer 1o... is attached to the wafer attachment plate 7...
Since the material must be peeled off from the surface, work efficiency is reduced.

(2) Since the wafers 10 are fixed to the wafer attaching grates 7 through the adhesive layers 9, adhesive remains on the back surfaces of the wafers 10. Therefore, in order to remove it, a cleaning process using an organic solvent such as trichlorethylene, perchloroethylene, or Freon is safe.

(3) In order to improve the finishing accuracy of wafers 10, the thickness of adhesive layers 9 are controlled on the order of microns, and wafers 1o are prepared without variations in adhesive layer thickness. Since the wafers must be adhered to the wafer attachment plate 7, the work of fixing the wafers 1o requires a great deal of skill and time.

(4) The wafer JO... is placed on the rotary disk 1 during polishing.
Since the upper wafer attachment plate 7 only performs a circular motion in the range where it is located, the influence of the flatness of the upper surface of the rotary disk 1 and the lower surface of the wafer attachment plate 7, especially the flatness of the adhesive layer As a result, the finished dimensional accuracy decreases.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and makes the wafer fixing work easier by fixing the wafer without using an adhesive layer, and also eliminates the work of peeling off the adhesive layer and the cleaning process using an organic solvent. The present invention provides a wafer polishing device with improved workability and high processing accuracy.

[Summary of the invention]

The present invention provides a sun gear with one or more planetary gears meshing with the sun gear, and a wafer guide having an opening for setting a plurality of wafers on the front and back sides of the planetary gear via a wafer suction and fixing pad. A rotating upper plate having an abrasive cloth affixed to its lower surface above the planetary gear and having an abrasive supply port penetrated in the vertical direction is provided concentrically with respect to the sun gear,
Furthermore, by providing a rotary lower plate with an abrasive cloth affixed to the upper surface below the planetary gear concentrically with respect to the sun gear, it is possible to easily attach and detach the wafer and improve work efficiency. , which improves machining accuracy.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to FIGS. 2 and 3.

11 in the figure is a sun gear made of stainless steel. Around the sun gear 11, an annular outer gear 12 made of stainless steel is provided concentrically with respect to the sun gear. Between the sun gear 11 and the outer gear 12, two planetary gears 131 and 132 made of stainless steel, for example, are provided in mesh with the gears 11 and 12. On the front and back sides of these planetary gears 131*132..., wafers with a thickness of around 1111111 are fixed by suction, f2 dors 14,...
..., 142... are provided. These /IP pads 14, 11..., 142... are made of, for example, commercially available artificial leather or rubber with uniform thickness, uniform surface, and minute pores. The same planetary gear 131
．． On the front and back sides of 132, the wafer suction and fixing i4 pad 1 is provided.
Wafer guides 16 are provided with openings 15 into which a plurality of wafers are to be set via wafer guides 16, 142, .

The wafer guide 16 is made of reinforced plastic, and its thickness is 10 mm compared to the wafer finishing thickness.

~500μm thin. Above the planetary gears 131 and 132, a rotating upper plate 18 made of stainless steel and having a polishing cloth 121 applied to its lower surface is provided.

This rotating upper plate 18 is concentric with the sun gear 11, and is moved up and down by a cylinder (not shown). A roll bearing is provided between the tip of this cylinder and the rotating upper plate 18. The rotating upper plate 18 and the polishing cloth 171
is provided with an abrasive supply port 19 that penetrates in the vertical direction. Further, below the planetary gears 12..., a rotary lower plate 20 made of stainless steel and having an abrasive cloth 172 applied to its upper surface is provided.

The upper end of a first cylindrical rotating shaft 21 is pivotally attached to the lower rotating plate 20 . The upper end of a second cylindrical rotating shaft 22 that passes through the cylindrical rotating shaft 21 is pivotally attached to the sun gear 1 .

The upper end of a rotating shaft 23 passing through the second cylindrical rotating shaft 22 is pivotally attached to the rotating upper plate 18 . Said first
A bevel gear 24 and a first gear 251 are provided at the lower end of the cylindrical rotating shaft 21, and the second cylindrical rotating shaft 22,
At the lower end of the rotating shaft 23, there are respectively second. Third gear 252
.

253 are provided respectively. Also, between the first and second cylindrical rotation shafts 21 and 22, and between the second cylindrical rotation shaft 2
Bearings 261% are installed at the upper and lower portions between the rotating shafts 23 and 23, respectively.
26+, 262.262 are interposed. A bowl-shaped member (not shown) having an open bottom and having a gear portion meshing with the outer peripheral gear 12 and the bevel gear 24 on its inner wall surface is provided below the rotating lower plate 2o. Furthermore, the above-mentioned No. 1. Near the second cylindrical rotation shaft 21.22 and the rotation shaft 23, the gears 251 to 25 of each of these rotation shafts 21 to 23 are
A rotating shaft (not shown) having a gear (not shown) that meshes separately with the rotating shaft 253 is provided parallel to the rotating shafts 21-23.

A worm gear (not shown) is provided at one end of the rotating shaft, and a worm attached to a motor (not shown) is meshed with the worm gear.

Next, the operation of the polishing apparatus having the above-described structure will be explained.

First, with the force of the cylinder released and the upper rotary plate 18 moved above the lower rotary plate 20, the planetary gears IJ, 132 are lifted up and the wafer is suctioned and fixed on the back side of the planetary gears 131 and 132. After wetting the wafers 27 with water, the wafers 27 are placed in the openings 15 of the wafer guides 16.
While storing the wafer 27 in the . . . surface, the wafer 27 is rubbed against the wetted . grading pad 142 and fixed. Next, the planetary gear 131.

After returning the wafers 132 to their original positions, the wafers 27... are placed on the wafer suction/fixing pads 141... in the openings 15 of the wafer guides 16... on the surface side of the planetary gears 131.13z. Fixed to. Next, the rotating upper plate 18 is lowered using a cylinder to a position where the planetary gears 131.13□ can rotate sufficiently. Next, the abrasive supply port 19.19
Grinding 9- While supplying grinding, the worm gear is
and the first to third gears 251 to 253 and the bevel gear 2
4 to the outer peripheral gear 12 and the rotating lower plate 20. The sun gear 1 is rotated counterclockwise and the rotating upper plate 18 is rotated clockwise, and the planetary gears 131, 13. was rotated clockwise to polish the surface of each wafer 27. The abrasive is mainly composed of 5102 with a particle size of 0.5 μm or less, and is polished with sodium hydroxide, potassium hydroxide, aqueous ammonia, etc.
H, adjusted to between 11 and 14 was used. After polishing the wafers 27..., stop dropping the abrasive and stop driving the motor, release the cylinder force, and move the rotating upper plate 18 above the rotating lower plate 2o. The wafers 27... are removed from the wafer suction/fixing pads 141..., 142... by infiltrating water between the surfaces and the wafer suction/fixing pads 14I..., 142... remove

According to the present invention, the following effects can be obtained.

(1) When fixing the wafers 27..., the wafer suction and fixation hat 14. . . , 142 . . . with water, the wafers 27 . . . can be easily fixed. Also, after polishing, the wafer 27... surface and the wafer are fixed by suction. Pad 141...
, 142 . . . by allowing water to penetrate between the surfaces, the wafers 27 . Therefore, work efficiency can be significantly improved compared to the conventional method.

(2) Instead of using a conventional adhesive layer and polishing the wafer while simply moving it in a circular motion, the planetary gears 131..., 13 are attached to the outer peripheral side of the sun gear 1.
2... are provided in a planetary motion, and wafer suction and fixing pads 14.2 are provided on the front and back sides of the sun gear 1. ..., 142・
The structure includes a wafer guide 16 having an opening 15 through which a plurality of wafers 27 are to be set. The wafers 27 can be polished uniformly, and the dimensional accuracy of the finished wafers 27 can be improved.

(3) The wafer 22... is connected to the planetary gear 131...
, 132 . . . , the number of wafers processed per unit time ab is approximately twice that of the conventional single-sided polishing method. In addition, the above-mentioned mechanism polishes the wafer 22..., and since the main component is 5102 with a particle size of 0.5 μm or less and PI (11 to 14) is used as the polishing agent, it is made of artificial leather or the like. Wafer suction fixation) GRADO 1
4. ..., 142... enables mechanical and chemical polishing, and the planetary gear 131.
The amount of polishing of the wafer 27 on the upper and lower sides of 13g can be made almost uniform.

In fact, using the polishing apparatus of the present invention, the wafers of lot A were placed on the upper rotating plate side and the lower rotating plate side.
8.20 rotation speed 60 rpm.

When the amount of polishing was examined under conditions where the polishing time was 40 minutes, the graphs shown in FIGS. 4(a) and 4(b) were obtained. Note that FIGS. 3A and 3B show the case of a wafer on the upper rotating plate side and a wafer on the lower rotating plate side, respectively. Figure (a)
, (b), the average value of the polishing amount of the wafers on the upper rotating plate side was 67.2 μm, while that of the wafers on the lower rotating plate side was 67.6 μm. Also, using the same device, B
When we investigated the polishing amount when the wafers of the lot were polished under the conditions of the rotating upper and lower plates 18.20 at a rotation speed of 60 rpm and a polishing time of 25 minutes, the graphs shown in Figures 5 (a) and (b) were obtained. was gotten. In addition, the same figure (,), (b
) indicate the cases of wafers on the upper rotating plate side and wafers on the lower rotating plate side, respectively. As shown in Figures (a) and (b), the average polishing amount of the wafers on the upper rotating plate side was 39.6 μm, while that of the wafers on the lower rotating plate side was 40.2 μm. From these results, it can be confirmed that there is almost no difference in the amount of polishing between the wafers on the upper rotating disk and the sea urchins on the lower rotating disk for each lot A and B under different test conditions.

In addition, when we investigated the parallelism after polishing (average value of 50 wafers processed) of 100-tone φ wafers using conventional and present invention equipment, we found that
The parallelism of the wafer produced by the conventional apparatus was 8.5 μm, while that of the wafer produced by the apparatus of the present invention was 4.3 μm. As a result, the apparatus of the present invention has a higher parallelism after polishing the wafer (
It can be confirmed that the flatness) can be improved approximately twice.

In the above embodiment, the case where the planetary gear is rotated by driving the sun gear and the outer gear is described, but the invention is not limited to this, and the planetary gear can be rotated by driving either the sun gear or the outer gear. You can also rotate it.

Furthermore, in the above embodiment, stainless steel was used as the material for the upper rotating plate, lower rotating plate, sun gear, planetary gear, and outer peripheral gear, but the material is not limited to this, and for example, aluminum, brass, reinforced plastic, etc. may be used. .

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a wafer polishing apparatus that can easily attach and detach a wafer to improve workability and improve processing accuracy.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional wafer polishing apparatus, a plan view with 14- removed, Fig. 4(a), (b), and Fig. 5(
=) and (b) are A by the polishing apparatus shown in Fig. 2, respectively.
, B is a graph diagram showing the relationship between the amount of polishing and the number of wafers on the upper rotary plate side and the lower rotary plate side wafers of each lot. 11... Sun gear, 12... Peripheral gear, 131. 132... Planetary gear, '4++142... Wafer suction fixing pad, 15... Opening part, 16... Wafer guide, 171*172... Polishing cloth, 18... Rotating upper plate, 19 ... Abrasive supply port, 20 ... Rotating lower plate, 2
1.22... Cylindrical rotating shaft, 23... Rotating shaft, 24
...Bevel gear, 251-253...Gear, 261°262...Bearing, 27...Wafer. Applicant's agent Patent attorney Takehiko Suzue 15- Figure 1 ♂<ζgigida 7 (Monster

Claims (1)

[Claims] A sun gear, one or more planetary gears meshed with the sun gear, and holes provided on the front and back sides of the planetary gear via wafer adsorption/grids, into which the number of wafers should be set. a rotating top having a wafer guide provided above the planetary gear concentrically with respect to the sun gear, an abrasive cloth affixed to the lower surface, and an abrasive supply port penetrating in the vertical direction; 1. A wafer polishing apparatus comprising: a rotating lower disc which is provided below the planetary gear concentrically with respect to the sun gear, and has a polishing cloth pasted on its upper surface.