JPS61110435A - Surface grinding method for semiconductor wafer - Google Patents

Abstract

PURPOSE:To prevent damage on the wafer surface by grain from generated during the grinding by executing the grinding after the surface protection film is deposited in such a way as the mound is formed at the periphery, covering the entire part of surface facing to the surface of wafer to be ground. CONSTITUTION:A wafer 10 is mounted on the spinner apparatus and resist is dropped as a protection film 11. When the wafer 10 on which resist is dropped is rotated, mound portion 12 is generated at the periphery of wafer 10. This wafer 10 is dried and it is placed on the spinner again. Resist is dropped and the wafer is rotated again. The mound portion 12 further grows at the periphery of wafer 10 when it is rotated. The wafer 10 having the mound portion in sufficient height is absorbed by a vacuum absorption table 13, a grind stone 14 located at the upper part of table 13 is rotated, and the grinding surface of the wafer 10 is ground to the predetermined thickness.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for grinding a flat surface of a semiconductor wafer.
More specifically, it relates to a method of grinding the element forming surface of a semiconductor wafer or its back surface using a mechanical grinding means such as a grindstone. Used in the manufacture of circuit devices, for example,
417, Special Publication No. 51-20267, Special Publication No. 53-1
4476, a plurality of grooves or holes are formed in one principal plane of a single crystal semiconductor wafer, a dielectric film is deposited on this formed surface, and a polycrystalline semiconductor layer is further grown to support the substrate. Build a body. Thereafter, the single crystal semiconductor wafer is ground until the opposing main planes reach the bottoms of the grooves or holes, thereby forming a dielectric isolation substrate.

In addition, there is a method called r, taring, in which a plastic strain layer (damage layer) is formed by mechanically damaging the back surface of a semiconductor wafer, and crystal defects caused by heavy metals in sea urchins are removed. For example, rsamiconduct
or World l 983.7's 33 easy ~ 37
As described throughout the page, the back side of the sea urchin is polished with a grindstone or abrasive grains, etc.

When grinding the surface of a semiconductor wafer using a whetstone or abrasive grains, a protective film such as a resist is coated to keep the surface facing the surface to be ground clean, but the abrasive grains during grinding are coated with a protective film such as resist. We often encounter the problem of penetrating deep into the protective film and damaging the surface of the film. This damage mode will be explained using FIGS. 2 and 3. Figure 2 (1) ~
(e) is a process cross-sectional view including the preparation process for this type of grinding work, and is a schematic diagram of the FIG. 3 d1 grinder, and (1) is a plan view, and (b) is a cross-sectional view.

First, during the grinding operation, as shown in FIG. 15 s at a speed of about rpm
Rotate by ec to uniformly coat the protective film 2 with a thickness of 3 μm. After drying, the vacuum suction table JK adsorbs the sea urchin... The sea urchin...-1 is ground to a predetermined thickness while supplying water with a water sprinkler (not shown).

(Problems to be Solved by the Invention) However, the 7917 pieces or abrasive grains (these are collectively represented as 5) 5 cut by the grindstone 4 during this grinding are
It enters from the peripheral edge of the table 3, breaks the protective film 2, and damages the surface of Ueno-1.

This is because the vacuum suction force of the grinder shown in FIGS. 3(B) and 3(b) is weak. That is, since this type of grinding involves the supply of water, a vacuum I ring with a high suction force cannot be used, and the suction phenomenon that occurs when air is supplied to the tube 5 in the direction shown by the thick line arrow, that is, the thin line arrow inside the tube 6. This is due to the fact that the periphery is weaker than the center because the suction force generated by air flowing in the direction shown by υ attracts the sea urchin...-1.

Therefore, the present invention provides a grinding method that does not damage the surface of a semiconductor sea urchin covered with a protective film even when the semiconductor sea urchin is held by a relatively weak suction force such as a pencheripong. (Means for Solving Interlayer Problems) This invention provides a surface trapping device for the entire surface of the semiconductor wafer, which is opposite to the plane to be ground, when the plane of the semiconductor wafer is ground by a predetermined amount using a mechanical grinding means such as a grindstone. Grinding is sometimes performed by forming a so-called bank-shaped surface protective film, which is applied so that the peripheral edge of the wafer is raised.

(Function) A characteristic effect of the method of the present invention is that due to the presence of the bank-shaped surface protective film provided on the peripheral edge of the semiconductor urchin, grinding debris generated during grinding is removed by the table that is in close contact with the surface on which the protective film is formed. The purpose is to perform grinding while preventing the particles from entering between the holes.

(Example) Figures 1 (for) and (C) are diagrams of a preferred embodiment of the method of this invention. First, as shown in (&),
The JO is mounted on a spinner device (rotational coating device), not shown, and renost having a viscosity of about t o cp, for example, is removed as the protective film 1 . The semiconductor wafer 10 with Lennost removed is heated for 5 seconds at a speed of about 3000 rpm, for example.
When you rotate ec, 1 or 2 will appear on the periphery of Ueno 10.
A raised portion 12 of μm is generated.

Then, this wafer 10 was dried at 120° C. for 5 minutes, and the wafer 10 was again mounted on a spinner device (not shown), the same resist as described above was removed, and the spinner was rotated for about 5 seconds at a speed of about 3000 rpm. As shown in (b), the raised portion 9 12 of the periphery of the sea urchin 100 is further raised. It is sufficient for the height of this raised portion 12 to be 3 μm4Q. Also, at this time, the raised part 12 of the protective film 1
The thickness other than that is 5 to 10 μm. Then, the wafer 10 having the raised portion 12 with a sufficient height is placed (cl
As shown in K, the wafer 0 is suctioned to the vacuum suction table 13, and the grindstone J4 placed on the top of the table saw is rotated to grind the surface of the wafer 0 to be ground to a predetermined thickness. During this grinding, the silicon pieces or abrasive grains (these are collectively designated as 15) 15 ground by the grinding wheel 14 are attached to the raised portion 12.
guarded by. This guard power is quite strong. That is the gap t between the vacuum suction table 3 and the sea urchin... created by the raised part 12 formed on the edge of the sea urchin 10.
15 becomes a positive pressure, and the upper part of this bulge comes into close contact with the vacuum suction daple 13 only at the bottom part 12.

(Effects of the Invention) As explained above, if the method of the invention is followed, the wafers that are attracted to the vacuum suction table are attracted only by the bulges (bank-like banks) formed at the periphery of the urchin. Therefore, even if a pentier-in-det type suction device, which has a relatively weak suction force, is used, the wafer surface can be protected from damage caused by K such as abrasive particles generated during grinding.

[Brief explanation of the drawing]

FIGS. 1(&) to (C) are process sectional views of a preferred embodiment method of the present invention, FIGS. 2(&) to (c) are process sectional views of a conventional method, and FIG. (b) is a schematic diagram of a grinder used in this type of method (~ shows a plan view, and (b) shows a cross-sectional view. 10... Semiconductor wafer, 1... Protective film, J2...・
- Raised portion, 13... Vacuum suction table, 14.
...Whetstone, 15...Silicon pieces and abrasive grains, slag...
Gap. Patent applicant Oki Electric Industry Co., Ltd. Miyazaki Oki Electric Co., Ltd. Figure 1 Showa Year Month Day

Claims (3)

[Claims] (1) After coating the surface of the semiconductor wafer opposite to the surface to be ground with a surface protective film, and placing the surface coated with the protective film on a flat vacuum suction table, the surface to be ground is placed in place by mechanical grinding means. In the quantitative grinding method, the surface protection film is applied so that the peripheral edge of the semiconductor wafer is raised, and then the semiconductor wafer is placed on the vacuum suction table. . (2) The coating of the surface protective film that bulges the peripheral edge of the semiconductor wafer is performed by dropping a highly viscous surface protective film material onto the semiconductor wafer and rotating the wafer at a low speed. A method for surface grinding a semiconductor wafer according to scope 1. (3) The method for surface grinding a semiconductor wafer according to claim 1, wherein the surface protective film is a photoresist.