JPS5980934A - Manufacture for semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the generation of a displacement largely from a circumferential edge, and to decrease defects in a photoetching process by each forming rectilinear tapers from the surface and the back extending over the whole circumference of a wafer and forming the ends of both tapers in arcuate circumferential ends. CONSTITUTION:A semiconductor base body 40 has a circumferential surface as the surface 11, the back 12, an arcuate circumferential end surface 20 and rectilinear tapered surfaces 21, 21'. A circumferential end angle alpha at a section 22 formed by the surface 11 and the inclined plane 21 and an angle alpha' at a section 22' formed by the back 12 and the inclined plate 21' are brought to obtuse angles of 90 deg. or more. Circumferential end angles beta and beta' each formed by the arcuate circumferential end surface 20 and both inclined planes 21 and 21' are also brought to 90 deg. or more.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a semiconductor device.

The edge of a substrate used in the manufacture of semiconductor devices according to the prior art has a structure as shown in FIG.

That is, FIG. 1 is a sectional view of the peripheral edge of the substrate, where 1 and 2 are the front and back surfaces of the substrate, 3 is the peripheral edge, and 4 and 4' are the front 1 and back 2 of the substrate. The "circumferential edge angle" of the substrate formed by the circumferential edge surface 3 and the circumferential edge surface 3, respectively, and 5 and 5 respectively indicate the substrate portions other than the circumferential edge corner portion. The circumferential end angles 4 and 4/ are approximately 90' as shown. In this way, the number of substrates used in the manufacture of semiconductor devices using conventional technology is approximately 9.
It had a "peripheral edge angle" of 0°. Therefore, through heat treatment (heating and cooling) during semiconductor device manufacturing.

Board peripheral edge angles 4, 4' and the board portion where the board peripheral edge angle is removed 5゜5
A difference in thermal effects occurs between the substrate and the substrate, and this difference generates local stress (that is, the stress is concentrated at the edge of the substrate).

Dislocation occurs from the circumferential edge angle 4.41 due to this stress.

The occurrence of such dislocations is particularly noticeable in so-called batch processing in which a large number of substrates or wafers are stacked and processed.

The dislocation further advances to the substrate portions 5, 5' other than the peripheral edge angle, and as a result, the P-N which is the electrical junction of the semiconductor device
It is known that this increases the leakage current of the junction or deteriorates the withstand voltage. Furthermore, dislocations occur from the 4.4' edge angle portion of the substrate used in the manufacture of conventional semiconductor devices due to an impact thereon.

This will produce the same result as above. and.

If the corner portion is chipped due to an impact on the corner portion, the chipped pieces may have interfered with photo-etching for pattern formation or damaged the mask used for pattern formation. It has drawbacks such as being extremely uneconomical and extremely difficult to obtain a high yield of non-defective products. On the other hand, in a semiconductor substrate (semiconductor wafer) as shown in FIG. 2, the above-mentioned drawbacks are eliminated. That is, in FIG. 2, the circumferential end surface 18 is formed in an arc shape, and a circumferential end angle α between these surfaces exists in a portion 19 where the surface 11 of the rear surface 11 and the arc-shaped circumferential end surface 18 are connected. Portion 1 where and peripheral end surface 18 are connected
There is a circumferential edge angle d formed by the surfaces 12 and 18 at 9/. Of course, the circumferential edge angle α and the angle are formed to be obtuse angles larger than 90°.

On the other hand, in a method of manufacturing a semiconductor device, a semiconductor substrate (semiconductor wafer) and a mask are often brought into close contact and separated from each other in a photolithography process. This separation is often carried out by blowing gas between the semiconductor substrate and the mask, but the structure shown in FIG. 2 has the disadvantage that separation cannot be performed with sufficient workability beyond the above steps.

Therefore, an object of the present invention is to provide an effective method for manufacturing a semiconductor device that eliminates all of the above-mentioned drawbacks.

The feature of the present invention is that the cross-sectional shape of the semiconductor substrate (semiconductor wafer) has a linear taper from the front surface and the back surface, respectively, and the tip of both tapers forms an arc-shaped peripheral edge. , a method of manufacturing a semiconductor device in which an active element is provided on this semiconductor substrate. Such a shape can be formed, for example, by rotating the semiconductor substrate and applying a knife, a grinder, etc. of a predetermined shape to the semiconductor substrate.

Since the substrate used in the present invention has the above-described structure, according to the present invention, dislocations generated from the peripheral edge angle due to heat treatment during semiconductor device manufacturing are significantly reduced, and By forming a large area of the receiving part, the impact stress is effectively reduced, and the occurrence of dislocations is also reduced.
(The number of chippings on the substrate was reduced by more than 1. Furthermore, the number of chippings on the substrate was reduced to 196 or less, and the number of defects in the photolithography process was significantly reduced.As explained above, 9 chips According to the invention, it is possible to significantly reduce the occurrence of dislocations from the peripheral edge of the substrate, and to significantly reduce defects in the photolithography process, thereby significantly increasing the yield rate in the manufacture of semiconductor devices. Further, the leakage current of the semiconductor device according to the present invention has been reduced by more than an order of magnitude on average.

Moreover, in the present invention, since the peripheral surface of the wafer is tapered, the mask will not be damaged when it comes into contact with the mask during the photolithography process.In addition, in this process, the mask and wafer are aligned, so the mask and wafer are aligned. The wafer must be frequently brought into close contact with the wafer and then peeled off. In order to achieve both adhesion and peelability, which are contradictory, it is necessary to taper the peripheral surface of the wafer. It is effective to facilitate the flow of gas, etc. between the maskle wafers.

Further, air bearings or the like are used to move the wafer between each process, and the smaller the resistance in the air, the easier the movement.

The shape of the present invention provides extremely low resistance in terms of fluid dynamics.

Further, the above effect is more effective than simply providing a straight taper shape from both sides because the circumferential surface is arcuate. However, in the present invention, since an arcuate shape is added to the linearly tapered shape from both sides, the processing cost is somewhat higher than that of a linearly tapered shape from both sides. This can be used depending on the purpose of use.

Next, an embodiment of the present invention is shown in FIG.

FIG. 3 is a partial cross-sectional view of the peripheral end of still another example of the substrate used in the method according to the present invention. The base body 4° is the surface 11. Back surface 121 arc-shaped peripheral end surface 20. It has peripheral surfaces such as linear inclined surfaces (tapered surfaces) 21, 21/. In the figure, the circumferential edge angle α of the portion 22 formed by the front surface 11 and the inclined surface 21, and the angle of the portion 2z formed by the rear surface 12 and the inclined surface 21' are obtuse angles of 90' or more. Needless to say, the circumferential edge angle β and the angle formed by the arcuate circumferential edge angle 2o and the inclined surfaces 21 and 21' are also 900 or more.

[Brief explanation of drawings]

1 and 2 are end cross-sectional views of a conventional semiconductor wafer, and FIG. 3 is an end cross-sectional view of a semiconductor wafer according to an embodiment of the present invention. In Figure 9, 1.11 is the front side, and 2.12 is the back side. 3.18.20 is the end face, 4.4', αd, β〆 is the peripheral edge angle 5.5' is the part other than the peripheral edge corner part of the board, 21.21
' is an inclined surface, and 30.40 is a base (semiconductor wafer). 187

Claims (1)

[Claims] The cross-sectional shape of the semiconductor substrate is as follows. 1. A method of manufacturing a semiconductor device, wherein linear tapers are provided from the front surface and the back surface, and arcuate peripheral ends are formed at the tips of the tapers, and an active element is provided on the semiconductor substrate.