JPH0479794B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The ID blade is a tool having a diamond grinding wheel layer 3 along the inner periphery 2 of an annular thin metal plate (core metal) 1 as shown in FIG. Used for cutting glass, ceramics, etc. The present invention relates to a diamond ID blade for slicing semiconductor materials such as silicon (Si) into thin plates (wafers).

[Conventional technology] The ID blade is held at its periphery, stretched up like the skin of a drum, and rotated at high speed to perform cutting. Because the blade is used under tension, it is characterized by its ability to remain flat even though it is extremely thin. This results in a flat and thin wafer, and while maintaining this condition there is less margin for cutting, ie less loss of expensive material.

Despite the above principle, in reality, sliced wafers are always accompanied by some warpage. Because the manufacturing process for semiconductor devices is extremely delicate and highly precise, it is desirable that the raw wafers be flat, and warping has always been a problem.

There are various factors that cause warpage, including the material to be cut and the machine conditions, but ultimately it comes down to the curvature of the ID blade. If the blade is displaced perpendicularly to the blade plate surface (hereinafter referred to as lateral direction) at the innermost circumference where the cutting action occurs, the blade will be curved, and the cutting groove that cuts into the material to be cut will also be curved. Thereafter, the curved groove guides the blade, so the curvature of the cutting surface progresses.

As mentioned above, the ID blade remains well flat when tensioned, which means it has the ability to resist external lateral forces. To be more precise, a force is generated to restore the lateral displacement, and the stronger the tension on the blade, the stronger the restoring force, so the blade always remains generally flat. However, the restoring force depends on displacement, and the restoring force is small for extremely small displacements, so if a lateral force is applied, small displacements, that is, curvature of the blade, are unavoidable.

In conventional blades, the direction of the blade's curvature is not constant, and as a result, the direction of warpage of the sliced wafer is also not constant.

Therefore, if the direction of warpage of a sliced wafer can be made constant, it is very useful for quality control of the wafer, for example, by being able to distinguish between the front and back sides of the wafer.

The idea of making the direction and degree of curvature of the wafer constant when slicing a single crystal etc. using an ID blade is described in Japanese Patent Application Laid-Open No. 119381/1983 and is well known. but,
In this type, the width of the abrasive grain layer from the cutting edge is different on one side and the other side, and the cutting resistance is greater on the wider side of the abrasive layer than on the narrower side, and the blade is curved toward the side with smaller cutting resistance and curved in a certain direction. The aim is to obtain curved wafers, but if the cutting resistance differs between the front and back sides of the blade, the number of defects in the sliced wafers will differ between the front and back sides. Furthermore, it is extremely difficult to control the amount of warpage using this method.

[Problems to be Solved by the Invention] An object of the present invention is to provide an ID blade in which the direction and degree of curvature of sliced wafers are constant without causing a difference in the number of defects between the front and back sides of the wafer. .

[Means for solving the problem] As shown in Fig. 2, cutting resistance acts on the cutting edge 4 of the diamond grinding wheel section 3, and is a force F in the direction in which the ID blade cuts into the material to be cut, that is, parallel to the blade plate surface. However, if the cutting edge 4 is inclined as shown in the figure, a lateral component force F' is generated, causing the blade 1 to curve.

As shown in FIG. 1, the means of the present invention is such that the inner circumferential end surface of the annular base metal 11 is inclined at a constant angle with respect to the blade plate surface over the entire circumference, and the inclined inner circumferential end surface 12 is
is provided, and diamond is electrodeposited along the inner circumferential portion of the base metal to form a grindstone portion 13 having a cutting edge 14 inclined along the inclined inner circumferential end surface 12.

[Function] In the ID blade of the present invention, the cutting edge 14 is oblique.
As a result, due to the above-mentioned reason, the lateral component of the cutting resistance F' causes the blade to curve, so that the sliced wafer exhibits a warp in a certain direction with respect to the material ingot. That is clear.

In other words, warping is intentionally generated, but it goes without saying that it is impossible if the warping becomes excessive. In reality, the warpage can be kept within a practical allowable range as shown in the examples described later. To this end, it is desirable to appropriately select the amount of asymmetry to be processed on the inner periphery of the core metal, and to use a core metal material with high tensile strength so that the blade can be strongly tensioned to ensure a strong lateral restoring force.

Wafers sliced by the ID blade of the present invention not only have a constant warp direction, but also a relatively uniform amount of warp, because the lateral component force F' due to the asymmetry of the cutting edge takes precedence and is due to the aforementioned accidental force. This seems to be because the indefinite lateral component force due to various causes is suppressed.

[Example] A thin plate of stainless steel SUS-301 hardened by rolling with a thickness of 0.13 mm was punched out, and the inner peripheral end face of the ring was tilted at 10 degrees with respect to the normal direction of the plate surface to form a core metal.
Grain size 40-60μm along the inner circumference in the same way as before
An ID blade with a nominal size of 23.5 inches was manufactured by electrodepositing diamonds. The thickness of the cutting edge is 0.28mm.

A silicon ingot with a diameter of 4 inches was sliced into wafers with a thickness of 0.7 mm using this ID blade.
Warpage was observed in all of the wafers, but the direction was constant, and the amount of warp was within the allowable range in almost all of the wafers.

[Effects] Although the ID blade of the present invention cannot prevent warpage of sliced wafers, since the direction of warpage is constant, there is an advantage that the growth direction of the material ingot can be identified for each wafer. Furthermore, since the number of defects in sliced wafers does not differ between the front and back sides of the sliced wafer due to the difference in cutting resistance between the front and back sides of the blade as in the conventional example, high-quality wafers can be produced.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view showing an embodiment of a diamond ID blade according to the present invention, Fig. 2 is a diagram illustrating the principle of the invention, and Fig. 3 is a generally used diamond ID blade.
FIG. 3 is a plan view of the ID blade. 11... Base metal, 12... Inclined inner peripheral end surface, 13...
...Whetstone part, 14...Blade tip.

Claims (1)

[Claims] 1. The inner peripheral end surface of the annular base metal is tilted at a certain angle with respect to the blade plate surface over the entire circumference to provide an inclined inner peripheral end face, and diamond is electrodeposited along the inner peripheral part of the base metal, A diamond ID formed with a grindstone portion having an inclined cutting edge along the inclined inner circumferential end surface.
blade.