JPH06813A - Method of cutting single-crystal gallium arsenide - Google Patents

Abstract

PURPOSE:To facilitate a flow of coolant liquid and remove defects due to cutting by masking use of warpages of a wafer caused by the crystal anisotropy of signal-crystal gallium arsenide and by cutting the monocrystal while giving relative movement for keeping the cut-in side of an inner peripheral blade cutter to be opened at all time. CONSTITUTION:At the time of cutting start, a single-crystal gallium arsenide (GaAs) ingot 2 is set so that a carbon base 5 comes to the side surface and, at the same time of cutting start, the ingot 2 made to move upward and then to rotate oppositely to the rotating direction of an inner peripheral blade cutter 1 about the central point O. By masking use of the nature in which the surface of GaAs warps to the opposite of the ingot 2, the ingot 2 is so rotationally controlled that GaAs comes to the inlet side of the inner peripherasl cutter 1, and thus cutting is effected in order that coolant liquid reaches the cutting part at all time. Thus, finally, cutting is conducted at the position where the carbon base 5 comes below the ingot 2, thereby cutting off the wafer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting method for cutting a gallium arsenide single crystal rod to obtain a wafer.

[0002]

2. Description of the Related Art A single crystal of gallium arsenide (GaAs) is
A single crystal rod (hereinafter referred to as an ingot) manufactured by the LEC method or the like with the <100> direction as the crystal growth direction has an outer periphery ground into a cylindrical shape, and further has orientation flat grinding, and thereafter an inner peripheral blade cutter. It is cut into a wafer by.

FIG. 2 is a view showing a cutting situation of the GaAs ingot 2 by the inner cutter blade 1. Inner peripheral blade cutter 1
Is a disk having concentric holes 1a, and the inner peripheral portion of the hole 1a serves as a cutting edge, and diamond abrasive grains 1b are electroformed on this cutting edge. When the wafer 3 is cut out from the ingot 2, the ingot 2 is inserted into the hole 1a of the cutter 1, and the coolant 4 is poured into the cutting portion to raise the carbon base 5 for cutting.

[0004]

When the wafer 3 is cut out by the inner peripheral blade cutter 1, the crystal anisotropy peculiar to GaAs is reflected, and as shown in FIG. 3, the (100) plane is on the ingot side (in the figure). (0 -1 -1) plane which is warped to the other side and is indicated by diagonal lines (here, -1 represents "1 with an upper bar", and so on)
Has a disadvantage that the wafer 3 is warped on the side opposite to the ingot (the front side in the figure), and the wafer 3 is warped in a saddle shape as a whole.

As shown in FIG. 4, when the warp of the wafer 3 is warped toward the ingot 2 side at the inlet side A of the inner peripheral blade when the cut portion is viewed from above, the coolant 4 is dammed and the cut portion is cut off. It will not reach the target and will cause defects such as saw marks and cracks. On the contrary, the warp of the wafer 3 is as shown in FIG.
When the inlet side A of the inner peripheral blade is warped to the side opposite to the ingot 2, the flow of the coolant 4 is improved and stable cutting can be performed.

However, in the conventional cutting method, since the cutting direction is fixed, the wafer 3 is cut so that the warp of the wafer 3 is separated from the inner cutter 1 at the inlet side A of the inner cutter over the entire cutting. However, there is an inconvenience that the cutting is partially unstable.

Therefore, an object of the present invention is to eliminate the instability of cutting due to the warp of the wafer when the wafer is cut out from the ingot.

[0008]

The present invention utilizes the warp of the wafer due to the crystal anisotropy of the gallium arsenide single crystal when the bar of the gallium arsenide single crystal is cut to obtain the wafer. It is characterized by cutting while giving relative movement between the single crystal rod and the inner peripheral blade cutter so that the notch side always opens.

[0009]

The present invention does not move a gallium arsenide single crystal rod (ingot) in one direction to cut the bar, but instead inserts the inner edge cutter and the ingot so that the inner edge always enters the portion where the wafer is separated from the broad. It is characterized in that the holder is cut while making an arbitrary relative movement. By doing so, the coolant liquid is always supplied to the cutting portion, and stable cutting can be performed.

[0010]

FIG. 1 is a schematic view showing an embodiment of a cutting method according to the present invention. The same parts as those in FIGS. In the figure, the GaAs single crystal ingot 2 is held by an ingot holder (not shown) so as to move vertically with respect to the inner cutter blade 1 and rotate about a center point O.

At the start of cutting, the ingot 2 is set so that the carbon base 5 is on the side surface, the ingot 2 is raised at the same time as the start of cutting, and the inner peripheral blade cutter 1 is rotated about the center point O. Conversely, rotate counterclockwise (Fig. A).

Utilizing the fact that the (0 -1 -1) plane of GaAs is warped to the side opposite to the ingot 2, the (0 -1 -1) plane comes to the inlet side A of the inner peripheral blade. 2 is rotationally controlled so that the coolant 4 always reaches the cutting portion (Fig. B). And finally, carbon base 5
The wafer 3 is cut at a position where it comes to the bottom of the ingot 2, and the wafer 3 is cut off (FIG. C).

[0013]

According to the present invention, since the ingot is rotated during cutting, and the wafer is cut so that the inner peripheral blade enters the ingot over the entire cutting so that the wafer always warps in the direction away from the inner peripheral blade. The flow of the coolant is improved, and defects due to cutting can be removed.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a cutting method according to the present invention.

FIG. 2 is a diagram showing a cutting situation of an ingot by an inner blade cutter.

FIG. 3 is a diagram for explaining a warp of a wafer.

FIG. 4 is a diagram showing the warp of the wafer when the cut portion is viewed from above.

FIG. 5 is a diagram showing a warp of a wafer when a cut portion is viewed from above.

[Explanation of symbols]

 1 Inner peripheral blade cutter 2 Ingot 3 Wafer 4 Coolant liquid 5 Carbon base

Claims (1)

[Claims] 1. When a bar of gallium arsenide single crystal is cut to obtain a wafer, the warp of the wafer due to the crystal anisotropy of the gallium arsenide single crystal is utilized so that the cut side of the inner cutter is always open. A method for cutting a gallium arsenide single crystal, characterized in that the gallium arsenide single crystal is cut while providing relative movement between the single crystal rod and the inner cutter.