JPH0136990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a rod-shaped single crystal body mainly used in a semiconductor laser device.

[Technical background of the invention and its problems]

Recently, semiconductor lasers have been used in many fields. Square rod-shaped gallium arsenide (GaAs) is used as the material for this semiconductor laser. The reason for this is that the 110 cleavage plane of GaAs has smoothness and cleanliness that cannot be obtained by other methods, and is optimal as a resonator plane for laser beam oscillation. By the way, GaAs wafers are generally extremely thin and easily damaged during handling. In addition, streaks tend to occur during cutting, and if streaks (damage) occur, performance tends to deteriorate later, resulting in extremely poor yield. Therefore, conventionally, a mask pattern is applied to the wafer and selective etching is performed using an anisotropic etching agent to form a V-shaped groove on the wafer surface along the cleavage direction, and mechanical cleaving is performed, for example, along this V-shaped groove. It was on. However, it is difficult to make the parallelism between the cleavage direction and the extending direction of the V-shaped groove formed using the mask pattern 10 seconds or less. Therefore, the crack line of the cleavage plane does not always propagate along the bottom linear part of the V-shaped groove, but tends to go up one slope of the V-shaped groove. arise. As a result, there is an imbalance in the rigidity of the crystal on both sides of the fractured surface, causing the fractured surface to bend toward the side with weaker rigidity, resulting in micro-stairs (steps of several to hundreds of angstroms, also called jogs). This occurrence is one of the causes of deterioration of resonance performance. In addition, minute cleavage does not necessarily occur at the part where the cutting blade comes into contact with it, and if it occurs at a shifted part, there is still an imbalance in rigidity, which has the disadvantage that the cut surface becomes curved. Furthermore, conventionally, 110
The cleavage plane was obtained by an expert holding a special steel razor blade in his hand under a stereomicroscope and cleaving the GaAs wafer along the 110 crystal plane. Alternatively, as a slightly more advanced method, there is a method in which a GaAs wafer placed on a position-adjustable holding table is cleaved using a tool made of cemented carbide. However, in the former method using a razor, the tip angle is 13 to 14 degrees, and in the latter method using a cemented carbide tool, the tip angle is around 30 degrees. However, on the other hand, the disadvantage is that the blade tends to chip and has a short lifespan.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned circumstances, and is capable of producing a rod-shaped single crystal that produces defect-free and beautiful cleavage planes at a high yield, provides a cutting tool with good sharpness, and has a long tool life. The purpose is to provide a method.

[Summary of the invention]

A dovetail groove is formed in a single crystal wafer, and a diamond cutting tool with a tip angle of 55 degrees to 75 degrees is brought into contact with the dovetail groove to cut the wafer.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a rod-shaped single crystal manufacturing apparatus used in the rod-shaped single crystal manufacturing method of this embodiment.
An X table 2 is placed on a rectangular parallelepiped base 1 so that its position can be adjusted in the direction of the arrow X and the direction of the arrow θ using a knob (not shown). Furthermore, a Y table 3 is mounted on the X table 2 so that its position can be adjusted in the direction of the arrow Y orthogonal to the direction of the arrow X by means of a knob (not shown). A displacement measuring device 4 such as Magnescale (trade name; manufactured by Sony Magnescale Co., Ltd.) is attached to the Y table 3.
The amount of displacement of the table 3 in the Y direction is detected on the order of μm. However, base 1,
The table 2 and the Y table 3 constitute an X-Y-θ table 5. On the other hand, a Z table 6 is installed on the side of the X-Y-θ table 5 so that its position can be adjusted by a knob (not shown) in the direction of an arrow Z perpendicular to the X and Y directions. A support plate 7 is fixed on the Z table 6 with a part thereof protruding laterally. A cutting tool 8 is attached to a tip end of the support plate 7 with a screw 8a so that the inclination angle can be adjusted freely.
Fixed by The cutting tool 8 is composed of a metal plate-shaped holding part 9 and a diamond blade part 10 held at the lower end of the holding part 9. As shown in FIGS. 2 and 3, this blade portion 10 has a pair of blade surfaces 11a having a V-shaped cross section,
It is more familiar than 11b. These blade surfaces 11a, 11
b forms a linear ridge line 11c at the tip. Further, the tip angle θ formed by these blade surfaces 11a and 11b is set within a range of 55 to 75 degrees. Further, the cutting tool 8 is supported so that the left-right symmetry plane 12 that passes through the ridge line 11c and divides the cutting tool 8 into two is orthogonal to the upper surface of the Y table 3, and the direction of the intersection line when they are orthogonal is parallel to the X direction. It is attached to plate 7. The direction of this intersection line is set to be a planned cutting line arrangement direction 13, which will be described later. Further, the inclination angle α between the ridge line 11c and the top surface of the Y table 3 is set to be 10 degrees or less (see FIG. 4). Therefore, an acceleration pickup 1 such as a piezoelectric element is mounted on the upper end surface of the support plate 7.
4 is attached. This acceleration pick up 1
4 is an indicator 15 that displays the detected acceleration change.
electrically connected to. These acceleration pickup 14 and indicator 15 constitute a contact sound detector 17 that detects contact of the cutting tool 8 with the GaAs wafer 16 placed on the Y table 3. The wafer 16 is placed such that one end surface thereof contacts the side surface of a positioning plate 18 fixed on the Y table 3. Furthermore, X
- Above the Y-θ table 5 is a two-field microscope 19.
is installed. This two-field microscope 19 has first and second objective lens systems 20a and 20b. These first and second objective lens systems 20
The intersection line between the plane on which the optical axes of a and 20b are located and the top surface of the Y table 3 is in the cutting planned line arrangement direction 13.
is set to match.

Next, a method for producing a rod-shaped single crystal according to this example using the apparatus having the above configuration will be described.

First, a square single-crystal GaAs wafer 1 with a thickness of approximately 100 μm and a side of 20 to 25 mm is shown in FIG.
The main surface 001 (corresponding to the back surface) which is far from the laser oscillation part 6 is etched using, for example, a 33% CrO ₃ --HF-based etching solution, and the pits are observed using a microscope to find the direction 110. This direction 110 is the direction of the intersection between the main surface 001 and the cleavage plane 110. A mask pattern (not shown) in which a plurality of parallel slits are formed at intervals of 0.25 mm is placed on the main surface 001 of the wafer 16 so that the longitudinal direction of the slits is parallel to the 110 direction.
A large number of dovetail grooves 22 having a flat bottom surface 21 shown in FIG. 6 are formed by selective etching at equal intervals, as shown in FIG. The depth D of these dovetail grooves 22 is 10 to 10 times the thickness of the wafer 16.
Etch to a thickness of 10 to 30 μm, which is 30%. If the depth D is deeper than this, it is undesirable because it becomes easy to break and becomes difficult to handle.On the other hand, if it is shallower, the effects described below cannot be fully exhibited. The optimal etching solution to be used at this time is one based on Br ₂ -CH ₃ OH.
For example, when using _Br2 concentration of 1% by weight,
The etching time is preferably 1 to 3 minutes. and,
As shown in FIG. 6, the surfaces where the side ends of the dovetail grooves 22 are open form cleavage surfaces 110. In addition, the direction perpendicular to the dovetail grooves 23... is the main surface 001.
and the cleavage plane 110 in the 110 direction, and when selectively etched in this direction, V
A groove 23 is formed. The side end of this V-groove 23 is open on the 110 side, which is parallel to the resonant end face of the semiconductor laser to be obtained by the cutting method of this embodiment. Next, the wafer 16 on which the dovetail grooves 22... have been formed is placed in the dovetail grooves 22.
... and the longitudinal direction of the positioning plate 18 are perpendicular to each other, and placed on the table 3 against the positioning plate 18. Next, the X direction is aligned with the longitudinal direction of the dovetail grooves 22 using the two-field microscope 19.
- Finely adjust the Y-θ table 5. That is, the center line of one arbitrarily selected dovetail groove 22 is the first
The X-Y-θ table 5 is arranged in the X, Y,
Make a slight movement in the θ direction. Furthermore, set X table 2 to
The cutting tool 8 is placed on one end of the bottom surface 21 of the dovetail groove 22 to make a minute cleavage of 3 to 10 μm, and the movement of the X table 2 is immediately stopped.
The wafer 16 of the blade part 10 of the cutting tool 8 at this time
The contact sound detector 17 detects contact with the wafer 16, that is, the cutting of the wafer 16 by the blade portion 10.
Furthermore, the X table 2 is moved relative to the cutting tool 8. Then, the wafer 16 is cut into two parts along the planned cutting line arrangement direction 13 on the bottom surface 21 of the dovetail groove 22. Then, while looking at the displacement measuring device 4, the same cutting operation is repeated to divide into halves and halves, and finally a GaAs rod-shaped single crystal body with a width of 0.25 mm is produced. Thereafter, by repeating the above-described cutting operation, a GaAs rod-shaped single crystal can be obtained.

In this way, in this embodiment, the cleavage is performed along the dovetail grooves 22, so even if there is an angular difference between the extending direction of the dovetail grooves 2 due to selective etching and the cleavage direction. As long as a planned cleavage line exists within each bottom surface 21 of the dovetail grooves 22 (the angular difference between the extension direction and the cleavage direction of the dovetail grooves 22 is ±3
Acceptable to some extent. ), there is a splitting crack and groove 22...
There is no climbing up the slope. Therefore, an imbalance in rigidity does not occur between the cut crystal bodies on both the left and right sides. Therefore, it is possible to prevent damage caused by bending the cleaved surface in a direction where the rigidity is weak, and to obtain a beautiful cleavage surface (resonant end surface) without any defects. Moreover, since the groove width can be widened, cutting with the cutting tool 8 becomes easy.
Therefore, the quality of the resonant end face is improved and the yield is improved. Furthermore, in the above embodiment, the tip angle θ of the diamond blade portion 10 of the cutting tool 8 is set to 55 to
Since the angle is 75 degrees (range A in Fig. 8), good sharpness is exhibited during cleavage, and a beautiful cleaved surface can be obtained with good reproducibility. Moreover, the tool life is extended, which is extremely advantageous in terms of profitability. By the way, the 8th
The figure shows the tip angle θ and the number of times the GaAs single crystal wafer is broken until its life when the inclination angle α is 5 degrees. As this figure shows, when the tip angle θ is 55 degrees or less, the tool life is significantly reduced. On the other hand, it was experimentally confirmed that when the tip angle θ is 75 degrees or more, the sharpness becomes dull. Further, in the above embodiment, the cutting tool 8 and the GaAs
Since the point of first cutting into the wafer 16 is detected using the contact sound detector 17, defects will not occur on the resonant end face.

Although the material to be cut in the above embodiment is GaAs, if the material is to be cut using the dovetail grooves formed by selective etching, GaP, InSb,
The present invention can also be applied to ZnS, CdWO ₄ and the like. Even in this case, the tip angle θ of the cutting tool 8
is preferably 55 to 75 degrees. Furthermore, even without using a selective etching solution, grooves with relatively flat groove bottoms can be formed in the direction of intersection between the cleavage plane and the main surface of the wafer using a method such as reactive ion etching. , may be cut. Furthermore, the grooves having a flat bottom surface may be formed only at the ends of the wafer 2 and then cut. Furthermore, although the rod-shaped single crystal production apparatus in the above embodiment is used for cutting single crystal wafers in which dovetail grooves have been formed by selective etching, it can also be used for cutting single crystal wafers that have not been selectively etched. Of course.

〔Effect of the invention〕

In the present invention, a dovetail groove is formed by selective etching along the cutting direction, and this dovetail groove is used to perform cutting, so there is an angular difference between the extending direction of the dovetail groove and the cleavage direction. Even if the dovetail groove is dovetailed, as long as there is a cleavage plane within the bottom surface of the dovetail groove, the trace of the fractured surface, or the crack line, will not climb up the slope of the groove. Therefore, beautiful cleavage planes without defects can be obtained. Moreover, since the groove width can be widened,
It becomes easier to cut with a knife. Furthermore, the present invention
The blade of the cutting tool is made of diamond, and the tip angle θ is set at 55 to 75 degrees, so cutting can be performed efficiently and reproducibly, and the tool life can be extended. Can be done.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part of an apparatus used in a method for producing a rod-shaped single crystal according to an embodiment of the present invention, FIG. 2 is a front view of a main part of the cutting tool shown in FIG. 1, and FIG. FIG. 4 is a diagram showing the inclination angle of the cutting tool, and FIG. 5 is a diagram showing the direction of dovetail groove formation in the method for producing a rod-shaped single crystal according to an embodiment of the present invention. A perspective view, FIG. 6 is an enlarged perspective view of essential parts showing the orientation relationship of the dovetail groove and the V-shaped groove, and FIG. 7 is a perspective view showing a plurality of dovetail grooves formed by selective etching.
FIG. 8 is a graph showing the relationship between the tip angle of the cutting tool and the number of cuttings until its life. 4: Displacement measuring device, 5: X-Y-θ table,
8: cutting tool, 11c: ridge line (blade edge), 13: planned cutting line (arrangement direction), 16: wafer (single crystal), 17: contact sound detector, 19: 2 field microscope.

Claims (1)

[Claims] 1. A method of selectively etching a single crystal wafer along a planned cleavage line to cause cleavage to form a dovetail groove with an almost flat bottom surface, and a V-shaped cross section with a tip angle of 55 degrees to 75 degrees on the bottom surface of the groove. A method of cutting the single crystal wafer by bringing a diamond cutting tool into contact with the single crystal wafer and moving the cutting tool relative to the single crystal wafer along the planned cutting line. A method for producing a rod-shaped single crystal.