JPS59200437A - Cutting method - Google Patents

Abstract

PURPOSE:To cut a wafer for a semiconductor laser along a cleavage plane even when there is a difference between angles within a predetermined range between the direction of a groove through selective etching and the direction of cleavage in the wafer by bringing cutter into contact with the dovetail groove, relatively moving the cutter and cutting the wafer. CONSTITUTION:A surface to which the side end sections of dovetail grooves 4... are opened forms a cleavage plane. The direction orthogonal to the dovetail grooves 4... is directed in the direction of 110 as the direction of a line crossing of a main surface 001 and the cleavage plane, and a V-shaped groove 5 is formed through selective etching in the direction. A surface to which the side end section of the V-shaped groove 5 is opened is represented as a 110 surface, and forms a surface parallel with the resonant end surface of a semiconductor laser. A wafer 2 to which the dovetail grooves 4... are shaped is fixed onto a table, a cutter 6 is brought into contact with one end section of the bottom 3 of the dovetail groove 4 at the central section of the wafer 2 or a section entering to the inside from an end section, and said section is slotted and cloven slightly. When the cutter 6 is further slotted and the table is moved under the state in which the cutter is tilted at a fixed angle theta, the edge 7 is shifted relatively along a cleavage prearranged line on the bottom 3, and the wafer 2 is cut into two sections.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cutting method for cutting a wafer for a semiconductor laser to obtain a strip-shaped body having a resonant end face.

[Technical background of the invention and its problems]

Recently, semiconductor lasers have become popular in fields such as optical gain digital audio discs.

Penetration If. This semiconductor manufacturing is performed through the following steps. That is, gallium arsenide (GaAs
) After forming 9 grooves on the wafer by etching, a multilayer film (Qa Ae As layer) is epitaxially grown. Next, after forming Au as an electrode metal, a cutting operation for creating a resonant end face is performed using the gaps between the folds. Then, a protective film is attached to the resonant end face while remaining in the shape of an elongated strip between the folds. Next, after cutting into chips, the chips are mounted on a submount substrate made of Cu, Si, etc. via a brazing material, and assembled into a socket cage.

By the way, in the above-mentioned cutting operation of the GaAs wafer,
The resonator length must be kept constant. However, GaAs wafers are generally extremely thin and easily damaged during handling. In addition, streaks tend to occur during cutting, and if streaks (damage) occur, the performance tends to deteriorate later, resulting in a very low yield.

Therefore, conventionally, as shown in FIG. 1, a mask cutter was formed and, for example, mechanical cutting was performed along the 7-shaped groove (1). However, it is difficult to make the parallelism between the interosseous direction and the extending direction of the 7-shaped groove formed using the mask turn less than 10 seconds. Therefore, the crease line on the fractured surface, which is the inter-fold surface, does not always propagate along the bottom linear part of the figure-7 groove, but tends to go up one slope of the figure-7 groove. occurs. As a result, an imbalance occurs in the rigidity of the crystals on both sides of the fractured surface, and the fractured surface bends toward the side with weaker rigidity, resulting in micro-stairs (steps with several to hundreds of holes, also called joy). ) is one of the causes of deterioration of resonance performance. Moreover, minute creases do not necessarily occur at the part where the cutter makes contact, and if they occur at a misaligned part, there is still an imbalance in rigidity, which has the disadvantage of bending the cut surface. .

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and even if there is an angular difference within a certain range between the direction of grooves formed by selective etching on a wafer for semiconductor lasers and the direction between the bones, it is possible to prevent cutting. The purpose of the present invention is to provide a cutting method that can be performed along a surface.

[Summary of the invention]

Selective etching is performed in advance using a mask pattern or the like along the planned cutting line that creates the creases in the single crystal wafer, thereby forming parallel grooves at desired intervals, and a cutter is brought into contact with the grooves. Afterwards, cutting is performed by relatively moving the blades.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. First, the thickness shown in Figure 2 is approximately 100 μm, and the -side is 20 μm.
The main surface (001) of the ~25 mm square single-crystal GaAs wafer (2) that is far from the laser oscillation part (corresponds to the back surface)
For example, the J (110) direction is searched by etching with a 33% Cry3-HF based etching solution and observing the bit with a microscope. This (110
) direction is the direction of the intersection between the main surface (001) and the interfold surface (110). A mask pattern (not shown) in which parallel slits are formed at equal intervals is placed on the wafer (2) so that the longitudinal direction of the slits is parallel to the (110) direction.
The flat bottom surface (ooi) shown in FIG.
3) are formed by selective etching in large numbers at equal intervals, as shown in FIG. The depth D of these sb grooves (4) is etched to 10 to 30 μm, which is 10 to 30% of the thickness of the wafer (2). If this depth D is deeper than this, it is not preferable because it becomes easy to break and becomes difficult to handle.
On the other hand, if it is shallow, the effects described below cannot be fully exhibited. The etching solution used at this time is Br,
-CH,OH type is most suitable, for example 13r
, when a concentration of 1% by weight is used, the etching time is preferably 1 to 3 minutes. As shown in Fig. 3, the surface where the side ends of the dovetail grooves (4) are open is the inter-fold surface (
110). In addition, the direction perpendicular to the foot grooves (4) is the [:110) direction, which is the direction of intersection between the main surface (ooi) and the inter-fold surface (110), and the selection is made in this direction. When etched, the figure 7 groove (
5) is formed. The surface on which the side end of this 7-shaped groove (5) is open is the (110) plane, which is parallel to the resonant end surface of the semiconductor laser to be obtained by the cutting method of this example. . Next, the wafer (2) in which the foot grooves (4) have been formed is fixed on a table (not shown). At this time, the table is installed so that the moving direction of the table matches the foot grooves (4). Furthermore, the cutlery (6) shown in FIG. Place it on the inside at the following distance and make a 3 to 10 μm incision to create minute folds. As shown in FIG. A 10 μm cut is made and the table is moved with the blade (6) tilted at a constant angle θ.Then, the blade (7) moves relatively along the planned expansion line on the bottom surface (3) and cuts the wafer. (2) is cut into two parts.The same cutting operation is then repeated in half and half to finally produce a strip-shaped body with a width of 0.25 myn.In this way, this example The cutting method is dovetail groove (
4) The arms are opened along the lines, so selective etching is used. Even if there is an angular difference between the elongation direction of the l groove (4) and the direction between the folds, the leg groove (4)...
)... each bottom (3)... As long as the inner KW opening door is present (the angular difference between the extension direction and the extension/opening direction of the dovetail groove (4)... is allowed up to about ±3 minutes. ), there is a splitting crack and it does not climb up the slope of groove (4)... Therefore, an imbalance in rigidity does not occur between the cut right and left crystal bodies. Therefore, it is possible to prevent damage caused by bending the fractured surface in a direction where the rigidity is weak, and to obtain a beautiful interfold surface (resonant end surface) without defects. Moreover, since the groove width can be widened, the blade (
5) The cutting becomes easier. Therefore, the quality of the resonant end face is improved compared to the case where a single-shaped groove is used for cutting, and the yield is improved.

In the above embodiments, the cutting was performed using a knife with a straight blade, but it is also possible to cut using a free-rotating Solopan ball-shaped knife with a cutting angle β of 3 to 4 degrees. good. Further, although the material to be cut in the above embodiment is GaAs, the present invention can also be applied to Gap, InSb, Zn8, etc. if the material is cut using the dovetail groove formed by selective etching. Furthermore, even without using a selective etching solution, for example, reactive ion etching (React Ion Etching) can be used.
A groove with a relatively flat groove bottom may be formed in the direction of the intersection between the inter-fold surface and the main surface of the wafer, and then cut. Furthermore, the groove with a flat bottom surface may be formed only at the end of the wafer (2) and then cut.

〔Effect of the invention〕

According to the present invention, the shear grooves are formed by selective etching along the cutting direction, and the dovetail grooves are used to perform cutting, so that the extension direction of the leg grooves and the direction between the folds are different. Even if there is an angular difference between the grooves, as long as there is an inter-fold surface within the bottom of the groove, the grooved wire will not climb up the slope of the groove. . Therefore, it is possible to obtain a beautiful, defect-free surface. Moreover, since the groove width can be made wider, cutting with a blade becomes easier. In particular, when the present invention is applied to the production of semiconductor laser chips, quality and yield can be improved compared to using V-shaped grooves for cutting.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a V-shaped groove used in the conventional cutting of 7% GaAs sea urchin, FIG. 2 is a perspective view showing the direction in which the groove is formed in an embodiment of the present invention, and FIG. FIG. 4 is a perspective view showing a plurality of grooves formed by selective etching, and FIGS. FIG. (2): Wafer, (3): Dovetail groove. +5): V-shaped groove, (61: Knives. Agent: Patent attorney Noriyuki Chika (and 1 other person)

Claims (6)

[Claims] (1) A method of selectively etching a single-crystal wafer along a planned cutting line that creates creases to form a groove with a substantially flat bottom, and a method of abutting a cutter against the bottom of the groove and then moving the cutter as described above. A cutting method characterized by comprising: a method of cutting the single crystal wafer by moving the single crystal wafer relative to the single crystal wafer. (2) The cutting method according to claim 1, wherein the groove is a reed groove. (3) The cutting method according to claim 1 or 2, wherein the single crystal wafer is gallium arsenide. (4) The depth of the groove is 10 to 30% of the thickness of the single crystal Ueno.
Claim 1 or 2 characterized in that
Cutting method described in section. (5) The cleaving method according to claim 1 or 2, wherein the angular difference between the extending direction of the groove and the interosseous direction at the bottom of the groove is 3 minutes or less. (6) The cutting method as set forth in claims 1 and xisii, wherein the selective etching is performed with a Br, -CHsOH based etching solution.