JPH09246663A - Manufacture of semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a breakage of a wafer during its cutting operation at a location where a substrate is made thin in its heat generation region. SOLUTION: In the method for fabricating a semiconductor laser; a first clad layer 11, an active layer 12, a second clad layer 13 and a contact layer 14 are first formed on a semiconductor substrate 10. Thereafter, trenches 18 are made in the laminated structure and an electrode formation groove 19 is made in a rear side of the substrate 10 at its position directly below the active layer 12 to thereby form a semiconductor laser. In this case, the electrode formation groove 19 and a chip formation groove are formed in the same step and the substrate 10 is cleaved along the chip formation groove in the last step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor laser capable of reducing troubles such as wafer cracking in a chip forming process.

[0002]

2. Description of the Related Art FIG. 4 is a schematic view of a conventional semiconductor laser. 41 is a semiconductor laser, 42 is a pn junction, 43 is a heat generating part, 44 is a GaAs substrate, 45 and 46 are electrodes, 47.
Is a fusion metal, and 48 is a heat sink. In the conventional structure, since the thermal conductivity of GaAs is extremely low, heat dissipation to the substrate side is poor, and the entire surface of the substrate is thinned by chemical etching or mechanical polishing. Was being done. On the other hand, as a method for cutting a semiconductor wafer on which such a circuit is formed to form a chip, a semiconductor wafer is cut by a dicing blade that rotates at high speed (for example,
Japanese Patent Application No. 5-11850), a method is employed in which a cutting line of a semiconductor wafer is scratched with diamond or the like and cleaved according to the scratch.

[0003]

The conventional method as described above is excellent in manufacturing efficiency because a semiconductor wafer can be cut at high speed, but it may cause wafer cracking. Further, the semiconductor laser in which the thickness of the substrate in the heat generating region is thin as described above has a problem that the semiconductor laser is damaged when the wafer is cut. Therefore, the present invention
It is an object of the present invention to provide a method for manufacturing a semiconductor laser that does not cause a wafer crack or damage in a thinned portion.

[0004]

According to the method of manufacturing a semiconductor laser of the present invention, a first clad layer, an active layer, a second clad layer and a contact layer are formed on a semiconductor substrate, and then a trench is provided to form a semiconductor laser. A method for manufacturing a semiconductor laser in which a groove for electrode formation is provided on the back side of the substrate located immediately below the active layer, and the groove for electrode formation and the groove for chip formation are formed in the same step. In the final step, the substrate is cleaved along the chip forming groove to form chips.

In the above-mentioned manufacturing method, the step of forming the semiconductor laser on the front surface of the semiconductor substrate and the step of patterning a resist on the back surface of the substrate to form the etching mask for the electrode forming groove and the chip forming groove in the same step. And the step of etching the substrate using the residual resist as a mask to form the electrode forming groove and the chip forming groove, the step of once removing the residual resist and applying the resist again, and the chip forming groove. Patterning so as to leave the resist of, the step of forming an electrode by embedding the electrode material in the electrode forming groove, removing the remaining resist, cleaving the substrate according to the formed chip forming groove to form a chip. And a forming step.

[0006]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. FIG.
1 is a perspective view showing a structure of a semiconductor laser according to the present invention, 10 is an n-InP substrate, 11 is an n-InP first cladding layer, 12 is an InGaAsP active layer, and 13 is p-In.
P second clad layer, 14 p-InGaAs contact layer, 15 SiO 2 film (silicon oxide film), 16 Ti
PtAu electrode, 17 is AuGeNiTiAu electrode, 18
Is a trench. Laser oscillation occurs in the InGaAsP active layer 12 between the two trenches 18. This portion serves as a heat generating portion, and the n-InP substrate 10 below the heat generating portion.
Has a smaller thickness than other portions, and heat can be efficiently conducted to the portion 17 formed thereunder.

According to the manufacturing method of the present invention, the first cladding layer 11, the active layer 12, and the second cladding layer 1 are formed on the semiconductor substrate 10.
3. Form a contact layer 14 and then form a trench 18 to form a semiconductor laser, and manufacture a semiconductor laser in which an electrode forming groove 19 is provided on the back side of the substrate 10 located immediately below the active layer 12. The method is characterized in that the electrode forming groove 19 and the chip forming groove 20 are formed in the same step, and in the final step, the substrate 10 is cleaved according to the chip forming groove 20 to form a chip.

The manufacturing process of the present invention will be described with reference to FIGS. The n-In is formed on the n-InP substrate 10 by the CVD method.
P first clad layer 11, InGaAsP active layer 12, p
A -InP second cladding layer 13 and a p-InGaAs contact layer 14 are grown, and a trench 18 is formed on the surface thereof by a wet etching method using a photolithography technique. A current injection region between the two trenches 18 causes laser oscillation in the active layer 12 (see FIG. 2).
(A)). Resists 1 and 2 are formed on the upper and lower surfaces of the substrate, respectively.
Is applied (FIG. 2 (b)). Next, the resist 2 is patterned on the back surface of the substrate 10 to form an electrode forming groove 19 and an etching mask for the chip forming groove 20 in the same step (FIG. 2C). Using the remaining resist 2 as a mask, the electrode forming groove 19 and the chip forming groove 20 are formed by an etching method (either chemical or dry). The electrode forming groove 19 is formed in the n-InP substrate 10 below the oscillation region. Since the thickness of the substrate 10 is 300 to 400 μm, the bottom of the groove 19 has a groove width of 20 μm or less because of its strength.
It is preferable that the contact layer 14 has a thickness of 10 μm or more (FIG. 2D). The resists 1 and 2 are removed (FIG. 2E). The resist 3 is applied to the back surface of the substrate 10 (see FIG. 3).
(F)). Patterning is performed so that the resist 3 remains in the chip forming groove 20 (FIG. 3G). Electrode forming groove 19
An electrode material is embedded in the electrode to form the electrode 17 (see FIG. 3).
(H)). The resist 3 is removed (FIG. 3 (i)). afterwards,
A semiconductor chip is formed by cleavage along the chip forming groove 20 (FIG. 3 (j)).

[0009]

The present invention is embodied in the form described above and has the following effects.

Since the groove for chip formation for cutting the substrate is formed by the etching method, no mechanical force is applied and the cracking of the wafer in the cutting process can be reduced.

Further, damage of the wafer can be reduced even in the oscillation region where the semiconductor substrate is thin for the same reason.

Although the manufacturing method includes a wafer cutting step, since the chip forming groove and the electrode forming groove are simultaneously formed in the same step, the time therefor is not extended and the whole process is not performed. Manufacturing time is reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a semiconductor laser according to the present invention.

FIG. 2 is a diagram illustrating a manufacturing process of a semiconductor laser according to the present invention.

FIG. 3 is a diagram illustrating a manufacturing process of a semiconductor laser according to the present invention.

FIG. 4 is a sectional view for explaining a conventional semiconductor laser.

[Explanation of symbols]

 1, 2 and 3: Resist 10: n-InP substrate 11: n-InP first cladding layer 12: InGaAsP active layer 13: p-InP second cladding layer 14: p-InGaAs contact layer 16: TiPtAu electrode 17: AuGeNiTiAu Electrode 18: Trench 19: Electrode forming groove 20: Chip forming groove 30: Semiconductor laser formed on substrate 41: Semiconductor laser 42: pn junction 43: Heat generating portion 44: GaAs substrate 45, 46: Electrode 47: Fused metal 48: Heat sink

Claims (3)

[Claims] 1. A first clad layer, an active layer, a second clad layer, and a contact layer are formed on a semiconductor substrate, and then a trench is provided to form a semiconductor laser, and a backside of the substrate located immediately below the active layer is formed. A method of manufacturing a semiconductor laser having an electrode forming groove, wherein the electrode forming groove and the chip forming groove are formed in the same step,
A method of manufacturing a semiconductor laser, comprising cleaving the substrate according to a chip forming groove in a final step to form a chip. 2. A step of forming the semiconductor laser on the front surface of a semiconductor substrate, and a step of patterning a resist on the back surface of the substrate to form an etching mask for an electrode forming groove and a chip forming groove in the same step, The substrate is etched using the remaining resist as a mask to form the electrode forming groove and the chip forming groove, the remaining resist is once removed and the resist is applied again, and the resist in the chip forming groove is left. Patterning step, the step of embedding an electrode material in the electrode forming groove to form an electrode, the step of removing the residual resist, and cleaving the substrate according to the formed chip forming groove to form a chip. The method for manufacturing a semiconductor laser according to claim 1, further comprising: 3. The semiconductor laser according to claim 1, wherein the depth of the electrode forming groove is 10 μm or more from the surface of the contact layer side, and the groove width is 20 μm or less. Production method.