JPH0724317B2 - Semiconductor laser manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a semiconductor laser.

[Conventional technology]

Figure 2 shows, for example, CLEO'87, TECHNICAL DIGEST SERIES (198
7) It is a cross-sectional view showing the manufacturing process of the conventional semiconductor laser shown in vol.14 pp.42-43, in which 1 is a semi-insulating semiconductor substrate, 2 is a high-resistance buffer layer, and 3 is a multiple layer. Quantum well structure (MQW) active layer, 4 is a high-resistance upper clad layer, 5 is a mask for forming a first conductivity type region, 6 is a first conductivity type region, and 7 is a mask for forming a second conductivity type region. , 8 is the second
A conductivity type region, 9 is a disordered region, 10 is an active region of a multiple quantum well structure, 11 is a first conductive side electrode, and 12 is a second electrode.
It is a conductive side electrode.

Next, the manufacturing process of this semiconductor laser will be described.

First, as shown in FIG. 2A, a high resistance buffer layer 2, an active layer 3 having an MQW structure, and a high resistance upper clad layer 4 are sequentially formed on a semi-insulating substrate 1. Next, as shown in FIG. 2B, a mask 5 for forming a first conductivity type region is formed, and a first conductivity type region 6 is formed by ion implantation or diffusion. Further, the mask 5 is removed, a mask 7 for forming a second conductivity type region is formed as shown in FIG. 2C, and a second conductivity type region 8 is formed by ion implantation or diffusion. After that, the mask 7 is removed to disorder the active layer portions in the first and second conductivity type regions as shown in FIG. 2 (d). As a result, the region of the active layer 3 into which the impurities are implanted becomes the disordered region 9, and the region in which the impurities are not implanted becomes the active region 10. After that, the electrodes 11 and 12 on the first and second conductive sides are formed, and the process is completed.

[Problems to be Solved by the Invention]

Since the conventional method for manufacturing a semiconductor laser is configured as described above, it is necessary to control the width of the active region to 1 to 2 μm in order to control the transverse mode of the laser. There is a problem in that it is difficult to accurately control the interval between the first and second conductive region forming masks and the yield is low.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a semiconductor laser having an active region having a width of 1 to 2 μm necessary for controlling a transverse mode with high yield.

[Means for Solving the Problems]

In the method of manufacturing a semiconductor laser according to the present invention, a mask for forming the first conductivity type region is formed of two kinds of mask materials, impurities are implanted, and then only a lower layer mask material is etched by a necessary amount by side etching. The upper layer mask material is removed, the second conductive type region forming mask is formed on the entire surface, and the first conductive type region forming mask and the second conductive type region forming mask in the upper layer portion thereof are removed by lift-off. Impurities are implanted using a patterned mask.

[Action]

In the present invention, since the mask for forming the second conductivity type region is formed using the mask for forming the first conductivity type region, patterning can be performed in a self-aligned manner, and the active region width can be stabilized. You can control.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a process drawing showing a method for manufacturing a semiconductor laser according to an embodiment of the present invention. In the drawing, the same reference numerals as those in FIG. 2 designate the same or corresponding portions, and 13 is different from the mask materials 5 and 7. It is a mask material.

Next, the manufacturing process will be described.

First, as shown in FIG. 1A, a high resistance buffer layer 2, an active layer 3 having an MQW structure, and a high resistance upper clad layer 4 are sequentially formed on a semi-insulating substrate 1. Next, as shown in FIG. 1B, two types of mask materials 5 and 13 (for example, SiO ₂ and photoresist) are formed, and the first conductivity type region 6 is formed by diffusion or ion implantation. Next, using a selective etching solution, only the mask material 5 is under-etched as shown in FIG. 1 (c), and then the mask material 13 is formed as shown in FIG. 1 (d).
To remove. Next, as shown in FIG. 1E, a mask material (for example, metal such as titanium) 7a different from the mask material 5 is formed on the entire surface. Then, as shown in FIG. 1 (f), the mask material 5 and the mask material 7a on the upper layer thereof are removed by lift-off, and the remaining mask material 7b is used as a mask to diffuse the second conductivity type region 8 by ion implantation or the like. To form. Then, as shown in FIG. 1 (g), the first and second conductivity type regions are formed.
The active layers in 6 and 8 are disordered to form the cladding region 9, the non-impurity-implanted region of the active layer 3 to be the active region 10, and the electrodes 11 and 12 on the first and second conductive sides are formed. Element is completed.

As described above, in this embodiment, the mask material 13 is used as a mask to under-etch the mask material 5 for forming the first-conductivity-type region only by the width of the active region, thereby processing the mask material 5 by a necessary amount. Since the mask material 7a for forming the second conductivity type region is patterned by lifting off the mask material, the mask can be formed by self-alignment and the width of the active region can be precisely controlled. Although the mask materials 5, 13, 7a are made of SiO ₂ , photoresist and titanium in the above embodiment, the mask material 5 and the mask 13 and the mask material 5 and the mask material 7a are selectively combined. Other mask materials may be used as long as they can be etched.

Further, although the active layer 3 has a multi-quantum well structure in the above embodiment, it may have a single quantum well structure or a normal double hetero structure.

Further, although the buffer layer 2 and the upper cladding layer 4 are high resistance layers, they may be p-type, n-type, or undoped layers.

〔The invention's effect〕

As described above, according to the present invention, in the method for manufacturing the semiconductor laser device, the mask for forming the first conductivity type region is formed of two kinds of mask materials, and the impurities are implanted to form the first conductivity type region. After that, only the required amount of the lower mask material is side-etched, the upper-layer mask material is removed, a second conductivity type region forming mask is formed on the entire surface, and the side-etched first mask material is formed.
Since the conductive type region forming mask and the second conductive type region forming mask in the upper layer thereof are removed by lift-off and the patterned mask is used to implant impurities to form the second conductive type region, Patterning can be performed in an aligned manner, and there is an effect that a semiconductor laser having an active region with a width of 1 to 2 μm necessary for controlling the transverse mode can be manufactured with high yield.

[Brief description of drawings]

FIG. 1 is a process sectional view showing a method for manufacturing a semiconductor laser according to an embodiment of the present invention, and FIG. 2 is a process sectional view showing a method for manufacturing a conventional semiconductor laser. 1 is a semi-insulating substrate, 2 is a high resistance buffer layer, 3 is an active layer having a multiple quantum well structure, 4 is a high resistance upper cladding layer, 5 is a mask for forming a first conductivity type region, and 6 is a first conductivity type Area, 7a
Is a mask material, 7b is a mask for forming a second conductivity type region, 8 is a second conductivity type region, 9 is a disordered region, 10 is an active region, 11 is a first conductive side electrode, and 12 is a second electrode. Conductive electrode. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first step of sequentially forming an n-type, p-type, undoped or high-resistance buffer layer, an active layer, and an n-type, p-type, undoped or high-resistance upper clad layer on a semiconductor substrate. A second step of forming a first conductivity type region by introducing impurities by using a mask formed by laminating at least two kinds of mask materials on the wafer and patterning these mask materials in the same pattern; Of the first mask material of the lowermost layer and the mask material of the upper layer, underetching is performed, and then the third step of removing the mask material of the upper layer is different from the first mask material. A fourth step of patterning the mask of the second mask material by lifting off the mask of the first mask material after forming a mask of the second mask material on the entire surface; Method for manufacturing a semiconductor laser which comprises a fifth step of forming a second conductivity type region by introducing an impurity using a grayed mask.