JPH04373182A - Manufacture of semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To form a current construction section which is coincident with the bent section of an active layer through a relatively simple process which does not require any alignment. CONSTITUTION:After a doped oxide 11 is applied to the surface of an n-type cap layer 5 provided with a groove formed coincidentally with the bent shape of an active layer 3 and the oxide 11 is removed so as to leave the oxide only in the groove of the layer 5, a current flowing route is formed by partially inverting the type of conductivity of a cap layer 3 to type (p) by diffusing impurities from the oxide 11 into the cap layer 4 so that the impurities can reach a p-type clad layer 4.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION This invention relates to a method for manufacturing a semiconductor light emitting device, and more particularly to a semiconductor light emitting device in which a part of an active layer has a concave bent portion bent toward a substrate, and the bent portion serves as an active region. The present invention relates to a method of manufacturing a semiconductor light emitting device that can form a current confinement structure with high precision.

0002

[Prior art] Figure 3 shows applied physics
This is a sectional view showing a conventional semiconductor laser device described in Letters, Volume 31, Page 466 (1977). In the figure, 1 is an n-type GaAs substrate, 2 is an n-type Al0
．． 3Ga0.7As lower cladding layer, 3 is undoped G
aAs active layer, 4 is p-type Al0.3 Ga0.7 As
Upper cladding layer, 5 p-type GaAs ohmic contact layer, 7 metal electrode, 8 SiO2 film, 9 SiO2
The striped openings in the film 8, 10 are the bent portions of the active layer 3 (
active area). And, Fig. 3(a) shows SiO2
In an ideal case where the opening 9 of the SiO2 film 8 coincides with the active region 10, FIG. 3(b) shows a case where the opening 9 of the SiO2 film 8 and the active region 10 are misaligned.

Next, the manufacturing method will be explained. On the substrate 1 with striped grooves formed on one main surface, MOCVD
Lower cladding layer 2, active layer 3, and upper cladding layer 4 are formed by
, and contact layer 5 are sequentially crystal-grown. Thereafter, a SiO2 film 8 is formed on the contact layer 5, and the active region 10 of the SiO2 film 8 is etched using photolithography and etching techniques.
A striped opening 9 is formed at a position opposite to. Then, the contact layer 7 exposed in the opening and the Si
After forming the metal electrode 7 on the O2 film 8 and the back surface of the substrate 1 by sputtering or the like, the chips are separated to complete the laser device.

Next, the operation will be explained. Between the electrodes 7,
When a forward voltage is applied to the pn junction of the active layer 3, a constricted current flows through the opening 9 of the SiO2 film 8, and radiative recombination occurs within the active layer 3. The light generated is
The fabric is guided by an optical waveguide composed of a refractive index step between the cladding layers 2 and 4 and the active layer 3 and an effective refractive index distribution caused by the bending of the active layer, and is composed of opposing cleavage planes. - Laser oscillation occurs within the Perot cavity. Here, in the case of Fig. 3(a), the gain distribution determined by the current distribution and the refractive index distribution due to the bending of the active layer match, so the device operates stably up to high output; b)
If the position shifts as in the above case, performance deterioration occurs, such as loss of linearity of optical output-current characteristics.

[0005]

[Problems to be Solved by the Invention] As described above, the conventional semiconductor laser device has a current confinement structure for concentrating the current at the bent portion of the active layer using a SiO2 film and a striped opening provided in the SiO2 film. Since the striped openings are formed by photolithography and etching, high precision is required to align the openings and the bends during photolithography, and variations in alignment are required. Therefore, there was a problem that variations in device characteristics occurred.

The present invention was made to solve the above-mentioned problems, and it is possible to form a current confinement portion that coincides with a bent portion of an active layer using a relatively simple process that does not require alignment. It is an object of the present invention to provide a method for manufacturing a semiconductor light emitting device, which allows a semiconductor light emitting device to be manufactured, which is suitable, and has uniform characteristics.

[0007]

[Means for Solving the Problems] A method for manufacturing a semiconductor light emitting device according to the present invention includes forming at least a cladding of a first conductivity type on a semiconductor substrate of a first conductivity type in which striped grooves are formed on one principal surface. A multilayer film for a semiconductor light emitting device is composed of an active layer, a cladding layer of a second conductivity type, and a cap layer of a first conductivity type. After crystal growth is performed so that striped grooves having substantially the same shape as the substrate are formed in the cap layer, a film containing impurity atoms imparting a second conductivity type is applied to the surface of the cap layer, and this film is applied to the cap layer. After removing the layer so that it remains only inside the groove, the impurity atoms are diffused from the film in the groove to reach the second cladding layer, so that a part of the cap layer is inverted to the second conductivity type. This is what I did.

[0008]

[Operation] In the present invention, a film containing impurities is formed on the surface of the cap layer having grooves formed to reflect the curved shape of the active layer, and this film is made to remain only inside the grooves of the cap layer. After removal, the impurity is diffused into the cap layer so as to reach the cladding layer from this film, partially inverting the conductivity type of the cap layer to form a current path. A current confinement structure can be formed in a self-aligned manner directly above the part, an alignment process is not necessary, and variations in characteristics due to positional deviation can be prevented.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are cross-sectional process diagrams showing a method for manufacturing a semiconductor light emitting device according to an embodiment of the present invention. In the figures, the same reference numerals as in FIG. It is oxide.

Next, the steps of this embodiment will be explained with reference to the drawings. First, stripe-shaped grooves are formed on the n-type GaAs substrate 1 by selective etching using a photolithography method, and then a vapor phase crystal growth method such as metal organic vapor phase crystal growth (MOCVD) or molecular beam epitaxy (MBE) is performed. As shown in FIG. 1A, AlGaAs multilayer films 2 to 5 having bent portions 10 corresponding to the grooves of the substrate are successively crystal-grown.

Next, as shown in FIG. 1(b), the protrusions of the wafer reflect doped oxide 11 (for example, OCD (product name) manufactured by Tokyo Ohka Kogyo Co., Ltd.) containing Zn atoms on the wafer surface. Apply it so that it is flat and not stained. Then, by dry etching, the doped oxide film 11 is partially removed so that the protrusions of the wafer are exposed and remain inside the grooves, as shown in FIG. 1(c). In this state, Zn atoms are diffused from the doped oxide 11 in the trench so as to reach the upper cladding layer 4, and the diffused portion 15 of the cap layer 5 is inverted to p-type as shown in FIG. 2(a). After this, as shown in Figure 2(b), the wafer surface and
After forming ohmic metal electrodes 7 on both back surfaces, each chip is separated to complete the device.

Next, the operation will be explained. Between the electrodes 7,
When a forward voltage is applied to the pn junction of the active layer 3, current flows in a confined manner only in the p-type region of the cap layer 5, and radiative recombination occurs within the active layer 3. The generated light is guided by an optical waveguide composed of an effective refractive index distribution caused by the refractive index step difference between the cladding layers 2 and 4 and the active layer 3 and the bending of the active layer, and is guided by an optical waveguide formed by an effective refractive index distribution caused by the refractive index step between the cladding layers 2 and 4 and the active layer 3, and is guided by an optical waveguide formed by an effective refractive index distribution caused by the bending of the active layer. Laser oscillation occurs within a Fabry-Perot resonator composed of

In this case, when fabricated by the process of this example, the current confinement part is formed at a position that automatically (self-aligns) coincides with the bending part of the active layer, so that the current confinement part is good and stable even during high output operation. A laser with uniform characteristics can be realized.

[0014] In the above embodiment, GaAs and Al0
．． 3 Ga0.7 As was used as the material, but AlA
The s composition is not limited to this. In addition, other semiconductor materials that can constitute a semiconductor laser device, such as InGa
AsP, InGaP, (AlGa)InP, etc. may also be used. Further, it is also possible to configure the conductivity type with p and n opposite. Furthermore, the present invention is not limited to the semiconductor laser shown in the above embodiments, but can be applied to any semiconductor light emitting device in which a part of the active layer has a concave bent portion bent toward the substrate side and the bent portion serves as an active region. It can also be applied to other semiconductor light emitting devices such as edge emitting LEDs and superluminescent diodes.

[0015]

As described above, according to the present invention, a film containing impurities is formed on the surface of the cap layer having grooves formed to reflect the curved shape of the active layer, and this film is applied to the surface of the cap layer. After removing the impurity so that it remains only inside the groove, the impurity is diffused into the cap layer so as to reach the cladding layer from this film to partially invert the conductivity type of the cap layer, thereby forming a current path. Therefore, a current confinement structure can be formed in a self-aligned manner directly above the bent portion of the active layer, and good characteristics can be obtained with good reproducibility.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional process diagram showing a part of a method for manufacturing a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional process diagram showing a part of a method for manufacturing a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional semiconductor laser device.

[Explanation of symbols]

1　　　　Substrate 2 Cladding layer 3 Active layer 4 Cladding layer 5 Cap layer 7 Electrode 10 Bent part of active layer 11 Doped oxide

Claims (1)

[Claims] 1. A semiconductor substrate of a first conductivity type in which striped grooves are formed on one main surface, at least a cladding layer of a first conductivity type, an active layer, a cladding layer of a second conductivity type, and a first conductivity type. A multilayer film for a semiconductor light emitting device consisting of a molded cap layer has a shape in which each layer follows the shape of one main surface of the substrate, and the outermost cap layer has a striped groove having approximately the same shape as the substrate. a step of growing a crystal so as to form a crystal, a step of applying a film containing impurity atoms imparting a second conductivity type to the surface of the cap layer, and a step of growing the film so that the film remains only inside the groove of the cap layer. The cap layer is characterized by comprising a step of removing the film, and a step of diffusing impurity atoms from the film in the trench to reach the second cladding layer and inverting a part of the cap layer to the second conductivity type. A method for manufacturing a semiconductor light emitting device.