KR100668306B1 - Edge emitting type semicondpctor laser diode and method of manufacturing the same - Google Patents

Abstract

An edge emitting semiconductor laser diode and a method of manufacturing the same are disclosed. The present invention discloses an n-type compound semiconductor layer, an n-type cladding layer, an active layer, a p-type cladding layer, a current-carrying layer, an easy-to-flow layer, a cap layer, which are sequentially provided on the n-type compound semiconductor layer, and the n-type compound semiconductor. An edge-emitting semiconductor laser diode comprising an n-type electrode formed on the bottom of the layer and a p-type electrode formed on the cap layer, wherein the conductive layer has a width smaller than that of the active layer and an air gap is formed around the active layer. It provides a manufacturing method.

Description

Edge emitting semiconductor laser diode and method of manufacturing the same {Edge emitting type semicondpctor laser diode and method of manufacturing the same}

1 is a cross-sectional view of a semiconductor laser diode according to the prior art.

2 is a cross-sectional view of an edge emitting semiconductor laser diode according to an embodiment of the present invention.

3 to 9 are cross-sectional views sequentially illustrating a method of manufacturing the edge emitting semiconductor laser diode of FIG. 2.

* Explanation of symbols for main parts of drawings *

40: n-type electrode 42: n-type compound semiconductor layer

44: n-type cladding layer 46: active layer

48: p-type cladding layer 50: p-type compound semiconductor layer

50a: conductive layer (p-type compound semiconductor layer pattern)

52: Easy energization layer 54: Cap layer

56: p-type electrode 60: air gap

The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly, to an edge emitting semiconductor laser diode and a method for manufacturing the same.

Since a semiconductor laser diode is used as a light source for recording and reproducing an optical recording device such as a CDP or a DVD, the mode is related to the noise characteristic of the device. Therefore, the semiconductor laser diode is preferably formed to have stable single mode oscillation. The single mode oscillation is enabled by the refractive index waveguide structure.

1 shows a semiconductor laser diode having a refractive index waveguide structure according to the prior art.

Referring to FIG. 1, the p-type electrode layer 19 is attached to the bottom surface of the p-GaAs substrate 23, and the easy conduction layer 16, the p-clad layer 15, and the active layer 14 are attached to the top surface. Laminated sequentially. The energizing easy layer 16, the p-clad layer 15, and the active layer 14 are p-InGaP layers, p-InGaAlP layers, and InGaP layers, respectively. There is an n-clad layer 13 on the active layer 14. The n-clad layer 13 has a ridge in which a predetermined region protrudes upward. The ridge is a (311) plane or a (111) plane whose sides have a constant inclination. And the top surface of the ridge and the flat top surface of the n-clad layer 13 around the ridge becomes the (100) plane. There is a current inducing layer 12 on the n-clad layer 13 having the flat surface and the inclined surface. The portion 22 of the current inducing layer 12 covering the flat portions of the ridge and n-clad layer 13 is doped with n-type dopant, and the portion 21 covering the inclined surface of the ridge is formed with a p-type dopant. The GaAs epitaxial layer that is alternately doped with n-type dopants or doped with p-type dopants serves to block current flow. Thus, current flows only through flat portions of the ridge doped with n-type dopants. An insulating layer 24 such as a silicon oxide film exists on the current inducing layer 12, but the insulating layer 24 is open at the ridge to provide a current path. An n-type electrode layer 20 is formed on the insulating layer 24 and in contact with the exposed front surface of the ridge.

Looking at the manufacturing process of the conventional semiconductor laser diode described above, the primary crystal growth from the p-type GaAs substrate 23 to the n- clad layer 13 is made. Subsequently, an etching process for forming a ridge in the n-clad layer 13 is performed, followed by secondary crystal growth for forming the current inducing layer 12 on the n-clad layer 13 in which the ridge is formed. .

As described above, since the crystal growth of the semiconductor laser diode according to the related art is performed in two steps, the inconvenience caused by the semiconductor laser diode is inevitable.

The technical problem to be achieved by the present invention is to improve the conventional problems, to reduce the hassle caused by recrystallization growth, increase the current blocking effect and additionally obtain multiple transverse mode suppression and index guiding effect (index guiding) effect An edge emitting semiconductor laser diode can be provided.

Another object of the present invention is to provide a method of manufacturing the edge-emitting semiconductor laser diode.

In order to achieve the above technical problem, the present invention is an n-type compound semiconductor layer, an n-type cladding layer, an active layer, a p-type cladding layer, a conductive layer, a conductive layer, a cap layer sequentially provided on the n-type compound semiconductor layer And an n-type electrode formed on the bottom of the n-type compound semiconductor layer and a p-type electrode formed on the cap layer, wherein the conductive layer has a narrower width than the active layer, and an air gap is formed around the n-type electrode. A laser diode of a semiconductor device is provided.

Here, the width of the conductive layer is about 10 μm to 200 μm.

In order to achieve the above another technical problem, the present invention is a first step of continuously growing an n-type cladding layer, an active layer, a p-type cladding layer, a conductive layer, a conductive layer and a cap layer on the n-type compound semiconductor layer; A second step of patterning the cap layer to a predetermined width; A third step of forming a photoresist pattern covering the exposed entire surface of the patterned cap layer on the conductive layer, and defining a predetermined region of the conductive layer; Etching the conductive layer and the conductive layer at least using the photoresist pattern as an etching mask; A fifth step of forming an air gap between the easy conducting layer and the p-type cladding layer by reducing the width of the conducting layer; A sixth step of removing the photoresist pattern; And a seventh step of cleaving the n-type compound semiconductor layer to the p-type cladding layer and an eighth step of attaching n-type and p-type electrodes to the bottom surface of the n-type compound semiconductor layer and the top surface of the cap layer, respectively. An edge emitting semiconductor laser diode manufacturing method is provided.

The thickness of the p-type cladding layer may also be removed after the conductive layer is etched in the fourth step of the manufacturing method.

In addition, in the fifth step, the width of the conductive layer may be reduced by wet etching the resultant for a predetermined time using a predetermined etchant capable of selectively etching only the conductive layer. Citric acid may be used as the etchant.

Using the present invention, since it can form all from the n-type compound semiconductor layer to the cap layer in one crystal growth, there is no troublesome recrystallization growth as in the prior art. In addition, since the air gap is formed around the conductive layer to block the current, the current blocking effect is excellent, and multiple transverse mode suppression and index guiding effects can also be obtained.

Hereinafter, an edge emitting semiconductor laser diode and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of layers or regions illustrated in the drawings are exaggerated for clarity.

First, an edge emitting semiconductor laser diode according to an embodiment of the present invention will be described.

Referring to FIG. 2, an edge-emitting semiconductor laser diode according to an embodiment of the present invention includes an n-type cladding layer 44, an active layer 46, and a p-type cladding layer 48 on an N-type compound semiconductor substrate 42. It is provided sequentially. The n-type compound semiconductor substrate 42 may be, for example, an n-GaAs substrate. The n-type cladding layer 44 may be an n-InGaAlP layer, the active layer 46 may be an InGaP layer, and the p-type cladding layer 48 may be a p-InGaAlP layer. Subsequently, the conductive layer 52 and the cap layer 54 are sequentially present on the p-type cladding layer 48, and the p-type cladding layer 48 and the conductive layer 52 are formed on the conductive layer 50a. Limited connection via The passivation layer 52 may be a p ⁺ -InGaP layer, and the cap layer 54 may be a p ⁺ -GaAs layer. The conductive layer 50a may be a p-GaAs layer, and the width thereof may be about 10 μm to 200 μm. The p-type cladding layer 48 around the energizing layer 50a and the diversion layer 52 are at least separated by the thickness of the energizing layer 50a. Therefore, an air gap 60 exists between the p-type cladding layer 48 around the conducting layer 50a and the conducting transfer layer 52. Presence in the air gap 60 can provide an excellent current blocking effect. An n-type electrode is attached to the bottom surface of the N-compound semiconductor substrate 42, and a p-type electrode 56 is attached to the cap layer 54.

Next, a method of manufacturing the edge emitting semiconductor laser diode of FIG. 2 will be described with reference to FIGS. 3 to 7.

First, referring to FIG. 3, the n-type cladding layer 44, the active layer 46, the p-type cladding layer 48, the p-type compound semiconductor layer 50, and the electricity supply are provided on the n-type compound semiconductor substrate 42. The bilayer 52 and the cap layer 54 are grown sequentially. The n-type compound semiconductor substrate 42 is preferably formed of an n-GaAs substrate, but may be formed of another n-type compound semiconductor substrate. The n-type cladding layer 44 is formed of an n-InGaAlP layer, and the active layer 46 is formed of an InGaP layer. The p-type cladding layer 48 is formed of a p-InGaAlP layer, and the p-type compound semiconductor layer 50 is formed of a p-GaAs layer. In addition, the energization easy layer 52 and the cap layer 54 can be formed with a p ⁺ -InGaP layer and a p ⁺ -GaAs layer, respectively. This material layer may be formed of a compound semiconductor material other than the compound semiconductor material, for example.

Next, as shown in FIG. 4, the cap layer 54 is patterned such that the width of the cap layer 54 is smaller than the width of the active layer 46 to be formed in a subsequent process, and then as shown in FIG. 5, the cap layer ( A photosensitive film pattern M is formed to cover the exposed front surface of 54. The photoresist pattern M is preferably formed to a size limiting the size of the laser diode to be finally formed. Next, referring to FIG. 6, using the photoresist pattern M as an etching mask, the material layers around the photoresist pattern M, that is, the p-type compound semiconductor layer 50 sequentially grown, and the easy-to-carry layer 52 are sequentially formed. Dry etch in reverse order. After the dry conductive layer 52 is dry etched, the p-type cladding layer 48 may also be removed by a partial thickness.

Next, in order to remove a part of the p-type compound semiconductor layer 50, the resultant product after the dry etching is wet etched using citric acid. The wet etching is performed until the width of the p-type compound semiconductor layer 50 is reduced to a predetermined width. Preferably, the wet etching may be performed until the width of the p-type compound semiconductor layer 50 becomes the width (10 μm to 200 μm) of the conductive layer 50a of FIG. 2. As a result of the wet etching, as illustrated in FIG. 7, a p-type compound semiconductor layer pattern 50a, that is, a conductive layer 50a, which connects the p-type cladding layer 48 and the conductive layer easily 54, is formed. An air gap 60 is formed between the conductive layer 50a to separate the p-type cladding layer 48 from the conductive layer 54. The air gap 60 is used as a current blocking layer.

Next, as shown in FIG. 8, the photoresist pattern M is removed, and the resultant is cleaved along the cutting line L. Next, as shown in FIG. The cutting line L passes through the cleaved surface of the n-type compound semiconductor layers 42 to p-type cladding layer 48. As a result of the cleavage, an independent edge emitting semiconductor laser diode is formed. 9, the n-type electrode 40 is attached to the bottom surface of the n-type compound semiconductor layer 42 of the edge-emitting semiconductor laser diode, and the p-type electrode 56 is formed on the cap layer 54. Attach.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, if one of ordinary skill in the art to which the present invention belongs, the present invention of the single crystal growth is used as it is, instead of forming an air gap around the conductive layer, the outer portion of the conductive layer by an external diffusion method May be oxidized and used as a current blocking layer.

As described above, the present invention may be modified in various ways, and therefore, the scope of the present invention should be determined by the technical spirit described in the claims rather than by the embodiments described.

As described above, the edge-emitting semiconductor laser diode of the present invention can be formed in one crystal growth from the n-type compound semiconductor layer 42 to the cap layer 54, so that there is no hassle of recrystallization growth as in the prior art. . In addition, since the air gap is used as the current blocking layer, the current blocking effect is excellent, and multiple transverse mode suppression and refractive index guiding effects can be obtained.

Claims (7)

n-type compound semiconductor layer; An n-type cladding layer, an active layer, a p-type cladding layer, an energizing layer, an easily conducting layer, and a cap layer sequentially provided on the n-type compound semiconductor layer; An n-type electrode formed on a bottom surface of the n-type compound semiconductor layer; And Including a p-type electrode formed on the cap layer, The conducting layer is narrower than the active layer, the edge emission type semiconductor laser diode, characterized in that the air gap formed around. The edge emission type semiconductor laser diode according to claim 1, wherein the width of the conductive layer is about 10 µm to 200 µm. a first step of continuously growing an n-type cladding layer, an active layer, a p-type cladding layer, an energizing layer, an energizing easy layer, and a cap layer on the n-type compound semiconductor layer; A second step of patterning the cap layer to a predetermined width; A third step of forming a photoresist pattern covering the exposed entire surface of the patterned cap layer on the conductive layer, and defining a predetermined region of the conductive layer; Etching the conductive layer and the conductive layer at least using the photoresist pattern as an etching mask; A fifth step of forming an air gap between the easy conducting layer and the p-type cladding layer by reducing the width of the conducting layer; A sixth step of removing the photoresist pattern; A seventh step of cleaving the n-type compound semiconductor layer to the p-type cladding layer; And And an eighth step of attaching n-type and p-type electrodes to the bottom surface of the n-type compound semiconductor layer and the top surface of the cap layer, respectively. 4. The method of claim 3, wherein the thickness of the p-type cladding layer is also removed after the conductive layer is etched in the fourth step. 4. The method of claim 3, wherein in the fifth step, the resultant of the fourth step is wet-etched for a predetermined time by using an etchant capable of selectively etching only the conductive layer. . 6. The method of claim 5, wherein citric acid is used as the etchant. The edge-emitting semiconductor laser diode of claim 3, wherein the width of the conductive layer is reduced to 10 µm to 200 µm in the fifth step.

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