KR20060037029A - Semiconductor laser diode and method of manufacturing the same - Google Patents

Abstract

A semiconductor laser diode and a method of manufacturing the same are disclosed. Herein, the present invention provides an n-type compound semiconductor substrate, and an n-type lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, and a ridge in the center of the upper surface, which are sequentially stacked on the compound semiconductor substrate. An upper cladding layer, a contact layer formed on an upper surface of the ridge, a current blocking means provided on an upper surface of the p-type upper clad layer, side surfaces of the ridge, and side surfaces of the contact layer, The present invention provides a semiconductor laser diode and a method of manufacturing the same, comprising a capping layer formed on the current blocking means and covering the exposed front surface.

Description

Semiconductor 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 a semiconductor laser diode according to an embodiment of the present invention.

3 to 5 are cross-sectional views illustrating a method of manufacturing the semiconductor laser diode of FIG. 2 step by step.

* Description of the symbols for the main parts of the drawings *

40: n-type compound semiconductor substrate 42: n-type lower clad layer

44: lower waveguide layer 46: active layer

48: upper waveguide layer 50A: p-type first upper clad layer

50R: p type second upper cladding layer (ridge) 52: contact layer

54: current blocking layer 56: capping layer

M: Etch Mask

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

The semiconductor laser diode includes an n-type lower compound semiconductor layer, a resonator layer including an active layer, and a p-type upper compound semiconductor layer. These material layers are formed by an epitaxial growth method called stacking. The interfacial properties of the first grown material layer affect the properties of the later grown material layer. Therefore, it is important to maintain good interfacial properties of each material layer in epitaxial growth.

1 shows a semiconductor laser diode according to the prior art.

Referring to FIG. 1, an n-type lower cladding layer 2, an undoped lower waveguide layer 4, an active layer 5, and an undoped upper waveguide layer 6 are sequentially formed on an n-type compound semiconductor substrate 10. It is provided with. On the upper surface of the upper waveguide layer 6, there is a p-type upper cladding layer 8 in which a ridge having a top surface is formed. The contact layer 9 is laminated on the top surface, that is, the upper surface of the ridge, to form an energization channel. N + current blocking layers 10 exist on both sides of the ridge. The current blocking layer 10 is formed up to the height of the contact layer 9. The cap layer 11 is laminated on the contact layer 9 and the current blocking layer 10.

In the above-described conventional semiconductor laser diode, the ridge is formed by wet etching, and it is difficult to accurately control the etching depth. In addition, after the ridge is formed, selective secondary crystal growth for forming the current blocking layer 10 is performed, and before the secondary crystal growth is performed, the p-type upper clad layer 8 is exposed to air. In the process, the aluminum (Al) component of the upper cladding layer 8 may react with air to oxidize or contaminate the surface of the upper cladding layer 8. In this case, the interfacial characteristics of the secondary crystal growth may be degraded, which may greatly degrade the characteristics and reliability of the semiconductor laser diode.

The technical problem to be achieved by the present invention is to improve the above-described problems of the conventional semiconductor laser diode, it is possible to accurately control the etching depth during ridge formation, the interface characteristics in the secondary crystal growth process is reduced It is to provide a semiconductor laser diode that can prevent the thing.

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

In order to achieve the above technical problem, the present invention is an n-type compound semiconductor substrate, and the n-type lower cladding layer, lower waveguide layer, active layer, upper waveguide layer and the upper surface ridge sequentially stacked on the compound semiconductor substrate a p-type upper clad layer having a ridge, a contact layer formed on an upper surface of the ridge, an upper surface of the p-type upper clad layer, a side surface of the ridge, and a current blocking provided on the side of the contact layer Means and a capping layer formed on the current interrupting means covering the exposed front surface of the contact layer.

The upper cladding layer may include a first upper cladding layer sequentially stacked and having different etching characteristics, and a second upper cladding layer forming the ridge.

The current blocking means may be a thin current blocking layer covering the upper surface of the p-type upper clad layer, the side of the ridge and the side of the contact layer, or the upper surface of the p-type upper clad layer, the side of the ridge and the It may be a depletion layer provided on the surface layer of the side of the contact layer.

In order to achieve the above another technical problem, the present invention provides an agent for sequentially forming an n-type lower clad layer, a lower waveguide layer, an active layer, an upper waveguide layer, a p-type upper clad layer, and a contact layer on an n-type compound semiconductor substrate. A first step of forming an etching mask on a predetermined region of the contact layer, a third step of removing a part of the thickness of the upper clad layer together with the contact layer around the mask, and a flat top of the upper clad layer A fourth step of forming a current blocking means on an exposed side surface and a side of the contact layer while removing a thickness of a surface and a portion around the mask; a fifth step of removing the mask; and removing the mask on the current blocking means. And a sixth step of forming a capping layer covering the entire surface of the exposed contact layer and planarizing the surface thereof. It provides a method for producing de.

In the manufacturing method, the p-type upper clad layer may be formed by sequentially growing first and second upper clad layers having different etching characteristics such as etching selectivity.

The current blocking means may be formed by forming an insulating layer or by forming a depletion layer on the flat upper surface of the upper clad layer, the exposed side surface while the partial thickness around the mask is removed, and the side surface layer of the contact layer.

By using the present invention, it is possible to accurately control the depth of etching, and to prevent the interfacial properties of the upper clad layer from deteriorating during secondary crystal growth after ridge formation.

Hereinafter, a 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, a semiconductor laser diode (hereinafter, referred to as the laser diode of the present invention) according to an embodiment of the present invention will be described.

Referring to FIG. 2, the laser diode of the present invention includes an n-type lower clad layer 42, a lower waveguide layer 44, an active layer 46, and an upper waveguide layer sequentially grown on an n-type compound semiconductor substrate 40. 48 is provided. The compound semiconductor substrate 40 may be an n-GaAs substrate or a III-V compound semiconductor substrate such as GaN. The n-type lower clad layer 42 may be a binary, tertiary or quaternary compound semiconductor layer containing an n-GalnP layer or a III-V group element. The lower waveguide layer 44 may be an undoped GaAs layer or a III-V compound semiconductor layer. The active layer 46 may be a ternary or quaternary compound semiconductor layer containing an InGaAs layer or a III-V group element. The upper waveguide layer 48 may be the same compound semiconductor layer as the lower waveguide layer 44. An upper clad layer 50 is present on the upper waveguide layer 48. The upper cladding layer 50 is composed of a first upper cladding layer 50A and a second upper cladding layer 50R, that is, a ridge 50R. The first upper cladding layer 50A and the second upper cladding layer ( 50R) may be a compound semiconductor layer having different etching characteristics, for example, the first upper cladding layer 50A may be a p-type GaInP layer, and the second upper cladding layer 50R may be a p-type InGaAs layer. A contact layer 52 is provided on the upper surface of the ridge 50R, and a current covering the side of the ridge 50R and the side of the contact layer 52 on the upper clad layer 50 around the ridge 50R. There is a blocking layer 54. The current blocking layer 54 is an example of one of the current blocking means The current blocking layer 54 has excellent interface characteristics with the upper cladding layer 50, and has a current blocking property. It may be a high material layer, for example a silicon oxide film, and the current blocking layer 54 is also provided with other current blocking means, for example a p-type first not shown in the figure. And a depletion layer having a predetermined thickness formed by doping an n-type dopant having the same concentration on the surface layers of the second upper clad layers 50A and 50R. The current blocking layer 54 and the contact layer 52 are formed. There is a capping layer 56 on it.

Next, the method of manufacturing the laser diode of the present invention described above will be described with reference to FIGS.

First, referring to FIG. 3, an n-type lower clad layer 42, a lower waveguide layer 44, an active layer 46, an upper waveguide layer 48, and a first upper cladding are formed on an n-type compound semiconductor substrate 40. The layer 50A, the second upper clad layer 50R, and the contact layer 52 are sequentially grown. In this case, it is preferable to grow the first and second upper clad layers 50A and 50R into compound semiconductor layers having different etching characteristics. For example, the first upper clad layer 50A may be formed of a p-type GaInP layer or a ternary compound semiconductor layer containing an element of group III-V, and the second upper clad layer 50R may be formed of p. It can be grown into a III-V compound semiconductor layer which is formed of a type AlGaAs layer or is not used as the first upper clad layer 50A.

Subsequently, a hard mask M that defines a predetermined region is formed on the contact layer 52 to form a ridge. The mask M may be formed of a silicon oxide film.

Next, the capping layer 52 and the second upper clad layer 50R around the mask M are sequentially etched. Due to the difference in etching characteristics of the first and second upper cladding layers 50A and 50R, the etching may be accurately stopped when the first upper cladding layer 50A is exposed. In other words, the depth of the etching can be accurately controlled. As a result of the etching, as shown in FIG. 4, the capping layer 52 and the second upper clad layer 50R remain only under the mask M. Referring to FIG. The second upper clad layer 50R remaining under the mask M is in the form of a ridge as shown in the figure.

Subsequent to the etching, as shown in FIG. 5, a thin current blocking layer 54 is formed on the exposed upper surface of the first upper clad layer 50A and the side surface of the second upper clad layer 50R having a ridge shape. do. Thereafter, the mask M is removed.

Although not shown in the drawings, the first upper cladding layer 50A and the first upper cladding layer 50A and the side surface of the second upper cladding layer 50R are formed on the upper surface of the first upper cladding layer 50A while the mask M is present. The n dopant may be injected at the same concentration as the doped concentration on the upper clad layer 50R. At this time, the n dopant is preferably injected only to the surface of the upper surface of the first upper clad layer 50A and the side surface of the second upper clad layer 50R. The n dopant is implanted into the upper surface of the first upper clad layer 50A and the side surface layer of the second upper clad layer 50R, whereby the upper surface of the first upper clad layer 50A and the second upper clad layer 50R A depletion layer is formed on the lateral surface layer of the layer. The depletion layer may block the flow of carriers, and thus the depletion layer may replace the current blocking layer 54.

Subsequently, after the current blocking layer 54 is formed, the mask M is removed. Subsequently, as shown in FIG. 2, a capping layer 56 covering the current blocking layer 54 and the contact layer 52 is formed to a sufficient thickness, and then the surface thereof is planarized. In this way, the semiconductor laser diode shown in FIG. 2 is completed.

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, one of ordinary skill in the art to which the present invention pertains may form the semiconductor laser diode of the present invention using various compound semiconductor materials in addition to the above materials, and in this process, the laser diode of the present invention may be Partial modifications will also be possible. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

As described above, the present invention uses two compound semiconductor layers having different etching characteristics as the upper clad layer, and any one of them is used as an etch stop layer. Therefore, the depth of etching can be precisely controlled during the formation of the ridge. In addition, the present invention can prevent the interfacial properties of the upper clad layer from deteriorating during the secondary crystal growth after ridge formation.

Claims (8)

n-type compound semiconductor substrate; An n-type lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, and a p-type upper cladding layer having a ridge in the center of the upper surface, sequentially stacked on the compound semiconductor substrate; A contact layer formed on an upper surface of the ridge; Current blocking means provided on an upper surface of the p-type upper clad layer, a side surface of the ridge, and a side surface of the contact layer; And And a capping layer formed on the current blocking means to cover the exposed front surface of the contact layer. The semiconductor laser diode according to claim 1, wherein the upper cladding layer comprises a first upper cladding layer which is sequentially stacked and has different etching characteristics from each other, and a second upper cladding layer forming the ridge. . The semiconductor laser diode of claim 1, wherein the current blocking means is a thin current blocking film covering an upper surface of the p-type upper clad layer, a side surface of the ridge, and a side surface of the contact layer. The semiconductor laser diode of claim 1, wherein the current blocking means is a depletion layer provided on a top surface of the p-type upper clad layer, a side surface of the ridge, and a surface layer of a side surface of the contact layer. . First step of sequentially forming an n-type lower clad layer, a lower waveguide layer, an active layer, an upper waveguide layer, a p-type upper clad layer, and a contact layer on an n-type compound semiconductor substrate A second step of forming an etch mask on a predetermined region of the contact layer Removing a portion of the upper clad layer along with the contact layer around the mask. A fourth step of forming a thin current blocking layer on the exposed side and the side of the contact layer while the flat top surface of the upper clad layer and a part of the thickness around the mask are removed; A fifth step of removing the mask and And forming a capping layer covering the entire surface of the contact layer exposed while the mask is removed on the current blocking layer, and planarizing the surface thereof. The method of claim 5, wherein the p-type upper clad layer is formed by sequentially growing first and second upper clad layers having different etching characteristics. The method of claim 5, wherein the current blocking layer is formed of an insulating layer. The method of claim 5, wherein the current blocking layer is formed by forming a depletion layer on the flat upper surface of the upper cladding layer, the side surface exposed while removing some thickness around the mask and the side surface layer of the contact layer. A semiconductor laser diode manufacturing method.

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