KR100261244B1 - Semiconductor laser diode and its manufacturing method - Google Patents

Abstract

PURPOSE: A semiconductor laser diode and a method for manufacturing the same are provided to improve an interface characteristic and manufacture it easily . CONSTITUTION: A semiconductor laser diode includes an n-type AlGaAs clad layer(202), an AlGaAs active layer(203), a p-type AlGaAs clad layer(204) and a p-type AlAs etch prevention layer(205), which are sequentially formed on an n-type GaAs substrate(201). A p-type AlGaAs ridge clad layer and a p-type GaAs ridge contact layer(209) are sequentially formed on the center of the p-type AlAs etch prevention layer(205), thus forming a ridge. An n-type GaAs current shield layer(207) and a p-type GaAs cap layer(208) are sequentially formed on the remaining portions of the p-type AlAs etch prevention layer(205). A p-type GaAs contact layer(210) is formed on the surface consisting of the p-type GaAs cap layer(208) and the p-type GaAs ridge contact layer(209).

Description

Semiconductor laser diode and manufacturing method thereof

1 (a) to 1 (d) are cross-sectional views of intermediate structures sequentially appearing in the manufacturing process of a conventional semiconductor laser diode.

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

FIG. 3 is a graph showing etching rates of GaAs, Al _y Ga _1-y As, and AlAs according to AsH ₃ flow rate during HCl gas etching.

* Explanation of symbols for main parts of the drawings

101: n-type GaAs substrate 102: n-type AlGaAs clad layer

103: active layer 104: p-type AlGaAs cladding layer

105: p-type GaAs ridge cap layer 106: SiN _x mask pattern

107: n-type GaAs current blocking layer 108: p-type GaAs cap layer

109: p-type GaAs contact layer 201: n-type GaAs substrate

202: n-type AlGaAs cladding layer 203: AlGaAs active layer

204: p-type AlGaAs clad layer 205: p-type AlAs etch stop layer

206: p-type AlGaAs ridge cladding layer 207: n-type GaAs current blocking layer

208 p-type GaAs cap layer 209 p-type GaAs ridge contact layer

210: p-type GaAs contact layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor laser diodes, and more particularly, to a buried litz type semiconductor laser diode and a method of manufacturing the same.

Semiconductor laser diodes are generally compact, lightweight, and control can be carried out electrically, so compact disks, laser disks, mini disks and magneto-optical disks It is mainly used as a light source of an optical information processing device such as. It is configured to include an active layer consisting of a light source a semiconductor laser diode increases _{Al x Ga 1-x As (} x ≒ 0.14) substances in which the oscillation of the laser beam having a wavelength of 780nm band is used as the optical information processing device.

On the other hand, the semiconductor laser diode used as a light source of the optical information processing device is required not only to be used as a light source for reproduction but also to be used as a light source for recording, and as a way to realize high output, a buried litz type semiconductor laser diode Is proposed.

1 (a) to 1 (d) are cross-sectional views of intermediate structures sequentially appearing in the manufacturing process of a conventional semiconductor laser diode.

First, referring to FIG. 1 (d), a conventional buried lead type semiconductor laser diode will be described. An n-type AlGaAs cladding layer 102, an active layer 103, and a p-type AlGaAs are formed on an n-type GaAs substrate 101. The cladding layer 104 is sequentially stacked. Here, the p-type AlGaAs cladding layer 104 has a ridge formed at a central portion thereof, and a p-type GaAs ridge cap layer 105 is formed at an upper portion of the ridge. The n-type GaAs current blocking layer 107 and the p-type GaAs cap layer 108 are sequentially stacked on the non-ridge portion of the p-type AlGaAs cladding layer 104, and the p-type GaAs cap layer 108 and the p-type The p-type GaAs contact layer 109 is stacked on the top surface of the GaAs ridge cap layer 105.

The manufacturing method of such a semiconductor laser diode is as follows.

Referring to FIG. 1A, an n-type AlGaAs cladding layer 102, an active layer 103, a p-type AlGaAs cladding layer 104, and a p-type GaAs ridge cap layer 105 are disposed on an n-type GaAs substrate 101. ) Grow sequentially. Then, the SiN _x mask pattern 106 is selectively formed on a portion of the surface of the p-type GaAs ridge cap layer 105 to be formed with ridges through conventional deposition and etching processes. After the SiN _x mask pattern 106 is formed, HCl (hydrogen chloride) gas etching is performed to form a p-type AlGaAs cladding layer 104 and a p-type GaAs ridge cap layer 105 as shown in FIG. 1 (b). Etch portions other than ridges. After the formation of the lid, as shown in FIG. 1 (c), the n-type GaAs current blocking layer 107 and the p-type GaAs cap layer (top) of the portions other than the lids on the surface of the p-type AlGaAs cladding layer 104 ( 108 is grown sequentially through metal organic chemical vapor chemical deposition (MOCVD).

As such, when the growth of the n-type GaAs current blocking layer 107 and the p-type GaAs cap layer 108, which causes the buried in the portions other than the ridge, is completed, the SiN _x on the top of the p-type GaAs ridge cap layer 105 is completed. The mask pattern 106 is removed. Then, as shown in FIG. 1 (d), the p-type GaAs contact layer 109 is grown on the top surface of the p-type GaAs ridge cap layer 105 and the p-type GaAs cap layer 108. Such a prior art has the advantage that the SiN _x mask pattern 106 acts as an etch mask and at the same time acts as a crystal growth prevention mask and forms a ridge through HCl gas etching, thereby improving the interfacial properties. That is, the conventional Al _y Ga _1-y As (y≥0.2) has a problem in that the oxidation is rapidly progressed when exposed to air and the interface property deteriorates upon regrowth.

However, in HCl gas etching, since the etching rates of GaAs and Al _y Ga _1-y As are significantly different, as shown in FIG. 3, it is difficult to accurately control the width and thickness of the ridge.

In the process of HCl gas etching the p-type AlGaAs cladding layer 104 and the p-type GaAs ridge cap layer 105 to form a ridge, the etch rate will be described with reference to FIG. 3.

3 shows the etching rates of GaAs, AlGaAs (particularly Al _0.48 Ga _0.52 As), and AlAs with respect to AsH ₃ flow rate in HCl gas etching. As can be seen from the figure, the AsH ₃ flow rate may be increased. As the etching rate decreases monotonously. In particular, as the AsH ₃ flow rate is higher for the reason that the AlGaAs etch rate decreases monotonically is because the AsH ₃ gas when HCl gas to suppress etching to be the AsCl ₃ gas generated from the surface of AlGaAs. Therefore, the conventional manufacturing process is dependent on such a property, and adjusted the thickness of the portion remaining in the p-type AlGaAs cladding layer 104 without being etched. In other words, by selecting the appropriate AsH ₃ flow rate to adjust the thickness of the portion remaining without etching. However, this requires a very strict control of the process conditions, there is a problem that the reproducibility is lowered and the productivity is lowered.

Accordingly, the present invention provides an ridge type semiconductor laser diode which can be manufactured more easily while improving the interfacial properties.

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

In order to achieve the above object, the semiconductor laser diode according to the present invention comprises a GaAs semiconductor substrate; A first conductive AlGaAs cladding layer, an AlGaAs active layer, a second conductive AlGaAs plane cladding layer and an etch stop layer sequentially formed on the substrate; A second conductive AlGaAs ridge cladding layer stacked on the center of the etch stop layer to form a ridge; And a first conductive GaAs current blocking layer stacked on the portion of the etch stop layer in which the second conductive AlGaAs ridge cladding layer is not stacked.

In the semiconductor laser diode according to the preferred embodiment, the etch stop layer is made of one of AlAs, InGaP and InGaAlP. In addition, a second conductive GaAs ridge contact layer stacked on top of the second conductive AlGaAs ridge cladding layer to form a ridge together with the second conductive AlGaAs ridge cladding layer, and the first conductive GaAs current blocking layer. And a second conductive GaAs cap layer stacked on top of the layer, and a second conductive GaAs contact layer stacked on top of the surface consisting of the second conductive GaAs ridge contact layer and the second conductive GaAs cap layer. The p-type AlGaAs surface cladding layer may be made of Al _0.45 Ga _0.55 As material.

In order to achieve the above another object, the method of manufacturing a semiconductor laser diode according to the present invention includes a first conductive type AlGaAs cladding layer, an AlGaAs active layer, a second conductive type AlGaAs surface cladding layer, an etch stop layer, and an upper portion of a predetermined semiconductor substrate. A first step of sequentially growing a two-conducting AlGaAs ridge cladding layer; Forming a mask pattern for forming a ridge on the second conductive AlGaAs ridge cladding layer; A third process of selectively etching the second conductive AlGaAs ridge cladding layer through gas etching with hydrogen chloride (HCl) using the mask pattern, and a first conductive layer on the surface of the etch stop layer exposed through the third process And a fourth step of growing the type GaAs current blocking layer.

In the semiconductor laser diode method according to a preferred embodiment of the present invention, the step of growing the etch stop layer is a step of growing any one of the AlAs, InGaP and InGaAlP layer having a second conductivity type to 300 Å thickness, the first process The method may further include growing a second conductive GaAs ridge contact layer on the second conductive AlGaAs ridge cladding layer, and in the second process, the second conductive together with the second conductive AlGaAs ridge cladding layer. The GaAs ridge contact layer is selectively etched.

In addition, a process of growing a second conductive GaAs cap layer on the first conductive GaAs current blocking layer, removing the mask pattern, the second conductive GaAs cap layer, and the second conductive GaAs ridge contact layer The method may further include growing a second conductive GaAs contact layer on an upper surface of the surface, wherein the mask pattern is formed of SiN _x .

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention.

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

Referring to FIG. 2, an n-type AlGaAs cladding layer 202, an AlGaAs active layer 203, a p-type AlGaAs surface cladding layer 204, and a p-type AlAs etch stop layer 205 on an n-type GaAs substrate 201. ) Are formed sequentially. The p-type AlGaAs ridge cladding layer 206 and the p-type GaAs ridge contact layer 209 are sequentially stacked on the central portion of the p-type AlAs etch stop layer 205 to form a ridge. The n-type GaAs current blocking layer 207 and the p-type GaAs cap layer 208 are sequentially stacked on top of the remaining portion of the layer 205. The p-type GaAs contact layer 210 is formed on the upper surface of the p-type GaAs cap layer 208 and the p-type GaAs ridge contact layer 209. That is, the present invention, unlike the prior art, does not constitute a single p-type AlGaAs cladding layer formed on the AlGaAs active layer 203, but a dual configuration. That is, one p-type AlGaAs cladding layer was formed in the form of a ridge, the other one was formed in the form of a film, and an etch stop layer was introduced therebetween. Here, it can be seen that the AlAs material constituting the etch stop layer acts as a mask because the etching rate is lower than that of GaAs or AlGaAs during HCl gas etching.

The p-type AlGaAs surface cladding layer 204 may be made of Al _0.45 Ga _0.55 As material, and the p-type AlAs etching stop layer 205 stacked thereon may be formed with the p-type AlGaAs surface cladding layer 204. Since there is a slight lattice mismatch, the thickness is approximately 300 kW so as not to adversely affect the optical waveguide.

In FIG. 2, the etch stop layer is made of a p-type AlAs material, but may also be made of InGaP or InGaAlP material. The AlGaAs active layer 203 is made of Al _x Ga _1-x As material, and the n-type AlGaAs cladding layer 202, the p-type AlGaAs surface cladding layer 204, and the p-type AlGaAs ridge cladding layer 206 are Al _y. Comprising a Ga _1-y As material, the composition ratio x of aluminum in the AlGaAs active layer 203 is smaller than the composition ratio y of aluminum in the other layers.

Next, the manufacturing process of the semiconductor laser diode according to the present invention will be described.

Referring again to FIG. 2, after the predetermined n-type GaAs substrate 201 is provided, the n-type AlGaAs cladding layer 202, the AlGaAs active layer 203, and the p-type AlGaAs surface on the n-type GaAs substrate 201. The cladding layer 204, the p-type AlAs etch stop layer 205, the p-type AlGaAs ridge cladding layer 206, and the p-type GaAs ridge contact layer 209 are sequentially grown. Then, SiN _x is applied over the entire surface of the p-type GaAs ridge contact layer 209 and then the remaining portions except for the portions where the ridges are to be formed are removed to form a SiN _x mask pattern. The p-type GaAs ridge contact layer 209 and the p-type AlGaAs ridge cladding layer 206 are selectively etched through HCl gas etching using the SiN _x mask pattern thus formed to form ridges.

Once the ridge is formed, the n-type GaAs current blocking layer 207 and the p-type GaAs cap layer 208 are selectively grown using a SiN _x mask pattern as an etch mask. The SiN _x mask pattern is then removed and the p-type GaAs contact layer 210 is grown on top of the surface consisting of the p-type GaAs cap layer 208 and the p-type GaAs ridge contact layer 209.

Here, the p-type AlAs etch stop layer 205 has an AsH ₃ flow rate of about 120 [sccm] as HCl gas etching process for the p-type AlGaAs surface cladding layer 204 formed at the bottom thereof, and HCl. Adjust the ratio of AsH ₃ to gas to about ₃ .

As described above, the semiconductor laser diode according to the present invention is manufactured by vapor etching and in-situ selective regrowth using HCl of MOCVD, thereby improving interfacial properties and etching. The inclusion of a barrier layer further reduces the process conditions during its manufacture, which greatly improves the reproducibility of ridge formation, resulting in increased productivity.

As mentioned above, although the semiconductor laser diode and its manufacturing method which concern on this invention were demonstrated to the specific Example, this invention is not limited to the said Example, The deformation | transformation and improvement are possible within the range of the common knowledge of those skilled in the art. do.

Claims (9)

GaAs semiconductor substrates; A first conductive type AlGaAs cladding layer, an AlGaAs active layer, a second conductive type AlGaAs surface bladder layer and an etch stop layer sequentially formed on the substrate; A second conductive AlGaAs ridge cladding layer stacked on the center of the etch stop layer to form a ridge; And a first conductive GaAs current blocking layer stacked on the portion of the etch stop layer in which the second conductive AlGaAs ridge cladding layer is not stacked. The semiconductor laser diode of claim 1, wherein the etch stop layer is made of one of AlAs, InGaP, and InGaAlP. The GaAs ridge contact layer of claim 1, further comprising: a second conductive GaAs ridge contact layer formed on the second conductive AlGaAs ridge cladding layer to form a ridge together with the second conductive AlGaAs ridge cladding layer; A second conductive GaAs cap layer stacked on the first conductive GaAs current blocking layer; And a second conductive GaAs contact layer stacked on an upper surface of the second conductive GaAs ridge contact layer and the second conductive GaAs cap layer. The semiconductor laser diode of claim 1, wherein the p-type AlGaAs surface cladding layer is made of Al _0.45 Ga _0.55 As material. A first step of sequentially growing a first conductive type AlGaAs cladding layer, an AlGaAs active layer, a second conductive type AlGaAs surface cladding layer, an etch stop layer, and a second conductive type AlGaAs ridge cladding layer on the semiconductor substrate; Forming a mask pattern for forming a ridge on the second conductive AlGaAs ridge cladding layer; A third process of selectively etching the second conductive AlGaAs ridge cladding layer through gas etching with hydrogen chloride (HCl) using the mask pattern; And a fourth step of growing the first conductive GaAs current blocking layer on the surface of the etch stop layer exposed through the third step. The method of claim 5, wherein the growing of the etch stop layer is a step of growing any one of the second conductive AlAs, InGaP, and InGaAlP layers. The method of claim 5, wherein the first process further comprises growing a second conductive GaAs ridge contact layer on the second conductive AlGaAs ridge cladding layer, and in the second process, the second conductive AlGaAs ridge. And selectively etching the second conductive GaAs ridge contact layer together with the ridge cladding layer. The method of claim 7, further comprising: growing a second conductive GaAs cap layer on the first conductive GaAs current blocking layer; Removing the mask pattern, and growing a second conductive GaAs contact layer on an upper surface of the second conductive GaAs cap layer and the second conductive GaAs ridge contact layer. The manufacturing method of the semiconductor laser diode. The method of claim 5, wherein the forming of the mask pattern comprises: forming a SiN _x layer over the entire surface; And etching a portion of the SiN _x layer other than the ridges in the SiN _x layer.