KR100283958B1 - Laser diode fabricating method - Google Patents

Abstract

The present invention relates to a method for fabricating a laser diode, comprising: a first step of sequentially growing a first cladding layer, an active layer, and a second cladding layer on a substrate; A second step of sequentially growing an etch stop layer and a capping layer of a predetermined material on the second clad layer; A third step of forming an oxide mask on the capping layer in a predetermined direction, and etching the capping layer with a first etchant to the first mesa and etching the remaining layers with a second etchant to the second mesa; A fourth step of sequentially growing a current blocking layer and a current blocking protective layer; A fifth step of sequentially etching an oxide mask, a capping layer, an etch stop layer, and a current blocking protective layer; And a sixth step of sequentially growing the contact layer and the ohmic contact layer.

According to the present invention, a peeling phenomenon of the silica oxide mask can be prevented by introducing a capping layer and an etch stop layer having sufficient adhesion with the silica oxide mask and introducing a current blocking protective layer during the second mesa etching and the first regrowth. Can be.

Description

Laser diode fabrication method

The present invention relates to a method of manufacturing a laser diode (LD), and more particularly, to a method of manufacturing a spot size convertor (SSC) LD.

Fabry-Perot LD of Planar Buried Heterostructure based on InP is used as a light source for optical communication. This is accompanied by. Therefore, recently, the SSC LD of which the laser radiation angle is narrow is manufactured, and there exist a vertical tapered SSC LD and a horizontal tapered SSC LD according to the manufacturing method.

1A to 1E illustrate a manufacturing process of a conventional SSC LD. The process shown in FIG. 1A is a process of growing a base epi. As shown in FIG. 1A, an n-type InP cladding layer 102, an active layer 104, a p-type InP cladding layer 106, and a capping layer 108 are grown on an n-type InP substrate 100 as shown in FIG. 1A. Has a structure. In this case, the capping layer 108 may be formed of indium gallium arsenide phosphide (PoE) having poor adhesion to a silica (SiO ₂ ) oxide mask in order to prevent the formation of reverse mesa during mesa etching. InGaAsP) is used.

1B is a profile of a silica oxide mask formed over a capping layer 108. Wide side 1.5 , Narrow side 0.4 And the length is 300 to be.

1C illustrates a mesa etching process. The silica oxide mask is formed in the <11> direction. Mesa etching is performed using an etchant of the HBr: H ₂ O ₂ : H ₂ O: (H ₃ PO ₄ ) family. The mesa shape formed at this time is a forward mesa shape, and the wide side is 1.5 , Narrow side 0.4 And its depth is 2.5 to be. At this time, if the reverse mesa is formed, it adversely affects the reliability of the LD element.

1D illustrates the primary regrowth process. That is, the mesa-etched wafer is first regrown in the process illustrated in FIG. 1C. The current blocking layer is not grown on the silica oxide mask 118 by the selective growth method on the mesa-etched epi wafer, and only the mesa-etched regions 110 to 116 are p-type InP 120 that is a current blocking layer. ), n-type InP 122 is 1.0 and 1.3, respectively. Lamination is grown to a thickness of.

Figure 1e shows a cross section of the grown SSC LD. After etching the capping layer of the silica oxide mask and InGaAsP after the first regrowth in the process shown in FIG. 1D, the contact layer (P ⁺ -contact layer) is secondly regrown. Secondary regrowth is about 1 P-type InP (p-InP) and 0.1 An InGaAs layer (p ⁺ -InGaAs), which is a p ⁺ type ohmic contact layer having a thickness, is grown.

However, in the SSC LD fabrication, a problem with the above-described process is that during the first regrowth, a silica oxide mask peeling phenomenon occurs in which the silica oxide mask of the narrower mesa width falls from the capping layer, thereby improving the primary regrowth yield of LD. To reduce. The silica oxide mask peeling phenomenon is caused by poor adhesion between the formed capping layer and the silica oxide mask to suppress the formation of reverse mesa. In other words, the formation of reverse mesa is suppressed, but the narrow mesa during the subsequent process of mesa etching does not sufficiently support the silica oxide mask, causing the silica oxide mask to be lifted up and fall off during the subsequent process. This peeling phenomenon decreases the primary regrowth yield.

The technical problem to be achieved by the present invention is to grow the capping layer with a good adhesion with the silica oxide mask, and to introduce an etch stop layer and a current blocking protection layer during the first regrowth between the capping layer and the cladding layer The present invention provides a manufacturing method of LD which prevents the peeling phenomenon of a silica oxide mask.

1A to 1E illustrate a manufacturing process of a conventional SSC LD.

2A to 2F illustrate the manufacturing process of the SSC LD according to the present invention.

In order to achieve the above technical problem, the present invention comprises a first step of sequentially growing a first cladding layer, an active layer and a second cladding layer on a substrate; A second step of sequentially growing an etch stop layer and a capping layer of a predetermined material on the second clad layer; after forming an oxidation mask on the capping layer in a predetermined direction, the capping layer is first mesa-etched with a first etchant; A third mesa etching of the remaining layers with a second etchant; A fourth step of sequentially growing a current blocking layer and a current blocking protective layer on the resultant of the step; A fifth step of sequentially etching the oxide mask, the capping layer, the etch stop layer, and the current stop protective layer; And a sixth step of sequentially growing a contact layer and an ohmic contact layer on the resultant of the step.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 2A to 2F illustrate the manufacturing process of the SSC LD according to the present invention. 2A shows a cross section of the base epi. Base epi is grown using Metal-Organic Chemical Vapor Deposition (MOCVD). The base epitaxial structure includes a first cladding layer 202, an active layer 204, and a second cladding layer 206, which are sequentially grown on an n-type InP substrate 200, and on the second cladding layer 206. An etch stop layer 208 and a capping layer 210 are grown in turn.

The active layer 204 is formed of a strained multi-quantum well (MQW) structure. The material of the first cladding layer 202 is, for example, n-type InP, the material of the second cladding layer 206 is p-type InP, the etch stop layer 208 is p-type InGaAsP, and the capping layer 210 is a silica oxide mask. P-type InP with good adhesion with is appropriate. The etch stop layer 208 grows to a thickness of about 50-200 mm 3, and the capping layer 210 grows to a thickness of about 2000-3000 mm 3.

After forming the silica oxide mask in the <11> direction for mesa etching, the capping layer 210 is etched with a first etchant capable of selectively etching InP as HCl: H ₃ PO ₄ series. FIG. 2B illustrates a cross section after primary mesa etching of the base epi shown in FIG. 1A. At this time, the first etchant used does not etch the etch stop layer 208. In addition, since the etched capping layer 212 has a good adhesion property with the silica oxide mask 214, an inverted mesa is formed during mesa etching, and a surface appearing on the formed inverted mesa surface is (111) B. Other reference numerals are the same as in the case of FIG. 2A.

Secondary mesa etching is performed using a second etchant of HBr: H ₂ O ₂ : H ₂ O: (H ₃ PO ₄ ) series. 2C shows a cross section of the base epi with secondary mesa expression. Mesa width is about 1.5 0.4 on the narrow side Mesa depth is about 2.5 to be. Reference numerals 230 to 238 denote etched first cladding layers, active layers, second cladding layers, and capping layers, respectively. 240 is a silica oxidation mask.

FIG. 2D is a cross-sectional view of the first regrowth of the current blocking layer in the resultant shown in FIG. 2C. Regrowth is accomplished using MOCVD. The primary regrowth is performed by first and second semiconductor layers 242, such as p-type InP and second semiconductor layers 244, such as n-type InP, respectively. Grows to the thickness of about. The current blocking protective layer 246 is grown on the second semiconductor layer 244 to protect the current blocking layers 242 and 244 during the subsequent etching of the capping layer 238. As the material of the current blocking protective layer 246, for example, p-type InGaAsP is preferable, and the thickness thereof is appropriately about 50 to 200 mA. At this time, the (111) B plane, which is an inverted mesa region, has a sufficiently fast surface movement of indium (In), which is a Group 3 raw material, so that growth is suppressed, and growth does not occur in the inverse mesa region. In addition, p-type InP, which is a material of the silica oxide mask 240 and the capping layer 238, has sufficient adhesiveness, so that the phenomenon of peeling of the silica oxide mask 240 does not occur.

2E shows an etching process after the first regrowth. After etching the silica oxide mask with H. H. (HF), the capping layer is etched with an etchant for selectively etching InP as HCl: H ₃ PO ₄ series. In addition, an etchant for selectively etching InGaAsP as an H ₂ SO ₄ : H ₂ O ₂ : H ₂ O series, an etch stop layer and a current stop protective layer of p-type InGaAsP material are sequentially etched.

FIG. 2F shows a cross section of the SSC LD completed by secondary regrowth in the resultant shown in FIG. 2E. Secondary regrowth is about 1 Thick contact layer 246 and about 0.1 A thick ohmic contact layer 248 is grown. The material of the contact layer 246 is, for example, p-type InP and the material of the ohmic contact layer 248 is, for example, p ⁺ type InGaAs.

According to the present invention, a peeling phenomenon of the silica oxide mask can be prevented by introducing a capping layer and an etch stop layer having sufficient adhesion with the silica oxide mask and introducing a current blocking protective layer during the second mesa etching and the first regrowth. Can be.

As a result, the production cost of the LD can be reduced by improving the regrowth yield by MOCVD in the production of the SSC LD used in the transmission module for the 155Mbps.

Claims (8)

A first step of sequentially growing a first cladding layer, an active layer, and a second cladding layer on the substrate; A second step of sequentially growing an etch stop layer and a capping layer of a predetermined material on the second clad layer; A third step of forming an oxide mask on the capping layer in a predetermined direction, then etching the capping layer with a first etchant using a first etchant and etching the remaining layers with a second etchant using a second etchant; A fourth step of sequentially growing a current blocking layer and a current blocking protective layer on the resultant of the step; A fifth step of sequentially etching the oxide mask, the capping layer, the etch stop layer, and the current stop protective layer; And And a sixth step of sequentially growing a contact layer and an ohmic contact layer on the resultant of the step. The method of claim 1, wherein the etch stop layer in the second step A method of fabricating a laser diode, characterized in that it is grown from a p-type InGaAsP material. The method of claim 1, wherein the capping layer of the second step And a p-type InP material having good adhesion to the oxidation mask. The method of claim 1, wherein the first mesa etching is performed in the third step. The etching stop layer is a laser diode manufacturing method characterized in that the etching is carried out with an etchant of HCl: H ₃ PO ₄ series to etch the capping layer without etching. The method of claim 1, wherein the second mesa etching is performed in the third step. A method of fabricating a laser diode, characterized in that it is performed with an etchant of HBr: H ₂ O ₂ : H ₂ O: (H ₃ PO ₄ ). The method of claim 1, wherein the current blocking protective layer in the fourth step The laser diode manufacturing method of the etching capping layer region is characterized in that the growth on the current blocking layer, not growth. The method of claim 6, wherein the current blocking protective layer A method of fabricating a laser diode, characterized in that it is grown from a p-type InGaAsP material. The method of claim 1, wherein the etch stop layer or the current blocking protective layer H ₂ SO ₄ : H ₂ O ₂ : H ₂ O-based laser diode manufacturing method characterized in that the etching with an etchant for selectively etching InGaAsP.