JPS63250889A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To eliminate the etching of a necessary ZnSe layer by laminating a silicon oxide or silicon nitride film on the layer, punching it in a stripe state, and etching the layer at the top of a rib with an etchant which contains nitric acid, hydrochloric acid and water. CONSTITUTION:In a semiconductor laser of a structure having a riblike optical guide 108, in which the side of the guide 108 is buried with a ZnSe layer 107 of II-VI compound semiconductor and having a stripelike electrode 109 for limiting a current path at the top of the guide 108, the steps of etching the layer 107 at the top of the rib for forming the electrode 108 include laminating a silicon oxide or silicon nitride film 208 on the layer 107, punching the film 208 in a stripe state, and etching the layer 107 at the top of the rib with an etchant which contains nitric acid, hydrochloric acid and water. Thus, the neces sary layer 107 can effectively be remained.

Description

[Detailed description of the invention] Cff1 industrial use field] The present invention relates to a method for manufacturing a 1fiJ semiconductor laser.

[Conventional technology]

II-Vl group compound semiconductors such as ZnSc have characteristics of high +11 resistivity and low 111 (refractive index) compared to ui-v group compound semi-JQ semiconductors such as ΔlGaΔS. When applied as a confinement layer, active current confinement and optical confinement become possible.

When applying the ZnSc layer to devices such as semiconductor lasers,
Processing such as etching removal of unnecessary parts is required to suit various device shapes, and nitric acid is used as an etching solution with excellent reproducibility and uniformity for etching the ZnSc layer.
For example, etching with hydrochloric acid and water for 7 nights.

However, if the necessary ZnSc layer is masked with a resist by a photo process and then etched with the above-mentioned etching solution, there is a problem that the etching solution penetrates from the resist surface and etches down to the necessary ZnSc layer.

(Problems to be Solved by the Invention) Therefore, when etching the Zn5c layer using a resist as a mask material, the necessary Zn5c layer will be etched away. 7. When applying the nSa layer to various devices, , the problem of having a great negative impact on the uniformity, reproducibility, and reliability of the characteristics of the manufactured device is addressed.

The present invention is intended to solve these problems, and its purpose is to clarify the mask material that will not be affected by the etching solution when Zn5clfl is applied to various devices. This makes it possible to manufacture devices with high uniformity, reproducibility, and reliability.

[Means for solving problems]

The method for manufacturing a semiconductor laser of the present invention has a rib-shaped guiding waveguide, the side surfaces of the guiding waveguide are buried with a Zn5c layer of a II-Vl group compound semiconductor*, and a current path is formed in two parts of the guiding waveguide. In a semiconductor laser having a structure in which striped electrodes are formed, the process of etching the Zn5c layer on the top of the ribs in order to fabricate the electrodes is carried out using the Zn5c layer.
The second layer is a film of silicon oxide or silicon nitride.
a step of removing the silicon oxide or silicon nitride film in stripes, and a step of removing the Zn5c layer on the top of the rib.
The method is characterized by a step of etching with an etching solution consisting of nitric acid, hydrochloric acid, and water.

〔Example〕

FIG. 1 is a main sectional view of a semiconductor laser in an embodiment of the present invention. 103 on 102 n-type GaAs single crystal substrate
n-type GaAs buffer layer, 104 n-type AlGaAs
Cladding layer, 105 GaAs or A! GaΔS active layer and 106 inverted mesa-shaped rib-shaped pbar 1Δ
IGaΔS cladding layer, and 108 p-type GaA
s : J cladding layer, both ends of the rib are 107 Zn
It is embedded with a 5c ■-■ group compound semiconductor. 10
The ZnSc on the contact layer 8 is removed by an etching process, and a p-mi ohmic electrode 109 is formed. An n-type Ohmifuku electrode 101 is formed, and a current flows between 109 and 101 in the forward direction, causing charge injection into the active layer 105, and light emission due to carrier recombination is amplified between the cavity end faces. Laser light is oscillated.

Here, the present invention is used in the etching process of the Zn5c layer on the contact layer 108.

FIG. 2(a) shows an n'M GaΔS single crystal substrate of 201, an n-type GaAs buffer layer of 202, an n-type AI GaAs craft layer of 203, and a GaAs or AlGaAs layer of 20. active layer, 2
05 p-type AlGaAs cladding layer, 20G P! ! G
Striped ribs were formed on a sequentially laminated aAs contact layer using a federal photo process, and a 207 Zn5c layer was buried and grown using the MOCVD method.

Next, in order to protect the Zn5c layer other than on the ribs in the Zn5c layer etching process, SiO! The films are laminated by a 16-pressure CVD method or the like. (Figure 3 (L
>)208). Then, a stripe was formed on the rib to form an electrode using the photo process again, and the 5ioz layer was removed using a tsubuic acid-based etching solution (Fig. 3(c)).
)X If the Zn5c layer is etched, Libouhi's Z
The n5c layer is removed, and the other Zn5c layers are covered with a dense layer of SiO* that is not immersed in the etching solution, so that the etching solution does not seep in and can be left securely.

In this example, SiO* is used as a layer to protect the Zn5c layer, but other silicon oxide films or silicon nitride films may be used as materials that are not affected by nitric acid-hydrochloric acid-water etching solution. Even if used, the above-mentioned effects can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the necessary Zn5c layer can be reliably left by using a silicon oxide or silicon nitride film in the Zn5c layer etching process.

Therefore, when a Zn5c layer is applied to a semiconductor laser as a current confinement layer or an optical confinement layer, there is no corrosion of the Zn5c layer due to penetration of the etching solution, and the reactive current flowing outside the active region can be suppressed as much as possible. Since light can be confined, a semiconductor laser capable of low-threshold 1-1 current oscillation and stable single-transverse mode oscillation can be manufactured.

[Brief explanation of drawings]

FIG. 1 is a main sectional view showing an embodiment of a semiconductor laser manufactured by the manufacturing method of the present invention. FIGS. 2(a) to 2(c) are manufacturing process diagrams showing one embodiment of the method for manufacturing a semiconductor laser of the present invention. 101 ・・・ ・・・ ・・・ ・・・
N type o-miss m4 provisional 102.2
01-n1iGaAs single crystal substrate 103.202-n
'MG a As buff 77 layers 104.203''-
n'M A I G a S cladding layer 105.
204...Activity notification 106.205-1) type ΔlGaAs cladding layer 108
．． 20G-pWIGaAs contact 107.20
?・ZnS e buried layer 100...
・・・・・・・・・P-type ohmic electric 1m208・・・・
......SiOs layer 209...
・・・・・・・・・Resist or higher

Claims (1)

[Claims] It has a rib-shaped optical waveguide, and the side surface of the optical waveguide is made of ZnS.
In a semiconductor laser having a structure in which a striped electrode is buried in the c layer and restricts a current path on the optical waveguide, the step of etching the ZnSe layer above the rib for forming the electrode is performed by etching the ZnSe layer on the ZnSe layer. A step of stacking a silicon oxide or silicon nitride film, a step of cutting out the silicon oxide or silicon nitride film in a stripe shape, and a step of etching the ZnSe layer above the rib with an etching solution consisting of nitric acid, hydrochloric acid, and water. A method for manufacturing a semiconductor laser characterized by: