JPH01295472A - Manufacture of semiconductor light emitting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] This method includes the steps of forming a mesa stripe by wet etching in a multilayer semiconductor stacked structure including an active layer, and growing buried layers on both sides of the mesa stripe by a slide boat method. Regarding the manufacturing method of a semiconductor light emitting device, in order to ensure that the buried layer is grown accurately, a stripe mask provided on the laminated structure and used for the etching has a convex cross-sectional shape; The side edges of the mask that form an eaves-like shape relative to the mesa stripes due to etching are removed using an etching solution, and the buried layer is grown with the mask remaining on the mesa stripes. Configure.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor light emitting device, and in particular, to a method for manufacturing a semiconductor light emitting device, in particular, forming a mesa stripe by wet etching in a multilayer semiconductor stacked structure including an active layer, and growing buried layers on both sides of the mesa stripe by a slide boat method. The present invention relates to a manufacturing method including a step.

In manufacturing semiconductor light emitting devices, particularly in manufacturing embedded semiconductor light emitting devices in which an active layer serving as a light emitting portion is embedded, the above steps are often adopted.

In that case, it is important to ensure that the buried layer is grown accurately.

[Conventional technology]

FIG. 2 is a sectional side view of a main part of an example of an embedded semiconductor light emitting device.

In the figure, 1 is an n-type TnP substrate, 2 is an n-type InP buffer layer, 3 is an InGaAs P active layer, and 4 is a p-type InP substrate.
P cladding layer, 5 is p-type 1nP buried layer, 6 is n-type 1
An nP buried layer, 7 a p-type 1nP cladding layer, and 8 a p-type 1nGaAs P contact layer constitute a semiconductor crystal portion. Electrodes and others are not shown.

In this light emitting device, when a current is passed from the contact layer 8 side to the substrate 1 side, the current is concentrated in the active layer 3 mainly due to the reverse pn junction between the buried layers 5 and 6, and light is emitted.
Laser oscillation occurs above the threshold current. Therefore, the buried layers 5 and 6 have the role of suppressing leakage current that bypasses the active layer 3 and becomes ineffective for light emission, thereby increasing light emission efficiency and lowering the threshold current.

Now, the conventional method for manufacturing this crystal part is as follows.

That is, first, referring to FIG. 3 (al), a buffer layer 2, an active layer 3, a cladding layer 4, and a cap layer 9 were grown on a substrate 1 by the slide boat method, that is, liquid phase growth using a slide boat. Then, a semiconductor stacked structure 10 is formed.The cap N9 is made of InGaAsP, and is removed from the crystal part during the process as described later.

Next, referring to FIG. 3(b), a flat band-shaped SiO2 stripe mask 21 is formed on the cap layer 9 by a normal photolithography technique.

Next, referring to FIG. 3C, mesa stripes 11 are formed in the laminated structure IO under the mask 21 by wet etching using the mask 21 as a mask. At this time, since the above-mentioned etching involves side etching, the side end portions of the mask 21 form an eave-like shape relative to the mesa stripe 11.

Next, referring to FIG. 3(d), with a mask 21 on the mesa stripe 11, buried layers 5 and 6 are grown by the slide boat method. The growth of the buried layers 5 and 6 on the mesa stripe 11 is suppressed by the mask 21, and they selectively fill both sides of the mesa stripe 11.

Next, referring to FIG. 2, mask 21 and cap layer 9
After removing , a cladding layer 7 and a contact layer 8 are grown by a slide boat method to complete the crystal part.

[Problem to be solved by the invention]

However, in this manufacturing method, since the buried layers 5 and 6 shown in FIG. The mask 21 may peel off from the mesa stripe 11 due to the melt, or the mask 2 may peel off from the mesa stripe 11.
The side edges of the mesa stripes 11 may be bent and attached to the side surfaces of the mesa stripes 11.

And when that happens, the buried layer 5. The growth of & and 6 will not be performed properly, resulting in a problem of lowering manufacturing yield.

To deal with this problem, there is a method in which the eave-shaped side edges of the stripe mask 21 are removed using an etching solution prior to the growth of the buried layers 5 and 6.
If the thickness of the mesa stripe 11 is uneven and there is a difference in thickness between the left and right side edges, there will be an inconvenience that the top surface of the mesa stripe 11 will be largely exposed on the other side before one side edge is removed. This cannot be a sufficient solution.

Therefore, the present invention manufactures a semiconductor light emitting device including the steps of forming mesa stripes on a multilayer semiconductor stacked structure including an active layer by wet etching, and growing buried layers on both sides of the mesa stripes by a slide boat method. In the method, it is an object of the present invention to ensure that the buried layer is grown accurately.

[Means to solve the problem]

The above purpose is to make the cross-sectional shape of a stripe mask provided on the laminated structure and used as a mask for the above etching into a convex shape, and to apply an etching solution to the side edges of the mask which become eaves-shaped with respect to the mesa stripes due to the etching. with the mask removed and left on the mesa stripe,
This problem is solved by the manufacturing method of the present invention in which the buried layer is grown.

[For production]

The present invention provides a method in which the eave-shaped side edges of the stripe mask 21 are removed using an etching solution prior to the growth of the buried layers 5 and 6, in which the left and right side edges are sufficiently removed. This mask has been modified to ensure that the stripe mask remains on the mesa stripe even if the stripe mask is advanced until the mesa stripe is removed.

In other words, by making the cross-sectional shape of the stripe mask convex, the side edges that become eaves become relatively thin and are removed preferentially, so that the portions corresponding to the convex portions of the mesa stripe are removed preferentially. will definitely remain in the field.

As a result, the above-mentioned disadvantages are eliminated, and the buried layer can be grown accurately.

〔Example〕

Embodiments of the present invention will be described below with reference to side cross-sectional views of FIGS. 1A to 2F and FIG.

This example is a case where the semiconductor light emitting device shown in FIG. 2 is manufactured.

First, referring to FIG. 1(a), as in the conventional case, a buffer layer 2, an active layer 3, a cladding layer 4, and a cap layer 9 are grown on a substrate l by the slide boat method to form a semiconductor stack. After forming the structure 10, a flat band-shaped SiO2 stripe mask 22 is formed on the cap layer 9 by conventional photolithography techniques. The thickness of the buffer layer 2, active layer 3, cladding layer 4, and camp layer 9 is 1 μm.
, 0.15 μm, 0.5 μm and 0.15 μm, and the thickness and width of the mask 22 are 0.2 μl and 3 μm, respectively.

Next, referring to FIG. 1(b), a layer of 0.1 μm thick is applied to the entire surface.
A resist mask 31 having a width of 1 μm and having a width of 1 μm is formed thereon, aligned with the mask 22.

Next, referring to FIG. 1C, the SiO2 film 23A is etched using a buffered hydrofluoric acid solution to expose the cap layer 9 on both sides of the mask 22. At that time, mask 22
Ensure that no SiO2 film 238 remains on either side of the surface. Then, the stripe mask 23, which is the remaining part of the SiO2 film 23A, and the mask 22 below it are integrated to form a 5i02 stripe mask 24 having a convex cross-sectional shape, and the mask 24 is placed on the cap layer 9. be in a formed state. After the mask 24 is formed, the resist mask 31 is removed.

Next, referring to FIG. 1(d), (HBr+f(202
Mesa stripes 11 are formed in the laminated structure 10 under the mask 24 by wet etching using +H20) as an etching solution and the mask 24 as a mask. This process corresponds to the conventional process of FIG.

Next, referring to FIG. 1(e), the mask 24 is immersed in a hydrofluoric acid solution and the side edges of the mask 24 are removed until the eaves-like portions of the side edges disappear. At this time, even if there is a difference in thickness between the left and right side edges, since the mask 24 has a convex portion formed by the mask 22, at least a portion corresponding to the convex portion remains on the mesa stripe ll. The inconvenience that the upper surface of the mesa stripe 11 is largely exposed does not occur.

Next, referring to FIG. 1(r), similar to the conventional process shown in FIG. 3(d), with a mask 24 on the mesa stripe 11, buried layers 5 and 6 are grown by the slide boat method. do. The growth of buried layers 5 and 6 is performed using mask 2.
Since the mask 4 does not peel off or break like the conventional mask 21, the desired state can be precisely achieved.

Next, referring to FIG. 2, mask 21 and cap layer 9
After removing, a cladding layer 7 and a contact layer 8 are grown by a slide boat method to complete the crystal part with a high yield.

After this, the light emitting device is completed by forming electrodes (not shown), and since the yield of the crystal portion is good, the manufacturing yield of the light emitting device is also good.

In this example, the material of the crystal part is InP/InGaAs.
Although the explanation has been given by taking as an example a case where P is used and SiO2 is used as the material of the stripe mask 24, it goes without saying that these materials are not limited to the above materials.

Further, the dimensions of each part are not limited to those in the embodiment.

〔Effect of the invention〕

As explained above, according to the structure of the present invention, a mesa stripe is formed by wet etching on a multilayer semiconductor stacked structure including an active layer, and a buried layer is grown on both sides of the mesa stripe by a slide boat method. In the method for manufacturing a semiconductor light emitting device including the above, the growth of the buried layer can be performed accurately, which has the effect of making it possible to improve the manufacturing yield of the light emitting device.

[Brief explanation of the drawing]

Figures 1 (a) to (f) are side sectional views explaining the embodiment, Figure 2 is a side sectional view of essential parts of an example of an embedded semiconductor light emitting device, and Figures 3 (a) to (dl are conventional methods). A side sectional view explaining the
It is. In the figure, 1 is an n-type 1nP substrate, 2 is an n-type 1nP buffer layer, 3 is an InGaAs P active layer, 4 is a p-type 1nP ground layer, 5 is a p-type 1nP buried layer, 6 is an n-type 1nP buried layer, 7 is a p-type 1nP ground layer, 8 is a p-type 1nGaAs P contact layer, 9 is InGa
10 is a semiconductor laminated structure; 11 is a mesa stripe; 21, 22, and 23 are strip masks; and 24 is a strip mask with a convex cross section. Figure 1

Claims (1)

[Claims] The method includes a step of forming a mesa stripe by wet etching in a multilayer semiconductor stacked structure including an active layer, and growing buried layers on both sides of the mesa stripe by liquid phase growth using a slide boat. In a method for manufacturing a semiconductor light emitting device, a stripe mask provided on the laminated structure and used as a mask for the etching has a convex cross-sectional shape, and the side of the mask becomes eaves-like with respect to the mesa stripe by the etching. A method for manufacturing a semiconductor light emitting device, characterized in that the end portion is removed with an etching solution and the buried layer is grown with the mask remaining on the mesa stripe.