JPS63249354A - Bridge wiring method - Google Patents

Abstract

PURPOSE:To enable a bridge wiring by which a desired shape is precisely obtained, by previously forming a groove extending through at least a layer applied with a side etching, and stopping the side etching with this groove as an etching stopper. CONSTITUTION:In the surface of a multilayered film substrate wherein an InP buffer layer 11, a GaInAsP active layer 12, a p-type InP clad layer 13 and a p-type GaInAsP cap layer 14 are sequentially stacked on an n-type InP substrate 10, a groove 15 is formed which has a depth of extending through at least the p-type GaInAsP cap layer 14. Since the groove part 15 functions as an etching stopper, no side etching occurs in the other parts even during a side etching. With this, the degree of freedom of a bridge part 25 increases, the etching time can have a sufficient margin, and a bridge wiring is enabled by which a desired shape can precisely be accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a bridging wiring method in an electronic device or an optical device having a step with device isolation using a groove.

(Prior Art) Bridging wiring methods have been applied to optoelectronic integrated circuits (e.g. I, Ury et al., Monolithic
Integration of an 1njec
tion 1aser and a metalsem
iconductor field effect
ransistor, Appl+Phys, Lett
, 34 (71pI), 430-431, IA
pri11979), the characteristics of these bridge wiring methods are:
The method is to form a bridge by removing the layer below the bridge by etching in a direction parallel to the plane, so-called side etching. However, the problem with these bridge wiring methods is that side etching occurs not only at the bridge portion but also at other portions.

A specific example will be described below with reference to the drawings.

FIG. 3 is a process sectional view showing an example of a mesa stripe laser device having conventional bridging wiring.

First, as shown in FIG. 3(a), an n fJI GaAlAs layer 32, a GaAs
Active layer 33, p-type GaAlAs layer 34, p-type GaA
An 8i01 layer 36 is formed as an insulating layer on the surface of a multilayer film substrate on which S layers 35 are sequentially laminated.

Next, as shown in FIG. 3(b), the p-type GaAlAs layer 3
A striped groove 37 is formed so that A 4 is exposed.
A u-Zn electrode 38 is formed. A u -Z n electrode 3
8 is a striped groove 37 as indicated by diagonal lines in FIG.
A stripe portion 41. extending along the stripe portion 41. , a bonding section 42 provided close to the stripe section 41 , and a bridging section 43 connecting the stripe section 41 and the bonding section 42 .

Next, as shown in FIG. 3(C), IfClAu-Zn electrode 3
Sin! in the area where 8 is not formed! Membrane 36 all 36,
Subsequently, the surface of the multilayer film substrate in the region where the A u -Z n electrode 38 is not formed is etched to form a mesa.

At this time, if a solution of sulfuric acid, dehydrogen peroxide and water (3:1:1) is used as the etching solution, the well-known side etching effect will occur: 1) Part of the multilayer substrate under the periphery of the Au-Zn electrode 38 is also removed. Also, the width of the stripe portion 410 is taken as W, and the mesa width after etching under the stripe portion 41 is W.
s, W, -Ws)W, when the width of the bridging portion 43 is a horse,
By providing the bridging portion 43 so that the bridging portion 43
The surface of the multilayer substrate underneath is completely removed by etching.

As a result, the mesa 44 under the stripe portion 41 and the bonding table 45 under the bonding portion 42 are formed separately. Next, as shown in FIG. 3(d), an A u -S n electrode 39 is formed on the back surface of the n-type GaAs substrate 31, and
A gold wire 47 is bonded to the bonding portion 42 of the u-Zfl electrode 38.

In the mesa stripe laser having the conventional bridging wiring formed in this way, the gold wire 47 is bonded to the bonding part 42 which is separated from the mesa 44 that contributes to light emission. No crystal defects occur within the mesa 44, which contributes to good light emission. Furthermore, no leakage current occurs in the mesa 44 that contributes to light emission. Furthermore, regardless of the shape and size K of the mesa 44 that contributes to light emission, the ponding portion 42 can be made sufficiently wide.
It has the characteristic that it is also possible to strengthen the adhesion strength of.

However, such conventional technology has the following drawbacks. That is, in the conventional bridging wiring method, when attempting to side-etch the bottom of the bridging portion 43, the bottom of the periphery of the stripe portion 41 and the bonding portion 420 will also be side-etched, so that Wl - Ws) w. There were problems in that the bridging portion 43 had to be provided and the etching time had to be precisely controlled.

Furthermore, due to the progress of side etching, the stripe portion 41
7. (Problem to be Solved by the Invention) As mentioned above, if there is a problem that the mesa 44 below has a protrusion at the junction with the bridge part 43 and cannot form a complete mesa stripe. 1. In the prior art, side etching occurs not only under the bridge but also in other parts. Therefore, the width of the bridge portion is limited, and the etching time for side etching must be precisely controlled. moreover,
There have been problems such as the inability to precisely control the shape of regions other than bridge portions such as striped portions.

SUMMARY OF THE INVENTION In view of the problems of the prior art, it is an object of the present invention to provide a bridge wiring method that does not cause side etching in areas other than under the bridge.

[Structure of the invention]

(Means for Solving the Problems) The gist of the present invention is to form a groove that penetrates at least a layer to be side-etched, and to use this groove as an etching stopper to stop side etching. This makes it possible to remove only the area below the desired area, making it possible to form a bridge wiring in which side etching does not occur in areas other than under the bridge.

(Function) According to the present invention, side etching can be automatically stopped by the etching stopper. For this reason,
The degree of freedom in the width of the bridge portion is increased, the etching time has sufficient margin, and furthermore, it is possible to form a bridge wiring in which a desired shape can be precisely realized.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

Fig. 3 is a process sectional view showing an example of a mesa stripe laser device having bridging wiring according to the present invention. First, as shown in FIG. 1(a), an n-type InP layer 77 layer 11, a GaInAsP active layer 12, a p-type InP cladding layer 13, and a p-type GaInAsP layer are formed on an n-type InP substrate 10.
At least a p-type G a I n A s P cap layer 14 is formed on the surface of the multilayer film substrate on which the cap layers 14 are sequentially laminated.
A groove 15 having a depth that penetrates through is formed. The groove 15 is formed by two substantially parallel grooves 21, as indicated by diagonal lines in FIG. 2(a).
1, 212 and a groove 22 surrounding the bonding area. Next, as shown in FIG. 1(b), S is used as an insulating layer.
in, forming the film 16 and p-type GaInAs
Striped grooves 1 are formed so that the surface of the P cap layer is exposed.
7 is formed between the two grooves 211 and 212, and the Au-Zn
Electrodes 18 are formed. The Au-Zn electrode 18 is shown in FIG.
), a bonding plate formed to at least cover the stripe portion 23 extending along the two grooves 211 and 212 and the groove 22 surrounding the bonding area.
It consists of a bridge section 24 and a bridge section 25 that connects the stripe section 23 and the bonding section 24. Next, as shown in FIG. 1(C), SiO! The film 16 is then coated with SiO,
Using the film as an etching mask, the p-type Ga InAaP cap layer 14 is removed by etching. At this time, if a solution of sulfuric acid + hydrogen peroxide + water (4:1:1) is used as an etching solution, the p-type GaInAsP cap layer 14 under the bridge portion 25 is etched away by the well-known side etching effect. It is possible to do so. Also, a sulfuric acid + hydrogen peroxide solution + water (4:1:1) solution acts on the GaInAsP layer, but it acts on the InP layer and 8i0! It has little effect on membranes. For this reason, etching automatically stops at the p-type InP layer 13 in the layer thickness direction, and automatically stops when it reaches the groove 15 in the direction parallel to the layer. At this time, side etching of the lower part of the bridge generally requires longer etching than normal etching, but according to the present invention, as mentioned above, the groove functions as an etching stopper, so side etching is possible. Side etching does not occur in other parts of the etching, and the disadvantages of the prior art do not occur.

Subsequently, the region where the p-type GaInAsP layer 14 was removed by etching is etched to form at least the GaInAsP active layer 1.
The striped mesa 26 and the bonding table 27 are formed separately by etching to a depth that penetrates through the striped mesa 26.

In this etching, there is no need to create a tunnel by side etching, so it is possible to set the etching so that side etching does not occur as much as possible. Next, as shown in FIG. 3(d), an A u -S n electrode 19 is formed on the back surface of the n-type InP substrate 10 , and an A u -Z n electrode 19 is formed on the back surface of the n-type InP substrate 10 .
A gold wire 29 is bonded to the bonding pad 24 of the n-electrode 18.

〔Effect of the invention〕

According to this invention, side etching can be automatically stopped by the etching stopper, so it is possible to remove only the area below the desired area. Therefore, in electronic devices, optical devices, or optoelectronic devices having steps that are separated by grooves, it is possible to create bridging wiring that can realize a desired shape precisely and with good reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the process for explaining the invention in detail;
FIG. 2 is a plan view, FIG. 3 is a process sectional view for explaining a conventional example, and FIG. 4 is a plan view. 18, 38"・Au-Zn electrode, 23.41・2 drive part, 24.42...Ponding pad, 25
．． 43...Bridge part, 26.44...Mesa, 27゜4
5... Bonding table, 211, 212.22...
groove. Agent Patent Attorney Noriyuki Chika Ken'''ff$-ff$ - Hisairi Patent Attorney Mitsuyuki Matsuyama 3rd Figure '4-7 Figure 4

Claims (3)

[Claims] (1) In bridging wiring that is wired in a bridge-like manner between electrodes or wiring areas that are electrically separated by a groove, a selectively removable spacer is placed in the area where the groove is formed, and is separated from the electrode or wiring area. a step of forming electrical connection means between the electrodes or wiring regions on the spacer; and a step of selectively removing the spacer. Wiring method. (2) The bridging wiring method according to claim 1, wherein the groove for electrical isolation is formed by selectively removing the spacer. 3. The bridging wiring method according to claim 1, further comprising the step of: forming a groove for electrical isolation using a region where the spacer is selectively removed as a window.