Method of fabricating ridge waveguide semiconductor...

Details Method of fabricating ridge waveguide semiconductor... Method of fabricating ridge waveguide semiconductor...

1999-03-30

2001-01-16

Chaudhuri, Olik (Department: 2814)

Semiconductor device manufacturing: process

Making device or circuit emissive of nonelectrical signal

Including integrally formed optical element

C438S039000, C438S046000, C257S094000

Reexamination Certificate

active

06174747

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of fabricating a ridge waveguide semiconductor light-emitting device in which the carrier concentration at the top surface of the ridge waveguide is higher than that at the lower portion thereof.
2. Description of Prior Arts
Semiconductor light-emitting devices have been widely developed due to the demands of data transmission and storage. Specially, a semiconductor laser can obtain a better performance for use in light transmission or storage partially because of its narrow frequency spectral width. Nowadays, there are various kinds of fabrication methods for semiconductor lasers. Further, a single mode semiconductor laser can prevent astigmatism and reduce the ratio of longitudinal and transversal divergence of the laser beam. Therefore, many conventional methods are provided to restrict the current to flow into the active layer through the vertex of the ridge waveguide only. Thus, the light-emitting region is restricted to the area of active layer under the ridge waveguide, thereby obtaining a single mode semiconductor laser. The conventional methods of restricting the flow of current include a method in which an insulating layer such as SiO
2
, Si
3
N
4
, etc., is coated on the chip except for the ridge waveguide to restrict the flow of current. U.S. Pat. Nos. 5,550,081 and 5,403,775 disclose the method of oxidizing the aluminum included in the epitaxial-layers to form an insulating layer of Al
2
O
3
so as to restrict the flow of current. U.S. Pat. No. 5,658,824 discloses a method of coating epoxy resin on the chip except for the ridge waveguide. Furthermore, U.S. Pat. No. 5,351,258 discloses a method of coating SiO
2
and epoxy resin to restrict the current. Additionally, U.S. Pat. No. 5,304,507 discloses a method to re-grow a semiconductor epitaxial layer of another conductivity type or an insulating on the chip except for the ridge waveguide by an epitaxial method so as to restrict the area and position of the active layer through which the current can flow.
In Taiwanese Patent Application No. 87109771, a self-aligned process for fabricating semiconductor lasers is disclosed, which includes the steps of: (1) referring to FIG.
1
a
, sequentially forming an n-AlInP layer
12
, an undoped AlGaInP layer
13
, a quantum-well active layer
14
, an undoped AlGaInP layer
15
, a p-AlInP layer
16
, a p-GaInP layer
18
, a p-GaAs layer
20
and a SiO
2
layer
22
on the substrate
10
; (2) referring to FIG.
1
b
, forming a photoresist layer
24
thereon and patterning the photoresist layer
24
by a photolithography process; (3) referring to FIG.
1
c
, etching the SiO
2
layer
22
that is not covered by the patterned photoresist layer
24
; (4) referring to FIG.
1
d
, removing the photoresist layer
24
; (5) referring to FIG.
1
e
, etching the above epitaxial layers very close to the AlGaInP layer
15
; (6) referring to FIG.
1
f
, removing the SiO
2
layer
22
; (7) referring to FIG.
1
g
, depositing a Si
3
N
4
layer
26
thereon; (8) referring to FIG.
1
h
, forming a first photoresist layer
28
; (9) referring to FIG.
1
i
, then forming a second photoresist layer
30
, and patterning the second photoresist layer
30
; (10) referring to FIG.
1
j
, etching the first photoresist layer
28
by a dry etching process until the Si
3
N
4
layer
26
on the ridge waveguide is not covered by the first photoresist layer
28
; (11) referring to FIG.
1
k
, etching the Si
3
N
4
layer
26
to expose the top surface of ridge waveguide; (12) referring to
FIG. 11
, removing the second photoresist layer
30
and the first photoresist layer
28
; (13) referring to FIG.
1
m
, forming a metal layer thereon. In this conventional process, an insulator is formed on the chip except for the ridge waveguide to restrict the flow of current. Such a conventional process is complex since it includes 13 steps, and it normally takes about 2 working days to accomplish.
SUMMARY OF THE INVENTION
Accordingly, to overcome the drawbacks of the above prior arts, the object of this invention is to provide a method of fabricating a ridge waveguide semiconductor light-emitting device, in which an oxide semiconductor having a heavy carrier concentration serves as the interface of the metal layer and the epitaxial layer to make the current flow through the ridge waveguide.
According to this invention, the method of fabricating a ridge waveguide semiconductor light-emitting device is simple and suitable for the fabrication of semiconductor lasers with a ridge width smaller than 3 &mgr;m. The fabrication method of this invention can avoid undertaking the complex steps of self-alignment and significantly reduce the production cost.
To achieve the above object, this invention forms an oxide semiconductor having a heavy carrier concentration thereon after finishing the basic structure of a ridge waveguide semiconductor light-emitting device, then forms a metal layer for interconnection.


REFERENCES:
patent: 5556804 (1996-09-01), Nagai
patent: 5898190 (1996-09-01), Iwata

Affiliated with

Also associated with

Rating

Method of fabricating ridge waveguide semiconductor... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of fabricating ridge waveguide semiconductor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of fabricating ridge waveguide semiconductor... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2542577