Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Compound semiconductor
Reexamination Certificate
1999-09-15
2001-10-09
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Compound semiconductor
C438S041000, C438S042000, C438S045000
Reexamination Certificate
active
06300153
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal organic vapor phase epitaxy (MOVPE) method. And the present invention relates to a method for manufacturing a semiconductor laser device, more particularly to a method for manufacturing a semiconductor laser device by MOVPE.
2. Description of the Related Art
A metal organic vapor phase epitaxy (MOVPE) method has been known as a technique for manufacturing a semiconductor laser device. Selective MOVPE realizes selective film formation. That is, a film (composition semiconductor film) is selectively formed on exposed regions which are not masked by an SiO
2
film.
“IEEE Photonics Technology Letter 9 (1997) p.291” (hereinafter referred to as Document 1) discloses a technique for manufacturing a double-channel planar buried heterostructure (DC-PBH) laser diode having InGaAsP multiquantum wells (MQW) structure by the selective MOVPE.
FIGS. 9A
to
9
F show steps of manufacturing a semiconductor laser diode by the technique disclosed in Document 1.
First, the chemical vapor deposition is carried out to deposit an SiO
2
film
180
having the thickness of 100 nm onto a (100) just oriented n-InP substrate
110
, as shown in FIG.
9
A.
Then, the SiO
2
film
180
is patterned so as to be striped masks as shown in FIG.
9
B. The mask width Wm is 8-micron wide and the width Wo of open stripe
180
A is 1.5 microns wide. These stripes are extending in the [011] direction.
Then, a waveguide
120
(having the double heterostructure) containing an MQW active layer is formed by selective MOVPE on the open stripe region
180
A as shown in FIG.
9
C. The MQW active layer,
121
consists of 0.7% compressively strained InGaAsP wells (5-nm thick) and InGaAsP barriers (each of which has the thickness of 8 nm, and emits lights having 1.13-micron wavelength), sandwiched by InGaAsP SCH layers (each of which has the thickness of 60 nm, and emits lights having 1.13-micron wavelength).
Then, an SiO
2
mask
190
is formed on the top of the waveguide
120
using a self-alignment process as shown in
FIG. 9D
, and the SiO
2
portion other than the SiO
2
mask
190
is removed.
A current-blocking layer
130
is selectively grown on the substrate
110
by selective MOVPE as shown in FIG.
9
E. The current-blocking layer
130
consists of p-InP (having the carrier concentration of 3×10
17
cm
−3
and the thickness of 0.75 microns), n-InP (having the carrier concentration of 3×10
17
cm
−3
and the thickness of 0.7 microns) and p-InP (having the carrier concentration of 3×10
18
cm
−3
and the thickness of 0.10 microns) layers. Then, the SiO
2
mask
190
is removed.
After the SiO
2
mask
190
is removed, a p-InP cladding layer
140
is formed on the waveguide
120
and the current-blocking layer
130
as shown in FIG.
9
F. Further, a p
−
-InGaAs contact layer
150
is formed on the p-InP cladding layer
140
.
Finally, a p-type electrode
160
is formed on the p
+
-InGaAs contact layer
150
and an n-type electrode
170
is formed on a back surface (a surface opposing to the surface on which the waveguide
120
is formed) of the substrate
110
. Thus, the DC-PBH structure semiconductor laser diode is completed by the selective MOVPE.
Document 1 discloses the process of manufacturing the semiconductor laser diode, however, it does not suggest that the shape of the diode surface (an uneven surface or a planar surface as shown in
FIG. 9F
) is selectable during the process disclosed in Document 1, because it does not mention at all the growth rate of the composition semiconductor film growing by MOVPE. Therefore, a case, wherein the diode must be processed so as to have a suitable surface shape in accordance with its purpose, may be required later.
“Journal of Crystal Growth 145 (1994) p.622” (hereinafter referred to as Document 2) discloses highly uniform InGaAsP growth by MOVPE with atmospheric pressure which is another technique for manufacturing a semiconductor laser device.
Since InGaAsP grows uniformly according to the technique disclosed in Document 2, a surface of the grown film will be uneven when a base layer beneath is uneven. In other words, a planar surfaced film is unavailable on an uneven base. A case, wherein the completed semiconductor laser device must be processed so as to have a suitable surface in accordance with its purpose, may be required later.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a metal organic vapor phase epitaxy method and a method for manufacturing a semiconductor laser device which can control a surface shape of a film (composition semiconductor film).
To achieve the above object, a metal organic vapor phase epitaxy method according to a first aspect of the present invention comprises:
preparing a base having a (100) oriented surface and a higher order surface; supplying a group III material including group III elements and a group V material including group V elements to the surface of said base as a material for a composition semiconductor film; and
forming the composition semiconductor film with the supplied group III material and group V material while controlling a migration length of the group III material on the surface.
According to this invention, a surface shape of the composition semiconductor film is controllable by changing the migration length of the group III material on the surface wherein the growth rates of the (100) oriented surface and the higher order surface depend on the migration length.
The forming may comprise controlling the migration length of the group III material on the surface by controlling a growth temperature of the composition semiconductor film.
The forming may comprise controlling the growth temperature so as to be equal to or lower than 600 degrees Celsius.
The forming may comprise expanding the migration length of the group III material on the surface by controlling the growth temperature so as to be in the range of 575 to 600 degrees Celsius.
The forming may comprise controlling the migration length of the group III material on the surface by controlling a pressure of the supplied group V material.
The forming may comprise expanding the migration length of the group III material on the surface by controlling the pressure so as to be in the range of 0.65 to 6.2 Torr.
The supplying and the forming may be carried out with an atmospheric pressure.
The forming may comprise:
using In as said group III elements; and
using P as said group V elements.
A method for manufacturing a semiconductor laser device comprises:
forming a waveguide, which lases in accordance with a predetermined voltage applied thereto, on a predetermined region of a substrate;
forming a current-blocking layer of group Ill material and group V material for blocking a current, by metal organic vapor phase epitaxy on the substrate and the waveguide except a top of the waveguide;
forming a cladding layer on said waveguide and said current-blocking layer;
forming a contact layer on said cladding layer;
forming an electrode on said contact layer and forming another electrode on a surface of the substrate which is opposite to the surface on which the waveguide is formed,
wherein the forming the current-blocking layer comprises:
supplying group III material including group III elements and group V material including group V elements to the surface of the substrate on which said waveguide is formed; and
forming the current-blocking layer while controlling a migration length of the group III material on the surface.
According to this invention, a surface shape of the current-blocking layer is controllable by changing the migration length of the group III material on the surface wherein the growth rate of the current-blocking layer depends on the migration length.
The forming the current-blocking layer may comprise controlling the migration length on the surface by controlling a growth temperature of the current-blocking layer.
The forming the current-blocking layer comprises controlling the growth tem
Hutchins, Wheeler & Dittmar
Le Dung A
NEC Corporation
Nelms David
LandOfFree
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