Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
2002-01-02
2004-06-08
Nhu, David (Department: 2818)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S535000, C438S798000
Reexamination Certificate
active
06746964
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of manufacturing semiconductor laser element/s for collectively forming semiconductor laser elements and then for forming each of the semiconductor laser elements. More particularly, this invention relates to a method of manufacturing semiconductor laser element/s capable of forming a semiconductor laser element having a diffraction grating for a short time.
BACKGROUND OF THE INVENTION
Conventionally, a semiconductor laser element is formed in such a manner that semiconductor laser elements are collectively formed on a compound semiconductor board using a semiconductor process technique and then, the semiconductor laser elements are cut out into separately by a cleavage. When a fine pattern such as a diffraction grating is formed on a portion of each the semiconductor laser element, since such a fine pattern exists, drawing processing is conducted by electron beam, and a step of conducting exposure processing by the drawing is necessary.
FIG. 7A
to
FIG. 7G
show the conventional semiconductor process for explaining how the diffraction grating is formed on a portion of a semiconductor laser element. First, a cladding layer
4
a
is deposited on an upper surface of a not shown active layer, and a diffraction grating film
13
a
forming the diffraction grating
13
is deposited on an upper surface of the cladding layer
4
a
. Further, an SiN film
21
is deposited on an upper surface of a diffraction grating film
13
a
as a file for forming a pattern of the diffraction grating
13
, a resist film
22
is applied on an upper surface of the diffraction grating film
13
a
, thereby forming the resist film
22
(see FIG.
7
A). This resist film
22
is a material reacting with electron beam exposure.
Then, the entire surface of the resist film
22
is subjected to electron beam exposure that draws a diffraction grating pattern with electron beam, and developing processing is conducted. As a result, a resist film
22
a
corresponding to the pattern of the diffraction grating
13
is formed (see FIG.
7
B).
Thereafter, as shown in (see FIG.
7
C), the SiN film
21
is subjected to reactive ion etching in CF
4
gas using the resist film
22
a
. As a result, an SiN film
21
a
corresponding to the pattern of the diffraction grating
13
is formed.
Thereafter, the resist film
22
a
is removed. Further, the diffraction grating film
13
a
and the cladding layer
4
a
are masked with an SiN film
21
a
having a pattern corresponding to the diffraction grating
13
and in this state, the diffraction grating film
13
a
and the cladding layer
4
a
are subjected to the reactive ion etching (see FIG.
7
E). With this operation, a shape of the diffraction grating
13
is formed.
Further, the SiN film
21
a
is removed (see FIG.
7
F), a cladding layer
4
c
that is the same as the cladding layer
4
b
is embedded in upper portions of the cladding layer
4
a
and the diffraction grating
13
and is allowed to grow, and the diffraction grating
13
is finally formed in a state in which the diffraction grating
13
is wrapped in the cladding layer
4
c
(see FIG.
7
G).
In the conventional method of manufacturing the semiconductor laser element, however, the entire surface of the resist film
22
is subjected to the electron beam exposure because of the diffraction grating
13
formed on a portion of the semiconductor laser element. Therefore, time required for the electron beam exposure becomes excessively long and as a result, there are problems that time required for manufacturing the semiconductor laser element and productivity is lowered.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of manufacturing a semiconductor laser element capable of enhancing the productivity of the semiconductor laser elements including a structure such as a partially formed diffraction grating.
The method of manufacturing a semiconductor laser element according to one aspect of this invention is a method of collectively forming, on a semiconductor board, a semiconductor laser element having a diffraction grating partially provided at least on the side of laser light emitting end surface or laser light reflection end surface side using a semiconductor process technique. The method comprises the steps of performing electron beam exposure or ion beam exposure for drawing only on a diffraction grating region on which the diffraction grating is provided in correspondence with a pattern of the diffraction grating; and masking the diffraction grating region and exposing a region other than the diffraction grating region with light or X-rays.
Thus, when the diffraction grating partially provided at least on the side of laser light emitting end surface or laser light reflection end surface side is formed, in the first exposing step, electron beam exposure or ion beam exposure is conducted for drawing only on a diffraction grating region on which the diffraction grating is provided in correspondence with a pattern of the diffraction grating, and in the second exposing step, the diffraction grating region is masked and the region other than the diffraction grating region is exposed with light or X-rays. With this method, time required for the electron beam exposure or ion beam exposure taking long exposing time per unit area is minimized.
The method of manufacturing a semiconductor laser element according to another aspect of this invention is a method of collectively forming, on a semiconductor board, a semiconductor laser element having a diffraction grating partially provided at least on the side of laser light emitting end surface or laser light reflection end surface side using a semiconductor process technique. The method comprises a first resist forming step of sequentially forming, on an upper surface of an upper cladding layer, a diffraction grating film for forming the diffraction grating, a pattern forming film for forming a pattern of the diffraction grating and a first resist film for electron beam exposure or ion beam exposure, a first exposing step of performing electron beam exposure or ion beam exposure for drawing the first resist film of the diffraction grating region on which the diffraction grating is provided in correspondence with the diffraction grating, and for carrying out developing, a first etching step of etching the pattern forming film by the pattern of the first resist film remained by the first exposing step, and for removing the first resist film, the second resist forming step of forming a second resist film for light exposure or X-ray exposure on an upper surface of pattern forming film exposed by the diffraction grating film and the first etching step, a second exposing step in which an upper surface of the diffraction grating region is masked, the first resist film formed on a region other than the diffraction grating region is exposed with light or X-rays, and developing is carried out, a second etching step of etching a pattern forming film exposed by the second exposing step, a removing step of removing the second resist film remained on an upper surface of the diffraction grating region, a third etching step in which etching is carried out using the pattern forming film exposed by the removing step, and an embedding step in which another upper cladding layer is further embedded in the diffraction grating exposed by the third etching step and an upper surface of the former cladding layer, and allowing the other cladding layer to grow.
Thus, when the diffraction grating partially provided at least on the side of laser light emitting end surface or laser light reflection end surface side is formed, in the first resist forming step, on an upper surface of an upper cladding layer, a diffraction grating film for forming the diffraction grating, a pattern forming film for forming a pattern of the diffraction grating and a first resist film for electron beam exposure or ion beam exposure are for sequentially forming, in the first exposing step, electron beam exposure or ion beam exposure is ca
Irino Satoshi
Tsukiji Naoki
Nhu David
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
The Furukawa Electric Co. Ltd.
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