Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Packaging or treatment of packaged semiconductor
Reexamination Certificate
1999-09-23
2001-10-09
Mulpuri, Savitri (Department: 2812)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Packaging or treatment of packaged semiconductor
C438S033000, C438S462000, C438S043000, C438S106000
Reexamination Certificate
active
06300151
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical element used in the field of optical communication and a method for aligning an optical fiber, laser diode chip or photodiode chip to connect an external optical communication system to the optical element.
Particularly, the present invention also relates to a method for manufacturing a laser diode chip which is used to convert electric signals into optical waves in the communication system using optical fibers.
Further, the present invention relates to a method for aligning the positions between a laser diode chip and an optical fiber as well as between a photodiode chip and an optical fiber in the optical fiber communication system.
BACKGROUND OF THE INVENTION
For an optical communication, an optical transmitting module to convert electric signals into optical signals for transmitting as well as an optical receiving module to convert optical signals into electric signals for receiving are essential.
In addition, the art with which a variety of optical elements for generating, detecting, modulating and distributing functions of a light are attached with optical fibers and packaged is essential for commercializing all sorts of communicating elements.
In the process for packaging optical modules, one of the most difficult and costly steps is that of aligning and fixing an optical fiber in the wave guiding path of an optical element which represents a determinant factor for the cost of an optical communication module.
That rests on the difficulty in spatially aligning an optical element and an optical fiber, and holding the both in the aligned position without displacement in view of the very small area for the optical input or output of an optical element in the order of a few square micrometers and also the small area for the optical input or output of an optical fiber in the order of several tens of square micrometers.
The conventional methods for aligning an optical transmitting module and an optical receiving module may be broadly divided into an active aligning method and a passive aligning method.
However, the active aligning method has a difficulty in cost reduction because it needs a long processing time and many parts due to the use of lenses and an expensive laser welder.
On the other hand, the passive aligning methods can be performed without the use of those lenses and laser welders and therefore are coming to the front as new methods for reducing the price of the optical communication modules.
According to a conventional passive aligning method as shown in
FIG. 14
, after the chip marker
1022
on the bottom surface of a laser diode chip
1010
is caused to match the substrate marker
1014
on the top surface of a substrate
1000
, the laser diode chip
1010
is bonded to the metal junction layer
1012
of the silicon substrate
1000
by using a flip chip bonder.
The method using markers as described above is not much more advantageous in the point of the required time for process as compared to the active aligning method and also has a drawback of an increased installation cost for the equipment like a flip chip bonder.
Another conventional passive aligning method is shown in FIG.
15
.
In this method, first a support
2040
loaded with a laser diode chip
2010
is fixed bonded on the surface of a substrate
2030
and then mounts
2050
and
2060
are fixed to the substrate
2030
. Subsequently, the optical fiber
2020
is caused to be received, with its end close to the laser diode chip
2010
, in the groove
2051
formed on the mount
2050
and then the optical fiber
2020
is aligned in its position with regard to the laser diode chip
2010
by adjusting the position of the end of the optical fiber
2020
, which end positions on the side of the mount
2050
. When the optical fiber
2020
has been precisely aligned in position through those procedures, the optical fiber
2020
is fixed to the mount
2060
, for example, through soldering.
For the optical communication module according to
FIG. 15
as described above, the positions in which the mounts and the support will be fixed are not exactly determined and therefore a great deal of time is spent to find optimum fixing positions at the time of mounting work. Nevertheless there arise deviations in the fixing positions depending on the individual products because the mounts or the supports are not exactly positioned.
Accordingly, the position alignment operation for the optical fiber with regard to the laser diode chip is not only difficult but the fixing positions of the mounts and supports with unduly high errors can also cause the problem that the optical fiber is not properly lined up with the axis of the laser diode chip.
An improved optical communication module intended to solve the above-described problem is disclosed in the Korean Patent Application No.
1997-044417.
Referring to
FIG. 16
concerning the corresponding art, the art is characterized in that the position determining means
3091
,
3092
and
3093
to define the positions in which the support
3040
and the mounts
3050
and
3060
are to be fixed are provided.
In particular, the support
3040
on which the laser diode chip
3010
is mounted is inserted into the first position determining groove
3091
on the substrate
3030
and fixed there through bonding or the like. Then, the mount
3050
is inserted into the second position determining groove
3092
and the mount
3060
is inserted into the third position determining groove
3093
on the substrate
3030
and then fixed through bonding.
Subsequently, after the optical fiber
3020
is placed on the mount
2050
with its end close to the laser diode chip
3010
received in the groove
3051
, the optical fiber
3020
is brought into a correct position for alignment with the laser diode chip
3010
by adjusting the position of the optical fiber
3020
at its end part on the side of the mount
3050
.
When the optical fiber
3020
has been precisely set in its desired position, the optical fiber
3020
is fixed to the mount
3060
through soldering or the like.
Because the support
3040
and the mounts
3050
and
3060
are fixed after they were inserted into their respective position determining grooves
3091
,
3092
and
3093
in the assembling operation as described above, even in the case of mass production of optical communication modules, the positions of the support
3040
and the mounts
3050
and
3060
relative to that of the substrate
3030
can always be maintained definite.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a process for manufacturing laser diode chips on a large scale, which diodes can be controlled within the order of ±1 micron in the tolerance of size, through an etching step.
The second object of the present invention is to improve the structure of a silicon substrate on which an optical fiber and a laser diode chip are positioned so that the optical fiber and the laser diode chip can be exactly aligned with each other.
The third object of the present invention is to provide a passive aligning method for an optical communication module which permits a precise positioning of an optical fiber and a laser diode chip on a substrate.
The fourth object of the present invention is to reduce the manufacturing cost for an optical communication module by enabling an optical fiber and a laser diode chip to be aligned in a passive manner on a silicon substrate without the use of high-priced bonding equipment.
The fifth object of the present invention is to improve the construction of a silicon substrate on which an optical fiber and a photodiode chip is positioned so that an exact alignment of the optical fiber with the photodiode chip can be achieved.
The sixth object of the present invention is to provide a passive method for aligning an optical receiving module which permits an exact positioning of an optical fiber and a photodiode chip on a silicon substrate.
The seventh object of the present invention is to reduce the cost for manufacturing an optical receivi
Jun Hong Jun
Koo Bon Jo
Lee Ho Sung
Shin Ki Chul
Song Jun Seok
LG Cable & Machinery Ltd.
Long Aldridge & Norman LLP
Mulpuri Savitri
LandOfFree
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