Optical waveguides – Planar optical waveguide – Thin film optical waveguide
Reexamination Certificate
2001-08-21
2003-09-23
Zarroli, Michael C. (Department: 2839)
Optical waveguides
Planar optical waveguide
Thin film optical waveguide
C257S460000, C257S461000
Reexamination Certificate
active
06625367
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to an optical fiber communications system and, more specifically, to an optoelectronic device having a P-contact and an N-contact located over a same side of a substrate, and a method of manufacture therefor.
BACKGROUND OF THE INVENTION
Various optical devices, such as lasers, P-type/intrinsic/N-type (PIN) photodetectors, optical lenses, and other similar devices, are currently widely used and accepted in today's complex optical communications systems. Currently, multiple optical devices are mounted to a substrate, such as an optical sub-assembly (OSA) or other similar substrate, for inclusion into an optical communications system. Typically, after the multiple optical devices are mounted on the substrate, contact pads and wire bonds are formed and connected, providing electrical connections to the various electrodes included within the various devices.
An example of a cross-sectional view of a conventional optical communications sub-system
100
, including an optical device
105
that is mounted to an OSA
190
, is illustrated in Prior Art
FIG. 1
, and will hereafter be described. In the current example, the optical device
105
, which is illustrated as a laser or a PIN photodetector, includes an optical substrate
110
having an buffer layer
120
located thereon. The optical device
105
further includes an absorber layer
130
located on the buffer layer
120
, and a cap layer
140
located on the absorber layer
130
. Located within the cap layer
140
and contacting the absorber layer
130
is a P++ diffusion region
150
. Likewise, contacting the P++ diffusion region
150
is a P-contact
160
, and contacting the substrate
110
are N-contacts
170
.
As illustrated, the P-contact
160
physically contacts a P-contact electrode
165
located on the OSA
190
. However, because the N-contacts
170
are located on an opposing side of the optical device
105
from the P-contact
170
, a wire bond
175
must be used to connect them to their respective N-contact electrodes
180
, which are also located on the OSA
190
. The inclusion of the wire bond
175
in the optical communications sub-system
100
introduces certain drawbacks, namely drawbacks associated with performance and manufacturing.
As just mentioned, the optical communications sub-system
100
experiences certain performance issues associated with the use of the wire bond
175
. One of such performance issues is an undesirably high wire bond inductance. It is currently unfavorable to have such high wire bond inductance, because the high wire bond inductance causes the optical device
105
to operate slower than desired, making the device less efficient, thus less preferred in the optoelectronics industry.
As also just mentioned, the optical communications sub-system
100
experiences certain manufacturing limitations associated with the use of the wire bond
175
. Because the wire bond
175
must be attached to both the N-contacts
170
and N-contact electrodes
180
, an additional complex manufacturing variable has been added to the process flow. Such additional complex manufacturing variables are generally unwanted, especially when they may cause up to a 2 percent reduction in optical communications sub-system
100
yields. While the reduction in optical communications sub-system
100
yields may be attributed to many things, it may particularly be attributed to the inherent difficulty in creating a wire bond to a silicon or an indium phosphide substrate, such as used in the N-contacts
170
or the OSA
190
.
Some of the difficulties associated with wire bonding in optical devices are demonstrated with respect to Prior Art FIG.
2
. More specifically, Prior Art
FIG. 2
illustrates micrographs
210
,
220
,
230
depicting examples of damage that may be caused while bonding a wire bond
240
to an optical device
250
. In a typical situation, such a damaged optical device
250
would subsequently be discarded, substantially increasing manufacturing costs. Likewise, because the wire bond
240
is also coupled to another device, such as an OSA, damage caused while bonding the wire bond
240
to the optical device
250
may also cause a fully assembled OSA, including multiple lasers, PIN photodetectors and lens, to be damages and also subsequently discarded. Additionally, not only does the inclusion of the wire bond
240
cause yield problems, it also adds additional manufacturing time, which one skilled in the art knows is undesirable.
Accordingly, what is needed in the art is an optical device and a method of manufacture therefor, that overcomes the deficiencies in the prior art, such as the problems associated with the use of wire bonds in optical devices.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides an optoelectronic device and a method of manufacture therefor. The optoelectronic device includes an optical active layer formed over a substrate and an active region formed in the optical active layer. The optoelectronic device further includes a P-contact and an N-contact formed over a same side of the substrate and associated with the active region.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
REFERENCES:
patent: 5208878 (1993-05-01), Thulke
patent: 5349210 (1994-09-01), Ackley et al.
patent: 5866922 (1999-02-01), Huang et al.
patent: 5942789 (1999-08-01), Morikawa
patent: 6320206 (2001-11-01), Coman et al.
patent: 6504180 (2003-01-01), Heremans et al.
patent: 2002/0158294 (2002-10-01), Fujiwara et al.
Coult David G.
Derkits, Jr. Gustav E.
Lentz Charles W.
Segner Bryan P.
Hitt Gaines PC
TriQuint Technology Holding Co.
Zarroli Michael C.
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