Optical waveguide platform and manufacturing method thereof

Details Optical waveguide platform and manufacturing method thereof Optical waveguide platform and manufacturing method thereof

2002-11-12

2004-10-12

Ullah, Akm Enayet (Department: 2874)

Optical waveguides

Planar optical waveguide

Thin film optical waveguide

C385S088000

Reexamination Certificate

active

06804444

ABSTRACT:

BACKGROUND OF THE INVENTION
This application claims the priority of Korean Patent Application No. 2002-17599, filed Mar. 30, 2002 in the Korean Intellectual Property Office, which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a planar optical waveguide-type optical transceiver module and a manufacturing method thereof, and more particularly, to an optical waveguide platform for mounting an optical device by a flip chip bonding method and a manufacturing method thereof.
2. Description of the Related Art
An optical device of a planar optical waveguide manufactured on a substrate, for example, a silicon substrate, by a flame hydrolysis deposition (FHD) method or a plasma enhanced chemical vapor deposition (PECVD) method, functions as a passive optical device. However, the optical device cannot function as a light emitting device, such as a laser diode (LD), a light receiving device, such as a photo diode (PD), nor any other active optical device that has electro-optical functions or active optical functions. Accordingly, in order to perform optical switching, optical exchanging, optical signal transmitting, and optical signal receiving functions, a separate active device chip has to be hybrid mounted with an optical waveguide device, so as to perform both the passive optical function of an optical waveguide and the active optical function of a semiconductor active device. In this case, it is necessary to make a small-sized active optical device in the form of a chip, using a semiconductor technique, and to precisely align and mount the active optical device on an optical waveguide device, so as to reduce optical contact loss. Accordingly, an optical waveguide platform for mounting an active optical device by a proper method, such as a flip chip bonding method, is required.
FIGS. 1A through 1G
are sectional views illustrating a conventional method of manufacturing an optical waveguide platform. A terrace
12
is formed on a silicon substrate
10
by an anisotropic etching method, as shown in FIG.
1
A. Thereafter, a lower clad layer
14
formed of a silica layer is formed on the silicon substrate
10
having the terrace
12
. Here, a step is formed on the surface of the lower clad layer
14
by the step of the terrace
12
, as shown in FIG.
1
B.
In order to remove the step on the surface of the lower clad layer
14
, which is formed by the step of the terrace
12
, the lower clad layer
14
is polished. Thus, a planarized lower clad layer
14
a
is formed, as shown in FIG.
1
C. Next, a core layer
16
is formed on the planarized lower clad layer
14
a
and etched into a waveguide pattern. An upper clad layer
18
is formed on the core layer
16
, as shown in FIG.
1
D.
Subsequently, the upper clad layer
18
, the core layer
16
, and the planarized lower clad layer
14
a
are dry etched to expose the terrace
12
. Accordingly, referring to
FIG. 1E
, a portion through which the terrace
12
is exposed becomes a trench
19
in which an optical device will be mounted. A dielectric layer
20
is formed on the floor of the terrace
12
, and under bump metal (UBM) layers
22
for forming electrodes and a solder pad are deposited on the dielectric layer
20
and on a portion of the upper clad layer
18
, as shown in FIG.
1
F.
Thereafter, solder is deposited on a solder pad formed of the UBM layers
22
to mount an optical device
24
, which is formed of a semiconductor chip, such as an LD or a PD. Then, a metal wire
26
connects the UBM layer
22
for forming an electrode, as shown in FIG.
1
G.
The conventional method for manufacturing an optical waveguide platform shown in
FIGS. 1A through 1G
requires a silicon precision process for forming the terrace
12
and a polishing process for polishing a silica layer composed of the lower clad layer
14
due to the step of the terrace
12
.
In this case, the silicon precision process for forming the terrace
12
has various restraints, such as requiring a photolithography process that uses a separate mask and being impossible to process a precise pattern when a crystal direction is wrong.
In addition, since the silica layer forming the lower clad layer
14
has a thickness of tens of &mgr;m, the lower clad layer
14
is difficult to be precisely polished. Moreover, when there is non-uniformity in polishing thickness, part of the resulting optical waveguide may be unusable.
In particular, in the case of a general silica optical waveguide device, a difference in the thermal expansion coefficients of a silica layer and the silicon substrate
10
causes the silicon substrate
10
to warpage. Therefore, it is impossible to precisely polish a lower clad layer
14
without variation in the polishing thickness. As a result, the conventional method requires an additional process, such as thermal treatment for eliminating warpage of the silicon substrate
10
.
FIGS. 2A through 2G
are sectional views illustrating a second conventional method of manufacturing an optical waveguide platform. A lower clad layer
32
and a core layer
34
are sequentially staked on a silicon substrate
30
, as shown in FIG.
2
A. Portions of the core layer
34
and the lower clad layer
32
are selectively dry etched to a predetermined depth to form a trench
36
in which an optical device will be mounted. In this case, the etch depth has to be finely adjusted to enable vertical alignment between the optical output of the optical device and the core layer
34
. Consequently, a fine waveguide pattern formed of a core layer pattern
34
a
and a lower clad layer pattern
32
a
having widths of several &mgr;m is exposed for a considerable height, as shown in FIG.
2
B.
Thereafter, an etch stopper pattern
38
is formed on the lower clad layer pattern
32
a
in the trench
36
, as shown in FIG.
2
C. Then, an upper clad layer
40
is deposited on the entire surface of the substrate
30
having the etch stopper pattern
38
and the core layer pattern
34
a
, as shown in FIG.
2
D.
By selectively etching the upper clad layer
40
in the trench
36
region, an upper clad layer pattern
40
a
, which exposes the etch stopper pattern
38
, is formed as shown in
FIG. 2E. A
metal layer
42
for supplying power for driving the optical device is formed on the etch stopper pattern
38
in the trench
36
as shown in FIG.
2
F. Subsequently, solder is deposited on the metal layer
42
to mount an optical device
44
formed of a semiconductor chip, such as an LD or a PD, by a flip chip bonding method, as shown in FIG.
2
G.
As described with reference to
FIGS. 2A through 2G
, the second conventional method of manufacturing an optical waveguide platform forms the etch stopper pattern
38
after the core layer pattern
34
a
is formed. In this case, the fine optical waveguide pattern having a width of several &mgr;m may be damaged by a mechanical impact, such as contact with a mask, in a lithography process for forming the etch stopper pattern
38
. In addition, in the case of forming the etch stopper pattern
38
by the lithography method, the heights of the upper surface of the core layer pattern
34
a
which the mask contacts and the etch floor on which the etch stopper pattern
38
is formed become different. Accordingly, defocus occurs in a contact aligner, thereby resulting in the formation of an imprecise etch stopper pattern. In particular, an align key for aligning and mounting the optical device cannot be precisely formed so that it is difficult to precisely align and mount the optical device.
Moreover, in order to perform the second conventional method of manufacturing the optical waveguide platform as shown in
FIGS. 2A through 2G
, the etch depths of the core layer
34
and the lower clad layer
32
have to be precisely adjusted to vertically align the optical device and the waveguide. In addition, in etching the upper clad layer
40
, the etch depth has to be precisely adjusted until the etch stopper pattern
38
is exposed.
SUMMARY OF THE INVENTION
To solve the above-described problems, it is an objecti

Affiliated with

Also associated with

Rating

Optical waveguide platform and manufacturing method thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Optical waveguide platform and manufacturing method thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical waveguide platform and manufacturing method thereof will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3273984