Optical: systems and elements – Mirror – With support
Reexamination Certificate
1998-07-15
2004-02-24
Shafer, Ricky D. (Department: 2872)
Optical: systems and elements
Mirror
With support
C359S883000, C359S900000, C359S850000, C216S024000, C216S038000, C216S039000, C257S098000, C427S162000, C438S029000, C438S043000, C438S761000
Reexamination Certificate
active
06695455
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a process for fabricating mirrors, and more particularly to a process for fabricating micro-mirrors on a silicon substrate.
2. Description of prior art
Nowadays, silicon-based optical systems or components dominate the development of micro-optics technology and are used indifferent ways, such as optical pick-up head apparatus, laser collimating lens and WDM for fiber-optical communication disclosed, for example, in U.S. Pat. No. 5,500,910.
Referring to
FIG. 1
, U.S. Pat. No. 5,293,038 has disclosed the structure of an optical pick-up head apparatus, which comprises a laser source
11
, a first semiconductor substrate
12
, a second semiconductor substrate
13
, a holographic optics
14
, a photo-detector
15
, mirrors
17
and
18
, an optical lens
19
and an optical disk
20
. In this structure, optical mirrors are fabricated on (
100
) silicon. 45° optical mirrors
17
are formed by etching the silicon at an angle of 9° from the {
110
} surface. The mirrors are coated with Au to increase the reflectance. All of the components of an optical pick-up head apparatus are integrated into a single chip to reduce its weight and volume. Therefore by using the prior-art structure the size of the pick-up head apparatus can be precisely controlled, the pick-up device is easy to mass-produce, and the manufacturing cost can be reduced. However, since the optical pick-up head is a micro-optics formed on silicon, the flatness of silicon surface must be controlled within &lgr;/4. To form micromirrors in a dimension of a few hundred micrometers to several ten micrometers is difficult when using conventional polishing. Accordingly, current research is primarily directed toward discovering how to improve the flatness of micromirror surfaces to reduce the scattering effect on the laser and to raise the S/N ratio.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a fabrication process of micromirrors on a silicon substrate to improve the flatness of micromirrors; thereby reducing the scattering effect on the laser, and increasing the S/N ratio.
The present invention is implemented on silicon. A SiO
2
layer is first coated on the surfaces of micromirrors after forming the micromirrors by etching the silicon. Then, a CO
2
laser with a wavelength of 10.6 &mgr;m is applied to illuminate the silicon substrate. The silicon substrate is transparent to the 10.6 &mgr;m CO
2
laser. That is the silicon substrate will not absorb the CO
2
laser light. On the contrary, SiO
2
is opaque to a 10.6 &mgr;m CO
2
laser. Therefore, a 10.6 &mgr;m CO
2
laser can be utilized to perform annealing for SiO
2
to improve the surface flatness. In this way, the roughness can be controlled under &lgr;/4.
Another implementation of this invention is to coat a layer of gold on the silicon to form a eutectic structure, which is then heated to increase the surface flatness.
After the flatness of the micro-mirror's surface has been improved, a layer of gold is coated to increase the reflectance of the micro-mirror.
REFERENCES:
patent: 3785892 (1974-01-01), Terry et al.
patent: 3990914 (1976-11-01), Weinstein et al.
patent: 3996492 (1976-12-01), McGroddy
patent: 4293826 (1981-10-01), Scifres et al.
patent: 4670969 (1987-06-01), Yamada et al.
patent: 4855102 (1989-08-01), Okada et al.
patent: 4873429 (1989-10-01), Kume et al.
patent: 4990465 (1991-02-01), Liau et al.
patent: 5017263 (1991-05-01), Clark
patent: 5087124 (1992-02-01), Smith et al.
patent: 5293038 (1994-03-01), Kadowaki et al.
patent: 5479426 (1995-12-01), Nakanishi et al.
patent: 5500910 (1996-03-01), Boudreau et al.
patent: 5565052 (1996-10-01), Papenburg et al.
patent: 5786925 (1998-07-01), Goossen et al.
patent: 5798283 (1998-08-01), Montague et al.
patent: 5828088 (1998-10-01), Mauk
patent: 5907791 (1999-05-01), Cappuzzo et al.
patent: 6426968 (2002-07-01), Strife et al.
Industrial Technology Research Institute
Quintero Nelson A.
Shafer Ricky D.
LandOfFree
Fabrication of micromirrors on silicon substrate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fabrication of micromirrors on silicon substrate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fabrication of micromirrors on silicon substrate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3326925