Browse Prior Art Database

POST ETCH METALLIZATION

IP.com Disclosure Number: IPCOM000025346D
Original Publication Date: 1984-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 6 page(s) / 218K

Publishing Venue

Xerox Disclosure Journal

Abstract

Referring to Figure 1, silicon microdeflectors are micro-miniature cantilever beams or fingers 5, typically Silicon Dioxide (Si02) which due to its resistance to fatigue is ideally suited for such structures. Typical dimensions of finger 5 are J? = approximately 100mm, d = approximately lOrnm, and t = approximately 0.35mm. The application of a voltage between the metallization on the finger 5 and the bottom of the well 6 in the Silicon (Si) wafer or chip 7 will result in a deflection of the finger. Many applications for microdeflectors have been disclosed in the literature, with much of the interest being due to the ability to incorporate on the same chip of silicon both the microdeflectors and associated driving and/or sensing circuitry.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 44% of the total text.

Page 1 of 6

XEROX DISCLOSURE JOURNAL

POST ETCH METALLIZATION Mehdi N. Araghi
Martin E. Banton
Joseph J. Daniele

Proposed Classification
U.S. Cl. 358/208 Int. C1. H04n 3/08

8

/

7

Volume 9 Number 5 September/October 1984 343

[This page contains 1 picture or other non-text object]

Page 2 of 6

POST ETCH METALLIZATION (Cont'd)

7 FIG. 3b

I

6

344 XEROX DISCLOSURE JOURNAL

Volume 9 Number 5 September/October 1984

[This page contains 1 picture or other non-text object]

Page 3 of 6

POST ETCH METALLIZATION (Cont'd)

Referring to Figure 1, silicon microdeflectors are micro-miniature cantilever beams or fingers 5, typically Silicon Dioxide (Si02) which due to its resistance to fatigue is ideally suited for such structures. Typical dimensions of finger 5 are J? = approximately 100mm, d = approximately lOrnm, and t = approximately 0.35mm. The application of a voltage between the metallization on the finger 5 and the bottom of the well 6 in the Silicon (Si) wafer or chip 7 will result in a deflection of the finger. Many applications for microdeflectors have been disclosed in the literature, with much of the interest being due to the ability to incorporate on the same chip of silicon both the microdeflectors and associated driving and/or sensing circuitry.

A technique is proposed here for eliminating the severe curling back of silicon microdeflector fingers that results during fabrication. One fabrication procedure for example starts with a < 100) wafer of silicon on which a thin, boron rich layer is created on the top of the wafer. This layer serves as the vertical etch stop. An epitaxial layer of Si, typically 5-15 microns thick is grown on top of which an Si@* layer 8 is grown. Then, a Cr-Au metallization layer, typicallv 10-15 nm of Cr 9 is laid down followed by 40 nm of Au 10 to provide the electrode 11. Then, a series of photoresist steps are performed to pattern the fingers 5 and remove the

    XEROX DISCLOSURE JOURNAL Volume 9 Number 5 September/October 1984 345

[This page contains 1 picture or other non-text object]

Page 4 of 6

POST ETCH METALLIZATION (Cont'd)

epitaxial silicon from beneath the SiO fingers. Unfortunately, curl back of the fingers 5 may result as shown in Figure 2 .

8 layer SiO the how is interest of procedure fabrication the of part The produced and when in the process the silicon is etched from beneath t I? e fingers 5. is The best characterized Si02 is that which is thermally grown. A typical growth temperature is 1150 degrees C. The thermal expansion coefficient of silicon is larger than that of the amorphous SO2 produced by the thermal growth process. This difference in thermal expansion results in the thin Si02 layer 8 being under compression when the system (Si + Si02) returns to room temperature. Clearly, when the silicon is etched from beneath the Si02, the Si02 is free to assume its equilibrium length. The metal electrode 11 is evaporated onto the SiO at a

below the Si02 growth temperature. Thus, the metallization is not under the...