Spatial light modulator and method

• US 4,566,935 A
• Filed: 07/31/1984
• Issued: 01/28/1986
• Est. Priority Date: 07/31/1984
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hornbeck, Larry J.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US06/635,967
• Time in Patent Office: 546 Days
• Field of Search: 156/626, 156/643, 156/644, 156/646, 156/650, 156/653, 156/656, 156/657, 156/659.1, 156/662, 204/192 E, 29/569 L, 350/356, 350/360, 357/30
• US Class Current: 438/29
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

Methods of fabrication of spatial light modulators with deflectable beams by plasma etching after dicing of a substrate into chips, each of the chips an SLM, is disclosed. Also, various architectures available with such plasma etching process are disclosed and include metal cloverleafs for substrate addressing, metal flaps formed in a reflecting layer over a photoresist spacer layer, and torsion hinged flaps in a reflecting layer.

Claims

1. A method of fabrication of spatial light modulators, comprising the steps of:

(a) form electrical addressing circuitry on a substrate;

(b) deposit a spacer layer on said substrate and over said circuitry;

(c) deposit a reflecting layer on said spacer layer;

(d) pattern said reflecting layer to define a plurality of pixel elements connected to the remainder of said reflecting layer; and

(e) plasma etch said spacer layer to form wells under said pixel elements, thereby freeing said pixel elements from said spacer layer and permitting them to be electrostatically deflected by signals on said addressing circuitry.

2. A method of fabrication of spatial light modulators, comprising the steps of:

(a) deposit a spacer layer on a conducting substrate;

(b) deposit a reflecting layer on said spacer layer;

(c) pattern said reflecting layer to define a plurality of pixel elements and electrodes; and

(d) plasma etch said spacer layer to form walls under said pixel elements, thereby freeing said pixel elements from said spacer layer and permitting them to be electrostatically deflected by signals applied between said electrodes and said substrate.

3. A method of fabrication of spatial light modulators, comprising the steps of:

(a) depositing a spacer on a substrate with electrical addressing circuitry;

(b) pattern post holes in said spacer extending down to said substrate;

(c) deposit a layer of metal on said spacer and post holes;

(d) pattern said layer of metal to define deflectable elements, each of said elements hinged to the metal deposited in one of said post holes; and

(e) remove said spacer.

4. The method of claim 3, wherein said removal is by plasma etching.

5. A method of fabrication of spatial light modulators, comprising the steps of:

(a) defining deflectable beams and supporting structure in a combination of layers of reflecting material and spacer, said reflecting material on said spacer on a substrate;

(b) applying a protective layer over said defined beams;

(c) dicing said substrate and layers into chips, each of said chips to become a spatial light modulator;

(d) alternately applying a solvent for said protective layer and spinning said chips to slough off portions of said protective layer softened or dissolved in said solvent;

(e) removing at least a portion of said spacer to free said deflectable beams from said spacer.

6. A method of monitoring the undercut of a plasma etch of a spacer between a substrate and a top layer, comprising the steps of:

(a) patterning substantially rectangular regions in said top layer, said rectangular regions with a progression of known widths;

(b) periodically observing said regions under light;

(c) determining the undercut to be about one half of the width of the widest rectangular region to have changed its reflectance of said light.