# US 5,706,122 A · Method for the formation of a thin film actuated mirror array

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,706,122 A
- Document ID: US5706122A
- Status: Granted
- Kind: A
- Application number: 08/698,383
- Filed: 1996-08-15
- Granted: 1998-01-06
- Earliest claimed: 1995-08-22
- Assignees: Daewoo Electronics Co., Ltd.
- Inventors: Yong-Geun Lim
- Web page: https://patentgrep.com/patent/US5706122A

## CPC

- G02B 26/0858: {the reflecting means being moved or deformed by piezoelectric means}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A method for the manufacture of an array of M.times.N thin film actuated mirrors for use in an optical projection system is disclosed. The method includes the steps of: providing an active matrix; depositing a thin film sacrificial layer; creating an array of empty cavities in the thin film sacrificial layer; forming an array of actuating structures on top of the thin film sacrificial layer including the empty cavities, each of the actuating structures including a first thin film electrode, a thin film electrodisplacive member, a second thin film electrode and an elastic member; forming a thin film protection layer completely covering each of the actuating structures; removing the thin film sacrificial layer by using an etchant; rinsing away the etchant by using a rinse which is DI water or hydrophilic and volatile; removing the rinse by a spin drying method followed by a heat treatment; and removing the thin film protection layer, thereby forming the array of thin film actuated mirrors.

## Claims

### Claim 1

A method for reducing the occurrence of an elastic member in a thin film actuated mirror sticking to an active matrix including a substrate with a connecting terminal formed on top of the substrate during the manufacture thereof, wherein the thin film actuated mirror is formed by: depositing a thin film sacrificial layer on top of the active matrix; creating an empty cavity on the thin film sacrificial layer, the empty cavity encompassing the connecting terminal; forming an actuating structure on top of the thin film sacrificial layer, including a first thin film electrode, a thin film electrodisplacive member, a second thin film electrode, an elastic member and a conduit; forming a thin film protection layer completely covering the actuating structure; removing the thin film sacrificial layer by using a first etchant; and removing the thin film protection layer, the method being characterized in that:
the first etchant is removed by using a first rinse; and
the first rinse is removed by using a spin drying method followed by a heat treatment.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first etchant used in the removal of the thin film sacrificial layer is hydrogen fluoride (HF).

### Claim 3 (depends on 1)

The method of claim 1, wherein the first rinse is DI water.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first rinse is hydrophilic and volatile.

### Claim 5 (depends on 4)

The method of claim 4, wherein the first rinse is isoprophyle alcohol (IPA).

### Claim 6 (depends on 1)

The method of claim 1, wherein the heat treatment takes place at a temperature ranging from 60.degree. to 200.degree. C.

### Claim 7 (depends on 1)

The method of claim 1, wherein the thin film protection layer is removed by using a plasma etching method.

### Claim 8 (depends on 1)

The method of claim 1, after the removal of the thin film sacrificial layer, further involves the steps of:
removing remnants of the thin film sacrificial layer by using a second etchant;
rinsing away the second etchant by using a second rinse; and
removing the second rinse by using a spin drying method followed by a heat treatment.

### Claim 9 (depends on 8)

The method of claim 8, wherein the second etchant is hydrogen fluoride (HF).

### Claim 10 (depends on 8)

The method of claim 8, wherein the second rinse is DI water.

### Claim 11 (depends on 8)

The method of claim 8, wherein the second rinse is hydrophile and volatile.

### Claim 12 (depends on 11)

The method of claim 11, wherein the second rinse is isoprophyle alcohol (IPA).

### Claim 13 (depends on 8)

The method of claim 8, wherein the heat treatment takes place at a temperature ranging from 60.degree. to 200.degree. C.

### Claim 14

A method for the manufacture of an array of M.times.N thin film actuated mirrors, wherein M and N are integers, for use in an optical projection system, the method comprising the steps of:
providing an active matrix including a substrate with an array of M.times.N connecting terminals;
depositing a thin film sacrificial layer on top of the active matrix;
creating an array of M.times.N empty cavities on the thin film sacrificial layer, each of the empty cavities encompassing one of the connecting terminals;
forming an array of M.times.N actuating structures on top of the thin film sacrificial layer including the empty cavities, each of the actuating structures including a first thin film electrode, a thin film electrodisplacive member, a second thin film electrode, an elastic member and a conduit;
forming a thin film protection layer completely covering each of the actuating structures;
removing the thin film sacrificial layer by using an etchant;
rinsing away the etchant by using a rinse;
removing the rinse by using a spin drying method followed by a heat treatment; and
removing the thin film protection layer, thereby forming the array of M.times.N thin film actuated mirrors.