Thin film actuated mirror array having dielectric layers

• US 5,636,051 A
• Filed: 01/03/1996
• Issued: 06/03/1997
• Est. Priority Date: 01/03/1996
• Status: Expired due to Fees

• Current Assignee: Dongbu Daewoo Electronics Corporation (Dayou Holdings Co.,Ltd.)
• Original Assignee: Daewoo Electronics Company Limited (Dayou Holdings Co.,Ltd.)
• Inventors: Lim, Yong-Geun
• Primary Examiner(s): Ben, Loha
• Application Number:
  US08/581,015
• Time in Patent Office: 517 Days
• Field of Search: 359/290, 359/291, 359/295, 359/221, 359/224, 359/846, 359/848, 359/230, 310/328, 310/333
• US Class Current: 359/290
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

An array of M×N thin film actuated mirrors includes an active matrix, an array of actuating structures, each of the actuating structures including an elastic member, a second thin film electrode, a thin film electrodisplacive member and a first thin film electrode, and M×N number of multilayer stacks of thin film dielectric members. In addition to providing a protection against chemical or physical attacks on the first thin film electrode which also acts as a mirror for reflecting a light beam, the multilayer stack of thin film dielectric members placed on top of each of the actuating structures provides the maximum reflectance in each of the thin film actuated mirrors to thereby ensure an optimum optical efficiency of the array.

Claims

1. An array of M×

N thin film actuated mirrors, wherein M and N are integers, for use in an optical projection system, the array comprising;

an active matrix including a substrate, an array of M×

N connecting terminals and an array of M×

N transistors, wherein each of the connecting terminals is electrically connected to a corresponding transistor in the array of M×

N transistors;

M×

N conduits, wherein each of the conduits is made of an electrically conducting material;

an array of M×

N actuating structures, each of the actuating structures being provided with a connecting and a light reflecting portions, each of the actuating structures including an elastic member, a second thin film electrode, a thin film electrodisplacive member and a first thin film electrode, wherein each of the conduits is located at the connecting portion in each of the actuating structures, extending from bottom of the second thin film electrode to top of the connecting terminal connected electrically to a corresponding transistor, to thereby allow the second thin film electrode to function as a signal electrode in each of the thin film actuated mirrors, and the first thin film electrode made of a light reflecting and electrically conducting material is grounded to thereby function as a mirror and a bias electrode in each of the thin film actuated mirrors; and

M×

N number of multilayer stacks of thin film dielectric members, each of the thin film dielectric members placed on top of the light reflecting portion in each of the actuating structures, wherein said each of the thin film dielectric members has a predetermined thickness and a specific refractive index.

2. The array of claim 1, wherein each of the thin film actuated mirrors is of a bimorph structure, the bimorph structure including a pair of electrodisplacive members separated by an electrode.

3. The array of claim 2, wherein each of the thin film actuated mirrors is further provided with an additional electrodisplacive layer and an additional electrode layer.

4. A method for the manufacture of an array of M×

N thin film actuated mirrors, the method comprising the steps of;

providing an active matrix including a substrate, an array of M×

N connecting terminals and an array of M×

N transistors, wherein each of the connecting terminals is electrically connected to a corresponding transistor;

depositing a thin film sacrificial layer on top of the active matrix;

creating an array of M×

N empty slots in the thin film sacrificial layer, each of the empty slots being located around top of the connecting terminals;

depositing an elastic layer made of an insulating material on top of the thin film sacrificial layer while filling the empty slots;

forming an array of M×

N conduits in the elastic layer, each of the conduits extending from top of the elastic layer to top of a corresponding connecting terminal;

depositing a second thin film layer, a thin film electrodisplacive layer and a first thin film layer successively on top of the elastic layer, wherein the second thin film layer is made of an electrically conducting material, and the first thin film layer is made of an electrically conducting and light reflecting material;

patterning the first thin film, the thin film electrodisplacive, the second thin film and the elastic layers, respectively, until the thin film sacrificial layer is exposed, thereby forming an array of M×

N semifinished actuating structures, wherein each of the semifinished actuating structures is provided with a first thin film electrode, a thin film electrodisplacive member, a second thin film electrode and an elastic member;

depositing a plurality of thin film dielectric layers successively on top of the semifinished actuating structures including the exposed thin film sacrificial layer, each of the thin film dielectric layers having a predetermined thickness;

patterning the plurality of thin film dielectric layers, respectively, into M×

N number of multilayer stacks of thin film dielectric members, until the thin film sacrificial layer is exposed again, thereby forming an array of M×

N semifinished actuated mirrors, wherein the plurality of thin film dielectric layers are patterned in such a way that each of the semifinished actuated mirrors is divided arbitrarily into an actuating and a light reflecting portions, each of the conduits and each of the thin film dielectric members being located at the actuating portion and the light reflecting portion in each of the semifinished actuated mirrors, respectively;

covering each of the semifinished actuated mirrors with a thin film protection layer to thereby form an array of M×

N protected actuated mirrors;

removing the thin film sacrificial layer; and

removing the thin film protection layer to thereby form the array of M×

N thin film actuated mirrors.

5. The method of claim 4, wherein the plurality of thin film dielectric layers are deposited by using a sputtering or an evaporation method.

6. The method of claim 4, wherein each of the thin film actuated mirrors has a bimorph structure, the bimorph structure including a pair of electrodisplacive members separated by an electrode.

7. The method of claim 4 further comprises the formation of an additional electrode layer and an additional electrodisplacive layer, successively, after depositing the electrodisplacive layer.