Thin film actuated mirror array in an optical projection system and method for manufacturing the same

• US 5,920,421 A
• Filed: 12/10/1997
• Issued: 07/06/1999
• Est. Priority Date: 12/10/1997
• Status: Expired due to Term

• Current Assignee: Wi-LAN Inc.
• Original Assignee: Daewoo Electronics Company Limited (Dayou Holdings Co.,Ltd.)
• Inventors: Choi, Yoon-Joon
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): BURKE, MARGARET A
• Application Number:
  US08/988,450
• Time in Patent Office: 573 Days
• Field of Search: 359/212, 359/224, 359/290, 359/291, 359/295, 359/318, 359/850, 359/855, 430/321
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means

Abstract

Thin film AMA in an optical projection system and a method for manufacturing the same are disclosed. The thin film AMA has an active matrix having electrical wiring and a connecting terminal, a first actuator, a second actuator, a supporting element, and a reflecting member. The first actuator and the second actuator are parallely formed and the supporting element is formed in the direction perpendicular to the first actuator and the second actuator. The reflecting member supported by a plurality of posts is tilted by a double displacement, so the quality of a picture projected onto a screen is greatly increased. Also, the first actuator and the second actuator respectively have symmetrical structures centering around the first anchor and the second anchor so that the first actuator and the second actuator have stable structures.

Claims

1. A thin film actuated mirror array comprising:

an active matrix having electrical wiring and a connecting terminal for receiving a first signal from outside and transmitting the first signal;

a first actuator having i) a first supporting layer having a bottom of a central portion attached to a first portion of said active matrix where the connecting terminal is formed and having lateral portions formed in parallel to and above said active matrix, ii) a first bottom electrode for receiving the first signal, said first bottom electrode being formed on said first supporting layer, iii) a first top electrode corresponding to said first bottom electrode for receiving a second signal and generating a first electric field between said first top electrode and said first bottom electrode, iv) a first active layer formed between said first top electrode and said first bottom electrode and deformed by the first electric field, and v) a first post having lateral ends respectively attached to said first top electrode and a central portion formed above said first top electrode;

a second actuator having a) a second supporting layer having a bottom of a central portion attached to a second portion of said active matrix where the connecting terminal is formed and having lateral portions formed in parallel to and above said active matrix, b) a second bottom electrode for receiving the first signal, said second bottom electrode being formed on said second supporting layer, c) a second top electrode corresponding to said second bottom electrode for receiving the second signal and generating a second electric field between said second top electrode and said second bottom electrode, d) a second active layer formed between said second top electrode and said second bottom electrode and deformed by the second electric field, and a second post having lateral ends respectively attached to said second top electrode and e) a central portion formed above said second top electrode;

a supporting means formed on a third portion of said active matrix; and

a reflecting means for reflecting a light, said reflecting means being formed on said first post, on said second post, and on said supporting means, so that the reflecting means tilts upward by a metal tension strip reaction between said first and second actuators and said first and second posts, respectively.

2. The thin film actuated mirror array as claimed in claim 1, said active matrix further comprising a passivation layer for protecting said active matrix and an etch stop layer for preventing said active matrix from etching.

3. The thin film actuated mirror array as claimed in claim 1, wherein said first actuator is formed in parallel to said second actuator and the supporting means faces said first actuator and said second actuator, so that said actuators and the supporting means form together a schematic U-shape.

4. The thin film actuated mirror array as claimed in claim 1, said supporting means further comprising a third supporting layer formed on the third portion of said active matrix, a third bottom electrode formed on said third supporting layer, a third active layer formed on said third bottom electrode, a third top electrode formed on said third active layer, and a third post formed on said third top electrode.

5. The thin film actuated mirror array as claimed in claim 1, wherein said first post and said second post are extended toward each other so that said first post and said second post together have an H-shape.

6. The thin film actuated mirror array as claimed in claim 5, wherein said reflecting means is formed from the extended portions of said first post and said second post to said third post, and has a rectangular shape.

7. The thin film actuated mirror array as claimed in claim 1, wherein said first top electrode has a first part and a second part respectively formed on said first active layer, and said second top electrode has a first part and a second part respectively formed on said second active layer.

8. The thin film actuated mirror array as claimed in claim 7, said first actuator further comprising a first via contact for transmitting the first signal from the connecting terminal to said first bottom electrode, said first via contact being formed in a first via hole which is formed from a central portion of said first active layer to the connecting terminal through said first bottom electrode and said first supporting layer, and said second actuator further comprising a second via contact for transmitting the first signal from the connecting terminal to said second bottom electrode, said second via contact being formed in a second via hole which is formed from a central portion of said second active layer to said connecting terminal through said second bottom electrode and said second supporting layer.

9. A thin film actuated mirror array comprising:

an active matrix having electrical wiring and a connecting terminal for receiving a first signal from outside and transmitting the first signal;

a first actuator having i) a first supporting layer having a bottom of a central portion attached to a first portion of said active matrix where the connecting terminal is formed and having lateral portions formed in parallel to and above said active matrix, ii) a first bottom electrode for receiving the first signal, said first bottom electrode being formed on said first supporting layer, iii) a first top electrode corresponding to said first bottom electrode for receiving a second signal and generating a first electric field between said first top electrode and said first bottom electrode, iv) a first active layer formed between said first top electrode and said first bottom electrode and deformed by the first electric field, and v) a first post having lateral ends respectively attached to said first top electrode and a central portion formed above said first top electrode;

a second actuator having a) a second supporting layer having a bottom of a central portion attached to a second portion of said active matrix where the connecting terminal is formed and having lateral portions formed in parallel to and above said active matrix, b) a second bottom electrode for receiving the first signal, said second bottom electrode being formed on said second supporting layer, c) a second top electrode corresponding to said second bottom electrode for receiving the second signal and generating a second electric field between said second top electrode and said second bottom electrode, d) a second active layer formed between said second top electrode and said second bottom electrode and deformed by the second electric field, and e) a second post having lateral ends respectively attached to said second top electrode and a central portion formed above said second top electrode, said second actuator being formed in parallel to said first actuator;

a supporting means formed on a third portion of said active matrix and facing said first actuator and said second actuator, so that said supporting means and said actuators form together a schematic U-shape, said supporting means having a third supporting layer formed on the third portion of said active matrix, a third bottom electrode formed on said third supporting layer, a third active layer formed on said third bottom electrode, a third top electrode formed on said third active layer, and a third post formed on said third top electrode; and

a reflecting means for reflecting a light, said reflecting means being formed on said first post, on said second post, and on said third post so that the reflecting means tilts upward by a metal tension strip reaction between said first and second actuators and said first and second posts, respectively.

10. The thin film actuated mirror array as claimed in claim 9, wherein said first post and said second post are extended toward each other so that said first post and said second post together have an H-shaped.

11. The thin film actuated mirror array as claimed in claim 10, wherein said reflecting means is formed from the extended portions of said first post and said second post to said third post, and has a rectangular shape.

12. The thin film actuated mirror array as claimed in claim 9, wherein said first top electrode has a first part and a second part respectively formed on said first active layer, said second top electrode has a first part and a second part respectively formed on said second active layer.

13. The thin film actuated mirror array as claimed in claim 12, said first actuator further comprising a first via contact for transmitting the first signal from the connecting terminal to said first bottom electrode, said first via contact being formed in a first via hole which is formed from a central portion of said first active layer to the connecting terminal through said first bottom electrode and said first supporting layer, and said second actuator further comprising a second via contact for transmitting the first signal from the connecting terminal to said second bottom electrode, said second via contact being formed in a second via hole which is formed from a central portion of said second active layer to said connecting terminal through said second bottom electrode and said second supporting layer.

14. A method for manufacturing a thin film actuated mirror array comprising the steps of:

providing an active matrix having electrical wiring and a connecting terminal for receiving a first signal from outside and transmitting the first signal;

forming a first sacrificial layer on said matrix;

patterning said first sacrificial layer to expose a first portion and a second portion of said active matrix where the connecting terminal is formed, and to expose a third portion of said active matrix in perpendicular direction to the first exposed portion and the second exposed portion;

forming a first layer, a bottom electrode layer, a second layer, and a top electrode layer on the exposed portions of said active matrix and on the first sacrificial layer;

forming a first actuator and a second actuator in parallel by patterning said top electrode layer to form a first top electrode and a second top electrode for respectively receiving a second signal and respectively generating a first electric field and a second electric field, by patterning said second layer to form a first active layer and a second active layer respectively deformed by the first electric field and the second electric field, by patterning said bottom electrode layer to form a first bottom electrode and a second bottom electrode for respectively receiving the first signal, and by patterning said first layer to form a first supporting layer having a central portion attached to the first exposed portion of said active matrix and lateral portions formed on said first sacrificial layer, and to form a second supporting layer having a central portion attached to the second exposed portion of said active matrix and lateral portions formed on said first sacrificial layer;

forming a supporting means by patterning said top electrode layer to form a third top electrode, by patterning said second layer to form a third active layer, by patterning said bottom electrode layer to form a third bottom electrode, and by patterning said first layer to form a third supporting layer attached to the third exposed portion of said active matrix;

forming a second sacrificial layer on said first actuator, on said second actuator, and on said supporting means;

patterning the second sacrificial layer to expose lateral portions of said first top electrode, lateral portions of said second top electrode, and a portion of said third top electrode;

forming a reflective metal on the exposed portion of said first top electrode, said second top electrode, and said third top electrode, and on the second sacrificial layer;

forming a first post on said first top electrode, forming a second post on said second top electrode, forming a third post on said third top electrode; and

forming a reflecting means by patterning the reflective metal.

15. The method for manufacturing the thin film actuated mirror array as claimed in claim 14, the step of forming said first actuator further comprising forming a first via hole from a central portion of said first active layer to the connecting terminal and forming a first via contact for connecting said first bottom electrode and the connecting terminal in the first via hole, and the step of forming said second actuator further comprising forming a second via hole from a central portion of said second active layer to the connecting terminal and forming a second via contact for connecting said second bottom electrode and the connecting terminal in the second via hole.

16. The method for manufacturing the thin film actuated mirror array as claimed in claim 14, wherein the step of forming the second sacrificial layer is performed by using a spin on polymer or photoresist.

17. The method for manufacturing the thin film actuated mirror array as claimed in claim 14, the step of forming said reflecting means further comprising removing the second sacrificial layer by using oxygen plasma and removing the first sacrificial layer by using a vapor of hydrogen fluoride.