Micromechanical display logic and array

• US 4,229,732 A
• Filed: 12/11/1978
• Issued: 10/21/1980
• Est. Priority Date: 12/11/1978
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Petersen, Kurt E., Hartstein, Allan M.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US05/968,054
• Time in Patent Office: 680 Days
• Field of Search: 340/719, 340/764, 340/373, 340/378.2, 358/230, 358/233, 29/592, 315/373
• US Class Current: 340/815.4
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A display device, addressing circuitry, and semiconductor control logic are all portions of an integrated structure formed by thin film technology on a single silicon wafer. The display comprises a thin film micromechanical electrostatic form of light reflective display formed by depositing thin films upon a silicon wafer and selectively etching to form metal-amorphous oxide micromechanical leaves deflected by applying potential thereto to provide electrostatic deflection. MOSFET devices are also formed upon the silicon wafer in juxtaposition with a plurality of micromechanical display elements. Addressing circuitry is connected to the MOSFET devices.

Claims

1. A display device suitable for X-Y matrix addressing comprising:

a (100) oriented p-Si wafer;

a first layer of silicon containing regions of heavily boron doped (p³⁰) type silicon on the order of 5×

10¹⁹ cm^-3 as an etchant barrier;

a second layer of silicon having a thickness of 5-10 μ

m taken from the group consisting of p-type and n-type positioned on top of said first layer;

a layer of SiO₂ 3000-5000 A thick above said second layer of silicon;

an MOS device formed in said second layer;

a plurality of hinged, electrostatically deflectable, metal coated oxide display members in spaced relation with said boron doped regions in said first layer and connected with a portion of said second layer, whereby said heavily boron doped region serves as a conductive region below each of said display members for provision of electrostatic control signals to said display member;

metallization forming the metal surface on said display members and forming an electrical x-y control matrix array deposited upon said layer of SiO₂ comprising Al/Au/Cr about 500 A thick; and

each of said display members comprising a leaf element hinged to said second layer at one small portion of the edge thereof, said leaf element being located above a hollow space in said display device.

5. A display device in accordance with claim 1 wherein each of said leaf elements comprises a substantially square structure hinged at one corner.

2. A display device comprising addressing circuitry, and semiconductor control logic deposited on an integrated structure formed by thin film technology on a single silicon wafer, said display device comprising an array of thin film micromechanical electrostatic form of light reflective display elements formed by depositing a thin film of an underlayer of an etchant resistant conductive film forming an electrode and subsequently depositing other thin films upon a semiconductor wafer and selectively etching to form metal-amorphous oxide micromechanical leaves, means for deflecting said leaves by applying potential thereto to provide electrostatic deflection and storage by operation of semiconductor logic devices formed upon said wafer in juxtaposition with said display elements, with matrix addressing means for activating said logic devices selectively and individually.

3. A display device in accordance with claim 2 wherein each of said micromechanical elements includes a hollow space below it with a conductive region in said wafer therebelow for providing one electrode with said element forming another electrode for providing electrostatic forces therebetween.

4. A display device in accordance with claim 2 wherein said logic devices are formed with electrical connections directly to a said juxtaposed micromechanical element, with a picture element of said display including at least one of said micromechanical elements and with a logic device provided for each of said picture elements of said display device located in juxtaposition with each micromechanical element for said picture element.

6. A display device in accordance with claim 2 wherein each of said display elements comprises a substantially square leaf element hinged at one corner thereof to said wafer above a hollow space in said wafer.

7. A display device in accordance with claim 3 wherein each of said micromechanical elements comprises a substantially square leaf element hinged at one corner thereof to said wafer above said hollow space.

8. A display device comprising addressing circuitry, and semiconductor control logic deposited on an integrated structure formed by thin film technology on a single silicon wafer;

said display device comprising an array of thin film micromechanical electrostatic form of light reflective display elements formed by depositing thin films upon a semiconductor wafer and selectively etching to form metal coated amorphous oxide micromechanical leaves;

means for deflecting said leaves by applying potential thereto to provide electrostatic deflection and storage by operation of semiconductor logic devices formed upon said wafer in juxtaposition with said display elements with addressing means for activating said logic devices selectively;

each of said micromechanical elements located above a hollow space in said wafer with a conductive region in said wafer below said hollow space for providing one electrode with said element forming another electrode for providing electrostatic forces therebetween;

said logic devices being formed with electrical connections directly to a said juxtaposed micromechanical element with a picture element of said display including at least one of said micromechanical elements and with a logic device provided for each of said picture elements of said display device located in juxtaposition with each micromechanical element for said picture element;

said wafer being coated with a first layer of silicon containing regions of heavily boron doped (p³⁰) type silicon on the order of 5×

10¹⁹ cm^-3 as a barrier for etching and forming said conductive regions below said micromechanical elements;

a second layer of silicon having a thickness of 5-10 μ

m taken from the group consisting of p-type and n-type positioned on top of said first layer

a layer of SiO₂ 3000-5000 A thick above said second layer of silicon;

a plurality of MOS devices formed in said second layer; and

each of said display elements comprising a substantially square leaf element hinged at one corner thereof to said wafer above said hollow space in said wafer with said metal coated oxide display elements in spaced relation with each of said boron doped regions in said first layer and connected with a portion of said second layer.