Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/015—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
  • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
  • G02B26/0858—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting means being moved or deformed by piezoelectric means
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/0102—Constructional details, not otherwise provided for in this subclass
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2203/00—Function characteristic
  • G02F2203/02—Function characteristic reflective

Definitions

• the present invention relates to an optical projection system; and, more particularly, to an array of M x N thin film actuated mirrors for use in the system and a method for the manufacture thereof, wherein each of the thin film actuated mirrors i ⁇ provided with a multilayer stack of dielectric members successively formed on top of each of the thin film actuated mirrors to produce an optimum optical efficiency thereof.
• an optical projection system is known to be capable of providing high quality displays in a large scale.
• light from a lamp is uniformly illuminated onto an array of, e.g., M x N, thin film actuated mirrors, wherein each of the mirrors is coupled with each of the actuators.
• the actuators may be made of an electrodisplacive material such as a piezoelectric or an electrostrictive material which deforms in response to an electric field applied thereto.
• the reflected light beam from each of the mirrors is incident upon an aperture of, e.g., an optical baffle.
• an electrical signal to each of the actuators, the relative position of each of the mirrors to the incident light beam is altered, thereby causing a deviation in the optical path of the reflected beam from each of the mirrors.
• the optical path of each of the reflected beams is varied, the amount of light reflected from each of the mirrors which passes through the aperture is changed, thereby modulating the intensity of the beam.
• the modulated beams through the aperture are transmitted onto a projection screen via an appropriate optical device such as a projection lens, to thereby display an image thereon.
• Figs. IA to IG there are illustrated manufacturing steps involved in preparing an array 10 of M x N thin film actuated mirrors 11, wherein M and N are integers, disclosed in a copending commonly owned application, U.S. Ser. No. 08/430,628, entitled "THIN FILM ACTUATED MIRROR ARRAY".
• the process for manufacturing the array 10 begins with the preparation of an active matrix 20 comprising a substrate 22, an array of M x N transistors(not shown) and an array of M x N connecting terminals 24.
• a thin film sacrificial layer 40 by using a sputtering or an evaporation method if the thin film sacrificial layer 40 is made of a metal, a chemical vapor deposition(CVD) or a spin coating method if the thin film sacrificial layer 40 is made of a phosphor-silicate glass(PSG), or a CVD method if the thin film sacrificial layer 40 is made of a poly-Si.
• CVD chemical vapor deposition
• PSG phosphor-silicate glass
• a supporting layer 15 including an array of M x N supporting members 30 surrounded by the thin film sacrificial layer 40 wherein the supporting layer 15 is formed by: creating an array of M x N empty slots(not shown) in the thin film sacrificial layer 40 by using a photolithography method, each of the empty slots being located around the connecting terminals 24; and forming a supporting member 30 in each of the empty slots by using a sputtering or a CVD method, as shown in Fig. IA.
• the supporting members 30 are made of an insulating material.
• an elastic layer 70 made of the same insulating material as the supporting members 30 is formed on top of the supporting layer 15 by using a Sol- Gel, a sputtering or a CVD method.
• a conduit 35 made of a metal is formed in each of the supporting members 30 by: first creating an array of M x N holes(not shown), each of the holes extending from top of the elastic layer 70 to top of the connecting terminals 24, by using an etching method; and filling therein with the metal to thereby form the conduit 35, as shown in Fig. IB.
• a second thin film layer 60 made of an electrically conducting material is formed on top of the elastic layer 70 including the conduits 35 by using a sputtering method.
• the second thin film layer 60 is electrically connected to the transistors through the conduits 35 formed in the supporting members 30.
• a piezoelectric material e.g., lead zirconium titanate(PZT)
• the thin film electrodisplacive layer 80, the second thin film layer 60 and the elastic layer 70 are patterned into an array of M x N thin film electrodisplacive members 85, an array of M x N second thin film electrodes 65 and an array of M x N elastic members 75 by using a photolithography or a laser trimming method until the supporting layer 15 is exposed, as shown in Fig. ID.
• Each of the second thin film electrodes 65 is connected electrically to a corresponding transistor through the conduit 35 formed in each of the supporting members 30 and functions as a signal electrode in each of the thin film actuated mirrors 11.
• each of the thin film electrodisplacive members 85 is heat treated to allow a phase transition to take place to thereby form an array of M x N heat treated structures(not shown). Since each of the thin film electrodisplacive members 85 is sufficiently thin, there is no need to pole it in case it is made of a piezoelectric material: for it can be poled with the electric signal applied during the operation of the thin film actuated mirrors 11.
• an electrically conducting and light reflecting material e.g., aluminum(Al) or silver(Ag
• each of the actuated mirror structures 95 includes a top surface and four side surfaces, as shown in Fig. IF.
• Each of the first thin film electrodes 55 functions as a mirror as well as a bias electrode in each of the thin film actuated mirrors 11.
• the preceeding step is then followed by completely covering the top ⁇ urface and the four side surfaces in each of the actuated mirror structures 95 with a thin film protection layer(not shown).
• the thin film sacrificial layer 40 in the supporting layer 15 is then removed by using an etching method.
• the thin film protection layer is removed by using an etching method to thereby form the array 10 of M x N thin film actuated mirrors 11, as shown in Fig. IG.
• a primary object of the present invention to provide an array of M x N thin film actuated mirrors capable of ensuring an optimum optical efficiency and a method for the manufacture thereof.
• an array of M x 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 x N connecting terminals and an array of M x N transistors, wherein each of the connecting terminals is electrically connected to a corresponding transi ⁇ tor in the array of M x N transistors; M x N conduits, wherein each of the conduits is made of an electrically conducting material; an array of M x 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
• a method for the manufacture of an array of M x N thin film actuated mirrors comprising the steps of: providing an active matrix including a substrate, an array of M x N connecting terminals and an array of M x N transistors, wherein each of the connecting terminals is electrically connected to a corresponding transi ⁇ tor; depositing a thin film sacrificial layer on top of the active matrix; creating an array of M x N empty slots in the thin film sacrificial layer, each of the empty slot ⁇ being located around top of the connecting terminals; depo ⁇ iting an ela ⁇ tic layer made of an insulating material on top of the thin film ⁇ acrificial layer while filling the empty slots; forming an array of M x 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 ⁇ econd thin film layer, a thin film electrodi ⁇ placive
• FIGS. IA to IG illustrate schematic cross sectional views setting forth manufacturing steps for an array of M x N thin film actuated mirrors previously disclosed;
• Fig. 2 presents a cross sectional view of an array of M x N thin film actuated mirrors in accordance with the present invention
• Figs. 3A to 3F provide schematic cros ⁇ ⁇ ectional views explaining the present method for manufacturing the array of M x N thin film actuated mirrors shown in Fig. 2.
• FIGs. 2 and 3A to 3F there are provided a cross sectional view of an array 200 of M x N thin film actuated mirrors 201, wherein M and N are integers, for use in an optical projection system and schematic cross sectional views setting forth a method for the manufacture thereof, respectively. It should be noted that like parts appearing in Figs. 2 and 3A to 3F are represented by like reference numerals.
• FIG. 2 there is provided a cros ⁇ sectional view of an array 200 of M x N thin film actuated mirrors 201 in accordance with one embodiment of the present invention, the array 200 including an active matrix 210, M x N conduits 225, an array of M x N actuating structures 300 and M x N number of multilayer stacks 400 of thin film dielectric members 401.
• the array 200 including an active matrix 210, M x N conduits 225, an array of M x N actuating structures 300 and M x N number of multilayer stacks 400 of thin film dielectric members 401.
• FIG. 2 there is shown an array 200 of M x N thin film actuated mirrors 201, each of the thin film actuated mirrors 201 having a multilayer stack 400 of thin film dielectric members 401, wherein the multilayer stack 400 consists of a pair of thin film dielectric members 401.
• the active matrix 210 includes a substrate 212, an array of M x N connecting terminals 214 and an array of M x N tran ⁇ istors(not shown), wherein each of the connecting terminals 214 is electrically connected to a corresponding transi ⁇ tor.
• Each of the actuating structures 300 is provided with a connecting and a light reflecting portions 330, 335, and includes an elastic member 235, a second thin film electrode 245, a thin film electrodisplacive member 255 and a first thin film electrode 265.
• Each of the conduits 225 made of an electrically conducting material i ⁇ located at the connecting portion 330 in each of the actuating structures 300, extending from bottom of the second thin film electrode 245 to top of a corresponding connecting terminal 214 connected electrically to the transistor, thereby electrically connecting the second thin film electrode 245 to the transistor, allowing the second thin film electrode 245 to function as a signal electrode in each of the thin film actuated mirrors 201.
• the first thin film electrode 265 made of an electrically conducting and light reflecting material, e.g., Al, is electrically connected to ground, allowing it to function as a mirror as well as a bias electrode in each of the thin film actuated mirrors 201.
• Each of the multilayer stacks 400 of thin film dielectric members 401 is placed on top of the light reflecting portion 335 in each of the actuating structures 300, wherein each of the thin film dielectric members 401 has a predetermined thickness and a specific refractive index.
• the characteristic reflectance R of a metal in air at normal incidence is l+[2n/ (l + n 2 + k 2 ))
• n and k are the refractive index and the extinction coefficient of the metal, respectively.
• the optical reflectance R thereof in air at normal incidence is
• the reflectance of any metal can be boosted by a pair of quarter-wave layers for which (n 1 /n.)>l, n, being on the outside and n 2 next to the metal.
• the higher this ratio the greater the increase in the reflectance.
• the reflectance of each of the thin film actuated mirrors 201 in the array 200 can be maximized by optimizing the thickness and the refractive index of each of the thin film dielectric members 401 constituting the multilayer stack 400, the number of thin film dielectric members 401 and the incidence through a simulation.
• Figs. 3A to 3F there are provided schematic cross sectional views explaining a method for the manufacture of the array 200 of M x N thin film actuated mirrors 201 shown in Fig. 2.
• the proces ⁇ for the manufacture of the array 200 begins with the preparation of an active matrix 210 including a substrate 212, an array of M x N connecting terminals 214 and an array of M x N transistors (not shown), wherein the substrate 212 is made of an insulating material, e.g., Si-wafer.
• a thin film sacrificial layer 220 having a thickness of 0.1 - 2 ⁇ m, and made of a metal, e.g., copper(Cu) or nickel(Ni) , a phosphor- ⁇ ilicate glass (PSG) or a poly-Si, is formed on top of the active matrix 210.
• the thin film sacrificial layer 220 is formed by using a sputtering or an evaporation method if the thin film sacrificial layer 220 is made of a metal, a chemical vapor deposition(CVD) method or a spin coating method if the thin film sacrificial layer 220 is made of a PSG, or a CVD method if the thin film sacrificial layer 220 is made of a poly-Si.
• an array of M x N empty slots (not shown) in the thin film sacrificial layer 220 by using a photolithography method.
• Each of the empty slots is located around top of the connecting terminals 214.
• an elastic layer 230 made of an insulating material, e.g., silicon nitride, and having a thicknes ⁇ of 0.1 - 2 ⁇ m, is deposited on top of the thin film sacrificial layer 220 including the empty slots by using a Sol-Gel, a sputtering or a CVD method.
• each of the conduits 225 is formed by: first creating an array of M x N holes(not shown), each of the holes extending from top of the elastic layer 230 to top of the connecting terminals 214 by using an etching method; and filling therein with the metal by using a sputtering method, as shown in Fig. 3A.
• a second thin film layer 240 made of an electrically conducting material, e.g., platinum(Pt) or platinum/titanium(Pt/Ti) , and having a thickness of 0.1 - 2 ⁇ m, is formed on top of the elastic layer 230 and the conduits 225 by using a sputtering or a vacuum evaporation method.
• an electrically conducting material e.g., platinum(Pt) or platinum/titanium(Pt/Ti)
• a thin film electrodisplacive layer 250 made of a piezoelectric material, e.g., lead zirconium titanate(PZT) , or an electrostrictive material, e.g., lead magnesium niobate(PMN) , and having a thickness of 0.1 - 2 ⁇ m, is deposited on top of the second thin film layer 240 by using a vacuum evaporation or a sputtering method.
• the thin film electrodisplacive layer 250 is then heat treated to allow a phase transition to take place.
• a first thin film layer 260 made of an electrically conducting and light reflecting material, e.g., aluminum(Al) or silver(Ag), and having a thickness of 0.1 - 2 ⁇ , is formed on top of the thin film electrodisplacive layer 250 by using a sputtering or a vacuum evaporation method, as shown in Fig. 3B.
• the first thin film layer 260, the thin film electrodisplacive layer 250, the second thin film layer 240 and the elastic layer 230 are, respectively, patterned until the thin film sacrificial layer 220 i ⁇ exposed, thereby forming an array 340 of M x N semifinished actuating structure ⁇ 341, a ⁇ ⁇ hown in Fig. 3C, wherein each of the ⁇ emifini ⁇ hed actuating ⁇ tructures 341 includes a first thin film electrode 265, a thin film electrodisplacive member 255, a second thin film electrode 245 and an elastic member 235.
• the second thin film electrode 245 in each of the semifinished actuating structure ⁇ 341 is electrically connected to the tran ⁇ istor through a corresponding conduit 225 and a corresponding connecting terminal 214, thereby functioning as a signal electrode in each of the thin film actuated mirrors 201.
• the first thin film electrode 265 in each of the semifini ⁇ hed actuating structure ⁇ 341 functions as a mirror and a bias electrode in each of the thin film actuated mirrors 201.
• a plurality of thin film dielectric layer(not shown) is deposited successively on top of the semifinished actuating structures 341 including the exposed thin film sacrificial layer 220 by using a sputtering or an evaporation method.
• Each of the thin film dielectric layers has a predetermined thickness and a refractive index. Again for the sake of simplicity, only two thin film dielectric layers are shown.
• the plurality of thin film dielectric layers are patterned, respectively, until the thin film sacrificial layer 220 is exposed again, into M x N number of multilayer stack ⁇ 400 of thin film dielectric member ⁇ 401 by u ⁇ ing a photolithography or a laser trimming method, thereby forming an array 320 of M x N semifinished actuated mirrors 321, as shown in Fig. 3D.
• the plurality of thin film dielectric layers are patterned in such a way that each of the semifinished actuated mirror ⁇ 321 ha ⁇ an actuating and a light reflecting portion ⁇ 330, 335, wherein each of the conduits 225 i ⁇ located at the actuating portion 330 in each of the semifini ⁇ hed actuated mirrors 321, and each of the multilayer stacks 400 of thin film dielectric members 401 is located at the light reflecting portion 335 in each of the semifinished actuated mirror ⁇ 321.
• Each of the semifinished actuated mirrors 321 include ⁇ the multilayer ⁇ tack 400 of thin film dielectric members 401, the fir ⁇ t thin film electrode 265, the thin film electrodisplacive member 255, the second thin film electrode 245 and the elastic member 235.
• each of the semifinished actuated mirrors 321 is completely covered with a thin film protection layer 290 to thereby form an array 310 of M x N protected actuated mirrors 311, as shown in Fig. 3E.
• the thin film sacrificial layer 220 is then removed by using an etching method.
• the thin film protection layer 290 i ⁇ removed to thereby form the array 200 of M x N thin film actuated mirror ⁇ 201, a ⁇ ⁇ hown in Fig. 3F.
• each of the thin film actuated mirrors 201 prepared using the inventive method has a unimorph ⁇ tructure
• the inventive method can be equally applied to manufacturing an array of thin film actuated mirror ⁇ , each of the thin film actuated mirror ⁇ having a bimorph structure, for the latter ca ⁇ e just involves the formation of an additional electrodisplacive layer and an additional electrode layer.
• inventive method may be modified to allow the manufacture of an array of thin film actuated mirrors having different geometries.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Nonlinear Science (AREA)
• Mechanical Light Control Or Optical Switches (AREA)
• Optical Elements Other Than Lenses (AREA)
• Transforming Electric Information Into Light Information (AREA)
• Video Image Reproduction Devices For Color Tv Systems (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)
• Liquid Crystal (AREA)
• Projection Apparatus (AREA)
• Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)

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• 1996
  • 1996-01-04 TW TW085100044A patent/TW348324B/zh active
  • 1996-01-31 KR KR1019960002315A patent/KR100229790B1/ko not_active IP Right Cessation
  • 1996-03-04 AR AR33563296A patent/AR001149A1/es unknown
  • 1996-03-20 PE PE1996000192A patent/PE47197A1/es not_active Application Discontinuation
  • 1996-03-22 UY UY24186A patent/UY24186A1/es not_active IP Right Cessation
  • 1996-04-08 PL PL96322490A patent/PL179839B1/pl unknown
  • 1996-04-08 WO PCT/KR1996/000048 patent/WO1997028653A1/en not_active Application Discontinuation
  • 1996-04-08 HU HU9801148A patent/HUP9801148A3/hu unknown
  • 1996-04-08 CN CN96192838A patent/CN1104815C/zh not_active Expired - Fee Related
  • 1996-04-08 CA CA002216557A patent/CA2216557A1/en not_active Abandoned
  • 1996-04-08 JP JP52750197A patent/JP4152437B2/ja not_active Expired - Fee Related
  • 1996-04-08 CZ CZ973041A patent/CZ304197A3/cs unknown
  • 1996-04-08 AU AU52899/96A patent/AU724477B2/en not_active Ceased
  • 1996-04-08 BR BR9607803A patent/BR9607803A/pt not_active Application Discontinuation

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