JP3768514B2 - Micromirror device, package for micromirror device, and projection system therefor - Google Patents

Abstract

A micro-mirror (24) is connected to a substrate (10) via a post (21), a hinge (18c), a post (16c) and metal areas (12a) and an array of the micro-mirrors is disposed in a rectangular shape with a capability of rotation around a switching axis between on and off states corresponding to pixels in a viewed image. Light is directed from a source to the mirrors non-perpendicularly to at least two sides of each mirror, while reflected light is received from collection optics. Independent claims are included for an array of movable micro-mirrors, for a method of positioning an image on a target, for a method of spatially modulating light beams, for an optical micro-mirror element, for a packaged micro-electromechanical device and for a method of making a micro-mirror.

Description

  The present invention relates to a movable micromirror and a micromirror array in a projection display or the like. Huybers U.S. Pat. Nos. 5,835,256 and 6,046,840 and Huybers et al U.S. patent application 09 / 617,419 include, for example, optical switches and / or displays (e.g., projection displays), etc. Microelectromechanical devices (MEMS) for guiding light have been disclosed, the contents of which are hereby incorporated herein by reference. As a general function, the micromirror element is movable, and there is an apparatus that sends light to various angles depending on the inclination angle of the micromirror element. Conventional direct view or projection display systems are provided with an array of reflective micromirror elements to form an image. The micromirror element is usually square and has a certain tilt angle to bring it to the “on” state, is horizontal in the “off” state, or tilt angles between the “on” and “off” states. Are the same, but the opposite is positive.

  In the present invention, in order to minimize light diffraction in the switching direction, in particular, light diffraction into the light receiving cone of the condensing system, it is not rectangular (here, “rectangular” includes square micromirrors). Provide micromirrors. Here, diffraction means scattering of light by a periodic structure, and this light is not necessarily monochromatic or coherent. In addition, in order to minimize the cost of the illumination system and the size of the display unit in the present invention, the light sources are arranged perpendicular to the rows (or columns) of the array, and together with or instead of the light sources. Are arranged perpendicular to the sides of the frame defining the effective area. The incident light is perpendicular to the rows (or columns) and / or the sides of the effective area, but not substantially perpendicular to the sides of the individual micromirrors in the array. The vertical side surface diffracts incident light in the switching direction of the micromirror, and even if the micromirror is in the “off” state, light leaks in the direction of the “on” state. This diffraction reduces the contrast ratio of the micromirror.

  The present invention optimizes the contrast ratio of the micromirror array so that when the micromirror is in the “off” state, the light that is mixed into the spatial area into which the light should be sent when the micromirror is in the “on” state is minimized. Turn into. More specifically, the present invention provides a specially arranged light source and incident light, in order to minimize the light diffracted into the light receiving cone of the projection (or viewing) system and improve the contrast ratio. It has micromirrors in the designed array. The structure and design of the present invention reduces the diffraction from the “off” to “on” state and increases the filling factor even when the micromirror is irradiated on a periodic axis in the array. By allowing tight alignment, non-reflective locations in the array are minimized. Specifically, this design optimizes the contrast ratio by providing an angular side surface that is non-parallel to the rotation axis of the micromirror, while requiring a relatively small area and suppressing unnecessary non-reflection areas. The filling rate is optimized by using a hinge that allows tiles of adjacent micromirrors to be tiled. The structure and shape of the micromirror in each embodiment of the present invention can further reduce crosstalk between adjacent micromirrors when the micromirror is electrostatically bent.

  A further aspect of the invention is a micromirror array in which individual micromirrors are tilted asymmetrically from a horizontal or undeflected state. By making the angle in the “off” state of the micromirror smaller than the reverse angle in the “on” state of the micromirror, a) the light that is diffracted from the edge of the micromirror and enters the focusing system is minimized, b) Light that scatters from under the micromirror and enters the light collection system is minimized; c) The displacement distance of the micromirror is shortened, and the possibility that adjacent micromirrors contact each other is minimized. It is possible to reduce the gap between the mirrors and increase the filling rate of the micromirror array, and d) to increase the deflection angle of the micromirror compared to the micromirror array structure having the same deflection angle in the on and off states. it can.

  A further aspect of the present invention is a package for a micromirror array having a light transmitting portion that is not parallel to the substrate on which the micromirror is formed. The translucent part is made of a suitable material such as glass, quartz, or polymer, and sends the specular reflection by the translucent substrate in a direction different from the direction when the translucent plate of the packaging is parallel. Preferably, the specular reflection is sent to a location far from the condensing system so that the specular reflection does not enter the condensing system when the illumination cone is made larger.

  A further aspect of the present invention is an active micromirror array, a micromirror, which can be rotated around a switching axis between an off state and an on state, and which is arranged in a rectangular shape corresponding to a pixel of an image to be viewed. A light source for sending light to the array, as viewed from the top of each micromirror, non-perpendicular to at least two sides of each micromirror and to at least the other two sides of each micromirror In some cases, a projection system comprising a light source arranged to transmit light in parallel and a light collection system arranged to receive light from an on-state micromirror.

  A further aspect of the present invention is a micromirror array, wherein each micromirror corresponds to a pixel of the image being viewed and has a shape consisting of a concave polygon or one or more non-rectangular parallelograms. A projection system comprising: a light source for sending light to the micromirror array; and a light collection system arranged to receive the light reflected from the micromirror.

  A still further aspect of the invention is a projection system comprising a light source for supplying incident light, an array of movable reflective elements, and a light collection system for projecting light from the array, from the projection system. The projected image is projected on the target as a rectangular image, and the image is composed of thousands to millions of pixels, and each pixel has a concave polygon, a single non-rectangular parallelogram or A projection system comprising a combination of a plurality of non-rectangular parallelograms.

  A further aspect of the invention is a projection system comprising a light source, an array of movable micromirror elements, and a collection system, each micromirror element in the array being on at least one side of the effective area of the array. A projection system having a switching axis that is substantially parallel to the micromirror element and has an angle of 35 to 60 degrees with respect to one or more sides of the micromirror element.

  A further aspect of the invention is a projection system comprising a light source and an array of movable micromirror elements, each micromirror element being non-perpendicular to the incident light and for each side of the effective area. By having a non-vertical head side, the projection system achieves an increase in contrast ratio of 2 to 10 times compared to a micromirror element having a side surface perpendicular to incident light.

  A further aspect of the invention is a projection system comprising a light source, a collection system, and an array of movable micromirror elements, having a diffraction pattern substantially identical to that shown in FIG. 21C.

  A further aspect of the invention is a projection system comprising a rectangular array of light sources and movable micromirrors, wherein the micromirrors can be displaced between an on state and an off state, and in the on state the light is given a predetermined spatial Reflected into the area, the light source is arranged to send light at substantially 90 degrees relative to at least one side of the rectangle defined by the array, and diffracts into a predetermined spatial area when the micromirror is off The projection system is substantially free of incident light.

  A further aspect of the invention is a method for projecting an image on a target, wherein the array is a rectangular micromirror array, wherein the micromirrors in the array are polygonal in shape and the light is all polygonal Light so that light is introduced at an angle of 90 degrees plus / minus 40 degrees with respect to the leading side of the rectangular array for an array arranged to be incident at an angle other than 90 degrees to the side , Projecting light from the micromirror onto the target and forming an image thereon.

  A further part of the invention is a projection system comprising a light source, a light collection system, and a micromirror array arranged to spatially modulate the light from the light source, wherein the array is formed on a substrate, each Designed to be in a first position when the micromirrors are not driven, each micromirror can be displaced to an on position to introduce light into the collection system of the array, away from the collection system Can be displaced in the opposite direction to the off position where light is introduced into the projection, the on position and the off position are both different from the first position, and the angle of the on position with respect to the first position is different from the off position. System.

  A further aspect of the invention is a method for spatially modulating light, wherein the method is arranged to spatially modulate light from a light source, formed on a substrate, and first when not modulated. Light from the light source is introduced into the condensing system through the micromirror array at the position, and each micromirror is displaced to the on position to send light to the condensing system of the array, and the light is emitted to a place away from the condensing system The micromirrors in the array are modulated so that they are displaced to the off position, and the on and off positions are both different from the first position, and the angle of the on position to the first position is different from the angle of the off position Is the method.

  A further aspect of the present invention is an optical micromechanical device formed on a substrate, having an on position at a first angle with respect to the substrate and having an off position at a second angle with respect to the substrate. , Having a third position that is different from the first and second angles and substantially parallel to the substrate, and has an optical micromechanical element formed on or on the substrate at both on and off positions. This is an optical micromechanical element that is determined by touching.

  A further aspect of the present invention is a method for modulating light, comprising the step of reflecting light by a flexible micromirror array provided on a planar substrate, wherein the micromirror is in a first position. Alternatively, the angle is inclined to the second position, and the angle between the first position and the substrate is substantially different from the angle between the second position and the substrate.

  A further part of the invention is a method for modulating light comprising a light source, a planar light modulator array having flexible elements and a light collection system, the elements being in at least two states. The selectively placed, first state element sends light from the light source to the light collection system through a first angle, and the second state element sends light from the light source to the second angle. Through the condensing system and having a third angle that reflects light as if the array is a mirror surface, and the difference between the first and third angles and between the second and third angles is substantially Is a different method.

  A further aspect of the present invention provides a light source for supplying light, a micromirror array having a plurality of micromirrors provided on the light path, and light entering the micromirror array, and turning on the micromirrors in the array. A light collection system provided on the light path after being reflected from the plurality of micromirrors as an off pattern, the micromirror array having a substrate, and each micromirror being in the on position from the non-deflection position And a projection system in which the micromirror array is supported on the substrate so that it can be displaced to the off position, and the on position is at an angle different from the off position with respect to the non-deflection position.

  A further aspect of the invention is a method for projecting an image onto a target, wherein light from a light source is sent onto a micromirror array, each micromirror is modulated to an on or off position, The mirror sends light to the light collection system arranged to receive light from the micro mirror at the on position, and the pattern of the on and off micro mirrors forms an image, and the position of the micro mirror at the on position is the off position. In this method, the angle is different from the angle of the micromirror.

  A further aspect of the present invention is a method for spatially modulating light, wherein the light is sent over a micromirror array, and the micromirror can be displaced to a first or second position, at the first position. The micromirrors send a portion of the light incident on it to the light collection system, and the minimum distance between adjacent micromirrors each in the second position is the minimum between adjacent micromirrors each in the first position The method is smaller than the distance.

  A further aspect of the present invention comprises a substrate on which a movable reflective or diffractive micromechanical device is formed, and a package for receiving a substrate having the movable micromechanical device, wherein the package is relative to the substrate. An apparatus having non-parallel translucent windows.

  A further part of the invention comprises a light source, a light collection system, a substrate on which a movable reflective or diffractive micromechanical device is formed, and a package for housing a substrate having a movable micromechanical device, The package has a transparent window that is non-parallel to the substrate, the packaged micromechanical device is placed on the light path to modulate the light from the light source, and the light collection system is modulated A projection system arranged to collect light.

  Further portions of the invention were modulated by a light source, a substrate having a micromechanical device, a packaged MEMS device having a window in a package disposed at an angle to the substrate, and a packaged MEMS device. It is a projector provided with a condensing system arranged to receive light from a light source later.

  A further aspect of the invention is a method for manufacturing a micromirror, comprising providing a substrate, forming a first sacrificial layer on the substrate, patterning, and forming at least one hinge layer on the sacrificial layer. Patterning the at least one hinge layer to form at least one flexible hinge, forming a second sacrificial layer, patterning, and forming at least one mirror layer on the second sacrificial layer; Forming a mirror element by patterning the at least one mirror layer and releasing the micromirror by removing the first and second sacrificial layers.

  Further aspects of the invention include a substrate, a first column on the substrate, a flexible hinge having a base on the column, a second column coupled to an end of the flexible hinge, and a second column. 1 is an optical micromechanical device having a flat plate coupled to the.

  Microfabrication methods for movable micromirrors and micromirror arrays are disclosed in U.S. Pat. Nos. 5,835,256 and 6,046,840 to Huybers, the contents of which are hereby incorporated herein by reference. Introduce into the book. A similar method for manufacturing the micromirrors of the present invention is shown in FIGS. FIG. 1 is a top view showing an embodiment of the micromirror of the present invention. As can be seen in FIG. 1, columns 21a and 21b support micromirror plate 24 on a lower substrate having electrodes (not shown) for tilting micromirror plate 24 via hinges 120a and 120b. . Although not shown in FIG. 1, as will be described in detail below, thousands or millions of micromirrors 24 are provided, and incident light is reflected to project an image onto a viewer or target / screen. be able to.

  The micromirror 24 and other micromirrors in the array can be manufactured by various methods. FIGS. 2A through 2E (showing a cross-section along 2-2 in FIG. 1) illustrate one method of fabricating a micromirror on a translucent substrate and attaching it to a circuit board. This method is described in U.S. Provisional Patent Application No. 60 / 229,246, filed August 30, 2000, and U.S. Patent Application No. 09/732, filed December 7, 2000, in Irkoff et al. Further details are disclosed in US Pat. Although this method will be described with a light-transmitting substrate, other suitable substrates such as a semiconductor substrate on which a circuit is mounted can be used. When a semiconductor substrate such as single crystal silicon is used, in the IC process, it is preferable that the column of the micromirror is electrically connected to the third metal layer and a conductive material is used for at least some of the micromirrors. A method for manufacturing the micromirror directly on the circuit board (not through another translucent substrate) is described in more detail below.

  As can be seen in FIG. 2A, a translucent substrate 13 is provided (e.g., at least before further layers thereon) of glass (e.g., Corning 1737F or Eagle 2000), quartz, Pyrex (TM), sapphire, etc. is there. By arbitrarily adding a light shielding layer to the lower side of the light-transmitting substrate, the substrate can be easily handled during processing. This light shielding layer may be a TiN layer formed to a depth of 2000 mm by reactive sputtering on the back side of the translucent substrate, and may be removed after the processing is completed. The shape and dimensions of the substrate are arbitrary, but those having a standard wafer shape used in an integrated circuit manufacturing facility are preferable.

  As can be further seen in FIG. 2A, a sacrificial layer 14 such as amorphous silicon is first formed. The sacrificial layer may be any other material that can later be removed from under the material of the micromechanical structure (eg, SiO2, polysilicon, polyimide, novolac, etc.). The thickness of the sacrificial layer can be set in a wide range depending on the dimensions of the movable element / micromirror and the desired tilt angle, but the thickness is preferably 500 mm to 50,000 mm, and preferably about 5,000 mm. Particularly preferred. In addition to amorphous silicon, the sacrificial layer can be made of various types of polymers, photoresists or other organic materials (and, depending on the etchant used and the material chosen to be resistant to the etchant, polysilicon) , Silicon nitride, silicon dioxide, or the like). Optionally, an adhesion promoter (eg, SiO 2 or SiN) can be provided prior to forming the sacrificial material.

  In order to provide a contact portion between the substrate 13 and the subsequently formed micromechanical structure layer, a hole 6 having a diameter d is formed in the sacrificial layer. The holes can be formed by spin-coating a photoresist and applying light using a mask to increase or decrease the solubility of the resist (depending on whether the resist is positive or negative). The dimension of d depends on the final dimensions of the micromirror and the micromirror array, but may be 0.2 to 2 microns (preferably about 0.7 μm). After developing the resist to remove the resist around the holes, the holes are etched into the sacrificial amorphous silicon with chlorine or other suitable etchant (depending on the sacrificial material). Next, the remaining photoresist is removed by oxygen plasma or the like. The size of the holes in the sacrificial layer is arbitrary, but those having a diameter of 0.1 to 1.5 μm are preferred, and those having a diameter of about 0.7 ± 0.25 μm are particularly preferred. Etching is performed until an intermediate layer such as a glass / quartz substrate or an adhesion promoting layer is reached. Even if the translucent substrate is etched, the amount is preferably less than 2000 mm. If the sacrificial layer 14 is made of a material that can be directly patterned (eg, novolac or other photosensitive photoresist), there is no need to form and develop a further photoresist layer on the sacrificial layer 14. In this case, the photoresist sacrificial layer is patterned to remove the material around the holes 6 and optionally hardened before further layers are formed.

  At this point, as shown in FIG. 2B, the first structural layer 7 is formed by, for example, chemical vapor deposition. The material is preferably silicon nitride or silicon oxide formed by LPCVD (low pressure chemical vapor deposition) or PECVD (plasma chemical vapor deposition), but at this point polysilicon, metal or metal alloy, silicon carbide or organic compounds, etc. ( Of course, layers of any thin film material can be formed, including sacrificial layers and etchants can be adapted to the structural material used. The thickness of this first layer can be varied appropriately depending on the dimensions of the movable element and the desired stiffness of the element, but in certain embodiments the thickness of this layer is between 100 and 3200 mm, more preferably between 900 and 1100 mm. is there. As can be seen in FIG. 2B, layer 7 extends into the hole etched in the sacrificial layer.

  As can be seen in FIG. 2C, a second layer 8 is also formed. The material may be the same as the first layer (for example, silicon nitride) or different (silicon oxide, silicon carbide, polysilicon, etc.) and can be formed by chemical vapor deposition as in the first layer. . The thickness of the second layer may be larger or smaller than the first layer, and is determined by the movable element, the desired flexibility of the hinge, the material used, and the like. In some embodiments, the thickness of the second layer is between 50 and 2100 inches, preferably about 900 inches. In other embodiments, the first layer is formed by PECVD and the second layer is formed by LPCVD.

  In the embodiment shown in FIGS. 2A-2E, the first and second layers are both formed in portions that define movable (micromirror) elements and columns. Depending on the desired rigidity of the micromirror element, only one of the first and second layers can be formed around the micromirror element. Also, a single layer can be provided on the entire surface of the microstructure instead of the two layers 7,8, but this may involve a tradeoff between substrate stiffness and hinge flexibility. In addition, when a single layer is used, a portion forming the hinge can be partially etched to suppress the thickness of the portion and increase the flexibility of the hinge. Further, by providing more than two layers, it is possible to obtain a laminated movable element that is particularly desirable when the dimension of the movable element is large, such as when switching light beams in an optical switch. The material of this layer may be made of an alloy of metal and dielectric, or a compound of metal and nitrogen, oxygen or carbon (particularly a transition metal). Such other materials are disclosed in US Provisional Application No. 60 / 228,007, the contents of which are hereby incorporated by reference.

As seen in FIG. 2D, a reflective layer 9 is also formed. The reflective material may be any of gold, silver, titanium, aluminum and other metals, and alloys of multiple metals, but is preferably aluminum formed by PVD. The thickness of the metal layer is 50 to 2000 mm, preferably about 500 mm. For example, a passivation layer (not shown) such as a 10 to 1100 silicon oxide layer formed on the layer 9 by PECVD may be optionally added. Other metal deposition methods such as chemical fluid deposition or electroplating can also be used to form the metal layer 9. After layer 9 is formed, the photoresist is spin coated and patterned, and then the metal layer is etched with a suitable metal etchant. In the case of an aluminum layer, chlorine (or bromine) based chemistry (eg Cl ₂ and / or BCl ₃ (or Cl ₂ , CCl ₄ , Br 2, CBr _4, etc.), optionally preferably inert such as Ar and / or He, etc. Plasma / RIE etching used with diluting material) can be used. The reflective layer does not need to be formed last, and is formed directly on the sacrificial layer 14, formed between other layers constituting the micromirror element, or formed as the only layer constituting the micromirror element. It should be noted that can be done. However, depending on the processing method, it may be desirable to form the metal layer after the dielectric layer in view of the high temperature at which many dielectrics are formed.

Referring to FIG. 2E, the reflective layer may be followed by etching the first and second layers 7, 8 with a known etchant or combination of etchants (depending on the materials used and the desired isotropicity). it can. For example, the first and second layers are etched using a chlorine-based chemical methods or fluorine-based (or other halogen) chemical methods _{(e.g., F 2, CF 4, CHF} 3, C 3 F 8, CH 2 F ₂ , C ₂ F ₆ , SF _6, etc., or more generally a combination of the above-mentioned compounds or other gases such as CF ₄ / H ₂ , SF ₆ / Cl ₂ , or multiple etchings such as CF ₂ Cl ₂ Plasma / RIE etching) using a seeded gas, all with one or more optional inert diluent materials. Of course, when different materials are used for the first layer and the second layer, it is also possible to employ different etching agents (plasma etching chemistry using materials well known in the art) for each layer. If a reflective layer is formed before the first and second layers, the etching chemistry is reversed. Also, depending on the materials used, all layers can be etched together. The gaps 20 a and 20 b having the width e shown in FIG. 2E are for separating the column 21 from the micromirror body 22.

  3A to 3D show the same process from another cross-section (cross-section 3-3 in FIG. 1), and shows a sacrificial layer 14 formed on the translucent substrate 13. FIG. A structural layer 7 is formed on the sacrificial layer 14. As can be seen in FIGS. 3B and 3C, a portion of layer 7 is removed prior to adding layers 8 and 9. This removed portion is the periphery of the place where the hinge is formed, and is for improving the flexibility of the hinge portion. The method of “shaving” the hinge portion in this way is based on US Patent Provisional Application No. 60 / 178,902 filed Jan. 28, 2000 and Tru, et al. Filed Jan. 22, 2001. U.S. Provisional Application No. 09 / 767,632, the contents of which are hereby incorporated by reference. After removing part of layer 7, layers 8 and 9 are added and layers 7, 8 and 9 are patterned as described above. As seen in FIG. 3D, the width a of the hinge 23 is 0.1 to 10 μm, preferably 0.7 μm. The hinges 23 are separated from each other by a gap b, and are separated from adjacent micromirror plates by a gap c. These dimensions are also 0.1 to 10 μm, preferably 0.7 μm.

The process steps outlined above can be performed in various ways. For example, a glass wafer (eg, Corning 1737F, Eagle 2000, quartz or sapphire wafer) is prepared, and the back side of the wafer is 2000 mm thick (depending on the material) to make the transparent substrate temporarily opaque for convenience of handling. More) Cr, Ti, Al, TaN, polysilicon or TiN, or other opaque coating. Next, according to FIGS. 1 to 4, an arbitrary adhesive layer (for example, a material having a silicon dangling bond such as SiN _{x -} or SiO _x , or a conductive material such as glassy carbon or indium tin oxide) is formed. After that, a sacrificial material made of hydrogenated amorphous silicon is deposited on a transparent wafer by a plasma chemical vapor deposition system such as Applied Materials P5000 to a thickness of 5000 Å (gas = SiH 4 (200 sccm), Ar 1500 sccm, power = 100 W, pressure = 3. 5T, temperature = 380 ° C., electrode spacing = 350 mil, or gas = SiHy 150 sccm, Ar 100 sccm, power = 55 W, pressure = 3 Torr, temperature = 380 ° C., electrode spacing = 350 mil, or gas = SiH 4200 sccm, Ar 1500 sccm, power = 1 At 00W, temperature = 300 ° C., pressure = 3.5T, or process point between these settings). Also, the sacrificial material can be formed by LPCVD at 560 ° C., as described in US Pat. No. 5,835,256 by Huybers et al. The sacrificial material may be formed by sputtering or a material that does not contain silicon such as an organic material (which is later removed by, for example, plasma oxygen ash). The aSi is patterned (using a photoresist and etching with chlorine-based chemistry such as Cl2, BCl3, and N2) so as to form a hole for attaching the micromirror to the glass substrate. In order to stiffen the micromirror and adhere the micromirror to the glass, the first layer of silicon nitride is PECVD (RF power = 150 W, pressure = 3 Torr, temperature = 360 ° C., electrode spacing = 570 mil, gas = N 2 / SiH 4 / NH 3 (1500/25/10), or RF power = 127 W, pressure = 2.5 Torr, temperature = 380 ° C., gas = N 2 / SiH 4 / NH 3 (1500/25/10 sccm, electrode spacing = 550 mil, or power 175 W and other process parameters such as pressure 3.5 Torr are used to form a thickness of 900 Å and patterning (pressure = 800 mT, RF power = 100 to 200 W, electrode spacing = 0.8 to 1.1 mm, gas = CF4 / CHF3 / Ar (60 or 70/40 to 70/60 To 800 sccm) and He = 0 to 200 sccm) to remove silicon nitride around the portion where the micromirror hinge is to be formed.Next, PECVD (RF power = 127 W, pressure = 2.5 T, temperature = 380 ° C., Gas = N2 / SiH4 / NH3 (1500/25/10 sccm), electrode spacing = 550 mil) forms a second layer of silicon nitride with a thickness of 900 angstroms, followed by a temperature of 140-180 ° C, power = 2000 W, Al is sputtered onto the second silicon nitride layer to a thickness of 500 Å under the condition of Ar = 135 sccm, and the material is aluminum alloy (Al—Si (1%), Al—Cu (0 .5%) or AlSiCu or AlTi), or implantation or It can also be a get-doped aluminum, which is patterned by chlorine-based chemistry (pressure = 40 mT, power = 550 W, gas = BCl 3 / Cl 2 / N 2 = 50/15/30 sccm) at P5000. The SiN layer is etched (pressure = 100 mT, power = 460 W, gas = CF 4 / N 2 (9/20 sccm)) and ashed by H 2 O + O 2 + N 2 based chemistry in the plasma, then the remaining structure is cleaned with ACT (acetone + Dl wafer solution) (This cleaning process can also be performed by EKS265 EKS265 photoresist residue remover or other solvent-based cleaners from EKC Technology.) Resist coated on the front side of the microstructured wafer Later, the backside TiN is etched by BCl3 / Cl2 / CF4 system chemistry (or other metal etchants described in CRC Handbook of Metal Etchants) in plasma, or polished or ground by CMP, It is removed by an acidic gas such as HF, and then a second ACT cleaning (acetone + Dl wafer solution) and a second spin drying are performed. The wafer is singulated into individual molds and exposed to a 300 W CF4 plasma (pressure = 150 Torr, 85 sccm for 60 seconds followed by 300 seconds of etching in a mixture of He, XeF2 and N2 (etching pressure 158 Torr). Etching is performed by placing the mold into a chamber filled with about 400 Torr of N2. The second area / chamber is provided with 3.5 Torr for XeF2 and 38.5 Torr for He. By removing the partition between the two areas / chambers, an etching mixture with a combination of XeF2, He and N2 is obtained.

  In addition, a transparent wafer (for example, Corning 1737F) is coated on the back side of the glass wafer with TiN to a thickness of 2000 angstroms. Then, according to FIGS. 1-4, without using an adhesive layer, a sacrificial material of hydrogenated amorphous silicon with a thickness of 5300 angstroms was formed on the glass wafer by Applied Materials P5000 (power = 100 W, pressure = 3.5 T, Temperature = 300 ° C., SiH 4 = 200 sccm, Ar = 1500 sccm, or pressure = 2.5 Torr, power = 50 W, temperature = 360 ° C., electrode spacing = 350 mil, SiH 4 flow rate = 200 sccm, Ar flow rate = 2000 sccm). The aSi is patterned so as to form a hole for attaching the micromirror to the glass substrate (using a photoresist, etching with chlorine-based chemistry such as Cl2, BCl3, and N2-50W). In order to stiffen the micromirror and adhere the micromirror to the glass, the first layer of silicon nitride is PECVD (pressure = 3 Torr, 125 W, 360 ° C., spacing = 570, SiH4 = 25 sccm, NH3 = 10 sccm, N2 = 1500 sccm ) To a thickness of 900 angstroms, and patterning (CF4 / CHF3) is performed to remove silicon nitride around the portion where the micromirror hinge is to be formed. Next, a second layer made of silicon nitride having a thickness of 900 Å is formed by PECVD (same conditions as the first layer). Next, Al is sputtered (150 ° C.) onto the second silicon nitride layer to a thickness of 500 Å. Aluminum is patterned by chlorine-based chemistry (BCl3, Cl2, Ar) at P5000. Subsequently, the SiN layer is etched (CHF3, CF4) and ashed with a barrel ashing device (O2, CH3OH at 250 ° C.). The remaining structure is then cleaned with an EKS265 photoresist residue remover from EKC Technology. After coating the resist on the front side of the microstructured wafer, the TiN on the back side is etched with SF6 / Ar plasma, followed by a second cleaning and a second spin drying.

  After forming the sacrificial layer and the structural layer on the wafer substrate, the wafer is singulated and each mold is loaded into a dry tech parallel plate RF plasma reactor. 100 sccm of CF 4 and 30 sccm of O 2 are flowed into the plasma chamber and treated at about 200 mTorr for 80 seconds. Next, etching is performed for 300 seconds at an etching pressure of 143 Torr (mixed XeF2, He and N2). Etching is performed by placing the mold in a chamber filled with about 400 Torr of N2. The second area / chamber contains 5.5 Torr of XeF2 and 20 Torr of He. By removing the partition between the two areas / chambers, an etching mixture with a combination of XeF2, He and N2 is obtained. The above processing can also be performed by a parallel plate plasma etching apparatus using CF4 (150 Torr, 85 sccm) with a power of 300 W in 120 seconds. Additional features of the second (chemical, non-plasma) etching process were filed on Pat. No. 09 / 427,841 filed Oct. 26, 1999 and Aug. 28, 2000. No. 09 / 649,569 to Patel et al., The contents of which are hereby incorporated herein by reference.

As described above, the hinge of each micromirror can be formed on the same plane as the micromirror element (in FIG. 3D, the micromirror body is layers 7, 8 and 9, and the micromirror hinge is layers 8 and 9). It can be formed as a part of another process (after the formation of the second sacrificial material) on a different plane parallel to the micromirror element. Such overlapping hinges are disclosed in FIGS. 8 and 9 of the aforementioned US Pat. No. 6,046,840, and more specifically, U.S. Patent Application No. 09 by Huyvers et al., Filed Aug. 3, 2000. No. 631/536, the contents of which are hereby incorporated by reference. As shown, whether the sacrificial layer is a single sacrificial layer or two sacrificial layers (or more) such as an overlapping hinge, the sacrificial layer is preferably an isotropic etchant, as described below. Removed by. This “opening” of the micromirror may be performed immediately following the above-described steps or may be performed immediately before incorporation into the circuit on the second substrate. When the circuit, the electrode, and the micromirror are not formed on the same substrate, after forming the micromirror on the translucent substrate as described above, the uppermost metal layer (for example, third metal) of the substrate (for example, silicon wafer) ) Is provided with a second substrate having a large electrode array. As can be seen in FIG. 11A, a translucent substrate 40 having an array of micromirrors 44 as described above has a second substrate 60 (FIG. 1) with electrodes and circuits of voltages V ₀ , V _A and V _B as the final layer. In the micromirror embodiment having only one displacement direction as shown in FIG. 1, one electrode can be provided for each micromirror. The micromirrors 44 are separated from the electrodes of the substrate 60 by spacers 41 (eg, photoresist spacers adjacent to each micromirror and / or spacers formed in the epoxy when the substrate 40 is bonded to the substrate 60). One or more electrodes on the circuit board electrostatically control the pixels of the microdisplay (one micromirror on the top light transmissive substrate). The voltage of each electrode on the back surface determines the “on” and “off” light of the corresponding micro display pixel, and as a result, a visible image is displayed on the micro display. Details regarding the back side and methods for generating pulse width modulated grayscale or color images are disclosed in US patent application Ser. No. 09 / 564,069 by Richards, the contents of which are hereby incorporated by reference. The process of assembling the first and second substrates is described in detail in the above-mentioned patent application by Irkoff et al. Known methods for bonding wafers include various methods such as adhesion, anode, eutectic, fusion, microwave, solder, and thermocompression bonding.

  The opening of the micromirror in the present invention is a single or multiple step process, the type of process depending on the type of sacrificial material used. In one embodiment of the invention, a first etch with a relatively low selectivity (eg, less than 200: 1, preferably less than 100: 1, more preferably less than 10: 1) is performed before high selectivity (eg, 100 1 or more, preferably 200: 1 or more, more preferably 1000: 1 or more). Such two-step etching is described in more detail in US Pat. Application No. 60 / 293,092 by Patel et al. Filed May 22, 2001, the contents of which are hereby incorporated by reference. Introduce. Of course, other opening methods are possible depending on the sacrificial material. For example, if the sacrificial layer is a photoresist or other organic material, oxygen plasma ashing or supercritical fluid methods can be used. From a plasma containing pure oxygen, a species is obtained that attacks organic materials and produces H2O, CO and CO2 as its products, but does not etch SiO2, Al or Si. Also, when the sacrificial material is SiO2, an isotropic dry etchant (CHF3 + O2, NF3 or SF6) can be used. When the sacrificial material is silicon nitride, isotropic etching of the silicon nitride can be performed using fluorine atoms (eg, CF4 / O2, CHF3 / O2, CH2F2, or CH3F plasma). If the sacrificial material is amorphous silicon, fluorine atoms can be used in the form of XeF2, BrF3 or BrCl3. If the sacrificial layer is aluminum, chlorine-based chemistry (BCl3, CCl4, SiCl4) can be used. Of course, any etchant (and sacrificial material) is selected based on at least the amount of undercut etching required.

  4A-4J illustrate another method for making micromirrors. As seen in FIG. 4A, a sacrificial material 31 is deposited on a substrate 30 (which may be any suitable substrate such as a glass / quartz substrate or a semiconductor circuit substrate). Any suitable material can be used, but one with a high selectivity ratio between the material to be etched and the sacrificial material. Examples of sacrificial materials that can be used include organic sacrificial materials such as photoresists and organic materials described in US Patent Application No. 60 / 298,529 filed on June 15, 2001 by Reed et al. . Depending on the exact configuration of the structural layer, other known MEMS sacrificial materials such as amorphous silicon or PSG can also be used. If the sacrificial material cannot be directly patterned, a photoresist layer 32 is added and developed to form one or more openings (FIG. 4B). Next, as seen in FIG. 4C, the openings 34 are etched into the sacrificial material 31 and the photoresist 32 is removed. As can be seen in FIG. 4D, a (preferably conductive) layer 35 is finally formed which at least constitutes the flexible part of the MEMS device (in this example a micromirror structure). The layer 35 may further form a pillar 36 for attaching the micromirror to the substrate, and further form all or part of the micromirror body. As will be described in more detail below, in a preferred embodiment of the present invention, the conductive layer 35 is metal-Si, Al, B-nitride, but the metal is preferably a transition metal, more preferably a late transition metal. is there. Further, the layer 35 may be one of a plurality of (preferably conductive) layers or a plurality of layers including other types (structural dielectric layer, reflective layer, anti-stick layer, etc.). . The layer 35 is not necessarily conductive, and the layer 35 may be an insulator depending on the actual method, target material, atmosphere, and the like used for the deposition process.

  FIG. 4E shows the addition of photoresist 37 (patterning) followed by partial etching of nitride layer 35 and removal of the photoresist (FIG. 4F). Next, as shown in FIG. 4G, a micromirror structure material layer 38 is formed. This material may be conductive or insulating, and may be composed of a plurality of layers. If the material is a single layer, it is preferably reflective (eg, an aluminum or gold layer or a metal alloy layer). Next, as seen in FIG. 4H, photoresist 39 is added and developed, and layer 38 is etched / removed (FIG. 4I) partially (eg, a portion that is bent during operation). Finally, as can be seen in FIG. 4J, the sacrificial layer is removed and the MEMS device is released as if it were self-supporting on the substrate. 4 shows a circuit formed on or in the substrate 30 (when the substrate is a circuit substrate) or a light shielding layer on the substrate 30 for improving automatic handling of the substrate (the substrate is made of glass, quartz, sapphire, etc.). In the case of a translucent substrate) is not shown.

  As can be seen in FIGS. 4A-4J, a free-standing MEMS structure is created where layer 35 forms a flexible portion of the MEMS device, while layer 38 forms a structure that is displaced by the flexibility of layer 35. . As shown, layer 38 forms a movable part and forms columns or walls that support the MEMS structure on substrate 30. The movable element can also be formed by a stack of layers 38 and 35 (or further layers if desired), or only layer 38 or only layer 35. The configuration of the movable and flexible elements is selected in consideration of the rigidity or flexibility that is ultimately required, the conductivity that is ultimately required, the MEMS device that is being created, and the like.

  The micromirrors made according to FIGS. 1 to 4 are preferably formed on a translucent substrate and are “off” when there is no deflection and “on” when there is deflection. However, the micromirror can be formed on the same substrate as the micromirror operating circuit and the electrode. In addition, the “on” state and the “off” state of the micromirror can both be set to positions other than the horizontal non-deflection state. In the embodiment shown in FIGS. 5 to 9, the micromirror is provided on the same substrate as the electrodes and circuits for moving the micromirror. Furthermore, the “on” state and the “off” state of the micromirror both have a bend, but the bend angle differs between “on” and “off”. As shown in FIGS. 5A to 5G, it is also possible to use a semiconductor substrate on which a circuit and electrodes have already been formed (or in it) as an original substrate for producing a micromirror according to the present invention. .

  As can be seen in FIG. 5A, a semiconductor substrate 10 having circuitry for controlling micromirrors is typically a patterned metal layer (eg, in a semiconductor process) that forms discrete areas 12a-12b, which are made of aluminum. Last metal layer). As seen in FIG. 5B, a sacrificial layer 14 is formed thereon. As in the above embodiment, the sacrificial material can be selected from a variety of materials depending on the adjacent structure and the desired etchant. In this example, the sacrificial material is a novolac photoresist. As can further be seen in FIG. 5B, openings 15a and 15b are formed in the sacrificial material by standard novolac photoresist patterning methods, thereby forming openings 15a to 15c for connecting metal areas 12a to 12c. As seen in FIG. 5C, after the openings 15a-15c are formed, plugs or other connections 16a-16c are formed according to conventional plug forming methods. For example, when forming tungsten (W) by CVD, a) silicon reduction: 2WF6 + 3Si → 2W + 3SiF4 (this reaction typically causes WF6 gas to react with the portion of solid silicon exposed on the wafer surface at a temperature of about 300 ° C. B) Hydrogen reduction: WF6 + 3H2 → W + 6HF (this treatment is usually carried out under reduced pressure at a temperature below 450 ° C.), or c) Silane reduction: 2WF6 + 3SiH4 → 2W + 3SiF4 + 6H2 (this reaction (about 300 ° C. LPCVD) may be any of (used to form a W nucleus layer for hydrogen reaction). It is also possible to use other conductive materials, particularly other heat resistant materials, for the plugs 16a to 16c. After forming the plug material layer, chemical mechanical polishing (CMP) is performed until the sacrificial layer is reached, thereby forming a plug as shown in FIG. 5C. Depending on the plug material, a liner is first formed to prevent delamination (eg, in the case of a tungsten plug, a TiN, TiW or TiWN liner surrounds the tungsten in the hole in the sacrificial material and after the sacrificial layer is opened. May also be preferred).

  As seen in FIG. 5D, conductive layers are formed and patterned to form individual metal areas 18a-18c that are electrically connected to the underlying metal areas 12a-12c by plugs 16a-16c, respectively. The conductive layer is made of any appropriate material (aluminum, aluminum alloy, other metal alloy, conductive ceramic compound, etc.) deposited by a suitable method such as physical vapor deposition or electroplating. The material preferably has a suitable combination of hardness, elasticity, etc., as well as conductivity (as will become apparent later, the area 18c is the portion that will become the hinge of the micromirror being fabricated). Of course, if different materials and properties are desired for each individual area, the individual areas 18a-18c need not be formed simultaneously (this is the same for other parts of the device such as areas 12a-12c and plugs 18a-18c). is there). Of course, if the material of each individual area in a layer is the same and is deposited at the same time, the number of process steps can be reduced. In a preferred embodiment, the conductive layer is an aluminum alloy deposited by reactive sputtering, or US Patent Application No. 60 / 228,007 by Reed, filed Aug. 23, 2000, hereby incorporated by reference. And conductive binary or ternary (or more) compounds as disclosed in US Patent Application No. 60 / 300,533 by Reed, filed June 22, 2001. The individual conductive areas 18a to 18c are formed by employing an appropriate etching chemistry (for example, chlorine-based chemistry for aluminum) to pattern the conductive layer.

  As further shown in FIG. 5E, a second sacrificial layer 20 is formed which may be the same as or different from the sacrificial material of layer 14 (preferably both are the same material so that they can be removed simultaneously). To do. Next, the layer 20 is patterned to form an opening 20a that reaches the area 18c. Similar to forming an opening in the sacrificial layer 14, this directly patterns the layer 20 by using an additional photoresist layer, or if the material is a photoresist or other directly patternable material. can do. As can be seen in FIG. 5F, the plug or connection 22 leaves the plug 22 connected to the individual area (hinge) 18c while depositing a preferably conductive material on the sacrificial layer 20 and chemical mechanical polishing. Can be formed. Next, as can be seen in FIG. 5G, a (preferably conductive) layer is deposited and patterned into the desired micromirror shape to form the micromirror body 24. As shown in FIG. 6A, various micromirror shapes are possible and are described in further detail below. However, the shape of the micromirror according to this embodiment of the invention is arbitrary, and a square or rhombus shape as shown in FIGS. 6B and 6C is also possible. Of course, it is preferable to use a shape in which the micromirrors can be tightly packed, and thus a high filling rate can be obtained (for example, the shape of the micromirror in FIG. 6A shown as an array close to FIG. 7). The dotted line 62 shown in FIG. 6C (and later in FIG. 12) is the rotation axis of the micromirror.

  The various layers used to create the micromirror according to FIGS. 5A-5G are shown as a single layer, but each layer (whether structural or sacrificial) is a stack, eg, a stack One layer of the body can have good mechanical performance, and the other layer can have good conductivity. Further, in the preferred embodiment, the structural material is conductive, but the micromirror element 24 (or the layer in the laminate 24) and the working electrodes 12d and 18b (and the layers / materials that connect the electrodes 12d and 18b to the semiconductor substrate) ) May be conductive. Further, the above-mentioned materials (metal, metal alloy, metal ceramic alloy, etc.) are those that do not contain metal, for example, silicon (eg, polycrystalline silicon) or silicon compounds (eg, Si3N4, SiC, SiO2, etc.). There may be. When Si3N4 is used as the structural material and amorphous silicon is used as the sacrificial layer, xenon difluoride can be used as a vapor phase etchant to remove the sacrificial amorphous silicon. If desired, the silicon or silicon compound (or other compound) used as the structural material can be annealed before and / or after removing the sacrificial layer to improve the stress characteristics of the structural layer. . FIG. 8 is an exploded view of the micromirror formed according to FIGS. 5A to 5G.

The sacrificial layers 14 and 20 are removed as a final process in forming the micromirror. FIG. 9A shows the micromirror after the two sacrificial layers have been removed, and it can be seen that the micromirror 24 is connected to the substrate 10 by the pillars 22, hinges 18c, pillars 16c and metal areas 12c. The micromirror shown in FIG. 9A is not displaced or deflected because no voltage is applied to the underlying electrode (individual metal area formed by the above-described processing), for example, the electrode 18b or 12d. . This non-deflection position is not the “off” position, which is usually the farthest angle from the “on” position in the projection system (to maximize the contrast of the projected image). The “on” state of the micromirror, ie the position of the micromirror that directs light to the receiving cone of the collection system is shown in FIG. 9B. When the voltage _VA is applied to the electrode 12d, the micromirror plate 24 is electrostatically pulled down until the edge of the micromirror plate 24 contacts the electrode 12e. Micromirror plate 24 and electrode 12e are both potential are identical, the voltage V ₀ in this embodiment. As shown in FIG. 9C, when the voltage V _B is applied to the electrode 18b, the micromirror 24 falls in the opposite direction, and its movement is stopped by the electrode 18a. Both the electrode 18a and the micromirror plate 24 are at the same potential (voltage V ₀ in this embodiment). Depending on the size of the electrode 18b relative to the electrode 12d and the distance between these electrodes and the micromirror plate 24, the voltages applied to the electrodes 18b and 12d need not be equal. This deflection position shown in FIG. 9C is an “off” position, which is the position that sends light farthest from the collection system.

  As can be seen by comparing FIGS. 9B and 9C, the angle of the off position (with respect to the substrate) is lower than the on position. Hereinafter, when referring to an on and off angle (or an angle with respect to a substrate or a non-deflection micromirror position), the sign of the angle (positive or negative with respect to the substrate or a non-deflection position) is used. The definition of positive and negative is arbitrary, but indicates that the micromirror enters the “on” position by rotating in a certain direction, and enters the “off” position by rotating in the opposite direction. The advantages of such asymmetry are described in more detail below. In one embodiment of the invention, the on position is between 0 and +30 degrees, the off position is between 0 and -30 degrees, and the displacement to the on position is greater than the displacement to the off position. For example, the on position is +10 to +30 degrees (or +12 to +20 degrees or +10 to +15 degrees), and the off position is greater than 0 and between 0 and −30 degrees (or from 0 to −10 or −12 degrees, Or -1 to -12 degrees, or -1 to -10 or -11, or -2 to -7 degrees). In a further embodiment, the micromirror rotates at least +12 degrees to the on position and -4 to -10 degrees to the off position. Depending on the material used for the hinge, a larger angle such as +10 to +35 degrees on rotation and -2 to -25 degrees off rotation (of course, material fatigue or creep may be a problem at very large angles) Can also be used. Even if the direction of rotation is not taken into account, the on and off states are preferably greater than 3 degrees and smaller than 30 degrees with respect to the substrate, and the on position is greater than +10 degrees and the mirror is turned off in the opposite direction. It is preferred to rotate 1 degree (or more) from the direction.

  Figures 10A to 10D show further methods and micromirror structures. Changes in materials, layers, sacrificial etching, deposition of structural layers, etc. are the same as those described above. In the method shown in FIGS. 10A to 10D, the substrate 40 may be a light-transmitting substrate (to be later combined with a second substrate having circuits and electrodes) or a semiconductor substrate on which circuits and electrodes are already mounted. . In this embodiment, which can be seen in FIGS. 11A-11B, the circuits and electrodes are formed on separate substrates.

  In FIG. 10A, a sacrificial layer 42 is deposited and patterned to form an opening 43. Next, as shown in FIG. 10B, plug 46 is formed (preferably by the process of FIGS. 5A to 5G, ie, by depositing a metal, metal alloy or other conductive layer and planarizing (eg by CMP). Create). Next, as shown in FIG. 10C, the hinge 50 is created by depositing a conductive material (having appropriate amorphousness, elasticity, hardness, strength, etc.). In the present embodiment, the hinge (and / or micromirror) is formed of a front transition metal such as Ta-Si-N and silicon nitride, a rear transition metal such as Co-Si-N and silicon nitride, or It is made of a metal such as a titanium-aluminum alloy or a titanium-aluminum oxide alloy, or a metal-ceramic alloy. After depositing such a material, a photoresist is deposited and patterned to etch / remove other than the hinge area 50. Next, as can be seen in FIG. 10D, to create the micromirror plate 44, first the hinge is protected with a photoresist, and the hinge structure layer is deposited and patterned to partially overlap the hinge 50 and thus connect. A micromirror plate 44 is formed. As with other embodiments, such micromirrors are created simultaneously as thousands to millions of arrays.

Next, in a wafer or mold, a substrate having micromirrors is attached to a substrate having operating circuits and electrodes. In this embodiment, each micromirror has two electrodes, one each for each deflection direction, preferably by contacting the micromirror itself (in any direction) with the same potential material as the micromirror itself. ) Has a third electrode to stop movement. FIG. 11A shows a second substrate 60 and a landing pad or electrode 70 having electrodes 72 and 74 that control the deflection of the micromirror. In FIG. 11A, the micromirror is in a non-deflection position. When the voltage V _A is applied to the electrode 72, the micromirror 44 falls until it contacts the electrode 70 (FIG. 11B). This is the “on” position of the micromirror for sending light to the collection system of the system. The gap between the substrates can be designed so that the end of the micromirror plate 44 contacts the electrode 70 and the substrate 40 simultaneously. When the voltage V _B is applied to the electrode 74, the micromirror plate 44 is now tilted in the opposite direction until the end of the micromirror contacts the substrate 40. This is the “off” position of the micromirror (FIG. 11C). Due to the arrangement of the hinge 50 and the column 46, the angle of the micromirror in this “off” position is smaller than the angle of the micromirror in the “on” position. FIG. 12 shows such a micromirror array, and FIG. 13 shows an exploded view of the micromirror created by the processes of FIGS. 10A to 10D.

  FIG. 14A shows that the micromirrors in the “off” state are in a non-deflection state (micromirror group 100), and the micromirrors in the “on” state (micromirror group 102) are in a place where light can be visually recognized (directly, FIG. 6 is a cross-sectional view showing a plurality of micromirrors in a micromirror array that are tilted from a horizontal state for projection onto a target in a single device or to a screen in the back of a room. 14B and 14C show such a micromirror array arrangement. As can be seen in FIG. 14B, when the micromirror is in the “on” state, the incident light cone 50 is reflected by the micromirror (all the micromirrors in this figure are in the “on” state), and this light is reflected by the light cone. 52 is projected onto the output aperture 60 and in most cases proceeds to the imaging system (eg projection lens). The cone 54 shows specular reflection by the transparent cover. FIG. 14C shows the micromirror in the “off” state, and the cone 52 shows the light reflected from the micromirror in the “off” state. In these figures, for convenience, the light cones are shown being focused on individual micromirrors, but the incident and reflective cones are actually incident across the entire array.

  The arrangements of FIGS. 14B and 14C have the advantage that when the micromirror is in the “off” (non-deflection) state, the amount of light that passes through the gap between the micromirrors and causes “gap scattering” is low. However, as shown in FIG. 14C, light may be refracted (lights 61 a and 61 b extending from both ends of the reflected “off” light cone 52) due to the repeating pattern of the micromirrors. This unnecessary light is caused by scattering or refraction by the edge of the micromirror (edge scattering). In particular, refracted light that extends outside the range of the reflected “off” light cone, such as light 61a, in order to make the incident light cone as large as possible (and thus also the emitted light cone) to improve efficiency. May enter the output aperture 60 (for example, the light condensing system) and cause a reduction in contrast ratio.

  By deflecting the micromirrors in the “on” and “off” states to prevent overlap of “off” state light (including refracted light) and “on” state light, which reduces the contrast ratio The “off” light and the “on” light can be further separated. As can be seen in FIG. 15A, when the micromirror is deflected as shown in the “off” state, some of the light is directed from the micromirror to the “on” state (ie, focused), as indicated by light ray 116. Reflected in the direction away from the system. Further, the other light 112 does not strike the micromirror, but is scattered on the surface of the lower substrate (eg, the lower circuit and the electrode), and enters the condensing system even though the adjacent micromirror is in the “off” state. Incident. Also, as indicated by the light beam 114, even if the incident light hits the micromirror, it is not guided to an appropriate “off” angle as the light beam 116, and may cause gap scattering. This “on” arrangement shown in FIG. 15B is identical to that shown in FIG. 14B. However, as shown in FIG. 15C, the refraction 61a caused by the periodicity of the micromirror along with the “off” state moves away from the “on” angle, and the contrast ratio due to refraction / edge scattering is improved (however, as described above, the gap The contrast ratio may be slightly reduced by scattering).

  To improve the micromirror array, maximize the distance between the “off” and “on” light cones (minimize edge scattering to the light receiving cone) and minimize the gap between adjacent micromirrors. It is desirable to minimize gap scatter. One suggestion is to use a micromirror array with micromirrors that deflect in opposite directions in the “on” and “off” states, as shown in FIGS. 15A-15C, and below the micromirrors to reduce gap scattering. A light absorbing layer can be provided. However, this increases processing complexity and absorbs light (to the light valve) into the micromirror assembly, increasing the temperature of the light valve, increasing thermal expansion, fatigue of the micromirror structure or drooping In other words, problems such as deterioration of the passivation layer, the self-forming single layer and / or the lubricant are caused.

  As can be seen in FIGS. 16A to 16C, micromirrors were provided that bend in both the “on” and “off” states, but with different deflection angles. As can be seen in FIG. 16A, the micro mirror 100 has a deflection angle of the micro mirror 100 in the “off” state shallower than the micro mirror 102 in the “on” state (deflection in the direction opposite to the horizontal or non-deflection position). As can be seen in FIG. 16B, the “on” state (incident light 50 is projected onto output aperture 60 as emitted light 52) includes some specular reflection 54 and is unchanged. In FIG. 16C, the micromirror in the “off” state can minimize the edge scattered light 61a reaching the output opening 60, but the gap angle in the off state is large, and thus the gap scattered light from below the micromirror is reduced. In order to minimize it, the bending is such that the edge scattered light does not enter the light receiving cone.

  A further feature of the present invention resides in device packaging. As described above, the reflection by the translucent substrate causes specular reflection. As can be seen in FIG. 17A, the incident light cone 50 reflects from the on-state micromirror to form a reflective cone 52. The specular reflection reflected from the surface of the translucent substrate 32 is shown as a light cone 54. In the projection system, in order to improve the efficiency of the etendue and the projection system, it is desirable to increase the extension angle of the cone. However, as can be seen in FIG. 17A, increasing the expansion angle of the cone 50 also increases the expansion angle of the cones 52 and 54, and the specularly reflected light of the cone 54 is output to the output aperture even when the micromirror is in the “off” state. 60 (thus, the contrast ratio decreases).

  In order to prevent specular reflection incident on the output aperture while increasing the extension angle of the light cone, the translucent substrate 32 is inclined with respect to the substrate 30 as shown in FIG. 17B. In many cases, the substrate 30 is a substrate on which micromirrors (or other optical MEMS elements) are formed, and the substrate 32 is a light transmission window of a package of the optical MEMS device. The angle of the window is -1 degree or more (the minus sign follows the direction of the micromirror and the angle). In some embodiments, the window angle is -2 to -15 degrees, or in the range of -3 to -10 degrees. In any case, the window is preferably in the same “direction” (with respect to the micromirror substrate and / or the bottom of the package) as the micromirror “off” position with respect to the micromirror substrate. As seen in FIG. 17B, when the micromirror is in the “on” state, there is a gap between the light reflected from the “on” micromirror (reflected light cone 52) and the specularly reflected light (light cone 54). This “gap” is due to the specular reflection cone 54 being reflected farther by the inclined translucent substrate. As can be seen in FIG. 17C, this arrangement increases the spread angle of the “on” micromirror (cone 52) and the specularly reflected light (light cone 54) incident light cone (and the corresponding reflected light cone). It becomes possible. (For ease of drawing, the reflection point of the light cone is intermediate between the micromirror and the translucent substrate, but actually the light cone 52 is reflected from the micromirror and the specular reflection cone 54 is the substrate 32. 17B and 17C allow for increased throughput, improved system efficiency, and improved light valve etendue (etendue = solid angle × area). The light valves shown in FIGS. 17B and 17C are more efficient because they can modulate larger etendue rays and allow more light to pass from the light source.

  17D and 17E show the packaged device. As can be seen in FIG. 17D, incident light 40 (which is viewed from the opposite angle as before) enters the array and is reflected. As can be seen in FIG. 17E, by providing the transparent substrate 32 (including the mask areas 34a and 34b) with an inclination, not only the expansion angle of the light cone is increased, but also the mask of the window 32 and the micromirror array. By minimizing the gap between them, light scattering and temperature rise in the package can be reduced. The angle of inclination of the transparent window is 1 to 15 degrees, preferably 2 to 15 degrees, more preferably 3 to 10 degrees with respect to the substrate. As can be seen in FIGS. 17D and 17E, a bond wire 37 (electrically connecting the substrate to the package to drive a micromirror or other micromechanical element) disposed at one end of the substrate in the package is tilted. Is at a position greater than the distance on the opposite side of the substrate. Thus, it is possible to minimize the distance between the transparent window and the micromirror substrate on the side of the substrate where no bond wires are present, while allowing the bond wires to be accommodated by tilting the window. Note that light enters the micromirror array from the side of the package that corresponds to the position of the bond wire and the high side of the tilted window. Other elements that can be contained within the package include package adhesives, molecular scavengers or other getters, sources of stiction agents (eg, chlorosilane, perfluorinated n-alkanoic acids, hexamethyldisilazane, etc.). .

  If the micromirror of the present invention is for a projection display, an appropriate light source for illuminating the array and projecting an image onto a target via a light collection system is required. In the present invention, the arrangement of the light source and incident light for the array and each micromirror that allows the contrast ratio to be improved while minimizing the traces of the projection system is shown in FIGS. 18 and 19a to 19c. As can be seen in FIG. 18, the light source 114 sends light 116 at an angle of 90 degrees to the leading side 93 of the effective area of the array (the effective area of the array represented by the rectangle 94 in the figure). The effective area 94 is usually composed of 64,000 to 2,000,000 pixels arranged in a rectangular shape as shown in FIG. The effective area 94 is reflected (by the “on” micromirror) through the light collection system 115 toward the target, and a corresponding rectangular image is projected on the target (eg, wall or screen). Of course, the array may have a shape other than a rectangle, in which case a corresponding shape is obtained on the target (if no mask is used). The light from the light source 114 is reflected by a particular micromirror (in the “on” state) in the array and passes through the optical system 115 (simplified as two lenses for clarity). The micromirror in the “off” state (non-deflection “stationary” state) sends light to area 99 in FIG. FIG. 18 shows a projection that may further comprise components well known in the art, such as a TIR prism, additional focusing or magnification lens, a color wheel for providing a color image, a light guide tube, etc. The system is simplified. Of course, if the projection system is used for non-color applications other than maskless lithography or for projecting color images (eg front or back screen projection televisions, personal computer monitors, etc.), different light collection systems and colors A wheel can be used. The target need not be a screen or a photoresist. For example, in the case of a direct-view display, the target may be the retina of the viewer. As can be seen in FIG. 18, every “on” micromirror in the array sends light to a single collection system, which is a single for directing / focusing / projecting light onto the target. Or a plurality of lenses.

  Whether the video is projected on a personal computer, television or movie screen, each pixel of the video on the screen (each pixel of the video corresponding to the micromirror element of the array) defines a rectangular video on the screen. Of the four sides, the sides are not parallel to the two sides. As can be seen in the micromirror element embodiment in FIGS. 19A-E, the incident light does not strike perpendicular to the sides of the micromirror element. FIG. 19A is a perspective view showing a state where light hits one micromirror element, FIG. 19B is a top view thereof, and FIG. 19C is a side view thereof. The incident light is 10 to 50 degrees (eg, 20 degrees) away from the normal (relative to the surface of the micromirror array). See angle 133 in FIG. 19C.

Regardless of the angle of incident light with respect to the plane of the micromirror, the sides of the micromirror are not perpendicular to the incident light (see FIG. 19D). In a preferred embodiment, the sides of the micromirror have an angle (131) of the incident optical axis to the projection on the micromirror plane (102) of less than 80 degrees, preferably less than 55 degrees, more preferably 45. Degrees or less, and most preferably 40 degrees or less. Conversely, the angle 132 is 100 degrees or more, preferably 125 degrees or more, more preferably 135 degrees or more, and most preferably 140 degrees or more. In FIG. 19D, the switching (ie, rotation) axis of the micromirror is indicated by a dotted line 103. Depending on the type of hinge used, this switching shaft can also be provided at other locations on the micromirror, such as line 106. As can be seen in FIG. 19D, the switching axis (eg 103 or 106) is perpendicular to the projection of incident light 102 onto the plane of the micromirror. FIG. 19E is a top view similar to FIG. 19D, but FIG. 19E shows the incident light 102 on the two-dimensional micromirror array together with the micromirror array. Note that in FIG. 19E, each micromirror has the micromirror shape shown in FIGS. As can be seen in FIG. 19E, the overall shape of the micromirror array is rectangular. Each of the four sides 117-120 of the array is drawn by drawing a line between the farthest pixels (121-124) in the last row and column of the effective area (eg, side 119 is a corner pixel 123 and 122). Defined by the line connecting In FIG. 19E, it can be seen that the “leading” (closest to the light source) and “tail” (farthest from the light source) sides 119, 117 of the effective area are jagged due to the shape of the micromirror in the effective area. Remember that there may be more than 3,000,000 micromirrors in an area of 1 cm ² to 1 in ² . Thus, unless it is very large, the effective area is substantially rectangular and the sides 118 and 120 (or 117 and 119) of the effective area are the micromirrors in FIG. 19D (the micromirror in FIG. 19D is FIG. 19E). Side 107 and 108 of the active area (which is one of the micromirror elements in the effective area) of the active area, and the effective area sides 117 and 119 (or 118 and 120) of each micromirror (see FIG. 19D). Parallel to the switching axis 103 (or 106), the sides 117 and 119 (or 118 and 120) of the effective area are non-perpendicular to the leading or trailing sides 125a-d of the micromirror (see FIG. 19D). . Moreover, FIG. 19E can also be regarded as a projection image composed of a large number of projection pixels (each projection pixel has the shape shown in FIG. 19D). Thus, the projected image sides 118 and 120 (or 117 and 119) are parallel to the projected pixel sides 107 and 108, and the projected image sides 117 and 119 (or 118 and 120) are projected pixel sides 125a. Non-perpendicular to ~ d.

  FIG. 20 shows a two-dimensional micromirror array (of course, the number of pixels is less than the normal effective area). To simplify the drawing (including FIGS. 21-26 and 29-32 together with FIG. 20), the number of micromirrors / pixels shown is less than 60, but a typical display has 64,000 pixels (320 × 200 pixels) to 1,920,000 pixels (1600 × 1200 pixels = UXGA) or more (eg, 1920 × 1080 = HDTV; 2048 × 1536 = QXGA). Since the size of each pixel in the present invention is very small, the achievable resolution is virtually infinite. As can be seen in FIG. 20, the side of each pixel is parallel to the corresponding side of the effective area. Therefore, all the sides of the micromirror are perpendicular to or parallel to the sides of the effective area. On the other hand, in the case shown in FIG. 21, the side of the micromirror is neither perpendicular nor parallel to the side of the effective area. As described below, in further embodiments, there may be sides that are not perpendicular or parallel to the sides of the effective area, but there are sides that are parallel to the sides of the effective area (from the incident light to the micromirrors). (It is also possible to be parallel to the line projected on the plane).

  The micromirror array shown in FIG. 22 realizes a high contrast ratio. However, the addressing method can be simplified by the micromirror structure shown in FIGS. More specifically, in FIGS. 23-29, the pixels need not be arranged in a matrix that is tilted with respect to the X and Y axes of the array. Since normal video image sources supply pixel color data as an XY grid, the structure of FIGS. 23-29 provides non-simple preprocessing to form an acceptable image on the display. Save time and effort. Also, the structure according to FIGS. 23-29 avoids complex rear layout of the display (possibly double the row or column wiring to the pixel control cells compared to those of FIGS. 13 and 14). You can also. In FIG. 22, horizontal lines 80 connect the uppermost rows of micromirror elements, and vertical lines 81A-D extend from each micromirror in the uppermost row (the horizontal and vertical lines are rows and columns for addressing the array). Equivalent to As can be seen in FIG. 22, in this way, only every other micromirror can be connected. Thus, the matrix required to address all the micromirrors is double the normal and the array addressing is more complex. FIG. 22 further shows support pillars 83 at the corners of the micromirrors, and these support pillars are hinges (not shown) located under each micromirror element (the “superimposed hinge” described above). Are connected to a translucent substrate (not shown) located on each micromirror element.

  In a more preferred embodiment of the invention shown in FIG. 23, an array 92 is provided. The light 90 is emitted from a direction in which the micromirror does not have a side perpendicular to the incident light. In FIG. 23, the top side of the micromirror (relative to the incident light 90) is inclined 135 degrees with respect to the incident light (90). This angle is preferably greater than 100 degrees, more preferably greater than 130 degrees. When the angle between the incident light and the leading side is 135 degrees or more, the contrast ratio is further improved, and may be 140 degrees or more. As can be seen in FIG. 23, the arrangement of the micromirror elements does not lead to addressing problems as described above for FIG. The pillar 95 is connected to a hinge (not shown) under each micromirror element in FIG. The hinge extends perpendicular to the direction of the incident light (and parallel to the leading and trailing edges 91B and 91D of the effective area). With this hinge, the rotation axis of the micromirror can be made perpendicular to the incident light.

  FIG. 24 is a schematic diagram showing a micromirror similar to that shown in FIG. However, in FIG. 24, the direction of the micromirror element is “reverse”, and the “concave” portion is the head side. Although the micromirror of FIG. 24 is the opposite of that shown in FIG. 23, the micromirror still has no sides perpendicular to the incident light. FIG. 24 shows the hinge 101 arranged on the same plane as the connected micromirror element. Both types of hinges are disclosed in the aforementioned '840 patent. FIG. 25 similarly shows a hinge 110 on the same plane as the micromirror array, but a “convex” portion 112 (“protruding portion”) and a “concave” portion 113 (“notch”) on the leading side of each micromirror. ) Both exist. The shape of each micromirror is a concave polygon due to the recess or notch of each micromirror. The micromirror may be a convex polygon (when the sides of the convex polygon micromirror are not parallel to the leading side of the effective area), but the micromirror preferably has a concave polygon shape. A convex polygon is a polygon in which no line including each side passes through the inside of the polygon. A polygon is a concave polygon only if it is not a convex polygon. The concave polygonal shape is a combination of a plurality of parallelograms (excluding rectangles), or at least one concave portion and at least one convex portion corresponding to the concave portion (to fit with the concave portion of the adjacent micromirror). However, the concave polygonal shape is arbitrary. Although not preferred, as described above, the shape of the micromirror may be a single parallelogram (excluding a rectangle). Although not shown, the corresponding one or more protrusions and one or more notches (and any side of the micromirror) are not necessarily made of straight lines, and may be curved. Good. In such an embodiment, the protrusions and cutouts are semicircular, but angular protrusions and cutouts as shown are preferred.

  Figures 26A-26F illustrate further embodiments of the present invention. Although the shapes of the micromirrors in each figure are different, they are common in that they do not have a side perpendicular to the incident light. Of course, when the side of the micromirror changes direction, there may be a portion where the side can be said to be instantaneously vertical even if it is minute. However, when it is stated that it does not have a vertical side, it should be noted that there are substantially no vertical locations, or that there are no such vertical locations at least on the leading and trailing sides of the micromirror. means. Even when the direction of the head side changes gradually (or when part of the head side is perpendicular to the incident light as shown in FIG. 29), it is perpendicular to the incident light. The portion preferably does not exceed 1/2 of the top side, more preferably does not exceed 1/4, and most preferably is 1/10 or less. The smaller the portion perpendicular to the incident light on the leading and trailing sides, the better the contrast ratio.

  Most micromirror configurations can be viewed as a combination of one or more parallelograms (eg, equivalent parallelograms). As can be seen in FIG. 27A, a single parallelogram has no sides perpendicular to the incident light (this light goes from the bottom to the top of the page and originates from the plane of the page) It is effective in reducing light diffraction. FIG. 27A shows a single parallelogram with a width “d” indicated by a horizontal arrow. The switching axis of the micromirror in FIG. 27A (and FIGS. 27B to 27F) is also along this horizontal direction. For example, the switching axis may be on the dotted line in FIG. 27A. FIGS. 27B and 27C show micromirror designs having two and three parallelograms, respectively, each parallelogram having the same shape, dimensions and appearance as those adjacent to it. With this structure, the leading side and the trailing side of the micromirror element have a “sawtooth” shape. Figures 27D-27F show two to four parallelograms. However, in FIG. 27D thru | or 27F, each parallelogram is not the same shape as an adjacent thing, but its mirror image. With this structure, the leading and trailing edges of the micromirror element become “jagged”. The parallelograms do not necessarily have the same width, and the line connecting the tips of the sawtooth or the jagged side does not need to be perpendicular to the incident light. If the parallelograms are all designed to have the same width, “d” = M / N where M is the overall width of the micromirror and N is the number of parallelograms. is there. As the number of parallelograms increases, the width “d” decreases (assuming that the width of the micromirror is constant). However, the width “d” is preferably much larger than the wavelength of the incident light. In order to keep the contrast ratio high, the number N of parallelograms (or the number of times the leading micromirror side changes direction) is 0.5 M / λ or less, preferably 0.2 M / λ, and further 0.1 M. / Λ or less. Here, λ represents the wavelength of incident light. In FIG. 27, the number of parallelograms is 1 to 4, but the number is arbitrary. However, if the number is 15 or less, preferably 10 or less, a better contrast ratio can be obtained. The number of parallelograms (4 or less) shown in FIG. 27 is most preferable.

  As can be seen in FIG. 28, hinges (or flexures) 191 and 193 are provided on the same surface as the micromirror element 190. Incident light 195 from a light source located outside the paper surface of FIG. 28 is incident on each leading edge of the micromirror 190, but none is vertical. The hinge preferably does not have a portion perpendicular to the incident light in order to reduce light diffraction in the switching direction of the micromirror.

  It should also be noted that the “straight line” micromirror sides shown parallel to the sides of the effective area (eg, micromirror sides 194, 196 in FIG. 28) can have other shapes. FIG. 21 described above is also one example in which the micromirror side parallel to the incident light 85 is not provided. 30 and 31 are further examples in which the micromirror side has no side perpendicular or parallel to the incident light, but does not involve the complexity of addressing as shown in FIG. Incident light irradiates perpendicularly to any of the four sides (see arrows 1 to 4) of the effective area in FIG. The array shown in FIG. 31 also has this feature. Furthermore, as can be seen in FIG. 29, a part of the head side of each micromirror can be perpendicular to the incident light, and a part can be non-perpendicular.

  FIGS. 32A through 32J show structures that can be used as hinges in the present invention. Similar to FIG. 24, in FIG. 32A, the micromirror 97 is connected to a support column 98 that extends parallel to the incident light (when viewed from the top as in this figure) and supports the micromirror element on the substrate. The micromirror which has the bending part 96 to do is shown. Incident light can be directed onto the array in the direction of arrows 5 or 6 in FIG. 32A (when viewed from the top). Of course, incident light is generated out of plane (see FIGS. 11A to 11E). This incident light is the same in FIGS. 32B to 32L. Figures 32C to 32E are further embodiments of this type of hinge. 32F to 32L, except for FIG. 32J, the hinge is not parallel to the incident light (or the head side of the effective area), but the micromirror has a rotation axis perpendicular to the incident light. Fig. 4 shows a further form of mirror.

  If the micromirror side parallel to the rotation axis of the micromirror (and perpendicular to the incident light) is not minimized, even if the micromirror is set to the “off” state, it is diffracted by the micromirror side. Light enters the light condensing system and the contrast ratio decreases. As seen in FIG. 33A, a “ten” -shaped diffraction pattern (obtained by irradiating a substantially square micromirror array as shown in FIG. 20 at an angle of 90 degrees with respect to the leading side of the array. ) Overlaps the light receiving cone (circle in the figure). In this figure, the diffraction pattern is a group of black spots (and a corresponding bright background) that forms one vertical line and one horizontal line that intersect just below the circle of the light receiving cone (shown by a solid circular line overlapping the diffraction pattern). ). Although not shown, when the micromirror is in the “on” state, the two diffraction lines intersect within the circle of the light receiving cone. Therefore, as seen in FIG. 33A, even when the micromirror is in the “off” state, the vertical diffraction lines enter the light receiving cone of the condensing system, and the contrast ratio is lowered. FIG. 33B is a diffraction pattern when a square micromirror is irradiated from an angle of 45 degrees. As can be seen in FIG. 33B, compared to FIG. 33A, the diffracted light entering the light receiving cone (small circle by the solid line in FIG. 33B) is reduced. However, as described above, diffraction can be reduced by irradiating in this way, but other problems occur.

  In contrast, the diffraction pattern according to the present invention (the “off” state of the micromirror in FIG. 28) shown in FIG. 33C is such that light is introduced in the light receiving cone of the condensing system or when the micromirror is in the “on” state. No diffraction lines extending into the spatial region. Therefore, the diffracted light is not substantially sent to the place where the light is sent when the micromirror is in the “on” state. A micromirror array that forms such a diffraction pattern while the illumination light is orthogonal to the sides of the effective area of the array (and / or orthogonal to the rows or columns) is novel. Similarly, the arrangement of the light sources with respect to this micromirror structure, the hinges therefor, and the micromirrors, the edges of the effective area and / or the matrix for addressing is also novel.

  The invention has been described with reference to specific embodiments. However, those skilled in the art will appreciate that various modifications are possible in view of the embodiments described herein. For example, the shape of the micromirror according to the present invention is an optical switch (eg, US patent application Ser. No. 09 / 617,149 filed by Huybers et al. Use in a micromirror in US Provisional Application No. 60 / 231,041 filed by Huybers on Sep. 8) can reduce diffraction in the switch. In addition, the micromirror according to the present invention includes US patent application No. 09 / 767,632 filed on January 22, 2001 by True et al. And US Patent Application No. 09 / 767,632 filed by Huyverse et al. No. 09 / 631,536, U.S. Patent Application No. 60 / 293,092 filed by Patel et al. On May 22, 2001, and U.S. Patent Application No. 06 / filed by Huyvers et al. 637,479 and can be manufactured by the structure and method. Also, standard red / green / blue or red / green / blue / white color wheels can be used in projection displays incorporating the micromirrors of the present invention, 2001 introduced here by reference. U.S. Provisional Application No. 60 / 267,648 filed by Huybers on Feb. 9 and U.S. Provisional Application No. 60 / 266,780 filed on February 6, 2001 by Richards et al. It is also possible to use other color wheels.

  The present invention also provides a detachable (and replaceable) substrate for singulation and assembly disclosed in US Provisional Application No. 60 / 276,222, filed March 15, 2001 by Patel et al. Suitable for the method used. The micromirrors of the present invention also have pulse widths as disclosed in US patent application Ser. No. 09 / 564,069 filed by Richards on May 3, 2000, the contents of which are hereby incorporated by reference. It can be driven in the array by modulation. Further, if interhalogen or noble gas fluoride is used to release the micromirror, US patent application Ser. No. 09 / 427,841 filed by Patel et al. On Dec. 26, 1999, which is hereby incorporated by reference. And the method described in US patent application Ser. No. 09 / 649,569, filed Aug. 28, 2000 by Patel et al. Also, the sacrificial material and the method for removing it may be those described in US Patent Application No. 60 / 298,529 filed on June 15, 2001 by Reed et al. Also, MEMS materials described in US Patent Application No. 60 / 228,007 filed on August 23, 2000 and US Patent Application No. 60 / 300,533 filed on June 22, 2001, etc. Other structural materials can also be used. Both of the above patents and patent applications are hereby incorporated by reference.

  In this specification, a structure or layer is described as being “on” (or formed on) another structure or layer, or on top, above, next to, or the like. This means directly or indirectly above, above, above, next to, etc., as recognized in the art, while the seal layer, adhesion promoting layer, conductive layer, stiction reduction. It will be appreciated that intermediate layers or structures may be present, including but not limited to layers and the like. Similarly, the structure of the substrate or the layer may be an additional structure or a stacked structure of layers. Also, the use of phrases such as “at least one” or “one or more” (or similar) is to emphasize that the structure or layer may have multi-layer characteristics. However, the presence of such phrases is not intended to deny the possibility of other structures or layers of layers not described as such. Similarly, when “directly or indirectly” is described, the meaning in a place where there is no such description is not limited to either direct or indirect. In addition, “MEMS”, “micromechanical” and “microelectromechanical” are used interchangeably herein, and the structure may or may not have an electric part. Finally, the term “means” in the description “means for” relates to the matter in the claim with the form “means for”, unless specifically stated in the claim. It is not intended to be interpreted according to special rules.

Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing a method for manufacturing a micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing showing another method for making the micromirror of the present invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows embodiment of the micromirror concerning this invention Drawing which shows another embodiment of the micromirror concerning this invention Drawing which shows another embodiment of the micromirror concerning this invention Drawing which shows another embodiment of the micromirror concerning this invention Drawing which shows another embodiment of the micromirror concerning this invention Drawing which shows another embodiment of the micromirror concerning this invention Drawing which shows another embodiment of the micromirror concerning this invention Drawing which shows another embodiment of the micromirror concerning this invention Drawing showing an example of a micromirror array Micromirror exploded view Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial sectional view of micromirror array showing operating state Partial cross section of packaged micromirror array Partial cross section of packaged micromirror array Diagram showing the arrangement of light sources and incident light Diagram showing the arrangement of light sources and incident light Diagram showing the arrangement of light sources and incident light Diagram showing the arrangement of light sources and incident light Drawing which shows the example of a micromirror element Drawing which shows the example of a micromirror element Diagram showing a two-dimensional micromirror array Drawing showing an embodiment in which the sides of the micromirror are neither perpendicular nor parallel to the sides of the effective area Drawing showing an example of a micromirror array realizing a high contrast ratio Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing an example of a micromirror array Drawing showing a further embodiment in which the micromirror side has no side perpendicular or parallel to the incident light Drawing showing a further embodiment in which the micromirror side has no side perpendicular or parallel to the incident light Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing which shows structure which can be used as a hinge in the present invention Drawing showing diffraction pattern Drawing showing diffraction pattern Drawing showing diffraction pattern

Claims (80)

A light source for supplying light to the micromirror array;
A micromirror array composed of quadrilateral micromirrors each defined by four sides;
A rear or front projection television with a screen on which images are displayed,
During operation, light from the light source is applied to the micromirror array and projected as a rectangular image on the screen.
Micromirrors can be moved between the off and on states by pulse width modulation to form a Film image on the screen,
Images displayed will have four sides, which of the displayed video pixel edges also rather parallel with any side of the image,
Incident light from the light source is incident at a right angle to one side of the micromirror array;
Further, below the micromirror, hinges that make the rotation axis of the micromirror perpendicular to the incident light are formed on different planes spaced in parallel with the micromirror. Or front projection TV.   The projection television according to claim 1, further comprising a color wheel. The projection television according to claim 2, further comprising a light guide tube . The projection television of claim 1 , wherein the micromirror achieves a gray scale image by the pulse width modulation . The projection television set according to claim 1, wherein each micromirror corresponds to a pixel of an image projected on a screen .   The projection television set according to claim 1, which is a rear projection television set.   The projection television set according to claim 1, which is a front projection television set.   2. The projection television according to claim 1, wherein when viewed from above the array, no side of the micromirror is parallel to the light beam irradiated.   The projection television according to claim 1, wherein the micromirrors are arranged in a lattice shape inclined with respect to the X axis and the Y axis of the array. The micromirror has a micromirror plate connected to the substrate by a hinge,
The projection television of claim 9 , wherein there is a first gap between the hinge and the micromirror plate, and a second gap between the micromirror plate and the substrate. The projection television according to claim 1 , wherein the micromirror array is housed in a package having a light transmissive window. The projection television set of claim 11 , wherein the package comprises a mask. The projection television of claim 11 , wherein the package is provided with a molecular scavenger. The projection television of claim 11 , wherein the package is provided with a getter. The projection television according to claim 11 , wherein the package is provided with a supply source of a reduction stiction agent. 2. The projection television according to claim 1 , wherein the beam of light applied to the micromirror array has an angle of 10 to 50 degrees with respect to a normal to a plane defined by the micromirror. The micromirrors may be at least 12 Dokai rolling when turned on, projection television of claim 16. Including an optical system including a plurality of lenses for projection shape from the micromirror array to the screen, projection television of claim 1. The projection television according to claim 1, further comprising a color wheel, a light guide tube, and a TIR prism.   The projection television according to claim 1, wherein the micromirror includes a metal and a dielectric material, and the dielectric material is any one of nitride, carbide, or silicon oxide. The projection television according to claim 1 , wherein the micromirror array is housed in a package, has a circuit and an electrode on a semiconductor substrate, and has a bond line for electrically connecting the substrate and the package. Said array having four sides are rectangular, the light from the light source is a beam-like light forms an angle in the range of 90 degrees ± 40 degrees with respect to the top sides of the rectangular array, in claim 1 The projection TV described. Each micromirror has at least one edge substantially parallel to the changeover axis of said array, projection television of claim 1. Each micromirror has a changeover shaft form an angle in a range of 60 degrees from 35 degrees to the sides of the micromirror, projection television of claim 23. 25. The projection television of claim 24 , wherein the light does not enter perpendicularly to any side of the micromirror. 26. The projection television according to claim 25 , wherein a width of the hinge is in a range of 0.1 to 10 [mu] m. 24. The projection television of claim 23 , further comprising a light absorbing layer below the micromirrors to reduce light diffused through the gaps between the micromirrors. 24. The projection television of claim 23 , wherein the array has 64,000 to 2,000,000 micromirrors. Further comprising a TIR prism, projection television of claim 1. The array has from 1920000 to 3145728 nine micro mirrors, projection television of claim 1. The projection television set according to claim 1, wherein there are 3 million or more micromirrors in an area of 1 square centimeter or more and 1 square inch . 24. The projection television of claim 23 , wherein the micromirror has a resolution of 1920000 or higher. 24. The projection television of claim 23 , having an HDTV format. The projection television of claim 23 , having a QXGA format. The projection television of claim 23 , having a UXGA format. A light source for supplying light to the micromirror array;
A micromirror array;
A rear or front projection television with a screen for projecting images,
During operation, light from the light source is applied to the micromirror array and projected as a rectangular image on the screen.
The micromirrors can be moved between the off and on states by pulse width modulation to display grayscale images on the screen, each micromirror corresponding to the pixels of the image projected on the screen,
The projected image has four sides, each micromirror projects a micromirror image on the screen, and the projected micromirror image has one convex shape on the side of the rectangular screen, which The side is not parallel to the side of the rectangular image ,
The irradiated light beam is incident perpendicular to one side of the micromirror array;
Below the micromirror, a hinge that makes the rotation axis of the micromirror perpendicular to the incident light is formed on different planes spaced in parallel with the micromirror. Projection television. The projection television set of claim 36 , further comprising a color wheel. The projection television set of claim 36 , further comprising a light guide tube . 37. The projection television of claim 36 , which is a rear projection television. The projection television of claim 36 , wherein the projection television is a front projection television. 37. The projection television of claim 36 , wherein when viewed from above the array, no side of the micromirror is parallel to the beam of light that is illuminated. 40. The projection television according to claim 39 , wherein the micromirrors are arranged in a lattice shape inclined with respect to the X axis and Y axis of the array. The micromirror has a micromirror plate connected to the substrate by a hinge,
40. The projection television of claim 39 , wherein there is a first gap between the hinge and the micromirror plate, and a second gap between the micromirror plate and the substrate. 40. The projection television of claim 39 , wherein the micromirror array is housed in a package having a light transmissive window. 45. The projection television of claim 44 , wherein the package comprises a mask. 45. The projection television of claim 44 , wherein the package is provided with a molecular scavenger. 45. The projection television of claim 44 , wherein the package is provided with a getter. 45. The projection television of claim 44 , wherein the package is provided with a supply of destiction agent. 40. The projection television of claim 39 , wherein the beam of light applied to the micromirror array has an angle of 10 to 50 degrees with respect to a normal to a plane defined by the micromirror. The micromirrors may be at least +12 Dokai rolling when turned on, projection television of claim 49. 41. The projection television of claim 40 , comprising an optical system including a plurality of lenses for projecting a shape from a micromirror array onto a screen. The projection television set according to claim 36 , further comprising a color wheel, a light guide tube, and a TIR prism. 37. The projection television of claim 36 , wherein the micromirror includes a metal and a dielectric material, and the dielectric material is one of nitride, carbide, or silicon oxide. 37. The projection television according to claim 36 , wherein the micromirror array is housed in a package, has a circuit and an electrode on a semiconductor substrate, and has a bond line for electrically connecting the substrate and the package. 37. The projection television of claim 36 , wherein the micromirror hinges are parallel to the leading and trailing edges of the micromirror array. 37. The projection television of claim 36 , wherein the micromirrors are arranged substantially without a gap. Said array having four sides are rectangular, the light from the light source is a beam-like light forms an angle in the range of 90 degrees ± 40 degrees with respect to the top sides of the rectangular array, in claim 36 The projection TV described. Each micromirror has at least one edge substantially parallel to the changeover axis of said array, projection television of claim 36. 59. The projection television of claim 58 , wherein each micromirror has a switching axis that forms an angle in the range of 35 to 60 degrees with respect to the sides of the micromirror. 59. The projection television of claim 58 , wherein the light does not enter perpendicularly to any side of the micromirror. 37. The projection television of claim 36 , wherein the hinge has a width in the range of 0.1 to 10 [mu] m. 37. The projection television of claim 36 , further comprising a light absorbing layer below the micromirrors to reduce light diffused through the gaps between the micromirrors. 37. The projection television of claim 36 , wherein the array has 64,000 to 2,000,000 micromirrors. 37. The projection television of claim 36 , further comprising a TIR prism. The array has from 1920000 to 3145728 nine micro mirrors, projection television of claim 36. 37. The projection television of claim 36 , wherein there are 3 million or more micromirrors in an area of 1 square centimeter or more and 1 square inch . 37. The projection television of claim 36 , wherein the micromirror has a resolution of 1920000 or higher. 37. The projection television of claim 36 , having an HDTV format. 37. The projection television of claim 36 , having a QXGA format. 37. The projection television of claim 36 , having a UXGA format. 37. The projection television of claim 36 , wherein none of the micromirror sides are substantially perpendicular to any array side. A packaged micromirror array for projection display comprising a micromirror array, each composed of a quadrilateral micromirror defined by four sides,
Micromirror is moved between the off and on states can form Film image on the target by a pulse width modulation,
A package having a light transmissive window, in which the micromirror array is provided;
With
A packaged micromirror array in which no side of the micromirror is parallel to any side of the rectangular mask ;
Incident light from the light source is incident at a right angle to one side of the micromirror array;
Further, below the micromirror, a hinge that makes the rotation axis of the micromirror perpendicular to the incident light is formed on different planes spaced in parallel with the micromirror. Mirror array. The packaged micromirror array of claim 72 , further comprising bond lines at one end of the package for electrically connecting the micromirror array to the package to drive the micromirror. The packaged micromirror array of claim 72 , wherein the mask is provided as part of a package. 75. The packaged micromirror array of claim 72 , wherein the micromirrors are arranged in a grid that is inclined with respect to the X and Y axes of the array. The micromirror has a micromirror plate connected to the substrate via a hinge,
74. The packaged micromirror array of claim 72 , wherein there is a first gap between the hinge and the micromirror plate and a second gap between the micromirror plate and the substrate. 73. The packaged micromirror array of claim 72 , wherein the micromirror array has circuitry and electrodes provided on a semiconductor substrate, and bond lines for electrically connecting the substrate to the package. 73. The packaged micromirror array of claim 72 , wherein the micromirror array is rectangular and each micromirror has a switching axis that is substantially parallel to at least one side of the array. A grayscale image can be projected on the target by moving between the off state and the on state by pulse width modulation, and each micromirror has a micromirror array corresponding to the pixels of the image projected on the target;
A package having a light transmissive window in which the micromirror array is provided;
A rectangular mask provided on or on the micromirror array,
Each of the micromirrors has one protrusion on the side of the rectangular array, and no side is parallel to the side of the rectangular array,
Incident light from the light source is incident perpendicular to one side of the micromirror array,
Furthermore, under the micromirror, a hinge that makes the rotation axis of the micromirror perpendicular to the incident light is formed on a different plane spaced in parallel with the micromirror. Packaged micromirror array for display. The micromirror has a micromirror plate connected to the substrate via a hinge,
80. The packaged micromirror array of claim 79 , wherein there is a first gap between the hinge and the micromirror plate, and a second gap between the micromirror plate and the substrate.

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