CN113031252B - Micro-mirror with micro-nano structure, micro-mirror preparation method and laser display system - Google Patents
Micro-mirror with micro-nano structure, micro-mirror preparation method and laser display system Download PDFInfo
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
- G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
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- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/10—Scanning systems
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- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
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- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
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- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/0002—Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
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- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
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Abstract
A micro-mirror with micro-nano structure, a micro-mirror preparation method and a laser display system. The invention provides a micro-mirror with a micro-nano structure, which comprises a substrate layer, a micro-nano structure layer and a reflecting layer, wherein the micro-nano structure layer is positioned above the substrate layer, the micro-nano structure layer is arranged in a specific area on the surface of the substrate layer, the micro-nano structure layer is a micro-lens array or a Fresnel lens array, and the reflecting layer is positioned above the micro-nano structure layer. The preparation of the micro-mirror is based on a nanoimprint technology, a nanoprinting technology or a photoresist hot melting technology, integrates a curved surface reflection micro-nano structure, has high precision and small size, can realize more uniform micro-nano structure distribution, ensures that the reflected sub-beam energy is more uniform, and ensures that the speckle inhibition effect is better.
Description
Technical Field
The invention relates to the field of optical display, in particular to a micro-mirror with a micro-nano structure, a micro-mirror preparation method and a laser display system.
Background
Speckle is a particulate speckle of random intensity that occurs when a coherent light source, such as a laser light source, irradiates an optically rough surface or passes through a non-uniform medium. A coherent light beam, such as a laser, is diffusely reflected at an optically rough surface to form a random distribution of light having a phase difference in space. Light generated by diffuse reflection has the same frequency as incident light, and interference occurs after space meeting, so that light intensity is randomly distributed in space, and speckle is formed.
Speckle has different meanings in different applications and fields. In coherent light display systems, such as laser display systems, speckle can result in a lack of displayed image information, reducing the resolution of the display, and thus speckle can be detrimental to coherent light display systems. In laser projection display systems, the primary parameter for measuring speckle is speckle contrast, which is defined as the ratio of the standard deviation to the mean of the intensity of light on a uniformly illuminated screen. When the speckle phenomenon is obvious, the C value is larger; conversely, C will tend to zero. For the human eye to not perceive the presence of speckle in the image, the speckle contrast value should be below 4%. According to the related study, when the speckle contrast is suppressed to below 4%, the human visual system cannot recognize the speckle in the projected image.
From the causal analysis of speckle, the root cause of speckle formation is that the illuminating beam has excellent coherence. Thus, the fundamental approach to speckle suppression is to reduce the coherence of the illuminating beam. Numerous speckle reduction techniques exist that can be broadly divided into three categories: the low coherence laser light source is formed by driving multiple lasers or the speckle brightness formed on average, the human vision is compensated by a vibrating projection screen, and the optical properties of the laser beam are influenced in time and/or space by adding optical elements with specific functions in the optical path. Wherein, due to the light emitting characteristic of the lasers, the total output light power is certain, and the power consumption for driving multiple lasers is larger than that for driving a single laser. Meanwhile, the number of lasers is increased, and the production cost is also increased. However, the technology for suppressing the speckle by vibrating the projection screen has an excessive limitation in practical application. Therefore, when speckle suppression is performed, the optical element with a specific function is added in the optical path, so that the optical element has the widest application prospect at the present stage.
Among the speckle reduction techniques, optical elements mainly used in the prior art include various types of diffusion sheets, diffractive optical elements, microlens arrays, and surface roughened MEMS micromirrors.
The scattering sheet has quite limited speckle inhibiting effect in a static state, and needs to be driven by a driving system, and a light beam penetrates through the rotating and/or vibrating scattering sheet to form sub-light beams with time-varying random phases. The speckle effect of the sub-beams is small and the overall effect is reduced after overlapping each other. However, adding an additional driving system in the laser display system may not only adversely affect the reliability of the precision optical system, but also may generate negative effects such as noise, and meanwhile, it is not beneficial to the integration and miniaturization of the system module, and limits the commercial application value of the system module.
The diffraction optical element can split the transmitted light beam in a static state, and the split sub-light beams have random phases due to the micro-nano structure of the diffraction optical element, so that the speckle effect formed by the sub-light beams is small and the whole effect is reduced after the sub-light beams are overlapped with each other. However, since a specific diffractive optical element can split only a coherent light beam of a specific wavelength, there is a certain limitation in use.
The microlens array refers to an arrangement combination of a certain number of spherical or free-form surface lenses with micro-nano dimensions. The periodic size of the microlens array is typically 500nm to 50 μm. The micro lens array can split the light beam in a static state, and has better beam splitting and homogenizing effects compared with the diffraction optical element. In general, microlens arrays typically require two arrays to be used in combination together. Since the homogenizing effect of a single microlens array is inferior to that of a microlens array group, the brightness distribution in the spot after homogenization is uneven, and the speckle suppression effect is poor. The use of multiple microlens arrays increases the module size. Meanwhile, two microlens arrays are needed to correspond to each other when the microlens arrays are used, and the requirements on the accuracy of the size and the position are high. In addition, due to the manufacturing process, a scattering phenomenon inevitably occurs when a lens array (not only a microlens array) is used, so that energy loss is caused, spot brightness is reduced, and the laser display is disadvantageous.
The surface roughened MEMS micro-mirror imparts a time-varying phase to the reflected beam by vibrating in one or more dimensions. However, the prior art still has certain disadvantages, such as complex process, poor stability of the finished product, high cost, low yield, and the like. Meanwhile, according to several documents, the height or depth of the projections formed by roughening is required to be 1/4 to 2 times the incident wavelength. Therefore, the precision requirement on the surface micro/nano structure of the roughened MEMS micro-mirror is high, so that certain limitation exists in practical use.
Disclosure of Invention
In order to solve the technical problems, the invention discloses a micro-mirror with a micro-nano structure, a micro-mirror preparation method and a laser display system.
In a first aspect of the present invention, there is provided a method for manufacturing a micromirror, comprising the steps of:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the wafer device layer;
heating the polymer layer to a temperature higher than the glass transition temperature of the polymer layer in a vacuum environment, stamping the liquid polymer layer to a certain depth by using a stamp, and keeping for a period of time to enable the liquid polymer to fill the gap of the stamp pattern;
step four, reducing the temperature to solidify the polymer and demolding to form a micro-nano structure layer;
evaporating and forming a reflecting layer on the surface of the micro-nano structure layer;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
Further, the polymer layer is a thermoplastic polymer.
Further, the thermoplastic polymer is made of polypropylene or polymethyl methacrylate.
Further, the vacuum degree of the vacuum environment in the third step is less than or equal to 1mbar.
Further, the heating temperature in the third step is 250-320 ℃.
Further, the pressure of the imprinting in the third step is 5bar to 70bar.
Further, the size of the seal is not more than 150mm, and the seal is made of quartz (Silicon) or Nickel (Nickel).
Further, the temperature is reduced in the fourth step so that the temperature of the thermoplastic polymer is lower than the glass transition temperature thereof.
In a second aspect of the present invention, there is provided a method for manufacturing a micromirror, comprising the steps of:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the wafer device layer;
third, stamping the liquid polymer layer to a certain depth by using a stamp in a vacuum environment, keeping for a period of time, filling the gap of the stamp pattern with the liquid polymer, and irradiating by using ultraviolet light through the stamp;
step four, solidifying the polymer layer filled in the seal and demolding to form a micro-nano structure layer;
Evaporating and forming a reflecting layer on the surface of the micro-nano structure layer;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
Further, the polymer layer is an ultraviolet light curing material.
Further, the vacuum degree of the vacuum environment in the third step is less than or equal to 1mbar.
Further, the pressure of the imprinting in the third step is 5bar to 70bar.
Further, the seal is made of quartz glass (Fused Silica).
In a third aspect of the present invention, there is provided a method for manufacturing a micromirror, comprising the steps of:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the wafer device layer;
scanning the surface of the device layer of the substrate layer by utilizing a two-photon polymerization technology to form a micro-nano structure layer with a designed pattern;
Step four, after the patterns of the micro-nano structure layer are completely formed by a two-photon polymerization technology, removing the redundant polymer layer;
evaporating and forming a reflecting layer on the surface of the micro-nano structure layer;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
Further, the polymer layer is a negative photoresist.
Further, depending on the complexity of the pattern to be processed, a Sol-gel (Sol-gel) photoresist is selected for more complex patterns, such as fresnel lens arrays; other patterns, such as micro lens arrays with slightly larger apertures, are selected from liquid photoresist.
And in the third step, under the control of a piezoelectric technology and a galvanometer technology, scanning layer by utilizing a two-photon polymerization technology.
And in the fourth step, the rest negative photoresist is directly removed, and the micro-nano structure layer is left.
In a fourth aspect of the present invention, there is provided a method for manufacturing a micromirror, comprising the steps of:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the device layer of the wafer;
step three, etching the polymer layer into a plurality of tiny cylindrical polymer layers through photoetching and developing;
step four, heating and baking to thermally melt a plurality of fine cylindrical polymer layers into a lens shape under the action of tension, and cooling to form a micro-nano structure with a micro-lens array;
evaporating and forming a reflecting layer on the surface of the micro-nano structure layer;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
Further, the polymer layer is a photoresist.
According to a sixth aspect of the present invention, there is provided a micromirror having a micro-nano structure, the micromirror manufactured according to the above-mentioned method for manufacturing a micromirror includes a substrate layer, a micro-nano structure layer and a reflective layer, wherein the micro-nano structure layer is located above the substrate layer, and the micro-nano structure layer is disposed in a specific area on the surface of the substrate layer, and the micro-nano structure layer is a micro-lens array or a fresnel lens array, and the reflective layer is located above the micro-nano structure layer.
In a seventh aspect of the present invention, there is provided a laser display system comprising a laser light source, a collimator unit, a beam combiner, a speckle suppression device, and a first micromirror device arranged in this order,
the laser light source receives the driving signal and emits at least one color laser beam;
the collimating unit respectively collimates the laser beams into collimated laser beams meeting the scanning beam size requirement;
the beam combiner forms collimated laser beams into combined beams;
the speckle suppression device is used for expanding, splitting, homogenizing and converging the beam-combining light to generate an emergent light beam composed of a plurality of sub-light beams;
the first micro-mirror device is used for reflecting the emergent light beam into a scanning light beam and projecting the scanning light beam to a projection surface for scanning display;
the speckle suppression device at least comprises a second micro-mirror device and a condensing lens, wherein the second micro-mirror device comprises a second micro-mirror and a second micro-mirror driving device, the second micro-mirror adopts the micro-mirror, the second micro-mirror driving device drives the second micro-mirror to do periodic translation or deflection movement in at least one dimension, and the incidence angle and the position of the beam expansion beam are periodically changed to form a reflected beam formed by a plurality of sub-beams; the condensing lens condenses and collimates the reflected light beam to form the emergent light beam.
Further, the first micromirror device comprises a first micromirror and a first micromirror driving device, and the first micromirror driving device drives the first micromirror to do periodic translational motion or deflection motion in at least one dimension.
As an embodiment, the speckle suppression device further comprises a beam expander.
In an eighth aspect of the present invention, there is provided a laser display system comprising a laser light source, a collimator unit, a beam combiner and a speckle suppression device arranged in this order,
the laser light source receives the driving signal and emits at least one color laser beam;
the collimating unit respectively collimates the laser beams into collimated laser beams meeting the scanning beam size requirement;
the beam combiner forms collimated laser beams into combined beams;
the speckle suppression device is used for expanding, splitting, homogenizing and converging the beam-combining light to generate a scanning light beam consisting of a plurality of sub-light beams and projecting the scanning light beam to a projection surface for scanning display;
the speckle suppression device at least comprises a micro-mirror device and a condensing lens, wherein the micro-mirror device comprises the micro-mirror and a micro-mirror driving device, the micro-mirror driving device drives the micro-mirror to perform periodic translation or deflection movement in at least one dimension, and the incidence angle and the position of a beam expansion beam are periodically changed to form a reflected beam formed by a plurality of sub-beams; the condensing lens condenses and collimates the reflected light beam to form the scanning light beam.
As an embodiment, the speckle suppression device further comprises a beam expander.
By adopting the technical scheme, the invention has the following beneficial effects:
1) The preparation of the micro-mirror is based on the nanoimprint technology and the nanoprinting technology, integrates the curved surface reflection micro-nano structure, has high precision and small size, can realize more uniform micro-nano structure distribution, ensures that the reflected sub-beam energy is more uniform, and ensures that the speckle suppression effect is better;
2) The micro-nano structure based on the pattern which is independently defined can be easily designed and manufactured based on the nanoimprint technology and the nanoprinting technology, and comprises micro-nano structures which cannot be manufactured or are difficult to manufacture by the traditional photoetching technology, such as a micro-lens array pattern, a Fresnel lens array pattern, a thin-layer grating and the like, and the micro-nano structure is integrated on the vibrating mirror surface of the MEMS micro-mirror, so that the sub-beam composition of the reflected light beam is more flexibly controlled, and the best beam splitting and homogenizing effect of the light beam at the same current stage as the micro-lens array is realized in a curved surface reflection mode;
3) The micromirror of the invention can realize beam splitting and beam homogenizing of all visible light by a single micromirror by controlling the special size and arrangement mode of the micro-nano structure;
4) The preparation of the micro-mirror is based on the nano-imprinting technology and the nano-printing technology, multiple times of photoetching are not needed, the process flow is simple, the process stability is good, the integrated manufacturing can be realized by utilizing the nano-printing technology, even a seal and a mask are not needed to be manufactured, and the process flow is simple;
5) The micro mirror does not need to be matched with a vibrating projection screen, so that the designed speckle suppression effect can be realized on a static screen, and the convenience and practicality of the system are improved;
6) The micro mirror does not need to reference additional precise optical elements such as a micro lens array, a diffraction optical element or a rotating scattering sheet for speckle suppression, and the like, so that the reliability of the module is higher, the integration degree is higher, and the size is smaller;
7) The micro mirror is driven by the micro mirror driving device, has low power consumption and basically no noise during operation, and can avoid damage to other components in the module caused by vibration and other factors possibly caused by other driving modes, thereby improving the reliability of equipment and the module;
8) The micro mirror provided by the invention has weak rejection to the prior art and good applicability, and can be used in combination with part of the prior art, such as a vibrating screen technology, a speckle suppression technology based on special optical components and the like, so that further speckle suppression is performed, and the defect of part of the prior art in speckle suppression degree is overcome;
9) When the invention is applied to the HUD system, the MEMS micro-mirror device can directly replace the MEMS micro-mirror device in the original laser display system, namely, only one micro-mirror device is needed in the system, so that the speckle suppression and scanning display functions can be realized at the same time, and the complexity of system integration and the power consumption of the system are not increased while the speckle suppression function is realized without introducing additional components.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIGS. 1 (a) -1 (g) are flowcharts showing a method for fabricating a micromirror according to example 1 of the present invention;
FIGS. 2 (a) -2 (g) are flowcharts showing a method for fabricating a micromirror according to example 2 of the present invention;
FIGS. 3 (a) -3 (g) are flowcharts showing a method for fabricating a micromirror according to example 3 of the present invention;
FIGS. 4 (a) -4 (g) are flowcharts showing a method for fabricating a micromirror according to example 4 of the present invention;
FIG. 5 is a schematic diagram of a micromirror structure according to embodiment 5 of the present invention;
FIG. 6 is a schematic diagram of a micromirror structure according to embodiment 6 of the present invention;
FIG. 7 is a schematic diagram of a laser display system according to embodiment 7 of the present invention;
fig. 8 is a schematic diagram of a laser display system according to embodiment 8 of the present invention.
The following supplementary explanation is given to the accompanying drawings:
101-a substrate layer; 101 a-a device layer; 101 b-an oxygen-buried layer; 101 c-a support layer; 102-a polymer layer; 103-seal; 104-a micro-nano structure layer; 105-a reflective layer;
201-a substrate layer; 201 a-device layer; 201 b-an oxygen-buried layer; 201 c-a support layer; 202-a polymer layer; 203-seal; 204-ultraviolet light; 205—micro-nano structured layer; 206-a reflective layer;
301a substrate layer; 301 a-device layers; 301 b-an oxygen-buried layer; 301 c-a support layer; 302-a polymer layer; 303-a micro-nano structural layer; 304-a reflective layer;
401a substrate layer; 401 a-device layer; 401 b-buried oxide layer; 401 c-a support layer; 402-a polymer layer; 403-a fine cylindrical polymer layer; 404—micro-nano structured layer; 405-a reflective layer;
501a substrate layer; 501 a-a device layer; 501 b-an oxygen-buried layer; 501 c-a support layer; 502—micro-nano structured layer; 503-a reflective layer;
601-a substrate layer; 601 a-device layer; 601 b-an oxygen-buried layer; 601 c-a support layer; 602—micro-nano structured layer; 603-a reflective layer;
71-a laser light source; 72-a collimation unit; 73-beam combiner; 74-speckle suppression means; 741-beam expander; 741 a-a first lens; 741 b-a second lens; 742-a second micromirror device; 742 a-a second micromirror; 742 b-a second micromirror drive; 75-a first micromirror device; 751-a first micromirror; 752-first micromirror driving device;
81-a laser light source; 82-a collimation unit; 83-beam combiner; 84-speckle suppressing means; 841-beam expander; 841 a-first lens; 841 b-a second lens; 842-a second micromirror device; 842 a-micromirrors; 842 b-micromirror driving device.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "top", "bottom", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may include one or more of the feature, either explicitly or implicitly. Moreover, the terms "first," "second," and the like, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein.
Example 1: (thermal nanoimprint Process)
As shown in fig. 1 (a) -1 (g), a micromirror manufacturing method:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
step two, uniformly coating a polymer layer 102 on the surface of the wafer device layer 101 a;
heating the polymer layer 102 to a temperature higher than the glass transition temperature of the polymer layer 102 in a vacuum environment, stamping the liquid polymer layer 102 to a certain depth by using the stamp 103, and keeping for a period of time to enable the liquid polymer to fill the pattern gaps of the stamp 103;
step four, the temperature is reduced to solidify the polymer and the polymer is demoulded to form the micro-nano structure layer 104;
step five, evaporating and forming a reflecting layer 105 on the surface of the micro-nano structure layer 104;
step six, removing the redundant polymer layer 102 on the device layer 101a, and then etching the equipment layer to the buried oxide layer 101b to form a main structure of an electric isolation groove and a micro mirror;
step seven, preparing a back cavity on the supporting layer 101c of the wafer, and etching the back cavity to the buried oxide layer 101b to expose the buried oxide layer 101b in the range of the back cavity;
and step eight, corroding the oxygen-buried layer 101b exposed in the back cavity range to release the movable part of the micromirror, thereby completing the micromirror manufacturing.
In the first step, the outline of the micromirror is defined by photolithography and shallow etching.
As shown in fig. 1 (a), the wafer is a substrate layer 101, and includes a device layer 101a, an oxygen-buried layer 101b and a supporting layer 101c, where the device layer 101a is a surface layer, and the oxygen-buried layer 101b is an intermediate layer; the supporting layer 101c is a bottom layer.
The material of the device layer 101a is monocrystalline silicon, the material of the buried oxide layer 101b is silicon dioxide, and the material of the support layer 101c is monocrystalline silicon.
The polymer layer 102 is a thermoplastic polymer.
The glass transition temperature (glass transition temperature) of the thermoplastic polymer is about 100 ° C higher than the temperature of the wafer when the metal is evaporated.
The thermoplastic polymer is made of Polypropylene (PS) or polymethyl methacrylate (Polymethyl methacrylate, PMMA).
And in the third step, the vacuum degree of the vacuum environment is less than or equal to 1mbar.
The heating temperature in the third step is 250-320 ℃.
The pressure of the imprinting in the third step is 5bar to 70bar.
The size of the seal 103 is not more than 150mm, and the material of the seal 103 is quartz (Silicon) or Nickel (Nickel).
The feature size of the pattern of the seal 103 is 20nm-300nm, and Electron Beam Lithography (EBL) is selected to manufacture the seal 103; the feature size of the pattern of the seal 103 is 300nm-2 mu m, and the seal 103 is manufactured by deep ultraviolet lithography (DUV); the feature size of the pattern of the seal 103 is more than 2 mu m, and the seal 103 is manufactured by conventional photoetching (UVL).
The pattern of the seal 103 is a micro lens array with caliber of 300nm-400 μm which is arranged in a hexagonal close arrangement or other arrangement modes.
The temperature is reduced in step four so that the temperature of the thermoplastic polymer is below its glass transition temperature.
In the fifth step, the reflective layer 105 is formed by vacuum vapor deposition (PVD) of metal, and the reflective layer 105 is a metal film.
The reflective layer 105 is made of aluminum or gold.
The thickness of the reflective layer 105 is 50nm to 500nm.
In the sixth step, the excess polymer layer 102 is removed by photolithography and etching, and the main structures of the electrically isolated grooves and the micromirrors, such as comb-tooth structures, are formed by photolithography and etching back the device layer to the buried oxide layer 101b.
In the seventh step, the back cavity is prepared in a defined range through photoetching and etching.
In the eighth step, the buried oxide layer 101b exposed in the back cavity is etched by hydrofluoric acid.
Example 2: (ultraviolet nanoimprint)
As shown in fig. 2 (a) -2 (g), a micromirror manufacturing method:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
step two, uniformly coating a polymer layer 202 on the surface of the wafer device layer 201 a;
Step three, in a vacuum environment, stamping the liquid polymer layer 202 to a certain depth by using the stamp 203, keeping for a period of time, filling the pattern gap of the stamp 203 with the liquid polymer, and irradiating the stamp 203 with ultraviolet light 204;
step four, curing the polymer layer 202 filled in the seal 203 and demolding to form a micro-nano structure layer 205;
step five, evaporating and forming a reflecting layer 206 on the surface of the micro-nano structure layer 205;
step six, removing the redundant polymer layer 202 on the device layer 201a, and then etching the equipment layer to the buried oxide layer 201b to form a main structure of an electric isolation groove and a micro mirror;
step seven, preparing a back cavity in the supporting layer 201c of the wafer, and etching the back cavity to the buried oxide layer 201b to expose the buried oxide layer 201b in the range of the back cavity;
and step eight, corroding the oxygen-buried layer 201b exposed in the back cavity range to release the movable part of the micromirror, thereby completing the micromirror fabrication.
In the first step, the outline of the micromirror is defined by photolithography and shallow etching.
The wafer is a substrate layer 201, and comprises a device layer 201a, an oxygen-buried layer 201b and a supporting layer 201c, wherein the device layer 201a is a surface layer, and the oxygen-buried layer 201b is an intermediate layer; the supporting layer 201c is a bottom layer.
The material of the device layer 201a is monocrystalline silicon, the material of the buried oxide layer 201b is silicon dioxide, and the material of the support layer 201c is monocrystalline silicon.
The polymer layer 202 is an ultraviolet light 204 curable material.
The glass transition temperature (glass transition temperature) of the uv 204 cured material is about 100 ° C higher than the temperature of the wafer when the metal is evaporated.
And in the third step, the vacuum degree of the vacuum environment is less than or equal to 1mbar.
The pressure of the imprinting in the third step is 5bar to 70bar.
The stamp 203 is made of quartz glass (Fused Silica).
The feature size of the pattern of the seal 203 is 20nm-300nm, and Electron Beam Lithography (EBL) is selected to manufacture the seal 203; the feature size of the pattern of the seal 203 is 300nm-2 mu m, and deep ultraviolet 204 lithography (DUV) is selected to manufacture the seal 203; the feature size of the pattern of the seal 203 is more than 2 mu m, and the seal 203 is manufactured by conventional photoetching (UVL).
The pattern of the seal 203 is a micro lens array with caliber of 300nm-400 μm which is arranged in a hexagonal close arrangement or other arrangement modes.
In the fifth step, the reflective layer 206 is formed by vacuum vapor deposition (PVD) of metal, and the reflective layer 206 is a metal film.
The reflective layer 206 is made of aluminum or gold.
The reflective layer 206 has a thickness of 50nm to 500nm.
In the sixth step, the excess polymer layer 202 is removed by photolithography and etching, and the main structures of the electrically isolated grooves and the micromirrors, such as comb-tooth structures, are formed by photolithography and etching back the device layer to the buried oxide layer 201b.
In the seventh step, the back cavity is prepared in a defined range through photoetching and etching.
In the eighth step, the buried oxide layer 201b exposed in the back cavity is etched by hydrofluoric acid.
Example 3: (nanometer printing Process)
As shown in fig. 3 (a) -3 (g), a micromirror manufacturing method:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
step two, uniformly coating a polymer layer 302 on the surface of the wafer device layer 301 a;
step three, scanning layer by layer on the surface of the device layer 301a of the substrate layer 301 by utilizing a two-photon polymerization technology to form a micro-nano structure layer 303 with a designed pattern;
step four, after the pattern of the micro-nano structure layer 303 is completely formed by a two-photon polymerization technology, removing the redundant polymer layer 302;
step five, evaporating and forming a reflecting layer 304 on the surface of the micro-nano structure layer 303;
step six, removing the redundant polymer layer 302 on the device layer 301a, and then etching the equipment layer to the buried oxide layer 301b to form a main structure of an electric isolation groove and a micro mirror;
Step seven, preparing a back cavity in the supporting layer 301c of the wafer, and etching the back cavity to the buried oxide layer 301b to expose the buried oxide layer 301b in the back cavity;
and step eight, corroding the oxygen buried layer 301b exposed in the back cavity range to release the movable part of the micromirror, thereby completing the micromirror fabrication.
In the first step, the outline of the micromirror is defined by photolithography and shallow etching.
The wafer is a substrate layer 301, and includes a device layer 301a, an oxygen-buried layer 301b, and a supporting layer 301c, where the device layer 301a is a surface layer, and the oxygen-buried layer 301b is an intermediate layer; the supporting layer 301c is a bottom layer.
The material of the device layer 301a is monocrystalline silicon, the material of the buried oxide layer 301b is silicon dioxide, and the material of the support layer 301c is monocrystalline silicon.
The polymer layer 302 is a negative photoresist.
The negative photoresist has a glass transition temperature (glass transition temperature) that is about 100 ° C higher than the wafer temperature at the time of metal evaporation.
According to the complexity of the pattern to be processed, for more complex patterns, such as Fresnel lens arrays, photoresist in Sol-gel state (Sol-gel) is selected; other patterns, such as micro lens arrays with slightly larger apertures, are selected from liquid photoresist.
In the third step, the layer-by-layer scanning is performed by utilizing a two-photon polymerization technology under the control of a piezoelectric technology (piezo technology) and a galvanometer technology (galvo technology).
In the fourth step, the remaining negative photoresist is directly removed, and the micro-nano structure layer 303 is left.
In the fifth step, the reflective layer 304 is formed by vacuum vapor deposition (PVD) of metal, and the reflective layer 304 is a metal film.
The reflective layer 304 is made of aluminum or gold.
The reflective layer 304 has a thickness of 50nm to 500nm.
In the sixth step, the excess polymer layer 302 is removed by photolithography and etching, and the main structures of the electrically isolated grooves and the micromirrors, such as comb-tooth structures, are formed by photolithography and etching back the device layer to the buried oxide layer 301b.
In the seventh step, the back cavity is prepared in a defined range through photoetching and etching.
In the eighth step, the buried oxide layer 301b exposed in the back cavity is etched by hydrofluoric acid.
Example 4: (Photoresist Hot melting Process)
As shown in fig. 4 (a) -4 (g), a micromirror manufacturing method:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
step two, uniformly coating a polymer layer 402 on the surface of the device layer 401a of the wafer;
Step three, etching the polymer layer 402 into a plurality of fine cylindrical polymer layers 403 by photolithography and development;
step four, heating and baking to thermally melt a plurality of fine cylindrical polymer layers 403 into a lens shape under the action of tension, and cooling to form a micro-nano structure with a micro-lens array;
fifthly, evaporating and forming a reflecting layer 405 on the surface of the micro-nano structure layer 404;
step six, removing the redundant polymer layer 402 on the device layer 401a, and then etching the equipment layer to the buried oxide layer 401b to form a main structure of an electric isolation groove and a micro mirror;
step seven, preparing a back cavity on the supporting layer 401c of the wafer, and etching the back cavity to the buried oxide layer 401b so that the buried oxide layer 401b is exposed in the range of the back cavity;
and step eight, etching the oxygen-buried layer 401b exposed in the back cavity range to release the movable part of the micromirror, thereby completing the micromirror fabrication.
In the first step, the outline of the micromirror is defined by photolithography and shallow etching.
The wafer is a substrate layer 401 and comprises a device layer 401a, an oxygen-buried layer 401b and a supporting layer 401c, wherein the device layer 401a is a surface layer, and the oxygen-buried layer 401b is an intermediate layer; the support layer 401c is a bottom layer.
The material of the device layer 401a is monocrystalline silicon, the material of the buried oxide layer 401b is silicon dioxide, and the material of the support layer 401c is monocrystalline silicon.
The polymer layer 402 is a photoresist. Negative tone photoresist may be selected as the material for forming the polymer layer 402 according to practical requirements.
In the fifth step, the reflective layer 405 is formed by vacuum vapor deposition (PVD) of metal, and the reflective layer 405 is a metal film.
The reflective layer 405 is made of aluminum or gold.
The thickness of the reflective layer 405 is 50nm to 500nm.
In the sixth step, the excess polymer layer 402 is removed by photolithography and etching, and the main structures of the electrically isolated grooves and the micromirrors, such as comb-tooth structures, are formed by photolithography and etching back the device layer to the buried oxide layer 401b.
In the seventh step, the back cavity is prepared in a defined range through photoetching and etching.
In the eighth step, the buried oxide layer 401b exposed in the back cavity is etched by hydrofluoric acid.
Example 5:
as shown in fig. 5, a micro-mirror with micro-nano structure includes a substrate layer 501, a micro-nano structure layer 502 and a reflective layer 503,
the micro-nano structure layer 502 is located above the substrate layer 501, and the micro-nano structure layer 502 is made by nano imprinting or nano printing in a specific area on the surface of the substrate layer 501, and the reflective layer 503 is located above the micro-nano structure layer 502.
The substrate layer 501 is a wafer, and the wafer includes a device layer 501a, an oxygen-buried layer 501b, and a support layer 501c, where the device layer 501a is a surface layer, and the oxygen-buried layer 501b is an intermediate layer; the supporting layer 501c is a bottom layer.
The material of the device layer 501a is monocrystalline silicon, the material of the buried oxide layer 501b is silicon dioxide, and the material of the support layer 501c is monocrystalline silicon.
The monocrystalline silicon device layer 501a has a thickness of between 10 μm and 100 μm.
The material of the buried oxide layer 501b is silicon dioxide.
The micro-nano structure layer 502 is made of polymer, and the micro-nano structure layer 502 is made of different materials and thicknesses according to different processing technologies.
The micro-nano structured layer 502 is a micro-lens array.
When the micro-nano structure layer 502 is prepared by adopting the nano imprinting technology, the thickness t of the micro-nano structure layer 502 1 Slightly larger than the aperture d of the unit lens so as to avoid the direct contact between the stamp and the substrate layer 501 during imprinting;
when the nano-printing technology is used to prepare the micro-nano structure layer 502, the thickness t of the micro-nano structure layer 502 1 Typically the same as the cell lens aperture d.
When the nano-imprint processing is performed, the thickness of the processed lens layer can be controlled by different means for different nano-imprint processing technologies. For example, for a partial thermal nanoimprint process, the thickness of the resulting lens layer after imprinting can be controlled by controlling the polymer thickness before imprinting and the depth of imprinting at the time of imprinting; for another part of the hot nanoimprint process, the thickness of the lens layer obtained after imprinting can be directly controlled by controlling the pattern of the stamp or mask used for imprinting.
The reflective layer 503 is a metal thin film formed by vapor deposition of metal on the micro-nano structure layer 502.
The reflective layer 503 is made of aluminum or gold.
Thickness t of the reflective layer 503 2 50nm-500nm.
Example 6:
as shown in fig. 6, a micromirror with micro-nano structure comprises a substrate layer 601, a micro-nano structure layer 602 and a reflective layer 603,
the micro-nano structure layer 602 is located above the substrate layer 601, and the micro-nano structure layer 602 is made by nano imprinting or nano printing in a specific area on the surface of the substrate layer 601, and the reflective layer 603 is located above the micro-nano structure layer 602.
The substrate layer 601 is a wafer, the wafer includes a device layer 601a, an oxygen-buried layer 601b, and a support layer 601c, the device layer 601a is a surface layer, and the oxygen-buried layer 601b is an intermediate layer; the supporting layer 601c is a bottom layer.
The material of the device layer 601a is monocrystalline silicon, the material of the buried oxide layer 601b is silicon dioxide, and the material of the support layer 601c is monocrystalline silicon.
The thickness of the monocrystalline silicon device layer 601a is between 10 μm and 100 μm.
The buried oxide layer 601b is made of silicon dioxide.
The micro-nano structure layer 602 is made of polymer, and the micro-nano structure layer 602 is made of material and has a thickness t according to the adopted processing technology 1 And also different.
When the nano-imprint processing is performed, the thickness of the processed lens layer can be controlled by different means for different nano-imprint processing technologies. For example, for a partial thermal nanoimprint process, the thickness of the resulting lens layer after imprinting can be controlled by controlling the polymer thickness before imprinting and the depth of imprinting at the time of imprinting; for another part of the hot nanoimprint process, the thickness of the lens layer obtained after imprinting can be directly controlled by controlling the pattern of the stamp or mask used for imprinting.
The reflective layer 603 is a metal film formed by vapor deposition of metal on the micro-nano structured layer 602.
The reflective layer 603 is made of aluminum or gold.
Thickness t of the reflective layer 603 2 50nm-500nm.
Example 7:
a laser display system includes a laser light source 71, a beam combiner 73, a speckle suppression device 74, and a first micromirror device 75 arranged in this order,
the laser light source 71 receives laser beams of three colors emitted by the driving signal;
the collimating unit 72 collimates the laser beams into collimated laser beams conforming to the scanning beam size requirement, respectively;
the beam combiner 73 combines the collimated laser beams into combined beams;
the speckle suppressing device 74 is configured to expand, split, homogenize, and contract the combined beam to generate an outgoing beam composed of a plurality of sub-beams;
The first micro-mirror device 75 is configured to reflect the outgoing light beam into a scanning light beam, and project the scanning light beam onto a projection surface for scanning display;
the speckle suppressing device 74 includes a second micromirror device 742 and a condenser lens (not shown), the second micromirror device 742 includes a second micromirror 742a and a second micromirror driving device 742b, the second micromirror driving device 742b drives the second micromirror 742a to perform periodic translational or deflecting motion in at least one dimension, and periodically changes the incident angle and position of the expanded beam, so as to form a reflected beam composed of a plurality of sub-beams, and the optical properties such as phase of the sub-beams have time variability; the condensing lens condenses and collimates the reflected light beam to form the emergent light beam.
The first micro mirror device 75 includes a first micro mirror 751 and a first micro mirror drive 752, the first micro mirror drive 752 driving the first micro mirror 751 in a periodic translational or deflecting motion in at least one dimension. As shown in fig. 7, the first micro mirror 751 is driven by the first micro mirror driving device 752 to perform periodic out-of-plane translation in the vertical direction.
In addition, the first micro mirror 751 may be driven by the first micro mirror driving device 752 to perform periodic in-plane translation in the horizontal direction, or to perform periodic translation or deflection in both the horizontal and vertical directions.
The second micromirror in this embodiment is the micromirror structure in embodiment 5, and the micro-nano structure layer of the second micromirror is a microlens array.
The second micromirror may also be the micromirror structure of embodiment 6, and the micro-nano structure layer of the second micromirror is a fresnel lens array.
Under the condition that the vibrating mirror structure of the second micro mirror and the surface contour of the vibrating mirror are certain, the larger the area of the vibrating mirror irradiated by the beam expanding beam, the better the speckle suppression effect is.
The speckle reduction device 74 further includes a beam expander 741, where the beam expander 741 is a lens group including a first lens 741a and a second lens 741b. The lens group may be omitted.
Example 8:
as shown in fig. 8, a laser display system includes a laser light source 81, a collimator unit 82, a beam combiner 83 and a speckle suppression device 84 arranged in this order,
the laser light source 81 receives laser beams of three colors emitted by the driving signal;
the collimating unit 82 collimates the laser beams into collimated laser beams meeting the scanning beam size requirement, respectively;
the beam combiner 83 combines the collimated laser beams into combined beams;
the speckle suppression device 84 is configured to expand, split, homogenize and converge the combined beam to generate a scanning beam composed of a plurality of sub-beams, and project the scanning beam onto a projection surface for scanning display;
The speckle suppressing device 84 comprises at least a micromirror device 842 and a condenser lens (not shown), the micromirror device 842 comprises the micromirror 842a and a micromirror driving device 842b, the micromirror driving device 842b drives the micromirror 842a to do periodic translational motion or deflection motion in at least one dimension, and periodically changes the incident angle and position of the expanded beam to form a reflected beam composed of a plurality of sub-beams; the condensing lens condenses and collimates the reflected light beam to form the scanning light beam.
The speckle reduction means 84 further comprises a beam expander 841. The beam expander 841 is a lens group, and includes a first lens 841a and a second lens 841b. The lens group may be omitted.
The micro-mirror 842a in this embodiment is the micro-mirror structure of embodiment 5, and the micro-nano structure layer of the micro-mirror 842a is a fresnel lens array.
The micromirror 842a may also be the micromirror structure of example 6, and the micro-nano structure layer of the micromirror 842a is a microlens array.
When the galvanometer structure and the surface profile of the galvanometer of the micromirror 842a are fixed, the larger the area of the galvanometer is irradiated by the beam-expanding beam, the better the speckle suppression effect is.
In particular, the laser display system can be applied to a HUD system.
According to the MEMS micro-mirror device, a micro-nano structure formed by special patterns is integrated on a micro-mirror surface of the MEMS micro-mirror device through a nano imprinting technology and a nano printing technology. Compared with the traditional roughening method, such as photoetching, the manufacturing method based on the nanoimprint technology and the nanoprinting technology can integrate the micro-nano structure which is smaller in size and higher in precision and can reflect the curved surface and is formed by special patterns on the surface of the micro-mirror vibrating mirror.
The manufacturing method can simply design the patterns and the distribution of the micro-nano structure according to actual requirements, and even can realize micro-nano structures which cannot be realized or are difficult to realize by the traditional method, such as a Fresnel lens array and the like, so that the best beam homogenizing and splitting effect at the same current stage as the micro-lens array is realized in a curved surface reflection mode, and the speckle suppression effect and the applicability of the micro-mirror integrated with the curved surface reflection micro-nano structure are far superior to those of the traditional roughened micro-mirror. In addition, for a partially simple micro-nano structure, such as a micro-lens array, direct processing can be performed by a hot-melt process of photoresist, etc.
The micro-mirror device of the invention is independent of the original MEMS micro-mirror device for scanning imaging in the scanning laser display system. The collimated laser beam generated by the laser is incident on the MEMS micro-mirror device, and the mirror surface of the micro-mirror device is provided with a micro-nano structure formed by a special pattern, so that after the laser beam is incident on the mirror surface, a reflected beam formed by a plurality of sub-beams is formed and reflected to the MEMS micro-mirror device for scanning imaging to become a scanning beam. The sub-beams forming the scanning beam form speckle patterns with smaller energy when the projection surface is imaged, the speckle pattern effects with smaller energy are overlapped with each other, the overall speckle effect is uniform, the brightness is weakened, and therefore the speckle generated during imaging is restrained. Meanwhile, the MEMS micro-mirror device can move in at least one dimension under the driving of the MEMS system, so that the incidence angle/position of an incident laser beam is periodically changed, and the reflected beam formed by the MEMS micro-mirror device also has time variability, thereby further realizing speckle suppression.
The micro-mirror device can be manufactured with low cost and high yield by combining the traditional MEMS micro-mirror manufacturing process with the nano-imprinting technology and the nano-printing technology.
By adopting the technical scheme, the invention has the following beneficial effects:
the preparation of the micro-mirror is based on the nanoimprint technology and the nanoprinting technology, integrates the curved surface reflection micro-nano structure, has high precision and small size, can realize more uniform micro-nano structure distribution, ensures that the reflected sub-beam energy is more uniform, and ensures that the speckle suppression effect is better.
The micro-nano structure based on the pattern which is independently defined can be easily designed and manufactured based on the nanoimprint technology and the nanoprinting technology, the micro-nano structure comprises micro-nano structures which cannot be manufactured or are difficult to manufacture by the traditional photoetching technology, such as micro-lens array patterns, fresnel lens array patterns, lamellar gratings and the like, and the micro-nano structure is integrated on the vibrating mirror surface of the MEMS micro-mirror, so that the sub-beam composition of the reflected light beam is more flexibly controlled, and the best beam splitting and homogenizing effect of the light beam at the same current stage as the micro-lens array is realized in a curved surface reflection mode.
The micromirror of the invention can realize beam splitting and beam homogenizing of all visible light by a single micromirror by controlling the special size and arrangement mode of the micro-nano structure.
The preparation of the micro-mirror is based on the nano-imprinting technology and the nano-printing technology, multiple times of photoetching is not needed, the process flow is simple, the process stability is good, the integrated manufacturing can be realized by utilizing the nano-printing technology, and even a seal and a mask are not needed to be manufactured, so the process flow is simple.
The micro mirror does not need to be matched with a vibrating projection screen, can realize the designed speckle suppression effect on a static screen, and improves the convenience and practicality of the system.
The micro mirror does not need to reference additional precise optical elements such as a micro lens array, a diffraction optical element or a rotating scattering sheet for speckle suppression, and the micro mirror has higher reliability, higher integration degree and smaller size.
The micro mirror is driven by the micro mirror driving device, has low power consumption and basically no noise during operation, and can avoid damage to other components in the module caused by vibration and other factors possibly caused by other driving modes, thereby improving the reliability of equipment and the module.
The micro mirror provided by the invention has weak rejection to the prior art and good applicability, and can be matched with part of the prior art for use, such as a vibrating screen technology, a speckle suppression technology based on special optical components and the like, so that further speckle suppression is performed, and the defect of part of the prior art in speckle suppression degree is overcome.
When the invention is applied to the HUD system, the MEMS micro-mirror device can directly replace the MEMS micro-mirror device in the original laser display system, namely, only one micro-mirror device is needed in the system, so that the speckle suppression and scanning display functions can be realized at the same time, and the complexity of system integration and the power consumption of the system are not increased while the speckle suppression function is realized without introducing additional components.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (10)
1. A method for preparing a micromirror, comprising the steps of:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the wafer device layer;
heating the polymer layer to a temperature higher than the glass transition temperature of the polymer layer in a vacuum environment, stamping the liquid polymer layer to a certain depth by using a stamp, and keeping for a period of time to enable the liquid polymer to fill the gap of the stamp pattern;
Step four, reducing the temperature to solidify the polymer and demolding to form a micro-nano structure layer;
evaporating and forming a reflecting layer on the surface of the micro-nano structure layer to form a curved surface reflecting micro-nano structure; the curved surface reflection micro-nano structure is used for splitting and homogenizing the light beam in a curved surface reflection mode;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
2. The method for manufacturing a micromirror as defined in claim 1, wherein: the polymer layer is a thermoplastic polymer, and the material of the thermoplastic polymer is polypropylene or polymethyl methacrylate.
3. A method for preparing a micromirror, comprising the steps of:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the wafer device layer;
Third, stamping the liquid polymer layer to a certain depth by using a stamp in a vacuum environment, keeping for a period of time, filling the gap of the stamp pattern with the liquid polymer, and irradiating by using ultraviolet light through the stamp;
step four, solidifying the polymer layer filled in the seal and demolding to form a micro-nano structure layer;
evaporating and forming a reflecting layer on the surface of the micro-nano structure layer to form a curved surface reflecting micro-nano structure; the curved surface reflection micro-nano structure is used for splitting and homogenizing the light beam in a curved surface reflection mode;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
4. A method of manufacturing a micromirror as defined in claim 3, wherein: the polymer layer is an ultraviolet light curing material.
5. A method for preparing a micromirror, comprising the steps of:
Step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the wafer device layer;
scanning the surface of the device layer of the substrate layer by utilizing a two-photon polymerization technology to form a micro-nano structure layer with a designed pattern;
step four, after the patterns of the micro-nano structure layer are completely formed by a two-photon polymerization technology, removing the redundant polymer layer;
evaporating and forming a reflecting layer on the surface of the micro-nano structure layer to form a curved surface reflecting micro-nano structure; the curved surface reflection micro-nano structure is used for splitting and homogenizing the light beam in a curved surface reflection mode;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
6. The method for manufacturing a micromirror as defined in claim 5, wherein: the polymer layer is a negative photoresist.
7. A method for preparing a micromirror, comprising the steps of:
step one, preparing a wafer, and defining the outline of a micromirror on the surface of the wafer;
uniformly coating a polymer layer on the surface of the device layer of the wafer, wherein the polymer layer is photoresist;
step three, etching the polymer layer into a plurality of tiny cylindrical polymer layers through photoetching and developing;
step four, heating and baking to thermally melt a plurality of fine cylindrical polymer layers into a lens shape under the action of tension, and cooling to form a micro-nano structure with a micro-lens array;
evaporating and forming a reflecting layer on the surface of the micro-nano structure layer to form a curved surface reflecting micro-nano structure; the curved surface reflection micro-nano structure is used for splitting and homogenizing the light beam in a curved surface reflection mode;
removing the redundant polymer layer on the device layer, and then etching the equipment layer to the buried oxide layer to form a main structure of the electric isolation groove and the micro mirror;
step seven, preparing a back cavity on the supporting layer of the wafer, and etching the back cavity to the oxygen-buried layer to expose the oxygen-buried layer in the range of the back cavity;
and step eight, corroding the oxygen buried layer exposed in the back cavity range to release the movable part of the micro mirror, thereby completing the micro mirror manufacture.
8. A micro-mirror with a micro-nano structure, characterized in that the micro-mirror is prepared according to the micro-mirror preparation method of claim 1, 3, 5 or 7, and comprises a substrate layer, a micro-nano structure layer and a reflecting layer, wherein the micro-nano structure layer is positioned above the substrate layer, the micro-nano structure layer is arranged in a specific area on the surface of the substrate layer, the micro-nano structure layer is a micro-lens array or a fresnel lens array, and the reflecting layer is positioned above the micro-nano structure layer.
9. A laser display system is characterized by comprising a laser light source, a collimation unit, a beam combiner, a speckle suppression device and a first micro-mirror device which are arranged in sequence,
the laser light source receives the driving signal and emits at least one color laser beam;
the collimating unit respectively collimates the laser beams into collimated laser beams meeting the scanning beam size requirement;
the beam combiner forms collimated laser beams into combined beams; the speckle suppression device is used for expanding, splitting, homogenizing and converging the beam-combining light to generate an emergent light beam composed of a plurality of sub-light beams;
the first micro-mirror device is used for reflecting the emergent light beam into a scanning light beam and projecting the scanning light beam to a projection surface for scanning display;
The speckle suppression device at least comprises a second micro-mirror device and a condensing lens, wherein the second micro-mirror device comprises a second micro-mirror and a second micro-mirror driving device, the second micro-mirror adopts the micro-mirror as claimed in claim 8, and the second micro-mirror driving device drives the second micro-mirror to do periodical translational motion or deflection motion in at least one dimension, so that the incidence angle and the position of the beam expansion beam are periodically changed, and a reflected beam formed by a plurality of sub-beams is formed; the condensing lens condenses and collimates the reflected light beam to form the emergent light beam.
10. A laser display system is characterized by comprising a laser light source, a collimation unit, a beam combiner and a speckle suppression device which are sequentially arranged,
the laser light source receives the driving signal and emits at least one color laser beam;
the collimating unit respectively collimates the laser beams into collimated laser beams meeting the scanning beam size requirement;
the beam combiner forms collimated laser beams into combined beams; the speckle suppression device is used for expanding, splitting, homogenizing and converging the beam-combining light to generate a scanning light beam consisting of a plurality of sub-light beams and projecting the scanning light beam to a projection surface for scanning display;
The speckle suppression device at least comprises a micro-mirror device and a condensing lens, wherein the micro-mirror device comprises the micro-mirror and a micro-mirror driving device, and the micro-mirror driving device drives the micro-mirror to do periodic translation or deflection movement in at least one dimension, so as to periodically change the incidence angle and the incidence position of the beam expansion beam and form a reflected beam formed by a plurality of sub-beams; the condensing lens condenses and collimates the reflected light beam to form the scanning light beam.
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| CN114518864B (en) * | 2022-02-17 | 2023-04-07 | 中国工程物理研究院电子工程研究所 | Flexible stretchable optical random number generator, preparation method and use method |
| CN115308897B (en) * | 2022-08-26 | 2024-09-24 | 觉芯电子(无锡)有限公司 | Electromagnetic driving micro-mirror with coil stacking structure and production process |
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| US8864316B2 (en) * | 2010-04-28 | 2014-10-21 | Lemoptix Sa | Optical MEMS scanning micro-mirror with speckle reduction |
| CN102722071A (en) * | 2011-03-30 | 2012-10-10 | 青岛海信电器股份有限公司 | Laser projection light source module and projector |
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