CN219978624U - Micro-mirror structure with low actuation voltage - Google Patents

Abstract

The utility model discloses a micro-mirror structure with low actuation voltage, which comprises: the micro mirror comprises an anchor point arranged on a substrate, a micro mirror surface connected with the anchor point through one end and suspended on the substrate, and an addressing electrode correspondingly arranged on the substrate below the micro mirror surface; the micromirror surfaces are arranged in one-to-one correspondence with the anchor points; the micromirror surface is tilted with respect to the substrate surface as a whole under electrostatic drive from the address electrode, and is elastically restored as a whole when electrostatic drive from the address electrode is lost. The utility model can effectively reduce the actuation voltage of the micromirror, is compatible with CMOS process design, and has the advantages of relatively simple structure and relatively low cost.

Description

Micro-mirror structure with low actuation voltage

Technical Field

The utility model relates to the technical field of micro-electromechanical systems (MEMS), in particular to a micro-mirror structure with low actuation voltage.

Background

Currently, projection display technology has increasingly high requirements for resolution. The structure of most of the applied micromirrors is complex and the size of the micromirrors is large (usually the micromirror size is in the range of 7-20 μm, and less than 5 μm).

Since the chip size with a large-scale micromirror array is relatively large, an increase in chip cost and an increase in cost of packaging and projection optical systems are caused.

Moreover, large-sized micromirror array chips are also unsuitable for applications requiring high size and weight, such as in wearable display devices, where smaller size and weight are required. For AR glasses and other applications, it is also desirable to use high resolution and small size micromirror array chips. These all require a miniaturization of the micromirror size.

Meanwhile, the existing micromirror generally adopts torsion arms fixedly supported at two ends to support the micromirror surface, and one common driving mode is an electrostatic driving mode, and the micromirror is driven to rotate around the torsion arms to control the deflection angle of the micromirror. Because both ends of the torsion arm are fixedly supported on the anchor points, when the electrostatic driver is adopted to drive the mirror surface of the micro mirror to deflect, the rigidity of the torsion arm structure needs to be overcome, which leads to higher actuation voltage required when driving the micro mirror and generally exceeds the working voltage (such as 5V,3.3V,1.8V and the like) of a conventional CMOS circuit. Therefore, the micromirror array chip generally needs high voltage chip matching when operating, a higher bias voltage is applied to the micromirror to make the micromirror in bistable state, and then a voltage compatible with the CMOS operating voltage is applied to the addressing electrode to deflect the micromirror. This results in increased complexity and increased cost of the system.

In addition, after the size of the micromirror is reduced, the area of the electrostatic driver is also reduced, and the pull-in voltage is difficult to be reduced proportionally.

Disclosure of Invention

The present utility model is directed to overcoming the above-mentioned drawbacks of the prior art and providing a micromirror structure with low actuation voltage.

In order to achieve the above purpose, the technical scheme of the utility model is as follows:

the utility model provides a micro-mirror structure with low actuation voltage, comprising:

the micro mirror comprises an anchor point arranged on a substrate, a micro mirror surface connected with the anchor point through one end and suspended on the substrate, and an addressing electrode correspondingly arranged on the substrate below the micro mirror surface;

wherein the micromirror surfaces are arranged in one-to-one correspondence with the anchor points;

the micro mirror surface is inclined relative to the surface of the substrate under the electrostatic drive of the addressing electrode, and is restored under the elastic action when the electrostatic drive of the addressing electrode is lost.

Further, the shape of the micromirror surface comprises a polygon, the anchor point comprises an elastic sheet-shaped support column arranged on the surface of the substrate, and the micromirror surface has elasticity and is directly connected to the anchor point by taking one corner end of the polygon as a connecting pivot point.

Further, the micro-mirror surface is connected with the first end of the elastic cantilever beam through one end, the second end of the cantilever beam is connected with the anchor point, and the micro-mirror surface is symmetrically distributed on two sides of a connecting line of the first end and the second end of the cantilever beam; the micro-mirror surface is arranged in one-to-one correspondence with the cantilever beams and the anchor points.

Further, the micromirror surface and the cantilever beam are positioned at the same level; the first end of the cantilever beam is directly connected with one end of the micro mirror surface, and the second end of the cantilever beam is directly connected to the top of the anchor point.

Further, the micromirror surface and the cantilever beam are positioned at different levels; the second end of the cantilever beam is directly connected to the top of the anchor point, and one end of the micro mirror surface is connected with the first end of the cantilever beam through a connecting column to be suspended between the substrate and the cantilever beam.

Further, the micromirror surface and the cantilever beam are positioned at different levels; the second end of the cantilever beam is directly connected to the top of the anchor point, and one end of the micro mirror surface is connected with the first end of the cantilever beam through a connecting column and lifted above the cantilever beam.

Further, the cantilever beam comprises a linear cantilever beam or a fold-line cantilever beam which is bent back and forth.

Further, the micromirror mirror surface shape includes a first quadrangle, and a corner portion of the first quadrangle where a corner end aligned with the anchor point is located is cut away symmetrically and inwardly along a diagonal line to form a second quadrangle notch smaller than the first quadrangle, the cantilever beam is located in the notch, and a first end and a second end of the cantilever beam are connected between the micromirror mirror surface and the anchor point along the diagonal line.

Further, the shape of the micromirror mirror surface comprises a first quadrangle, the corner of the first quadrangle, where a second corner end aligned with the anchor point is located, is cut off symmetrically inwards along a diagonal line to form a second quadrangle notch smaller than the first quadrangle, and the first end and the second end of the cantilever beam are connected between the first corner end of the first quadrangle and the anchor point of the micromirror mirror surface along the diagonal line.

Further, the micromirror mirror shape comprises a quadrilateral, the first end and the second end of the cantilever beam are connected between the first corner end of the quadrilateral and the anchor point along the diagonal of the quadrilateral, and the second corner end of the quadrilateral opposite to the first corner end is aligned up and down with the anchor point.

According to the technical scheme, the mirror surface of the micro mirror is arranged in a one-to-one correspondence manner with the anchor points, and is directly connected with the anchor points by one end or is indirectly connected with the anchor points by one end of the cantilever beam, so that the mirror surface of the micro mirror is fixedly supported by one end and is suspended on the substrate, and therefore, under the driving of small electrostatic force (attraction voltage) of the addressing electrode (electrostatic driver), the micro mirror can be integrally inclined (deflected) by utilizing the elastic action of the self or the cantilever beam, and can be integrally restored under the elastic action when the electrostatic driving is lost, thereby remarkably solving the problem of higher attraction voltage required by driving the micro mirror by adopting the torsion arm with the double-end fixedly supported mode in the prior art, and effectively reducing the attraction voltage of the micro mirror. In addition, by forming an anchor point in the form of a sheet-shaped support column directly connected with the micromirror surface, the micromirror surface is more easily inclined as a whole under the drive of a small electrostatic force by means of the elasticity of the support column; the linear cantilever beam or the linear cantilever beam which is bent back and forth is formed between the mirror surface of the micro mirror and the anchor point, so that the length of the cantilever beam can be prolonged as much as possible, the elasticity of the cantilever beam can be properly reduced, and the actuation voltage of the micro mirror can be further reduced; in addition, the whole structural rigidity of the micro-mirror can be regulated by hanging the micro-mirror surface below the cantilever beam or lifting the micro-mirror surface above the cantilever beam in a single-end manner, so that the actuation voltage of the micro-mirror is further reduced, the micro-mirror surface can be enabled to obtain a nondestructive area in a lifted state, and the filling factor is improved to the greatest extent.

Drawings

FIGS. 1-4 are schematic diagrams showing a low pull-in voltage micromirror structure according to one embodiment of the utility model;

FIG. 5 is a schematic bottom view of a micromirror structure according to a preferred embodiment of the utility model;

FIGS. 6-7 are schematic bottom views of a micromirror structure according to a preferred embodiment of the utility model;

FIGS. 8-9 are schematic top views of a micromirror structure according to a preferred embodiment of the utility model;

FIGS. 10-11 are schematic bottom views of a micromirror structure according to a preferred embodiment of the utility model;

fig. 12-17 are schematic views illustrating a method for manufacturing a low pull-in voltage micromirror structure according to a preferred embodiment of the utility model.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions in the embodiments of the present utility model will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model. Unless otherwise defined, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this utility model belongs. As used herein, the word "comprising" and the like means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof without precluding other elements or items.

The utility model provides a micro-mirror structure with low actuation voltage, comprising: the micro mirror comprises an anchor point arranged on a substrate, a micro mirror surface connected with the anchor point through one end and suspended on the substrate, and an addressing electrode correspondingly arranged on the substrate below the micro mirror surface; wherein the micromirror surfaces are arranged in one-to-one correspondence with the anchor points; the micromirror surface is tilted with respect to the substrate surface as a whole under electrostatic drive from the address electrode, and is elastically restored as a whole when electrostatic drive from the address electrode is lost.

The utility model adopts a one-to-one correspondence mode to set the micro mirror surface and the anchor point, and adopts a single-end connection mode that one end of the micro mirror surface is directly connected with the anchor point or an indirect connection mode is formed between one end of the cantilever beam and the anchor point, so that the micro mirror surface is fixedly supported by a single end and is suspended on a substrate, thus the micro mirror surface can be integrally inclined (deflected) under the driving of small electrostatic force (attraction voltage) of an addressing electrode (electrostatic driver) by utilizing the elastic action of the micro mirror surface or the cantilever beam, and can be integrally restored under the elastic action when electrostatic driving is lost. Therefore, the problem of higher actuation voltage required by driving the micromirror caused by the existing mode of supporting the micromirror by adopting the torsion arms with the fixed supports at the two ends can be remarkably solved, and the actuation voltage of the micromirror can be effectively reduced.

Further, by forming anchor points in the form of sheet (or bar) support posts directly connected to the micromirror surface, the micromirror surface can be more easily tilted as a whole under the drive of a smaller electrostatic force by means of the elasticity of the support posts.

Further, by forming a straight cantilever beam or a reciprocating bent broken-line cantilever beam between the mirror surface and the anchor point of the micromirror, the length of the cantilever beam can be extended as much as possible, so as to properly reduce the elasticity of the cantilever beam, and further reduce the actuation voltage of the micromirror.

Furthermore, the whole structural rigidity of the micro-mirror can be regulated by hanging the micro-mirror surface below the cantilever beam or lifting the micro-mirror surface above the cantilever beam in a single-end manner, so that the actuation voltage of the micro-mirror is further reduced, the micro-mirror surface can be enabled to obtain a nondestructive area in a lifted state, and the filling factor is improved to the greatest extent.

The utility model also provides a manufacturing method of the micro-mirror structure with low actuation voltage, which can design the micro-mirror structure according to the design rule of the CMOS process and can be manufactured by adopting the standard CMOS process, so that the manufacturing process of the micro-mirror structure can be simplified, the micro-mirror with relatively simple structure can be manufactured, the continuous miniaturization of the micro-mirror is promoted, and meanwhile, the requirement of reducing the actuation voltage of the micro-mirror is effectively met.

The following describes the embodiments of the present utility model in further detail with reference to the accompanying drawings.

Referring to fig. 1, fig. 1 is a schematic diagram of a low pull-in voltage micromirror structure (schematic cross-sectional structure, hereinafter referred to as "cross-sectional structure"). As shown in fig. 1, a low actuation voltage micromirror structure of the present utility model may include an elastic sheet-like (or strip-like) support column 120 vertically disposed on a substrate 10 as an anchor point 12, a polygonal micromirror surface 13 directly connected to the top of the support column 120 with one end as a connection fulcrum, and an address electrode 14 disposed on one side of the support column 120 and corresponding to the surface of the substrate 10 under the micromirror surface 13. Therefore, the small-size micro mirror with compact structure, which adopts the one-to-one correspondence of the micro mirror surface 13 and the anchor point 12, can be formed.

The micromirror mirror 13 is connected to the support columns 120 by a single end, thereby obtaining the support effect of the support columns 120 and suspended above the substrate 10.

The micromirror plate 13 may be generally made of a metal material, and for example, the micromirror plate 13 may be an aluminum micromirror plate 13, thus having a certain elasticity.

The support posts 120 may be fabricated from the same or different metallic material as the micromirror mirror 13. The sheet (or strip) support post 120 structure may be formed using trench sidewalls in the sacrificial layer (see below for details of the fabrication process) to reduce the stiffness of the anchor points and provide some flexibility to the support post 120. A media support layer may be provided on the side surfaces of the support columns 120.

In some embodiments, the support posts 120 may be connected to the substrate 10 by connection electrodes 11 provided on the surface of the substrate 10, such that the micromirror mirror 13 may be connected to an electrostatic driver provided in the substrate 10 through the support posts 120 and the connection electrodes 11. The address electrode 14 is also connected to an electrostatic driver so that a pair of parallel plate capacitive electrodes can be formed with the micromirror mirror 13. In this way, the micro mirror 13 is driven by the static electricity from the addressing electrode 14 through the power-on operation of the static electricity driver, and the micro mirror 13 is attracted under the attraction of the static electricity to incline integrally relative to the surface of the substrate 10, and when the static electricity from the addressing electrode 14 is lost, the micro mirror returns integrally under the elastic action of the micro mirror and the supporting column 120.

Landing electrodes 15 may also be provided on the surface of the substrate 10 other than the side (shown as the right side) of the address electrodes 14 remote from the support posts 120. The landing electrode 15 is generally maintained at the same potential as the micromirror surface 13, and after the micromirror surface 13 is attracted and tilted downward, it can rest on the landing electrode 15 to avoid direct contact with the surface of the substrate 10.

The address electrode 14, the landing electrode 15, and the connection electrode 11 may be made of the same or different metal materials as the micromirror mirror 13.

Referring to fig. 5, a bottom view structure corresponding to the micromirror structure of fig. 1 with the substrate 10 omitted is shown. In some embodiments, the micromirror mirror 13 may be square in shape as shown in the figures, and may be directly attached to the top of the support column 120 with one corner of the square (one corner shown as the left (square vertex, second corner)) as the attachment fulcrum.

The landing electrode 15 may be provided at a position corresponding to the other opposite corner end (one corner end, the first corner end, illustrated as the right side) of the square micromirror mirror 13.

The address electrode 14 may have a shape corresponding to the micromirror mirror 13, for example, the address electrode 14 may have a square shape corresponding to the micromirror mirror 13, and may have a notch to avoid the connection electrode 11 (the support column 120) and the landing electrode 15.

In this embodiment, the micromirror mirror 13 of the present utility model supports the micromirror mirror 13 by fixing the single end and the anchor point 12, so that the structure of the micromirror mirror is significantly different from the structure of the prior art that uses torsion arms with both ends fixed to support the micromirror.

The micromirror of the present utility model can have two states, among others: one is a state in which the micromirror mirror surface 13 remains horizontal (or nearly horizontal) when no electrostatic force is applied; the other is a state in which the micromirror is driven by an electrostatic driver and the micromirror surface 13 is tilted. When the driving voltage exceeds the actuation voltage of the micromirror, the micromirror will tilt significantly. After the driving voltage is removed, the micromirror 13 can be restored to the horizontal state by the elastic action of the micromirror 13 itself and the support posts 120. Therefore, the actuation voltage of the micromirror can be effectively reduced in a tiny space.

The method for manufacturing the low-actuation-voltage micro-mirror structure of the present utility model can be used for manufacturing the low-actuation-voltage micro-mirror structure shown in fig. 1 (fig. 5), and can include the following steps:

please refer to fig. 1 (fig. 5). First, a conventional semiconductor substrate 10, such as a silicon substrate 10, may be used, and circuit structures including a CMOS front-end device, etc., required for forming MEMS, including electrostatic drivers, may be fabricated on the substrate 10.

Then, a first metal layer may be formed on the surface of the substrate 10 using, for example, a deposition process or the like, and patterned using photolithography and etching processes or the like to form the connection electrode 11, the address electrode 14, and the landing electrode 15. The first metal layer material may be, for example, metallic aluminum or the like.

Next, a sacrificial layer may be deposited on the surface of the substrate 10 using, for example, a deposition process or the like, covering the connection electrode 11, the address electrode 14, and the landing electrode 15. The sacrificial layer material may be, for example, silicon dioxide or polyimide, etc.

Next, a trench may be formed on the surface of the sacrificial layer using photolithography and etching processes, and stopped on the top surface of the connection electrode 11 at one side of the address electrode 14. The grooves may be rectangular grooves, circular grooves, or the like, and the present utility model is not limited thereto.

Thereafter, a second metal layer may be conformally formed on the inner wall of the trench, for example, by a conformal deposition process, etc., so that the second metal layer is connected to the connection electrode 11; the second metal layer is also deposited on the surface of the sacrificial layer outside the trench, thereby forming a continuous second metal layer on the surface of the sacrificial layer and on the sidewalls (inner walls) of the trench.

Then, the second metal layer may be patterned using photolithography and etching processes, a polygon (e.g., square as shown in fig. 5) shaped micromirror 13 corresponding to the position of the address electrode 14 is formed on the surface of the sacrificial layer, and a sheet-like (or stripe-like) support post 120 connected to the substrate 10 through the connection electrode 11 and serving as an anchor point 12 is formed on the sidewall of the trench (which may include a portion of the bottom surface of the trench), with one corner end (illustrated as the left corner end) of the polygon micromirror 13 serving as a fulcrum connection being located on top of the support post 120. Thereby forming anchor points 12 and micromirror surfaces 13 arranged in one-to-one correspondence.

Finally, the sacrificial layer may be removed by an etching process (e.g., a release process of wet etching) and with a high etching selectivity of the sacrificial layer material relative to other structural materials such as the substrate 10, the first metal layer, and the second metal layer, so that the micromirror mirror surface 13 and the anchor point 12 are released, thereby forming a micromirror structure with a low actuation voltage as shown in fig. 1 (fig. 5).

It should be noted that the anchor points 12 (the support posts 120) and the micromirror mirror 13 may also be formed by separate process steps and different materials (the same applies below).

Referring to fig. 2, fig. 2 is a schematic diagram of a low pull-in voltage micromirror structure according to a second preferred embodiment of the utility model. As shown in fig. 2, a low actuation voltage micromirror structure of the present utility model may include an anchor point 12 (conductive support post) vertically disposed on a substrate 10, and a polygonal-shaped micromirror mirror 13 single-ended supported on top of the anchor point 12 by an elastic conductive cantilever 16.

The anchor point 12 may be connected to the substrate 10 through a connection electrode 11 provided on the surface of the substrate 10; an address electrode 14 and a landing electrode 15 may be sequentially disposed on the surface of the substrate 10 at one side of the connection electrode 11 (the anchor point 12), and the address electrode 14 is correspondingly located below the micromirror surface 13. Therefore, the small-size micro mirror with compact structure, which adopts the one-to-one correspondence arrangement of the micro mirror surface 13, the cantilever beam 16 and the anchor point 12, can be formed.

The micromirror mirror 13 may be directly connected to a first end of the cantilever beam 16 (illustrated as a right end of the cantilever beam 16) by one end (illustrated as an end point a of the left side of the micromirror mirror 13 where the anchor point 12 is located away from the notch in fig. 1 and 6), and a second end of the cantilever beam 16 (illustrated as a left end of the cantilever beam 16) may be directly connected to a top of the anchor point 12. Thereby forming a micromirror structure in which the micromirror mirror 13 and the cantilever beam 16 are positioned at the same horizontal level.

In addition, the micromirror mirror 13 may be symmetrically distributed at two sides of the connection line between the first end and the second end of the cantilever beam 16.

The cantilever beam 16 may be fabricated from the same or different materials as the micromirror mirror 13.

Referring to fig. 6, a bottom view structure corresponding to the micromirror structure of fig. 2 with the substrate 10 omitted is shown. In some embodiments, the cantilever beam 16 may comprise a linear cantilever beam 16. The micromirror mirror 13 may be shaped as a first square (first quadrangle) as shown, and the corner of the first square where one corner end (shown as a cut corner end (square vertex, second corner end)) aligned with the anchor point 12 is cut symmetrically inward along the diagonal line B where the corner end is located, forming a second square (second quadrangle) notch C smaller than the first square. The cantilever beam 16 is located in the relief notch C, and the first end and the second end of the cantilever beam 16 may be connected between the micromirror mirror 13 and the anchor point 12 along the direction of the diagonal B.

In some embodiments, the cantilever beam 16 may also include a reciprocally curved, dog-leg shaped cantilever beam 16 (or a reciprocally curved, curvilinear cantilever beam), as shown in fig. 7.

In this embodiment, the cantilever beam 16 is adopted to connect the micromirror mirror 13 with the anchor point 12 in a single-end manner, so as to support the micromirror mirror 13, so that the length of the cantilever beam 16 can be elongated as much as possible in the space of the tiny second square notch C, and the elasticity of the cantilever beam 16 can be properly reduced by using a linear cantilever beam 16 or a multi-zigzag polygonal cantilever beam 16, thereby further reducing the actuation voltage of the micromirror.

The method for manufacturing the low actuation voltage micro-mirror structure of the present utility model can be used for manufacturing the low actuation voltage micro-mirror structure shown in fig. 2 (fig. 6-7), and can include the following steps:

please refer to fig. 2 (fig. 6-7). First, a first metal layer may be formed on the surface of the substrate 10 using, for example, a deposition process or the like, and patterned using, for example, photolithography and etching processes to form the connection electrode 11, the address electrode 14, and the landing electrode 15.

Then, a sacrificial layer may be deposited on the surface of the substrate 10 using, for example, a deposition process or the like, covering the connection electrode 11, the address electrode 14, and the landing electrode 15.

Next, a via hole may be formed on the surface of the sacrificial layer using photolithography and etching processes, and stopped on the top surface of the connection electrode 11.

Then, a second metal layer may be formed on the surface of the sacrificial layer using, for example, a deposition process, etc., and the via hole is filled.

Then, the second metal layer may be patterned using photolithography and etching processes, anchor points 12 in the form of conductive vias connected to the substrate 10 through the connection electrodes 11 are formed in the vias, micromirror mirrors 13 corresponding to the positions of the address electrodes 14 are formed on the surface of the sacrificial layer, and cantilever beams 16 (may be straight-line-shaped cantilever beams 16 or reciprocally bent-line-shaped cantilever beams 16) connected between the micromirror mirrors 13 and the anchor points 12.

In this step, through patterning, the shape of the formed micromirror mirror 13 may be a first square (a first quadrangle), and the corner where one corner end aligned with the anchor point 12 on the first square is cut away symmetrically along the diagonal line B, so as to form a second square (a second quadrangle) notch C smaller than the first square, so that the cantilever beam 16 formed synchronously is located in the avoidance notch, and two ends of the cantilever beam 16 are connected between the micromirror mirror 13 and the anchor point 12 along the diagonal line, and the two sides of the connecting line (including the connecting line extension line) of the two ends of the cantilever beam 16 of the micromirror mirror 13 are symmetrically distributed, so as to form the micromirror mirror 13, the cantilever beam 16 and the anchor point 12 which are set in one-to-one correspondence.

Finally, the sacrificial layer may be removed by an etching process (e.g., a release process of wet etching) and with a high etching selectivity of the sacrificial layer material relative to other structural materials such as the substrate 10, the first metal layer, and the second metal layer, so that the micromirror mirror 13, the cantilever beam 16, and the anchor point 12 are released, thereby forming a micromirror structure with a low actuation voltage, such as that shown in fig. 2 (fig. 6-7).

Referring to fig. 3, fig. 3 is a schematic diagram of a low pull-in voltage micromirror structure according to a third preferred embodiment of the utility model. As shown in fig. 3, a low actuation voltage micromirror structure of the present utility model may include an anchor point 12 (conductive support column) vertically disposed on a substrate 10, and a polygonal-shaped micromirror mirror 13 single-ended supported (suspended) on top of the anchor point 12 by an elastic conductive cantilever 16.

The anchor point 12 may be connected to the substrate 10 through a connection electrode 11 provided on the surface of the substrate 10; an address electrode 14 and a landing electrode 15 may be sequentially disposed on the surface of the substrate 10 at one side of the connection electrode 11 (the anchor point 12), and the address electrode 14 is correspondingly located below the micromirror surface 13. Therefore, the small-size micro mirror with compact structure, which adopts the one-to-one correspondence arrangement of the micro mirror surface 13, the cantilever beam 16 and the anchor point 12, can be formed.

Wherein the micromirror mirror 13 and the cantilever beam 16 are at different horizontal levels, the micromirror mirror 13 is located between the substrate 10 and the cantilever beam 16, and the cantilever beam 16 is located above the micromirror mirror 13. The second end of the cantilever beam 16 is directly connected to the top of the anchor point 12, and one end (first corner end) of the micromirror mirror 13 is connected to the first end of the cantilever beam 16 through a connection post 17, so that the micromirror mirror 13 is suspended between the substrate 10 and the cantilever beam 16. In addition, the micromirror mirror 13 may be symmetrically distributed at two sides of the connection line between the first end and the second end of the cantilever beam 16.

The cantilever beam 16 may be fabricated from the same or different materials as the micromirror mirror 13.

Referring to fig. 8, a top view of the micromirror structure of fig. 3 is shown. In some embodiments, the cantilever beam 16 may comprise a linear cantilever beam 16. The shape of the micromirror mirror 13 may include a first square (first quadrangle), and the corner of the first square where a second corner end (shown as a cut corner end (square vertex) on the left side) aligned with the anchor point 12 is cut symmetrically inward along the diagonal line where the second corner end is located, forming a second square (second quadrangle) notch smaller than the first square (as will be understood with reference to fig. 6, below). The first and second ends of the cantilever beam 16 may be connected in the diagonal direction above the first angular end of the first square of the micromirror mirror 13 and between the anchor points 12.

In some embodiments, the anchor 12 may be formed by connecting a first anchor 121 (a first support column) and a second anchor 122 (a second support column), and other connecting material layers (e.g., a micromirror mirror 13 material layer may be provided) may be further disposed between the first anchor 121 and the second anchor 122.

The first anchor point 121 may be made of the same or different material as the micromirror mirror 13. The second anchor point 122 and the connecting post 17 may be fabricated from the same or different materials as the cantilever beam 16.

In some embodiments, the cantilever beam 16 may also include a reciprocally curved, dog-leg shaped cantilever beam 16 (or a reciprocally curved, curvilinear cantilever beam), as shown in fig. 9.

In this embodiment, the cantilever beam 16 and the micromirror mirror 13 are arranged at different levels, so that the length of the cantilever beam 16 can be prolonged to the greatest extent, the rigidity of the whole structure of the micromirror can be adjusted, the elasticity of the cantilever beam 16 can be reduced, and the actuation voltage of the micromirror can be further reduced.

The method for manufacturing the low actuation voltage micro-mirror structure of the present utility model can be used for manufacturing the low actuation voltage micro-mirror structure shown in fig. 3 (fig. 8-9), and can include the following steps:

please refer to fig. 3 (fig. 8-9). First, a third metal layer may be formed on the surface of the substrate 10 using, for example, a deposition process or the like, and third patterning may be performed using a photolithography and etching process or the like to form the connection electrode 11, the address electrode 14, and the landing electrode 15.

Then, a first sacrificial layer may be deposited on the surface of the substrate 10 using, for example, a deposition process or the like, covering the connection electrode 11, the address electrode 14, and the landing electrode 15.

Next, a first via hole may be formed downward on the surface of the first sacrificial layer using photolithography and etching processes, and stopped on the top surface of the connection electrode 11.

Then, a first metal layer may be formed on the surface of the first sacrificial layer using, for example, a deposition process, etc., and the first via hole may be filled.

Then, the first metal layer may be first patterned using photolithography and etching processes, a micromirror mirror 13 corresponding to the address electrode 14 is formed on the surface of the first sacrificial layer, and a conductive via-shaped first anchor 121 separated from the micromirror mirror 13 and connected to the substrate 10 through the connection electrode 11 is formed in the first via.

In this step, the first patterning is performed to form the micromirror mirror 13 into a first square (a first quadrangle), and the corner of the first square where a second corner end aligned with the first anchor point 121 is located is symmetrically cut away inward along the diagonal line to form a second square (a second quadrangle) notch smaller than the first square, so that the formed micromirror mirror 13 is symmetrically distributed on two sides of the diagonal line.

A second sacrificial layer may then continue to be formed on the first sacrificial layer surface, covering the micromirror mirror 13 and the first anchor 121, using, for example, a deposition process, etc. The second sacrificial layer material may be the same as the first sacrificial layer material.

Then, a photolithography and etching process may be used to form a second via and a third via down on the surface of the second sacrificial layer, such that the bottom of the second via stops on top of the first anchor point 121 and the bottom of the third via stops on the surface of the micromirror mirror 13 and is aligned with the first corner position of the first square of the micromirror mirror 13 opposite the second corner.

Then, a second metal layer may be formed on the surface of the second sacrificial layer using, for example, a deposition process, etc., and the second and third vias may be filled.

Then, a second patterning process may be performed on the second metal layer by using photolithography and etching processes, a second anchor point 122 connected to the first anchor point 121 is formed in the second via hole, a connection post 17 connected to the micromirror mirror 13 is formed in the third via hole, and a cantilever 16 (which may be a straight cantilever 16 or a bent-back type cantilever) having both ends connected to the micromirror mirror 13 and the second anchor point 122 is formed on the surface of the second sacrificial layer. Thereby forming cantilever beams 16, micromirror mirrors 13, and first and second anchor points 121, 122 (the connected first and second anchor points 121, 122 together form anchor point 12) arranged in a one-to-one correspondence.

Finally, the micromirror structure with low actuation voltage, such as that shown in fig. 3 (fig. 8-9), can be formed by etching (e.g. wet etching release process) and removing the second sacrificial layer and the first sacrificial layer by using the high etching selectivity of the first sacrificial layer material and the second sacrificial layer material with respect to the substrate 10, the first metal layer to the third metal layer, and other structural materials, so as to release the micromirror mirror surface 13, the cantilever beam 16, and the anchor point 12.

Referring to fig. 4, fig. 4 is a schematic diagram of a low pull-in voltage micromirror structure according to a fourth preferred embodiment of the utility model. As shown in fig. 4, a low actuation voltage micromirror structure of the present utility model may include an anchor point 12 (conductive support column) vertically disposed on a substrate 10, and a polygonal-shaped micromirror mirror 13 supported (lifted) on top of the anchor point 12 by a single-ended elastic conductive cantilever 16.

The anchor point 12 may be connected to the substrate 10 through a connection electrode 11 provided on the surface of the substrate 10; an address electrode 14 and a landing electrode 15 may be sequentially disposed on the surface of the substrate 10 at one side of the connection electrode 11 (the anchor point 12), and the address electrode 14 is correspondingly located below the micromirror surface 13. Therefore, the small-size micro mirror with compact structure, which adopts the one-to-one correspondence arrangement of the micro mirror surface 13, the cantilever beam 16 and the anchor point 12, can be formed.

Wherein the micromirror mirror 13 and the cantilever beam 16 are at different horizontal levels, the cantilever beam 16 is located between the substrate 10 and the micromirror mirror 13, and the micromirror mirror 13 is located above the cantilever beam 16. The second end of the cantilever beam 16 is directly connected to the top of the anchor point 12, and one end (first corner end) of the micromirror mirror 13 is connected to the first end of the cantilever beam 16 through a connection post 17, so that the micromirror mirror 13 is lifted above the cantilever beam 16. In addition, the micromirror mirror 13 may be symmetrically distributed at two sides of the connection line between the first end and the second end of the cantilever beam 16.

The cantilever beam 16 may be fabricated from the same or different materials as the micromirror mirror 13. Anchor point 12 may be fabricated from the same or a different material than cantilever beam 16. The connection posts 17 may be made of the same or different material as the micromirror mirror 13.

Referring to fig. 10, a bottom view structure corresponding to the micromirror structure of fig. 4 with the substrate 10 omitted is shown. In some embodiments, the cantilever beam 16 may comprise a linear cantilever beam 16. The shape of the micromirror mirror 13 may include a square (quadrilateral), the first and second ends of the cantilever beam 16 may be connected along one of the diagonals of the square between below the first angular end of the square of the micromirror mirror 13 and the top of the anchor point 12, and the second angular end of the square of the micromirror mirror 13 opposite the first angular end is aligned up and down with the anchor point 12.

In some embodiments, the cantilever beam 16 may also include a reciprocally bent, dog-leg shaped cantilever beam 16 (or a reciprocally bent, curved cantilever beam), as shown in fig. 11 (substrate 10, connection electrode 11, address electrode 14, and landing electrode 15 are omitted from the drawing).

In this embodiment, the cantilever beam 16 and the micromirror mirror 13 are arranged at different levels, so that the length of the cantilever beam 16 can be prolonged to the greatest extent, the rigidity of the whole structure of the micromirror can be adjusted, the elasticity of the cantilever beam 16 can be reduced, the actuation voltage of the micromirror can be further reduced, and the micromirror mirror 13 can obtain a nondestructive area in a lifted state, so that the filling factor is improved to the greatest extent.

Referring to fig. 12-17, fig. 12-17 are schematic views illustrating steps of a method for fabricating a low pull-in voltage micromirror structure according to a preferred embodiment of the utility model. As shown in fig. 12-17, a method for manufacturing a low actuation voltage micromirror structure according to the present utility model can be used to manufacture a low actuation voltage micromirror structure as described above, for example, in fig. 4 (fig. 10-11), and can include the following steps:

please refer to fig. 12. First, a third metal layer may be formed on the surface of the substrate 10 using, for example, a deposition process or the like, and third patterning may be performed using a photolithography and etching process or the like to form the connection electrode 11, the address electrode 14, and the landing electrode 15.

Please refer to fig. 13. Then, a first sacrificial layer 18 may be deposited on the surface of the substrate 10 using, for example, a deposition process or the like, covering the connection electrode 11, the address electrode 14, and the landing electrode 15.

Next, a first via 181 may be formed downward on the surface of the first sacrificial layer 18 using photolithography and etching processes, and stopped on the top surface of the connection electrode 11.

Please refer to fig. 14. Next, a first metal layer may be formed on the surface of the first sacrificial layer 18 using, for example, a deposition process, etc., and the first via 181 is filled.

The first metal layer may then be first patterned using photolithography and etching processes, anchor points 12 in the form of conductive vias connected to substrate 10 through connection electrodes 11 are formed in first vias 181, and cantilever beams 16 connected to anchor points 12 through second ends are formed on the surface of first sacrificial layer 18.

Please refer to fig. 15. Then, a second sacrificial layer 19 may be formed on the surface of the first sacrificial layer 18, covering the cantilever beam 16 and the anchor point 12, using, for example, a deposition process or the like. The second sacrificial layer 19 material may be the same as the first sacrificial layer 18 material.

Next, a photolithography and etching process may be used to form a second via 191 downwardly on the surface of the second sacrificial layer 19 such that the bottom of the second via 191 stops on the first end surface of the cantilever 16 opposite the second end.

Please refer to fig. 16. Next, a second metal layer may be formed on the surface of the second sacrificial layer 19 using, for example, a deposition process, etc., and the second via 191 is filled.

Then, the second metal layer may be subjected to a second patterning using photolithography and etching processes, connection posts 17 connected to the first ends of the cantilever beams 16 are formed in the second via holes 191, and the micromirror mirrors 13 connected to the connection posts 17 are formed on the surface of the second sacrificial layer 19.

In this step, the shape of the formed micromirror mirror 13 is square by the second patterning, and the first corner end of the first corner end and the second corner end of the micromirror mirror 13 located on the same diagonal line of the square are connected to the connecting post 17, and the second corner end is aligned up and down to the anchor point 12, and the micromirror mirror 13 is symmetrically distributed on both sides of the diagonal line. Thereby forming a micromirror mirror 13, a cantilever beam 16 and an anchor point 12, which are arranged in a one-to-one correspondence.

Please refer to fig. 17. Finally, the second sacrificial layer 19 and the first sacrificial layer 18 may be removed by an etching process (e.g., a wet etching release process) and using a high etching selectivity of the material of the first sacrificial layer 18 and the material of the second sacrificial layer 19 with respect to the material of the other structures, such as the substrate 10, the first metal layer to the third metal layer, etc., so that the micromirror mirror 13, the cantilever beam 16 and the anchor point 12 are released, thereby forming a micromirror structure with a low actuation voltage as shown in fig. 4 (fig. 10-11).

In summary, the low actuation voltage micromirror structure of the present utility model can be designed according to the design rule of the CMOS process and can be manufactured by using a standard CMOS process, so that the manufacturing process of the micromirror structure can be simplified, and the micromirror with a relatively simple structure can be manufactured, thereby realizing the continuous miniaturization of the micromirror and simultaneously effectively meeting the requirement of lowering the actuation voltage of the micromirror. Therefore, the utility model has popularization and application prospect in the technical field of projection display with high resolution, small size and small weight requirements, and has the advantage of lower cost.

While embodiments of the present utility model have been described in detail hereinabove, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. It is to be understood that such modifications and variations are within the scope and spirit of the present utility model as set forth in the following claims. Moreover, the utility model described herein is capable of other embodiments and of being practiced or of being carried out in various ways.

Claims (10)

1. A low actuation voltage micromirror structure comprising:

the micro mirror comprises an anchor point arranged on a substrate, a micro mirror surface connected with the anchor point through one end and suspended on the substrate, and an addressing electrode correspondingly arranged on the substrate below the micro mirror surface;

wherein the micromirror surfaces are arranged in one-to-one correspondence with the anchor points;

the micro mirror surface is inclined relative to the surface of the substrate under the electrostatic drive of the addressing electrode, and is restored under the elastic action when the electrostatic drive of the addressing electrode is lost.

2. The low actuation voltage micromirror structure of claim 1, wherein the micromirror mirror surface shape comprises a polygon, the anchor point comprises an elastic sheet-like support post provided on the substrate surface, the micromirror mirror surface has elasticity, and one corner of the polygon is directly connected to the anchor point as a connection fulcrum.

3. The low actuation voltage micro-mirror structure of claim 1, wherein the micro-mirror surface is connected to the first end of the elastic cantilever beam through one end, the second end of the cantilever beam is connected to the anchor point, and the micro-mirror surface is symmetrically distributed on two sides of a connection line between the first end and the second end of the cantilever beam; the micro-mirror surface is arranged in one-to-one correspondence with the cantilever beams and the anchor points.

4. The low actuation voltage micromirror structure of claim 3, wherein the micromirror mirror surface is at the same level as the cantilever beam; the first end of the cantilever beam is directly connected with one end of the micro mirror surface, and the second end of the cantilever beam is directly connected to the top of the anchor point.

5. The low actuation voltage micromirror structure of claim 3, wherein the micromirror mirror surface is at a different level than the cantilever beam; the second end of the cantilever beam is directly connected to the top of the anchor point, and one end of the micro mirror surface is connected with the first end of the cantilever beam through a connecting column to be suspended between the substrate and the cantilever beam.

6. The low actuation voltage micromirror structure of claim 3, wherein the micromirror mirror surface is at a different level than the cantilever beam; the second end of the cantilever beam is directly connected to the top of the anchor point, and one end of the micro mirror surface is connected with the first end of the cantilever beam through a connecting column and lifted above the cantilever beam.

7. The low actuation voltage micro-mirror structure of claim 3, wherein the cantilever beam comprises a linear cantilever beam or a back and forth folded polyline cantilever beam.

8. The low actuation voltage micro-mirror structure of claim 4, wherein the micro-mirror shape comprises a first quadrilateral, and a corner of the first quadrilateral at which a corner end aligned with the anchor point is located is cut away symmetrically inward along a diagonal line to form a second quadrilateral notch smaller than the first quadrilateral, the cantilever beam is located in the notch, and the first end and the second end of the cantilever beam are connected between the micro-mirror surface and the anchor point along the diagonal line.

9. The low actuation voltage micro-mirror structure of claim 5, wherein the micro-mirror shape comprises a first quadrilateral, and a corner of the first quadrilateral where a second corner end aligned with the anchor point is located is symmetrically cut away inward along a diagonal line to form a second quadrilateral gap smaller than the first quadrilateral, and the first end and the second end of the cantilever are connected between the first corner end and the anchor point of the first quadrilateral of the micro-mirror along the diagonal line.

10. The low actuation voltage micromirror structure of claim 6, wherein the micromirror mirror shape comprises a quadrilateral, wherein the first and second ends of the cantilever beam are connected between the first angular end of the quadrilateral of the micromirror mirror and the anchor point along a diagonal of the quadrilateral, and wherein the second angular end of the quadrilateral opposite the first angular end is aligned up and down with the anchor point.