A MEMS micromirror with high filling factor and manufacturing method thereof

Abstract

The present invention discloses a high-fill-factor MEMS micromirror and a manufacturing method. The micromirror includes a microbridge structure disposed on a substrate, the microbridge structure including support and electrical connection posts and a microbridge deck. The micromirror surface is disposed on the microbridge deck, and the micromirror surface is electrically connected to the substrate via the support and electrical connection posts. The support and electrical connection posts are formed in a first trench disposed in a first sacrificial layer located between the substrate and the microbridge deck. The support and electrical connection posts include a conductor formed on a portion of the sidewall surface of the first trench and a support located inside the conductor. The micromirror surface is electrically connected to the substrate via the conductor, and the microbridge deck is supported on the support and conductor. The microbridge structure is released by removing the first sacrificial layer. The present invention can reduce the area occupied by the support and electrical connection posts in the micromirror, thereby effectively increasing the area of the micromirror surface, thereby significantly improving the fill factor and product performance.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems (MEMS), and in particular to a MEMS micromirror with a high filling factor and a manufacturing method thereof. Background Art

[0002] MEMS mirrors are a hot topic among MEMS products, with a wide range of applications, including optical communications, 3D cameras, and projectors. In recent years, they have become a crucial component in automotive LiDAR (LiDAR). With the advancement of autonomous driving technology, market demand for MEMS mirrors is increasing, placing higher demands on their technology.

[0003] MEMS micromirrors are generally implemented using a micromirror array, and generally use an electrostatic drive mode to drive the micromirror to rotate around a rotation axis (torsion arm) to achieve control of the micromirror deflection angle. The rotation axis is usually electrically connected and mechanically supported by a support column. The existing support column manufacturing method is generally formed by forming a groove in a sacrificial layer and then filling the groove with metal and dielectric. However, since the area occupied by the groove in the micromirror is relatively large, the area occupied by the mirror surface of the micromirror is relatively reduced, that is, the fill factor is reduced, which causes the reflection effect of the entire micromirror array to decrease, thereby adversely affecting the performance of the product. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and provide a MEMS micromirror with a high fill factor and a manufacturing method thereof.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] The present invention provides a MEMS micromirror with a high fill factor, comprising:

[0007] A microbridge structure is provided on a substrate, the microbridge structure comprising support and electrical connection posts, and a microbridge deck supported on the support and electrical connection posts; a micromirror surface is provided on the microbridge deck, and the micromirror surface is electrically connected to the substrate via the support and electrical connection posts;

[0008] In which, the support and electrical connection column is formed in a first groove, the first groove is arranged in a first sacrificial layer, the first sacrificial layer is located between the substrate and the microbridge bridge surface, the support and electrical connection column includes a conductor formed on a part of the side wall surface of the first groove and a support body located inside the conductor, the micromirror surface is electrically connected to the substrate through the conductor, and the microbridge bridge surface is supported on the support body and the conductor; the microbridge structure is released by removing the first sacrificial layer.

[0009] Furthermore, the lower end of the conductor also extends to part of the bottom surface of the first groove to form an L-shaped bending structure, and is electrically connected to the substrate through the horizontal part of the L-shaped bending structure. The support body is arranged on the inner side of the L-shaped bending structure and is located on the horizontal part of the L-shaped bending structure.

[0010] Furthermore, a metal electrical connection structure is provided on the surface of the substrate, the metal electrical connection structure is electrically connected to the substrate, the support and electrical connection columns are provided on the metal electrical connection structure, and the horizontal portion of the L-shaped bending structure contacts and is located on the metal electrical connection structure.

[0011] Furthermore, there are two support and electrical connection columns, which are arranged in parallel on the substrate, and a conductive torsion arm is arranged between the top ends of the two support and electrical connection columns. The microbridge bridge surface is connected to the torsion arm and is supported, and the micromirror surface is electrically connected to the substrate through the torsion arm, the support and electrical connection columns.

[0012] Furthermore, the microbridge deck includes a first sub-microbridge deck and a second sub-microbridge deck, the first sub-microbridge deck and the second sub-microbridge deck are coplanarly arranged and respectively connected to both sides of the torsion arm.

[0013] Furthermore, a conductive bearing structure is provided on the top surface of the support and electrical connection column, and both ends of the torsion arm are inserted into the bearing structure to form a movable fit with the bearing structure.

[0014] Furthermore, the micromirrors are arranged in rows and columns on the substrate to form a micromirror array; wherein, any two adjacent micromirrors in the same row or column share the same support and electrical connection column, or, the respective support and electrical connection columns of any two adjacent micromirrors in the same row or column are arranged close to each other and formed on the sidewalls on opposite sides of the same first groove.

[0015] The present invention also provides a method for manufacturing a MEMS micromirror with a high fill factor, comprising:

[0016] providing a substrate;

[0017] forming a first metal layer on the surface of the substrate and patterning it to form a metal electrical connection structure;

[0018] forming a first sacrificial layer on the surface of the substrate and covering the metal electrical connection structure;

[0019] forming a first trench on the surface of the first sacrificial layer and stopping on the top surface of the metal electrical connection structure;

[0020] forming a second metal layer on the inner wall of the first trench, then filling the first trench with a support layer, planarizing the first trench, and removing excess second metal layer material and the support layer material outside the first trench;

[0021] Removing a portion of the second metal layer material and the support layer material in the first trench along the longitudinal direction to form a second trench penetrating the first trench, and forming a support and electrical connection column in the first trench outside the second trench; wherein the support and electrical connection column includes a conductor formed by the remaining second metal layer material in the first trench, and a support formed by the remaining support layer material;

[0022] Filling the second trench with a second sacrificial layer, planarizing the second trench, and removing excess second sacrificial layer material outside the second trench;

[0023] forming a third metal layer on the surface of the first sacrificial layer, the second sacrificial layer and the support and electrical connection pillars, and patterning the third metal layer to form a micromirror surface electrically connected to the conductor;

[0024] The first sacrificial layer and the second sacrificial layer are removed to release the micromirror surface.

[0025] Furthermore, when forming the second groove, the second groove is located on one side of the first groove, so that the formed support and electrical connection column is located on the other opposite side of the first groove, and when forming the micromirror surface, a micromirror surface is formed on both sides of any one of the support and electrical connection columns, and the two micromirror surfaces are electrically connected to the support and electrical connection columns; or, when forming the second groove, the second groove is located in the middle of the first groove, so that an unconnected support and electrical connection column is formed on both sides of the second groove, and when forming the micromirror surface, a micromirror surface is formed on both sides of any one of the first grooves, and the two micromirror surfaces are each electrically connected to a support and electrical connection column located on the corresponding side of the first groove.

[0026] Furthermore, before forming the third metal layer, a physical bombardment treatment is first performed on the front surface of the third metal layer before formation, and then the third metal layer is formed through a deposition process.

[0027] As can be seen from the above technical solution, when the present invention utilizes the first groove to form the support and electrical connection pillars of the microbridge structure on the micromirror, the second metal layer material and the support layer material filled in the first groove are partially removed along the longitudinal direction, and only the remaining second metal layer material and the support layer material are used to form the support and electrical connection pillars. This can reduce the area occupied by the formed support and electrical connection pillars in the micromirror, thereby effectively increasing the area of the micromirror surface, thereby significantly improving the fill factor and product performance. Furthermore, by forming the second groove in the first groove, the shape and area of the second metal layer material and the support layer material that need to be removed in the first groove can be precisely controlled, effectively ensuring that the formed support and electrical connection pillars have good conductivity and sufficient support force, while avoiding material redundancy. Moreover, the area occupied by all the support and electrical connection pillars in the entire micromirror array can be reduced by making adjacent micromirrors share the same support and electrical connection pillar, or by forming a support and electrical connection pillar of each adjacent micromirror in the same first groove. This effectively increases the area of all micromirror surfaces in the micromirror array, thereby further improving the fill factor and product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1-Figure 2 This is a schematic structural diagram of a MEMS micromirror with a high fill factor according to a preferred embodiment of the present invention;

[0029] Figure 3 for Figure 2 Schematic diagram of the partial perspective structure of ;

[0030] Figure 4-Figure 5 This is a schematic structural diagram of a MEMS micromirror with a high fill factor according to a second preferred embodiment of the present invention;

[0031] Figure 6 for Figure 5 Schematic diagram of the partial perspective structure of ;

[0032] Figure 7-13 Schematic diagram of the process steps of a method for manufacturing a MEMS micromirror with a high fill factor according to a third preferred embodiment of the present invention;

[0033] Figure 14-17 Schematic diagram of the process steps of a method for manufacturing a MEMS micromirror with a high fill factor according to a fourth preferred embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the invention belongs. The words "including" and similar words used in this article mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0035] The present invention provides a MEMS micromirror with a high fill factor, comprising:

[0036] A microbridge structure is provided on a substrate, the microbridge structure comprising support and electrical connection posts, and a microbridge deck supported on the support and electrical connection posts; a micromirror surface is provided on the microbridge deck, and the micromirror surface is electrically connected to the substrate via the support and electrical connection posts;

[0037] In which, the support and electrical connection column is formed in a first groove, the first groove is arranged in a first sacrificial layer, the first sacrificial layer is located between the substrate and the microbridge bridge surface, the support and electrical connection column includes a conductor formed on a part of the side wall surface of the first groove and a support body located inside the conductor, the micromirror surface is electrically connected to the substrate through the conductor, and the microbridge bridge surface is supported on the support body and the conductor; the microbridge structure is released by removing the first sacrificial layer.

[0038] The present invention also provides a method for manufacturing a MEMS micromirror with a high fill factor, comprising the following steps:

[0039] providing a substrate;

[0040] forming a first metal layer on the surface of the substrate and patterning it to form a metal electrical connection structure;

[0041] Depositing a first sacrificial layer on the surface of the substrate to cover the metal electrical connection structure;

[0042] forming a first trench on the surface of the first sacrificial layer and stopping on the top surface of the metal electrical connection structure;

[0043] forming a second metal layer on the inner wall of the first trench, then filling the first trench with a support layer, planarizing the first trench, and removing excess second metal layer material and the support layer material outside the first trench;

[0044] Removing a portion of the second metal layer material and the support layer material in the first trench along the longitudinal direction to form a second trench penetrating the first trench, and forming a support and electrical connection column in the first trench outside the second trench; wherein the support and electrical connection column includes a conductor formed by the remaining second metal layer material in the first trench, and a support formed by the remaining support layer material;

[0045] Filling the second trench with a second sacrificial layer, planarizing the second trench, and removing excess second sacrificial layer material outside the second trench;

[0046] forming a third metal layer on the surface of the first sacrificial layer, the second sacrificial layer and the support and electrical connection pillars, and patterning the third metal layer to form a micromirror surface electrically connected to the conductor;

[0047] The first sacrificial layer and the second sacrificial layer are removed to release the micromirror surface.

[0048] When the present invention utilizes the first groove to form the support and electrical connection columns of the microbridge structure on the micromirror, the second metal layer material and the support layer material filled in the first groove are partially removed in the longitudinal direction, and only the remaining second metal layer material and the support layer material are used to form the support and electrical connection columns. Therefore, the occupied area of the formed support and electrical connection columns in the micromirror can be reduced, thereby effectively increasing the area of the micromirror surface, thereby significantly improving the fill factor and product performance.

[0049] Moreover, by forming a second groove in the first groove, the shape and area of the second metal layer material and the support layer material portion that need to be removed in the first groove can be precisely controlled, which can not only effectively ensure that the formed support and electrical connection columns have good conductivity and sufficient supporting force, but also avoid material redundancy.

[0050] Moreover, the area occupied by all the support and electrical connection pillars in the entire micromirror array can be reduced by making adjacent micromirrors share the same support and electrical connection pillar, or by forming a support and electrical connection pillar of each adjacent micromirror in the same first groove. This effectively increases the area of all micromirror surfaces in the micromirror array, thereby further improving the fill factor and product performance.

[0051] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0052] See also Figure 1-Figure 2 , Figure 1-Figure 2 FIG. 1 is a structural diagram of a MEMS micromirror with a high fill factor according to a preferred embodiment of the present invention. Figure 1-Figure 2As shown, a high fill factor MEMS micromirror 20 of the present invention includes a microbridge structure 30 disposed on a substrate 10. The microbridge structure 30 includes support and electrical connection posts 16 and a microbridge deck 17 supported on the support and electrical connection posts 16. A micromirror surface 11 (mirror layer) is disposed on the microbridge deck 17; the micromirror surface 11 is electrically connected to the substrate 10 via the support and electrical connection posts 16.

[0053] The support and electrical connection column 16 is formed in the first trench 12 (indicated by the dotted outline); the first trench 12 is arranged in the first sacrificial layer 18 (indicated by the dotted outline); the first sacrificial layer 18 is located on the substrate 10, and the microbridge bridge surface 17 is located on the first sacrificial layer 18.

[0054] The difference from the prior art is that the support and electrical connection pillars 16 of the present invention are arranged longitudinally along the sidewalls of the first trench 12, but only occupy a portion of the area of the first trench 12. In other words, the cavity 13 (second trench 131) that penetrates the first trench 12 is formed in the remaining area of the first trench 12 not occupied by the support and electrical connection pillars 16. As a result, the lateral dimensions of the support and electrical connection pillars 16 of the present invention are reduced compared to existing support pillars.

[0055] Specifically, the support and electrical connection pillar 16 of the present invention includes a conductor 15 formed longitudinally on a portion of the sidewall surface of the first trench 12 and a support 14 located inside the conductor 15. The microbridge bridge surface 17 is supported on the support 14 and the conductor 15, and thus supported on the support and electrical connection pillar 16. The micromirror surface 11 on the microbridge bridge surface 17 is in contact with the conductor 15, and can be electrically connected to the substrate 10 through the conductor 15.

[0056] The first sacrificial layer 18 is removed after the micro-bridge structure 30 is formed, so that the micro-mirror surface 11 (micro-bridge surface 17 ) is released and can be controlled to perform deflection movement relative to the support and electrical connection pillars 16 .

[0057] In some embodiments, the substrate 10 may be a commonly used semiconductor substrate 10, such as a silicon substrate 10, or may be a substrate 10 made of a light-transmitting material such as glass, and circuit structures such as CMOS front-end devices may be fabricated on the substrate 10.

[0058] In some embodiments, the material of the micromirror surface 11 and the conductor 15 can be a conductive material such as metal.

[0059] In some embodiments, the material of the micromirror surface 11 and the material of the conductor 15 may be the same or different.

[0060] In some embodiments, the material of the micromirror surface 11 and / or the conductor 15 may be at least one of metals such as aluminum (Al), platinum (Pt), gold (Au), silver (Ag), and metal alloys.

[0061] In some embodiments, the support body 14 may be made of a dielectric material, such as at least one of SiO 2 , SiN, SiON, and SiC.

[0062] In some embodiments, the first sacrificial layer 18 may be made of a dielectric material having a high etching selectivity between the substrate 10 and the microbridge structure 30 during a release process. For example, the first sacrificial layer 18 may be made of amorphous silicon, polymer, polyimide, polysilicon, silicon nitride, or silicon dioxide.

[0063] See also Figure 1 In some embodiments, the lower end of the conductor 15 may further extend from the sidewall of the first trench 12 to a portion of the bottom surface of the first trench 12, forming an L-shaped bent structure, and electrically connected to the substrate 10 through the horizontal portion of the L-shaped bent structure. The support body 14 may be disposed inside the L-shaped bent structure and located on the horizontal portion of the L-shaped bent structure.

[0064] In some embodiments, the support body 14 may be formed of a single film layer or a stack of multiple film layers.

[0065] In some embodiments, the support body 14 may also be formed of a split structure consisting of a single film layer or a stack of multiple film layers.

[0066] In some embodiments, the conductor 15 may be formed of a single film layer or a stack of multiple film layers.

[0067] In some embodiments, the conductor 15 may also be formed of a separate structure consisting of a single film layer or a stack of multiple film layers.

[0068] In some embodiments, a metal electrical connection structure 19 may be provided on the surface of the substrate 10; the metal electrical connection structure 19 is electrically connected to the substrate 10. The support and electrical connection pillars 16 may be provided on the metal electrical connection structure 19, and the horizontal portion of the L-shaped bend structure of the conductor 15 may contact the metal electrical connection structure 19, thereby electrically connecting the micromirror surface 11 to the substrate 10 via the support and electrical connection pillars 16 and the metal electrical connection structure 19.

[0069] In some embodiments, the metal electrical connection structure 19 may be made of a conductive material such as metal, for example, aluminum or tungsten.

[0070] See also Figure 2 In conjunction with Figure 1In some embodiments, each micromirror 20 (micromirror 20 unit) may be provided with two support and electrical connection posts 16, and the two support and electrical connection posts 16 are arranged side by side on the substrate 10. A conductive torsion arm 21 (hinge) may be provided between the top ends of the two support and electrical connection posts 16. The microbridge deck 17 may be connected to the torsion arm 21 and supported. In this way, the micromirror surface 11 on the microbridge deck 17 can be electrically connected to the substrate 10 through the torsion arm 21 and the support and electrical connection posts 16 in sequence.

[0071] In some embodiments, the torsion arm 21 may be a straight torsion arm 21, such as Figure 2 shown.

[0072] In some embodiments, the torsion arm may also be a broken line torsion arm or a curved torsion arm, etc.

[0073] In some embodiments, both ends of the torsion arm 21 may extend on the top surfaces of the two support and electrical connection pillars 16 and expand to cover the top surfaces of the support and electrical connection pillars 16 to enhance the connection strength and supporting force.

[0074] In some embodiments, the micromirror surface 11 can be connected to the torsion arm 21 via a connecting arm 22. Preferably, the micromirror surface 11 can be connected to the middle portion of the torsion arm 21. The periphery of the micromirror surface 11 outside the connecting arm 22 maintains a certain distance from the support and electrical connection pillars 16 and the torsion arm 21, and does not contact each other.

[0075] In some embodiments, a conductive layer may be provided on the torsion arm 21 and the connecting arm 22. The conductive layer may preferably be formed of the same material as the micromirror surface 11.

[0076] In some embodiments, a dielectric support surface (support surface layer) may be provided on the microbridge deck 17, the torsion arm 21, and the connecting arm 22. The dielectric support surface may be provided below and / or above the micromirror surface 11 and the conductive layer to support the micromirror surface 11 and the conductive layer. The dielectric support surface material may be, for example, at least one of SiO2, SiN, SiON, and SiC.

[0077] In some embodiments, a dielectric protective surface (protective surface layer) may be provided on the microbridge deck 17, the torsion arm 21, and the connecting arm 22. The dielectric protective surface may be provided on the top layer of the microbridge deck 17, the torsion arm 21, and the connecting arm 22 to protect the micromirror surface 11 and the conductive layer surface. The dielectric protective surface material may be, for example, at least one of SiO2 and SiON.

[0078] In some embodiments, the microbridge deck 17 may be a rectangular plane surface (ignoring the local contours of the avoidance support and electrical connection columns 16), such as Figure 2 shown.

[0079] In some embodiments, the micro-bridge deck 17 may also adopt other shapes suitable for forming an array other than a rectangular plane surface.

[0080] In some embodiments, the microbridge deck 17 may include a first sub-microbridge deck and a second sub-microbridge deck. The first sub-microbridge deck and the second sub-microbridge deck may be coplanar and connected to both sides of the torsion arm 21, respectively. Figure 2 shown.

[0081] See also Figure 2 In conjunction with Figure 1 In some embodiments, the micromirrors 20 may be arranged in rows and columns on the substrate 10 to form a micromirror 20 array. Figure 2 The diagram exemplifies three micromirrors 20 arranged in a horizontal direction (which can be represented as a row or column direction) (only a partial structure of the two micromirrors 20 on the left and right sides is shown). Any two adjacent micromirrors 20 (microbridge decks 17) in the same row or column share the same support and electrical connection post 16. For example, the first micromirror 20 on the far left and the second micromirror 20 in the middle share the first support and electrical connection post 16 on the left, while the third micromirror 20 on the far right and the second micromirror 20 in the middle share the second support and electrical connection post 16 on the right.

[0082] It should be noted that, since each support and electrical connection column 16 only occupies a part of the total area of the first groove 12, when the first micromirror 20 located on the far left of the figure and the second micromirror 20 located in the middle share the first support and electrical connection column 16 on the left, the first micromirror 20 located on the far left of the figure can cross the first groove 12 where the first support and electrical connection column 16 is located and move closer to the first support and electrical connection column 16. At the same time, when the second micromirror 20 located in the middle of the figure and the third micromirror 20 located on the far right share the second support and electrical connection column 16 on the right, the second micromirror 20 located in the middle of the figure can also cross the first groove 12 where the second support and electrical connection column 16 is located and move closer to the second support and electrical connection column 16.

[0083] Figure 3 The top view of the micromirror 20 array is shown after the extended portion of the torsion arm 21 covering the top surface of the support and electrical connection pillar 16 has been removed. This allows the positional relationship between the top surface of the support body 14 and the conductive body 15 of the support and electrical connection pillar 16 and the two micromirrors 20 on its left and right sides to be clearly seen. Specifically, the edges of the two micromirrors 20 on the left and right sides of each support and electrical connection pillar 16 are aligned with the distance between the support and electrical connection pillar 16.

[0084] As can be seen, the aforementioned micromirror structural design of the present invention significantly reduces the redundant design area of the support and electrical connection pillars 16. This saved area of support and electrical connection pillars 16 can not only be used to increase the area of the micromirror surface 11 within a single micromirror 20, but also significantly increase the total area of the micromirror surface 11 within the entire array by allowing any two adjacent micromirrors 20 in the same row or column to share the same support and electrical connection pillars 16. In other words, the present invention can reduce the area of the micromirror array 20 while maintaining the same number of micromirrors 20; alternatively, it can increase the number of micromirrors 20 while maintaining the same array area. This effectively improves the fill factor, thereby enhancing product performance.

[0085] See also Figure 4-Figure 5 , Figure 4-Figure 5 FIG. 1 is a structural diagram of a MEMS micromirror with a high fill factor according to a preferred embodiment 2 of the present invention. Figure 4-Figure 5 As shown, Figure 1-Figure 2 The difference between the embodiments is that, in this embodiment, a MEMS micromirror 20 with a high fill factor of the present invention has two supporting and electrical connection pillars 16 formed in the same first trench 12 .

[0086] In some embodiments, the two support and electrical connection pillars 16 are disposed separately and can be formed on the left and right sidewalls of the same first trench 12. Specifically, a cavity 13 (second trench 131) is formed in the central portion of the first trench 12 that is not occupied by the two support and electrical connection pillars 16, extending through the first trench 12. Consequently, compared to conventional support pillars, the lateral dimensions of each support and electrical connection pillar 16 in this embodiment are reduced.

[0087] Each support and electrical connection post 16 is independently connected to a corresponding metal electrical connection structure 19 below, and each support and electrical connection post 16 belongs to two different micromirrors 20. In other words, the area originally used to form one support and electrical connection post 16 on one micromirror 20 can now be used to form two support and electrical connection posts 16 belonging to two different micromirrors 20. This also reduces the area occupied by the support and electrical connection posts 16 on each micromirror 20, and correspondingly increases the area of the micromirror surface 11, thereby improving the fill factor.

[0088] When a plurality of micromirrors 20 are formed into an array, the support and electrical connection posts 16 of any two adjacent micromirrors 20 in the same row or column are arranged close to each other and formed on opposite sidewalls of the same first trench 12 (in this case, the two adjacent micromirrors 20 no longer share the same support and electrical connection posts 16, but instead share the occupied area of the same first trench 12). Therefore, the fill factor of the micromirror 20 array is significantly improved.

[0089] Figure 6 The top view of the micromirror 20 array is shown after the extended portion of the torsion arm 21 covering the top surface of the support and electrical connection pillar 16 is removed, so that the positional relationship between the top surfaces of the support bodies 14 and the conductors 15 of the two support and electrical connection pillars 16 and the two micromirrors 20 on their left and right sides can be seen. The two support and electrical connection pillars 16 located in the same first groove 12 can have a consistent distance from the edges of the two micromirrors 20 on their corresponding sides, and the distance between the two support and electrical connection pillars 16 can be adjusted by adjusting the size of the second groove 131.

[0090] In other embodiments, a conductive bearing structure (not shown) may be provided on the top surface of the support and electrical connection pillars 16, and the two ends of the torsion arm 21 may be inserted into the bearing structure to form a movable fit between the bearing structures. The micro-bridge deck 17 (micro-mirror surface 11) of the micro-mirror 20 is supported on the two support and electrical connection pillars 16 via the torsion arm 21, which forms a movable fit with the bearing structure, and a conductive movable fit surface is formed between the torsion arm 21 and the bearing structure. In this way, when controlling the deflection of the micro-mirror surface 11 (micro-bridge deck 17) about the torsion arm 21, it is no longer necessary to overcome the rigidity of the torsion arm 21 structure as in the past. Instead, the micro-mirror surface 11 is deflected about the movable axis formed by the torsion arm 21, thereby reducing the pull-in voltage of the micro-mirror 20 and, in turn, the operating voltage of the device.

[0091] A method for manufacturing a MEMS micromirror with a high fill factor according to the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0092] See also Figure 7-13 , Figure 7-13 Schematic diagram of the process steps of a method for manufacturing a MEMS micromirror with a high fill factor according to a third preferred embodiment of the present invention. Figure 7-13 As shown, the high fill factor MEMS micromirror manufacturing method of the present invention can be used to manufacture, for example Figure 1 ( Figure 2 ) is a high fill factor MEMS micromirror 20, which may include the following steps:

[0093] See also Figure 7 First, a semiconductor substrate 10, such as a silicon substrate 10, may be used, and circuit structures such as CMOS front-end devices required for forming MEMS may be fabricated on the substrate 10.

[0094] Then, a first metal layer may be formed on the surface of the substrate 10 by, for example, a deposition process, and patterned by photolithography and etching processes to form a pattern of the metal electrical connection structure 19 .

[0095] Next, a first sacrificial layer 18 may be deposited on the surface of the substrate 10 using, for example, a deposition process, and covers the metal electrical connection structure 19. The first sacrificial layer 18 may be made of, for example, polyimide.

[0096] Next, a photolithography and etching process may be used to form a first trench 12 on the surface of the first sacrificial layer 18 , and the first trench 12 stops on the top surface of the metal electrical connection structure 19 .

[0097] The first groove 12 may be a rectangular groove or a circular groove, etc., and the present invention is not limited thereto.

[0098] See also Figure 8 Afterwards, a conformal deposition process, for example, can be used to conformally form a second metal layer 151 on the inner wall of the first trench 12. The material of the second metal layer 151 can be, for example, aluminum. Then, a dielectric deposition process can be used to further fill the first trench 12 within the second metal layer 151 with a support layer 141, completely filling the first trench 12. The material of the support layer 141 can be, for example, silicon nitride.

[0099] See also Figure 9 Next, the surface of the structure after the above steps can be planarized by, for example, a chemical mechanical polishing (CMP) process to remove excess second metal layer 151 material and support layer 141 material on the surface of the first sacrificial layer 18 outside the first trench 12 .

[0100] See also Figure 10 Then, a photolithography and etching process can be used to remove part of the second metal layer 151 material and the support layer 141 material in the first trench 12 in the longitudinal direction. As a result, a second trench 131 penetrating the first trench 12 is formed in the first trench 12 after the part of the second metal layer 151 material and the support layer 141 material is removed. At the same time, a support and electrical connection column 16 is formed in the first trench 12 outside the second trench 131. The support and electrical connection column 16 includes a conductor 15 formed by the second metal layer 151 material remaining after the first trench 12 is removed, and a support body 14 formed by the remaining support layer 141 material.

[0101] Furthermore, when forming the second groove 131, a photolithography mask can be used to locate the second groove 131 on one side of the first groove 12 (the left side as shown), so that the formed support and electrical connection column 16 is located on the other side of the first groove 12 (the right side as shown).

[0102] When forming the micromirror surface 11, a micromirror surface 11 of a micromirror 20 can be formed on both sides of any support and electrical connection column 16, and the two micromirror surfaces 11 are electrically connected to the support and electrical connection column 16 (refer to FIG. Figure 2-Figure 3 ).

[0103] The area of the second trench 131 can be adjusted by photolithography, thereby controlling the lateral size of the formed support and electrical connection pillars 16 .

[0104] See also Figure 11 Next, a deposition process, for example, can be used to fill the second trench 131 formed in the previous step with the second sacrificial layer 23, completely filling the second trench 131 (the first trench 12). The second trench 131 (the first trench 12) is then planarized, and the excess second sacrificial layer 23 material on the surface of the first sacrificial layer 18 outside the second trench 131 is removed. The second sacrificial layer 23 can preferably be made of the same material as the first sacrificial layer 18, such as polyimide. Alternatively, the second sacrificial layer 23 can be made of a different dielectric material than the first sacrificial layer 18.

[0105] See also Figure 12 Next, a third metal layer can be formed on the surface of the structure formed after the above steps, i.e., the surface of the first sacrificial layer 18, the second sacrificial layer 23, and the support and electrical connection pillars 16, using a metal deposition process, and patterned to form the micromirror surface 11 electrically connected to the conductor 15 and the microbridge surface 17. The material of the third metal layer can be, for example, aluminum.

[0106] When the third metal layer is patterned to form the micromirror surface 11, structures such as the torsion arm 21 for connecting the support and electrical connection pillars 16 and the connecting arm 22 for connecting the torsion arm 21 and the micromirror surface 11 may also be formed. Furthermore, film layers such as a dielectric support surface and a dielectric protection surface may also be formed on the microbridge surface 17.

[0107] Preferably, before forming the third metal layer, the front surface of the third metal layer, that is, the surface of the first sacrificial layer 18, the second sacrificial layer 23 and the support and electrical connection column 16, can be physically bombarded to remove a certain thin layer thickness on the surface of the first sacrificial layer 18, the second sacrificial layer 23 and the support and electrical connection column 16; then, the third metal layer is formed through a deposition process.

[0108] See also Figure 13 Finally, the first sacrificial layer 18 and the second sacrificial layer 23 can be removed by an etching process (release process) and utilizing the high etching selectivity of the first sacrificial layer 18 and the second sacrificial layer 23 relative to other structural materials to release the micromirror surface 11 (microbridge surface 17), forming, for example Figure 1 ( Figure 2 ) shows a high fill factor MEMS micromirror 20 structure.

[0109] See also Figure 14-17 , Figure 14-17Schematic diagram of the process steps of a method for manufacturing a MEMS micromirror with a high fill factor according to a fourth preferred embodiment of the present invention. In this embodiment, a method for manufacturing a MEMS micromirror with a high fill factor according to the present invention can be used to manufacture, for example, Figure 4 ( Figure 5 ) is a high fill factor MEMS micromirror 20, and can be used in Figure 14-17 Before the process steps shown, the same steps as in the above embodiment 3 are included. Figure 7-Figure 9 The process steps shown in FIG. 1 can be understood by referring to the above description and will not be described in detail. The difference from the above embodiment 3 is that in this embodiment, in the example Figure 7-Figure 9 The process steps shown are followed by the following distinguishing steps:

[0110] See also Figure 14 After removing the excess second metal layer 151 material and support layer 141 material on the surface of the first sacrificial layer 18 outside the first trench 12 by planarization, a photolithography and etching process can be used to remove a portion of the second metal layer 151 material and support layer 141 material in the middle of the first trench 12 in the longitudinal direction, thereby forming a second trench 131 penetrating the first trench 12 in the middle of the first trench 12 after the portion of the second metal layer 151 material and support layer 141 material is removed, and the bottom of the second trench 131 stops on the surface of the substrate 10, cutting the metal electrical connection structure 19 below the first trench 12 into two sub-metal electrical connection structures 19. When forming the second trench 131, by positioning the second trench 131 in the middle of the first trench 12, an unconnected support and electrical connection column 16 is formed in each of the first trenches 12 on both sides of the second trench 131, and each of the two support and electrical connection columns 16 is independently connected to a sub-metal electrical connection structure 19 thereunder. When forming the micromirror surface 11, a micromirror surface 11 of a micromirror 20 is formed on each side of any first trench 12, and each of the two micromirror surfaces 11 is electrically connected to a support and electrical connection column 16 located on the corresponding side of the first trench 12.

[0111] The two supporting and electrical connection pillars 16 located in the same first trench 12 each include a conductor 15 formed of the second metal layer 151 material remaining after the first trench 12 is removed, and a support body 14 formed of the remaining supporting layer 141 material.

[0112] When forming the second trench 131, a photolithography mask can be used to position the second trench 131 in the middle of the first trench 12. The area of the second trench 131 can be adjusted by photolithography to control the lateral dimensions of the two support and electrical connection pillars 16 formed.

[0113] See also Figure 15Next, a deposition process, for example, can be used to fill the second trench 131 formed in the previous step with the second sacrificial layer 23, completely filling the second trench 131 (the first trench 12). The second trench 131 (the first trench 12) is then planarized, and the excess second sacrificial layer 23 material on the surface of the first sacrificial layer 18 outside the second trench 131 is removed. The second sacrificial layer 23 can preferably be made of the same material as the first sacrificial layer 18, such as polyimide. Alternatively, the second sacrificial layer 23 can be made of a different dielectric material than the first sacrificial layer 18.

[0114] See also Figure 16 Next, a third metal layer may be formed on the surface of the structure formed after the above steps, i.e., the first sacrificial layer 18, the second sacrificial layer 23, and the surface of the support and electrical connection pillars 16, by, for example, a metal deposition process, and patterned to form two micromirror surfaces 11 electrically connected to a conductor 15 located on the corresponding side of the first groove 12, and correspondingly form two microbridge surfaces 17 belonging to the two micromirrors 20 (refer to Figure 5-Figure 6 ). The material of the third metal layer can be, for example, metal aluminum.

[0115] When the third metal layer is patterned to form the micromirror surface 11, structures such as the torsion arm 21 for connecting the support and electrical connection pillars 16 and the connecting arm 22 for connecting the torsion arm 21 and the micromirror surface 11 may also be formed. Furthermore, film layers such as a dielectric support surface and a dielectric protection surface may also be formed on the microbridge surface 17.

[0116] Preferably, before forming the third metal layer, the front surface of the third metal layer, that is, the surface of the first sacrificial layer 18, the second sacrificial layer 23 and the support and electrical connection column 16, can be physically bombarded to remove a certain thin layer thickness on the surface of the first sacrificial layer 18, the second sacrificial layer 23 and the support and electrical connection column 16; then, the third metal layer is formed through a deposition process.

[0117] See also Figure 17 Finally, the first sacrificial layer 18 and the second sacrificial layer 23 can be removed by an etching process (release process) and utilizing the high etching selectivity of the first sacrificial layer 18 and the second sacrificial layer 23 relative to other structural materials to release the micromirror surface 11 (microbridge surface 17), forming, for example Figure 4 ( Figure 5 ) shows a high fill factor MEMS micromirror 20 structure.

[0118] In summary, when the present invention utilizes the first trench 12 to form the support and electrical connection pillars 16 for the microbridge structure 30 on the micromirror 20, the second metal layer 151 material and the support layer 141 material filled in the first trench 12 are partially removed longitudinally, and only the remaining portion of the second metal layer 151 material and the support layer 141 material after removal is used to form the support and electrical connection pillars 16. This reduces the area occupied by the formed support and electrical connection pillars 16 in the micromirror 20, thereby effectively increasing the area of the micromirror surface 11, thereby significantly improving the fill factor and product performance. Furthermore, by forming the second trench 131 in the first trench 12, the shape and area of the portion of the second metal layer 151 material and the support layer 141 material to be removed in the first trench 12 can be precisely controlled, effectively ensuring that the formed support and electrical connection pillars 16 have good conductivity and sufficient support force while avoiding material redundancy. Moreover, the area occupied by all the support and electrical connection pillars 16 in the entire micromirror 20 array can be reduced by making adjacent micromirrors 20 share the same support and electrical connection pillar 16, or by forming one support and electrical connection pillar 16 of each adjacent micromirror 20 in the same first groove 12. This effectively increases the area of all the micromirror surfaces 11 in the micromirror 20 array, thereby further improving the fill factor and product performance.

[0119] While the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations of these embodiments are possible. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the claims. Furthermore, the invention described herein is susceptible to other embodiments and may be practiced or implemented in a variety of ways.

Claims

1. A MEMS micromirror with a high fill factor, characterized in that: include: A microbridge structure provided on a substrate, the microbridge structure comprising support and electrical connection posts, and a microbridge deck supported on the support and electrical connection posts; A micromirror surface is provided on the microbridge surface, and the micromirror surface is electrically connected to the substrate through the support and electrical connection pillars; The support and electrical connection pillars are formed in a first trench, the first trench is provided in a first sacrificial layer, the first sacrificial layer is located between the substrate and the microbridge deck, the support and electrical connection pillars include a conductor formed on a portion of the sidewall surface of the first trench and a support located inside the conductor, the micromirror surface is electrically connected to the substrate via the conductor, and the microbridge deck is supported on the support and the conductor; The microbridge structure is released by removing the first sacrificial layer; The lower end of the conductor further extends to a portion of the bottom surface of the first groove to form an L-shaped bending structure, and is electrically connected to the substrate through the horizontal portion of the L-shaped bending structure. The support body is provided on the inner side of the L-shaped bending structure and is located on the horizontal portion of the L-shaped bending structure. A metal electrical connection structure is provided on the surface of the substrate, the metal electrical connection structure is electrically connected to the substrate, the support and electrical connection columns are provided on the metal electrical connection structure, and the horizontal portion of the L-shaped bending structure is in contact with and located on the metal electrical connection structure; There are two support and electrical connection columns, which are arranged in parallel on the substrate. The conductive torsion arm is arranged between the top ends of the two support and electrical connection columns. The microbridge bridge surface is connected to the torsion arm and is supported. The micromirror surface is electrically connected to the substrate through the torsion arm, the support and electrical connection columns.

2. The high fill factor MEMS micromirror according to claim 1, characterized in that: The microbridge deck includes a first sub-microbridge deck and a second sub-microbridge deck. The first sub-microbridge deck and the second sub-microbridge deck are coplanar and respectively connected to both sides of the torsion arm.

3. The high fill factor MEMS micromirror according to claim 1, characterized in that: A conductive bearing structure is provided on the top surface of the support and electrical connection column, and both ends of the torsion arm are inserted into the bearing structure to form a movable fit with the bearing structure.

4. The high fill factor MEMS micromirror according to claim 1, wherein: The micromirrors are arranged in rows and columns on the substrate to form a micromirror array; wherein, any two adjacent micromirrors in the same row or column share the same support and electrical connection pillar, or, the respective support and electrical connection pillars of any two adjacent micromirrors in the same row or column are arranged close to each other and formed on the sidewalls on opposite sides of the same first groove.

5. A method for manufacturing a MEMS micromirror with a high fill factor, characterized in that: include: providing a substrate; forming a first metal layer on the surface of the substrate and patterning it to form a metal electrical connection structure; forming a first sacrificial layer on the surface of the substrate and covering the metal electrical connection structure; forming a first trench on the surface of the first sacrificial layer and stopping on the top surface of the metal electrical connection structure; forming a second metal layer on the inner wall of the first trench, then filling the first trench with a support layer, planarizing the first trench, and removing excess second metal layer material and the support layer material outside the first trench; Removing a portion of the second metal layer material and the support layer material in the first trench along the longitudinal direction to form a second trench penetrating the first trench, and forming a support and electrical connection column in the first trench outside the second trench; wherein the support and electrical connection column includes a conductor formed by the remaining second metal layer material in the first trench, and a support formed by the remaining support layer material; Filling the second trench with a second sacrificial layer, planarizing the second trench, and removing excess second sacrificial layer material outside the second trench; forming a third metal layer on the surface of the first sacrificial layer, the second sacrificial layer and the support and electrical connection pillars, and patterning the third metal layer to form a micromirror surface electrically connected to the conductor; The first sacrificial layer and the second sacrificial layer are removed to release the micromirror surface.

6. The method for manufacturing a MEMS micromirror with a high fill factor according to claim 5, wherein: When forming the second groove, the second groove is located on one side of the first groove, so that the formed support and electrical connection column is located on the other opposite side of the first groove, and when forming the micromirror surface, a micromirror surface is formed on both sides of any one of the support and electrical connection columns, and the two micromirror surfaces are electrically connected to the support and electrical connection columns; or, when forming the second groove, the second groove is located in the middle of the first groove, so that an unconnected support and electrical connection column is formed on both sides of the second groove, and when forming the micromirror surface, a micromirror surface is formed on both sides of any one of the first grooves, and the two micromirror surfaces are each electrically connected to a support and electrical connection column located on the corresponding side of the first groove.

7. The method for manufacturing a MEMS micromirror with a high fill factor according to claim 5, wherein: Before forming the third metal layer, a physical bombardment treatment is first performed on the front surface of the third metal layer before formation, and then the third metal layer is formed through a deposition process.

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