MEMS device and method of fabrication

Abstract

The present disclosure provides a MEMS device and a preparation method. Specifically, the MEMS device comprises a substrate and a functional layer disposed at least partially suspended on the substrate, wherein the thickness of the functional layer is greater than or equal to 1 micrometer and less than or equal to 5 micrometers. By increasing the thickness of the functional layer to be greater than or equal to 1 micrometer and less than or equal to 5 micrometers, the strength of the suspended structure of the functional layer can be increased to effectively avoid its collapse, and at the same time, the requirements of the MEMS device for driving the suspended structure can also be met.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of MEMS devices, and particularly relates to a MEMS device and a preparation method. BACKGROUND

[0002] Micro-Electro-Mechanical System (MEMS) is a kind of integration of micro-circuits and micro-machines on a chip according to functional requirements, which is conducive to the integration and miniaturization of devices. The preparation of micro-electro-mechanical systems involves traditional semiconductor technologies such as photolithography and etching, and integrates ultra-precision machining, and combines knowledge and technical basis of mechanics, chemistry, optics and other disciplines, which is high requirement and high difficulty. SUMMARY

[0003] Therefore, the purpose of the present disclosure is to provide a MEMS device and a preparation method to solve the problem of functional layer collapse.

[0004] To achieve the above purpose, in a first aspect, the present disclosure provides a MEMS device, comprising:

[0005] a substrate; and

[0006] a functional layer, at least partially suspended on the substrate; wherein the thickness of the functional layer is greater than or equal to 1 μm and less than or equal to 5 μm.

[0007] Further, a sacrificial layer is arranged between the substrate and the functional layer; the suspended structure of the sacrificial layer and the functional layer has no overlap.

[0008] Further, the material of the sacrificial layer is selected from at least one of photoresist, SiNx, organic resin, polyimide and metal.

[0009] Further, the functional layer comprises a movable comb, a fixed comb and a plating auxiliary structure; the plating auxiliary structure is used to connect the movable comb and the fixed comb during plating.

[0010] Further, the plating auxiliary structure comprises a plating auxiliary electrode and a first plating auxiliary line; wherein the first plating auxiliary line can be cut to disconnect the connection between the plating auxiliary electrode and the movable comb and the fixed comb.

[0011] Further, the plating auxiliary structure comprises a plating auxiliary first sub-electrode, a plating auxiliary second sub-electrode and a second plating auxiliary line connecting the two; wherein the second plating auxiliary line can be cut to disconnect the connection between the plating auxiliary first sub-electrode and the plating auxiliary second sub-electrode.

[0012] Further, the functional layer comprises a first functional sub-layer and a second functional sub-layer and a thickened insulating layer between the two.

[0013] Further, the thickened insulating layer comprises a via, and the first functional sub-layer and the second functional sub-layer are conductive through the via.

[0014] Further, the size of the thickened insulating layer is smaller than the size of the first functional sub-layer and the second functional sub-layer, so that the first functional sub-layer and the second functional sub-layer are conductive in lap joint.

[0015] Further, the thickened insulating layer is selected from at least one of photoresist, SiNx, organic resin and polyimide; and / or

[0016] The material of the thickened insulating layer and the sacrificial layer is different.

[0017] Further, the thickness of the thickened insulating layer is 0.5-3.0 μm.

[0018] Further, the material of the functional layer is selected from at least one of ITO, Mo, Al, Cu, Ti and Au.

[0019] Further, the width of the overhanging structure of the functional layer is ≤4 μm.

[0020] Further, the substrate is a glass substrate.

[0021] In a second aspect, the disclosure also provides a preparation method of a MEMS device, the preparation method comprising:

[0022] providing a substrate;

[0023] forming a sacrificial layer on the substrate;

[0024] forming a functional layer on the sacrificial layer and patterning; wherein the thickness of the functional layer is ≥1 μm and ≤5 μm;

[0025] releasing the sacrificial layer, so that the functional layer forms an overhanging structure.

[0026] Further, the step of forming a sacrificial layer on the substrate comprises:

[0027] coating photoresist on the substrate; and patterning the photoresist using a first mask plate to form the sacrificial layer; or

[0028] sputtering metal Mo on the substrate; and patterning the metal Mo by a photolithography process or a Lift-off process to form the sacrificial layer.

[0029] Further, the step of forming a functional layer on the sacrificial layer and patterning, specifically comprises:

[0030] depositing a seed layer on the sacrificial layer and patterning; wherein the seed layer comprises a movable comb tooth area, a fixed comb tooth area and a plating auxiliary structure area; the plating auxiliary structure area connects the movable comb tooth area and the fixed comb tooth area;

[0031] thickening the seed layer to form the functional layer by using a plating process; wherein the movable comb tooth area, the fixed comb tooth area and the plating auxiliary structure area form a movable comb tooth, a fixed comb tooth and a plating auxiliary structure respectively.

[0032] Further, the plating auxiliary structure comprises a plating auxiliary electrode and a first plating auxiliary line;

[0033] The preparation method further comprises cutting the first plating auxiliary line; or

[0034] The plating auxiliary structure comprises a plating auxiliary first sub-electrode, a plating auxiliary second sub-electrode and a second plating auxiliary line connecting the two;

[0035] The preparation method further comprises cutting the second plating auxiliary line.

[0036] Further, the step of forming a functional layer on the sacrificial layer and patterning, specifically comprises:

[0037] depositing a first functional sub-layer on the sacrificial layer and patterning;

[0038] depositing a thickening insulating layer on the first functional sub-layer;

[0039] depositing a second functional sub-layer on the thickening insulating layer and patterning; and

[0040] patterning the thickening insulating layer by etching.

[0041] Further, the material of the sacrificial layer is non-metal;

[0042] The gas for dry etching the thickening insulating layer is selected from at least one of sulfur hexafluoride SF6 and carbon tetrafluoride CF4; and the gas for releasing the sacrificial layer is oxygen; or

[0043] The gas for releasing the sacrificial layer is selected from at least one of sulfur hexafluoride SF6 and carbon tetrafluoride CF4; and the gas for dry etching the thickening insulating layer is oxygen.

[0044] Further, it further comprises:

[0045] A via is formed on the thickened insulating layer to expose the first functional sub-layer, so as to connect the first functional sub-layer and the second functional sub-layer.

[0046] Further, the method further comprises:

[0047] The thickened insulating layer is patterned to expose a partial area of the first functional sub-layer, and the first functional sub-layer and the second functional sub-layer are connected through the partial area.

[0048] Further, the material of the functional layer is ITO.

[0049] The preparation method further comprises:

[0050] Annealing is performed after the functional layer is patterned.

[0051] As can be seen from the above, the MEMS device and the preparation method provided by the present disclosure can increase the strength of the suspended structure of the functional layer by increasing the thickness of the functional layer to ≥1 μm and ≤5 μm, thereby effectively avoiding the collapse of the suspended structure, and at the same time meeting the requirements of the MEMS device for driving the suspended structure. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the present disclosure or the related art, the drawings needed to be used in the embodiments or the related art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor. In the drawings, the thickness and shape of some layers and regions may be exaggerated for better understanding and ease of description.

[0053] Figure 1 A partial structure side view of a MEMS device is provided for an embodiment of the present disclosure;

[0054] Figure 2 Another partial structure side view of a MEMS device is provided for an embodiment of the present disclosure;

[0055] Figure 3 Another partial structure side view of a MEMS device is provided for an embodiment of the present disclosure;

[0056] Figure 4 Another partial structure side view of a MEMS device is provided for an embodiment of the present disclosure;

[0057] Figure 5 Another partial structure side view of a MEMS device is provided for an embodiment of the present disclosure;

[0058] Figure 6A top view schematic diagram of a partial structure of a MEMS device is provided for an embodiment of the present disclosure;

[0059] Figure 7 A top view schematic diagram of a partial structure of a MEMS device is provided for another embodiment of the present disclosure;

[0060] Figure 8 A flow chart of a preparation method of a MEMS device is provided for an embodiment of the present disclosure;

[0061] Figures 9A-9B An intermediate structure schematic diagram of a preparation method of a sacrificial layer is provided for an embodiment of the present disclosure;

[0062] Figures 10A-10E An intermediate structure schematic diagram of a preparation method of a functional layer is provided for an embodiment of the present disclosure;

[0063] Figures 11A-11H An intermediate structure schematic diagram of another preparation method of a functional layer is provided for an embodiment of the present disclosure;

[0064] Figures 12A-12C An intermediate structure schematic diagram of a method for connecting a first functional sub-layer and a second functional sub-layer is provided for an embodiment of the present disclosure;

[0065] Figures 13A-13C An intermediate structure schematic diagram of another method for connecting a first functional sub-layer and a second functional sub-layer is provided for an embodiment of the present disclosure;

[0066] Figures 14A-14C A collapse simulation result of different thickness of comb teeth is provided for an embodiment of the present disclosure; wherein, Figure 14A corresponding to 100 nm; Figure 14B corresponding to 1 μm; Figure 14C corresponding to 2 μm;

[0067] Figures 15A-15D A collapse simulation result of different length of comb teeth is provided for an embodiment of the present disclosure; wherein, Figure 15A corresponding to 40 μm; Figure 15B corresponding to 20 μm; Figure 15C corresponding to 10 μm; Figure 15D corresponding to 5 μm;

[0068] Figures 16A-16C A collapse simulation result of different thickness of comb teeth is provided for an embodiment of the present disclosure; wherein, Figure 16A corresponding to 50; Figure 16B corresponding to 30; Figure 16C corresponding to 15;

[0069] Figure 17 A scanning picture of a MEMS device prepared for an embodiment of the present disclosure. DETAILED DESCRIPTION

[0070] In order to make the objects, technical solutions and advantages of the present disclosure clearer, the present disclosure will be described in further detail below with reference to specific embodiments and with reference to the drawings.

[0071] It should be noted that, unless otherwise defined, technical terms or scientific terms used in the embodiments of the present disclosure should be understood as their common meanings to those skilled in the art of the present disclosure. The terms "first", "second" and similar terms used in the embodiments of the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. The terms "include", "contain" and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms do not mean physical or mechanical connection, but can include electrical connection, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships may also change accordingly.

[0072] When terms such as "upper", "above", "below" and "beside" are used to describe the positional relationship between two components, unless these terms are used together with the term "immediately" or "directly", one or more components can be located between the two components.

[0073] When an element or layer is disposed "on" another element or layer, another layer or element can be directly inserted between the other element or between them.

[0074] The present inventors found that the overhanging structure of the functional layer has a collapse problem in the preparation process of the MEMS device. As can be understood by those skilled in the art, the overhanging structure can move under the action of a driving voltage to realize signal conduction and other functions. If the overhanging structure collapses, it loses the ability to move at the end and cannot function. For example, the overhanging structure includes a moving comb tooth.

[0075] In view of this, in a first aspect, the present disclosure provides a MEMS device to avoid the problem of collapse of the overhanging structure.

[0076] Please refer to Figures 1-5 , the MEMS device comprises:

[0077] a substrate 101; here, the substrate 101 can be an insulating substrate made of glass, quartz, ceramic, plastic, etc. As an optional embodiment, the substrate 101 is a glass substrate.

[0078] The functional layer 103 is at least partially suspended on the substrate 101; wherein the thickness of the functional layer 103 is ≥ 1 μm and ≤ 5 μm. It should be understood that the portion of the functional layer 103 that is suspended forms a suspended structure, such as a moving comb tooth.

[0079] For example, the thickness of the functional layer 103 can be 1.0 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.2 μm, 4.0 μm, 4.6 μm, 5.0 μm, etc.

[0080] Here, by increasing the thickness of the functional layer to ≥ 1 μm, the strength of the suspended structure of the functional layer can be increased to effectively prevent it from collapsing, while also meeting the requirements of the MEMS device for driving the suspended structure.

[0081] In some embodiments, as shown in Figures 2-5 The MEMS device further includes a sacrificial layer 102 disposed between the substrate 101 and the functional layer 103; the suspended structure of the functional layer 103 and the sacrificial layer 102 have no overlap.

[0082] It should be noted that in order to form the suspended structure of the functional layer 103, the sacrificial layer 102 needs to be formed first during the fabrication of the MEMS device, the functional layer 103 is formed on the sacrificial layer 102, and then the sacrificial layer 102 is released to form a gap between the functional layer 103 and the substrate 101, so that the functional layer 103 has a suspended structure.

[0083] As shown in Figure 1 If the sacrificial layer 102 and the functional layer 103 do not overlap at the position of the non-suspended structure, the sacrificial layer 102 will disappear after the release step. As shown in Figures 2-5 If the sacrificial layer 102 and the functional layer 103 overlap at the position of the non-suspended structure, the sacrificial layer 102 will be partially retained after the release step.

[0084] Optionally, the material of the sacrificial layer 102 is selected from at least one of photoresist (PR), SiNx, organic resin, polyimide (PI), and metal. Here, the metal can be Mo, Al, etc. The organic resin can be optically clear adhesive (OCA), which is not limited here.

[0085] The prior art process for depositing the functional layer 103 can only obtain a thickness of nanometers, which cannot meet the design requirement of the functional layer 103 of the present disclosure, i.e., the thickness ≥ 1 μm. Therefore, in order to increase the thickness of the functional layer 103, the inventors of the present disclosure use a seed layer to increase the thickness of the seed layer by electroplating to prepare the functional layer 103.

[0086] However, for the MEMS device, the movable comb teeth 201 and the fixed comb teeth 202 are driven by power, and thus the movable comb teeth 201 and the fixed comb teeth 202 are not conductive. In order to facilitate the application of the entire functional layer 103 as an electrode to the electroplating process, the inventors of the present disclosure further add the electroplating auxiliary structure 203.

[0087] Referring to Figure 6 and Figure 7 , the functional layer 103 includes the movable comb teeth 201, the fixed comb teeth 202, and the electroplating auxiliary structure 203; the electroplating auxiliary structure 203 is used to connect the movable comb teeth 201 and the fixed comb teeth 202 during electroplating.

[0088] By connecting the movable comb teeth 201 and the fixed comb teeth 202 through the electroplating auxiliary structure 203, the functional layer 103 can be electroplated as an electrode, which has the advantages of strong operability, controllable thickness, etc.

[0089] For the specific structure of the electroplating auxiliary structure 203, the present disclosure also provides multiple embodiments.

[0090] As shown in Figure 6 , the electroplating auxiliary structure 203 includes an electroplating auxiliary electrode 2031 and a first electroplating auxiliary line 2032; wherein the first electroplating auxiliary line 2032 can be cut to disconnect the connection between the electroplating auxiliary electrode 2031 and the movable comb teeth 201 and the fixed comb teeth 202.

[0091] As can be understood by those skilled in the art, one end of the first electroplating auxiliary line 2032 is connected to the movable comb teeth 201 or the fixed comb teeth 202, and the other end is connected to the electroplating auxiliary electrode 2031. The electroplating auxiliary structure 203 can be formed at the same time as the movable comb teeth 201 and the fixed comb teeth 202, and after electroplating is completed, the first electroplating auxiliary line 2032 is cut according to the position of the dashed line in Figure 6 , which can disconnect the connection between the electroplating auxiliary electrode 2031 and the movable comb teeth 201 and the fixed comb teeth 202. The electroplating auxiliary electrode 2031 will not affect the normal driving of the movable comb teeth 201 and the fixed comb teeth 202, and will not increase the volume of the MEMS device, which is conducive to obtaining a small-volume MEMS device.

[0092] In addition, the functional layer 103 can also include a lead electrode 204, which can be in communication with the movable comb teeth 201 and the fixed comb teeth 202, respectively.

[0093] As an alternative embodiment, as shown in Figure 7 , the electroplating auxiliary structure 203 includes an electroplating auxiliary first sub-electrode 2033, an electroplating auxiliary second sub-electrode 2034, and a second electroplating auxiliary line 2035 connecting the two; wherein the second electroplating auxiliary line 2035 can be cut to disconnect the connection between the electroplating auxiliary first sub-electrode 2033 and the electroplating auxiliary second sub-electrode 2034.

[0094] In this technical solution, the electroplating auxiliary structure 203 has two sub-electrodes and a second electroplating auxiliary line 2035. After electroplating is completed, the second electroplating auxiliary line 2035 is cut (along...). Figure 7 (As shown by the dashed line in the middle) The two sub-electrodes are independent of each other, and the moving comb tooth 201 and the fixed comb tooth 202 can even be driven by the two sub-electrodes respectively, which provides more possibilities for driving the moving comb tooth 201 and the fixed comb tooth 202, and makes the device more flexible.

[0095] In addition to the above-mentioned technical solution of increasing the thickness of the functional layer 103 by electroplating, this disclosure also provides another alternative implementation method, which is detailed below:

[0096] Please see Figures 3-5 The functional layer 103 includes a first functional sublayer 1031, a second functional sublayer 1033, and a thickened insulating layer 1032 located between the two. By providing the thickened insulating layer 1032, the thickness of the functional layer 103 is increased, thereby improving the strength of the functional layer 103 and effectively preventing the collapse of the suspended structures (e.g., moving comb teeth) included in the functional layer 103, thus effectively ensuring the quality of the MEMS device.

[0097] In some embodiments, the thickness of the thickened insulating layer 103 is 0.5–3.0 μm, for example 0.5 μm, 0.7 μm, 1.0 μm, 1.5 μm, 1.8 μm, 2.4 μm, or 3.0 μm. It should be understood that those skilled in the art can reasonably select the thickness of the thickened insulating layer 103 according to design requirements.

[0098] Optionally, the thickened insulating layer 103 is selected from at least one of photoresist, SiNx, organic resin and polyimide.

[0099] Here, the materials of the thickened insulating layer and the sacrificial layer are repeated. In order to avoid the release of the sacrificial layer 102 during the preparation process from affecting the thickened insulating layer 1032, the materials of the thickened insulating layer 1032 and the sacrificial layer 102 are different. This helps to avoid mutual interference between the patterning process of the thickened insulating layer 1032 and the release process of the sacrificial layer 102.

[0100] As those skilled in the art will understand, the addition of the thickened insulating layer 1032 renders the first functional sublayer 1031 undriveable, allowing only the second functional sublayer 1033 to be driven, resulting in low overall driving performance of the functional layer 103.

[0101] Therefore, in some embodiments, such as Figure 4 As shown, the thickened insulating layer 1032 includes vias ( Figure 4The first functional sub-layer 1031 and the second functional sub-layer 1033 are connected through the via hole, so that the first functional sub-layer 1031 and the second functional sub-layer 1033 are driven at the same time, thereby effectively improving the driving force of the comb teeth.

[0102] As an alternative implementation, as shown in FIG. 10, the thickened insulating layer 1032 has a size smaller than that of the first functional sub-layer 1031 and the second functional sub-layer 1033, so that the first functional sub-layer 1031 and the second functional sub-layer 1033 are connected through the overlap. Figure 5

[0103] Here, by adjusting the size of the thickened insulating layer 1032, the first functional sub-layer 1031 and the second functional sub-layer 1033 are directly connected through the overlap, and the first functional sub-layer 1031 and the second functional sub-layer 1033 are driven at the same time, thereby effectively improving the driving force of the comb teeth.

[0104] Optionally, the first functional sub-layer 1031 and the second functional sub-layer 1033 are connected through the overlap at the end.

[0105] In some embodiments, the material of the functional layer is a conductive material, for example, at least one selected from indium tin oxide (ITO), Mo, Al, Cu, Ti, and Au. When the sacrificial layer 102 is metal, the material of the functional layer and the material of the sacrificial layer need to be selected considering that both are not affected.

[0106] In some embodiments, the width of the overhanging structure of the functional layer 103 is ≤4 μm. As can be understood by those skilled in the art, the overhanging structure (for example, the comb teeth) has a certain extension length, and accordingly, has a certain width in the direction perpendicular to the extension square. By setting the width ≤4 μm, in combination with the lateral etching depth of the sacrificial layer 102 ≥2 μm, it can be ensured that the sacrificial layer 102 has no residue.

[0107] In a second aspect, the disclosure also provides a preparation method of a MEMS device. As shown in FIG. 11, the preparation method comprises the following steps. Figure 8

[0108] Step S801: providing a substrate 101; here, the substrate can be a glass substrate, and the glass substrate usually needs to be cleaned.

[0109] Step S802: forming a sacrificial layer 102 on the substrate 101; here, the thickness of the sacrificial layer 102 can be 0.3 μm-3.0 μm, for example, 0.5 μm, 0.8 μm, 1.5 μm, 2.1 μm, or 2.6 μm. Optionally, the thickness of the sacrificial layer 102 is 0.8 μm-2.0 μm. ​​

[0110] In some embodiments, a sacrificial layer 102 is formed by coating a predetermined thickness of PR adhesive, optical adhesive, depositing SiNx, sputtering Mo, etc. In this manner, the sacrificial layer 102 covers the entire glass substrate, ultimately forming a structure such that... Figures 2-5 The device shown.

[0111] Coating with PR adhesive, optical adhesive, and sputtering Mo can be done using conventional processes, and no specific limitations are made here.

[0112] Alternatively, SiNx can be deposited using the Thin Film Encapsulation Chemical Vapor Deposition (TFECVD) method.

[0113] Optionally, when the material of the sacrificial layer 102 is SiNx, the process conditions for forming the sacrificial layer include: a deposition temperature of 190–210°C, for example, 200°C; a deposition power of 1300–1500 W, for example, 1400 W; a plate spacing of 1200–1300 mil, for example, 1250 mil; a gas pressure of 1100–1300 mTorr, for example, 1200 mTorr; a SiH4 / NH3 / N2 flow rate of 160–200 / 700–750 / 2800–2950 sccm, for example, 180 / 720 / 2880 sccm; and a deposition thickness of [missing information]. For example Here, if the thickness of a single deposition is In order to obtain a thickness of The sacrificial layer 102 can be deposited twice. As those skilled in the art will understand, a thicker sacrificial layer can be obtained through multiple depositions.

[0114] In some alternative embodiments, by patterning the sacrificial layer, the sacrificial layer 102 is completely released, forming as shown in the figure. Figure 1 The device shown.

[0115] Optionally, such as Figures 9A-9B As shown, photoresist (PR adhesive) is coated on substrate 101. Figure 9A ); and using a first photomask to pattern the photoresist to form a sacrificial layer 102 ( Figure 9B ).

[0116] It should be noted that using PR adhesive as the sacrificial layer 102 may cause problems when depositing the functional layer on top: after subsequent UV exposure and heating, moisture may be released from the sacrificial layer (PR), which can easily lead to the functional layer 103, such as the ITO layer, cracking. Therefore, it is considered to replace the sacrificial layer with other metals such as Mo or Al.

[0117] Optionally, the disclosure provides an embodiment of preparing the sacrificial layer 102 using metal Mo. Specifically comprising: sputtering metal Mo on the substrate; and patterning the metal Mo to form the sacrificial layer 102 by a photolithography process or a lift-off process.

[0118] Here, the lift-off process comprises coating photoresist on the substrate, then performing patterned exposure on the photoresist coated on the substrate, developing to remove the exposed photoresist, then sputtering metal Mo to form a film, and finally peeling off the remaining photoresist and the film formed thereon, and the remaining on the substrate is the desired sacrificial layer 102.

[0119] Step S803: forming a functional layer 103 on the sacrificial layer 102 and patterning; wherein the thickness of the functional layer is ≥ 1 μm and ≤ 5 μm.

[0120] Here, the material of the functional layer 103 can be one of ITO, Mo, Al, Cu, Ti, Au.

[0121] Optionally, the material of the functional layer is ITO; the preparation method further comprises: performing annealing after patterning the functional layer. By annealing, the ITO can be changed from a-ITO to p-ITO, and metal wet etching will not affect the p-ITO, which helps to improve the stability of the functional layer 103.

[0122] In some embodiments, as shown in Figures 10A-10E forming a functional layer 103 on the sacrificial layer 102 and patterning specifically comprises:

[0123] Figure 10A The substrate 101 and the sacrificial layer 102 located thereon are shown; a seed layer is deposited on the sacrificial layer 102 and patterned; specifically comprising: first, depositing a seed layer 1034 on the sacrificial layer 102 (as shown in Figure 10B ); for example, the thickness of the seed layer can be 200 nm to 400 nm, for example, 300 nm; here, the material of the seed layer 1034 is generally a conductive material, such as ITO, Mo, Al, Cu, Ti, Au, etc.; then spin-coating PR glue on the seed layer 1034, and using a mask to perform exposure patterning on the PR glue (as shown in Figure 10C ); then, etching the seed layer 1034 to expose the patterned seed layer 1034 by peeling off the PR glue (as shown in Figure 10D ); finally, using an electroplating process, the seed layer 1034 is thickened to form a functional layer 103 (as shown in Figure 10E ). Here, the PR glue can be AZ AZGXR-601 positive glue.

[0124] Optionally, the electroplated metal can be Cu, Ni, Zn, Cr, Ag, Au, etc.

[0125] Optionally, the plating thickness can be 1-6 μm, such as 2 μm, 4 μm, 5 μm, etc.

[0126] It is to be noted that, please refer to Figure 6 and Figure 7 Before plating, the seed layer 1034 includes the moving comb tooth area, the fixed comb tooth area and the plating auxiliary structure area; the plating auxiliary structure area connects the moving comb tooth area and the fixed comb tooth area; after plating, the moving comb tooth area, the fixed comb tooth area and the plating auxiliary structure area form the moving comb tooth 201, the fixed comb tooth 202 and the plating auxiliary structure 203 respectively.

[0127] Optionally, the plating auxiliary structure 203 includes the plating auxiliary electrode 2031 and the first plating auxiliary line 2032; then after plating, it further includes the step of cutting the first plating auxiliary line 2032.

[0128] Optionally, the plating auxiliary structure 203 includes the plating auxiliary first sub-electrode 2033, the plating auxiliary second sub-electrode 2034 and the second plating auxiliary line 2035 connecting the two; then after plating, it further includes the step of cutting the second plating auxiliary line 2032.

[0129] It is to be noted that, cutting the first plating auxiliary line 2032 or cutting the second plating auxiliary line 2032 can be directly performed after plating or can be performed after the release of the sacrificial layer, which is not specifically limited in the present disclosure.

[0130] Optionally, cutting the first plating auxiliary line 2032 or cutting the second plating auxiliary line 2032 can be performed by laser or cutter wheel. Those skilled in the art can reasonably select the specific cutting method according to the needs.

[0131] As an alternative embodiment, the present disclosure further provides another method for preparing the functional layer 103.

[0132] Please refer to Figures 11A-11H The step of forming the functional layer on the sacrificial layer and patterning includes:

[0133] Firstly, Figure 11A The substrate 101 and the sacrificial layer 102 located thereon are shown.

[0134] Then, the first functional sub-layer is deposited on the sacrificial layer 102 and is patterned. Specifically, the first functional sub-layer 1031 (such as Figure 11B ) is deposited; then PR glue is coated, exposed and developed (such as Figure 11C ); then the first functional sub-layer 1031 is etched and patterned (such as Figure 11D ).

[0135] Then, a thickened insulating layer 1032 is deposited on the first functional sub-layer 1031 (such as Figure 11E );for example, SiN X 0.5-3.0μm;

[0136] Next, a second functional sub-layer 1033 is deposited on the thickened insulating layer and patterned; specifically including: depositing a second functional sub-layer 1033 (such as Figure 11F );then coating PR glue, exposing and developing; then etching the second functional sub-layer 1033 to be patterned (such as Figure 11G )。

[0137] Finally, the thickened insulating layer 1032 is patterned by etching (such as Figure 11H ). Alternatively, dry etching is used to pattern the thickened insulating layer 1032.

[0138] It should be noted that in the above technical solution, one mask plate can be used to pattern the first functional sub-layer 1031, the thickened insulating layer 1032 and the second functional sub-layer 1033.

[0139] As can be understood by those skilled in the art, this way can increase the thickness of the functional layer 103 and avoid the collapse of the suspended structure, but due to the addition of the thickened insulating layer 1032 in the middle, only the second functional sub-layer 1033 can be driven, and the first functional sub-layer 1031 cannot be driven, so the driving force of the functional layer 103 is limited.

[0140] Therefore, the embodiments of the present disclosure propose further improvement schemes.

[0141] Please refer to Figures 12A-12C , Figure 12A shows a structure including a patterned first functional sub-layer 1031. Next, as shown in Figure 12B , a thickened insulating layer 1032 is formed and a via hole (the position pointed by the arrow in the figure) exposing the first functional sub-layer is formed on the thickened insulating layer 1032 to conduct the first functional sub-layer and the second functional sub-layer; finally, a second functional sub-layer 1033 is deposited (such as Figure 12C ), the second functional sub-layer 1033 extends to the first functional sub-layer 1031 through the via hole, realizing the conduction of the first functional sub-layer 1031 and the second functional sub-layer 1033.

[0142] For example, the via hole can be prepared by mask exposure etching, which is not described here.

[0143] As an alternative embodiment, please refer to Figures 13A-13C , Figure 13AThe structure including the first functional sub-layer 1031 after patterning is shown. Then, the thickened insulating layer 1032 is deposited and patterned to expose a partial area of the first functional sub-layer, and the first functional sub-layer and the second functional sub-layer are overlapped through the partial area (for example Figure 13B ); finally, the second functional sub-layer 1033 (for example Figure 13C ) is deposited, and the second functional sub-layer 1033 extends to the first functional sub-layer 1031 through the partial area, so as to realize the conduction of the first functional sub-layer 1031 and the second functional sub-layer 1033.

[0144] Step S804: releasing the sacrificial layer 102 to form a suspended structure of the functional layer 103. Here, the structure of the Figure 10E is released to obtain a MEMS device as shown in Figure 2 ; the structure of the Figure 11H is released to obtain a MEMS device as shown in Figure 3 ; the structure of the Figure 12C is patterned, and the sacrificial layer is released to obtain a MEMS device as shown in Figure 4 ; the structure of the Figure 13C is patterned, and the sacrificial layer is released to obtain a MEMS device as shown in Figure 5 .

[0145] It should be noted that the release of the sacrificial layer can be wet release or dry release. The wet release is isotropic release, and there is a problem of release time control. The etching depth is controlled by the release time, and the damage of the suspended structure caused by the wet release and post-processing needs to be considered. Alternatively, if the sacrificial layer 102 is metal, for example, Mo, the wet etching can be used.

[0146] The dry release is solved by reactive ion etching (RIE) or oxygen plasma on the sacrificial layer. The dry etching needs to pay attention to the lateral dry etching depth of the sacrificial layer to ensure the minimum lateral etching depth, for example, ≥2 μm, so as to ensure that there is no residual of the sacrificial layer corresponding to the suspended structure. For example, for SiNx with a thickness of 2 μm, the lateral penetration of 2 μm on one side can be achieved by RIE method in 3 minutes.

[0147] Generally, if the width of the suspended structure is W, the minimum one-side etching depth is W / 2, and a little over-etching is generally performed, that is, > W / 2.

[0148] In some embodiments, the material of the sacrificial layer is non-metal, for example, PI, PR, OCA; and the thickened insulating layer can be SiNx.

[0149] The gas for dry etching the thickened insulating layer is selected from at least one of sulfur hexafluoride SF6 and carbon tetrafluoride CF4; and the gas for releasing the sacrificial layer is oxygen; or

[0150] The gas used for dry etching the thickened insulation layer is oxygen; the gas released from the sacrificial layer is selected from at least one of sulfur hexafluoride (SF6) and carbon tetrafluoride (CF4).

[0151] In this way, the mutual interference between the release of the sacrificial layer and the dry etching thickening of the insulating layer can be reduced.

[0152] Finally, the MEMS device fabricated using the fabrication method of this disclosure embodiment is described in the following figure. Figure 17 . Figure 17 The diagram shows the moving and fixed comb teeth, with the fixed comb teeth on the left and the moving comb teeth on the right. As can be seen from the diagram, the moving and fixed comb teeth have a fine and uniform structure, meeting the design requirements.

[0153] It should be noted that the above description describes some embodiments of this disclosure. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result.

[0154] This disclosure also utilizes ANSYS software to study the factors influencing the collapse of suspended structures; for details of this study, please refer to [link to relevant documentation]. Figures 14A-16C It should be understood that, apart from the variable factor, all other factors are the same. That is to say, if the study is about the effect of the thickness of the comb teeth on the collapse, then the length and number of the comb teeth remain unchanged.

[0155] Specifically, Figures 14A-14C The above are simulation results of the collapse of comb teeth of different thicknesses in this embodiment of the invention. The number of comb teeth is 30, and the length of the comb teeth is 40 μm; wherein, Figure 14A The corresponding thickness is 100nm, with a depression of 2.34μm; Figure 14B The corresponding thickness is 1μm, and the depression is 0.022μm; Figure 14C The corresponding thickness is 2μm, with a collapse of 0.0055μm. This shows that increasing the thickness of the comb teeth, that is, increasing the thickness of the functional layer, can significantly improve the collapse.

[0156] Figures 15A-15D The following are the collapse simulation results for different comb tooth lengths according to the embodiments of this disclosure; wherein, Figure 15A The corresponding length is 40μm, and the depression is 66μm; Figure 15B The corresponding length is 20μm, and the depression is 17.3μm; Figure 15C The corresponding length is 10μm, and the depression is 14.9μm; Figure 15DCorresponding length 5 μm, subsidence 14.6 μm. Thus, reducing the length of the comb teeth can also reduce the subsidence degree, but the dynamic tooth gravity collapse amount is basically at the same level, and the change is small.

[0157] Figures 16A-16C The subsidence simulation results of different comb tooth thicknesses for the embodiments of the present disclosure are shown in Table 1. Figure 16A Corresponding 50, subsidence 66 μm; Figure 16B Corresponding 30, subsidence 2.34 μm; Figure 16C Corresponding 15, subsidence 0.153 μm. Thus, reducing the number of comb teeth can significantly improve the subsidence amount.

[0158] Through the analysis of the ANSYS software, it is clear that the technical solution of increasing the thickness of the functional layer provided by the embodiments of the present disclosure can significantly improve the subsidence degree of the suspended structure. According to the design requirements of the number and length of the comb teeth, a matching functional layer thickness can be selected, for example, 1 μm, 2 μm, to avoid the subsidence of the suspended structure represented by the dynamic comb teeth.

[0159] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary and is not intended to limit the scope of the present disclosure (including claims) to these examples; under the idea of the present disclosure, the above embodiments or technical features in different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the embodiments of the present disclosure as described above. In order to be brief, they are not provided in detail.

[0160] In addition, in order to simplify the description and discussion, and so as not to make the embodiments of the present disclosure difficult to understand, the known power / ground connections of integrated circuit (IC) chips and other components can or can not be shown in the provided drawings. In addition, the devices can be shown in the form of block diagrams in order to avoid making the embodiments of the present disclosure difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present disclosure are to be implemented (i.e. these details should be fully within the understanding of those skilled in the art). Where specific details (e.g. circuits) are set forth in order to describe an exemplary embodiment of the present disclosure, it will be apparent to those skilled in the art that the present disclosure can be practiced without these specific details or with variations on these specific details. Therefore, these descriptions should be considered illustrative rather than limiting.

[0161] While the present disclosure has been described in connection with certain embodiments thereof, many modifications, substitutions, and variations will be apparent to those of ordinary skill in the art from the foregoing description. For instance, other memory architectures (e.g., dynamic RAM (DRAM)) can use the embodiments discussed.

[0162] Embodiments of the disclosure are intended to cover all such alternatives, modifications, and variations as falling within the broad scope of the appended claims. Accordingly, any one or more of the above-described embodiments can be combined with any one or more of the above-described embodiments in any manner within the scope of the disclosure.

Claims

1. A MEMS device, characterized in that, include: substrate; as well as A functional layer is at least partially suspended on the substrate; wherein the thickness of the functional layer is ≥1 μm and ≤5 μm; The functional layer includes moving comb teeth, fixed comb teeth, and an electroplating auxiliary structure; the electroplating auxiliary structure is used to connect the moving comb teeth and the fixed comb teeth during electroplating, and disconnects from the moving comb teeth and the fixed comb teeth after electroplating.

2. The MEMS device according to claim 1, characterized in that, It also includes a sacrificial layer disposed between the substrate and the functional layer; the suspended structures of the sacrificial layer and the functional layer do not overlap.

3. The MEMS device according to claim 1, characterized in that, The electroplating auxiliary structure includes an electroplating auxiliary electrode and a first electroplating auxiliary line; wherein the first electroplating auxiliary line can be cut to disconnect the electroplating auxiliary electrode from the moving comb teeth and the fixed comb teeth.

4. The MEMS device according to claim 1, characterized in that, The electroplating auxiliary structure includes an electroplating auxiliary first sub-electrode, an electroplating auxiliary second sub-electrode, and a second electroplating auxiliary line connecting the two; wherein the second electroplating auxiliary line can be cut to disconnect the connection between the electroplating auxiliary first sub-electrode and the electroplating auxiliary second sub-electrode.

5. The MEMS device according to claim 1, characterized in that, The functional layer includes a first functional sublayer and a second functional sublayer, as well as a thickened insulating layer located between the two.

6. The MEMS device according to claim 5, characterized in that, The thickened insulating layer includes vias through which the first functional sublayer and the second functional sublayer are connected.

7. The MEMS device according to claim 5, characterized in that, The size of the thickened insulating layer is smaller than the size of the first functional sublayer and the second functional sublayer, so that the first functional sublayer and the second functional sublayer overlap and conduct.

8. The MEMS device according to claim 5, characterized in that, The thickened insulating layer is selected from at least one of photoresist, SiNx, organic resin, and polyimide; and / or The thickened insulating layer and the sacrificial layer are made of different materials.

9. The MEMS device according to claim 5, characterized in that, The thickness of the thickened insulating layer is 0.5~3.0 μm.

10. The MEMS device according to claim 1, characterized in that, The width of the suspended structure of the functional layer is ≤4μm.

11. A method for fabricating a MEMS device, characterized in that, The preparation method includes: Provide a substrate; A sacrificial layer is formed on the substrate; Forming and patterning a functional layer on the sacrificial layer, specifically including: A seed layer is deposited and patterned on the sacrificial layer; wherein the seed layer includes a moving comb tooth region, a fixed comb tooth region, and an electroplating auxiliary structure region; the electroplating auxiliary structure region connects the moving comb tooth region and the fixed comb tooth region; The seed layer is thickened using an electroplating process to form the functional layer; wherein the moving comb tooth area, the fixed comb tooth area, and the electroplating auxiliary structure area respectively form moving comb teeth, fixed comb teeth, and electroplating auxiliary structures; wherein the thickness of the functional layer is ≥1 μm and ≤5 μm; the electroplating auxiliary structure is disconnected from the moving comb teeth and fixed comb teeth after the electroplating process; The sacrificial layer is released to allow the functional layer to form a suspended structure.

12. The preparation method according to claim 11, characterized in that, The step of forming a sacrificial layer on the substrate includes: Coating photoresist onto the substrate; and patterning the photoresist using a first mask to form the sacrificial layer; or Metal Mo is sputtered onto the substrate; and the sacrificial layer is formed by patterning the metal Mo using a photolithography process or a lift-off process.

13. The preparation method according to claim 11, characterized in that, The electroplating auxiliary structure includes an electroplating auxiliary electrode and a first electroplating auxiliary line; The preparation method further includes cutting the first electroplating auxiliary line; or The electroplating auxiliary structure includes an electroplating auxiliary first sub-electrode, an electroplating auxiliary second sub-electrode, and a second electroplating auxiliary line connecting the two. The preparation method further includes cutting the second electroplating auxiliary line.

14. The preparation method according to claim 11, characterized in that, The step of forming and patterning the functional layer on the sacrificial layer specifically includes: A first functional sublayer is deposited and patterned on the sacrificial layer; A thickened insulating layer is deposited on the first functional sublayer; Depositing and patterning a second functional sublayer on the thickened insulating layer; and The thickened insulating layer is patterned by etching.

15. The preparation method according to claim 14, characterized in that, The material of the sacrificial layer is non-metallic; The gas used for dry etching the thickened insulating layer is selected from at least one of sulfur hexafluoride (SF6) and carbon tetrafluoride (CF4); the gas released from the sacrificial layer is oxygen; or The gas used to dry-etch the thickened insulating layer is oxygen; the gas released from the sacrificial layer is selected from at least one of sulfur hexafluoride (SF6) and carbon tetrafluoride (CF4).

16. The preparation method according to claim 14, characterized in that, Also includes: A via is formed on the thickened insulating layer to expose the first functional sublayer, thereby connecting the first functional sublayer and the second functional sublayer.

17. The preparation method according to claim 14, characterized in that, Also includes: The thickened insulating layer is patterned to expose a portion of the first functional sublayer, and the first functional sublayer and the second functional sublayer overlap through the portion of the layer.

18. The preparation method according to claim 11, characterized in that, The material of the functional layer is ITO; The preparation method further includes: Annealing is performed after the functional layer pattern is formed.

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