Suspended micro-nano device and forming method of suspended micro-nano device

Abstract

The invention discloses a suspended micro-nano device and a forming method of the suspended micro-nano device, and the suspended micro-nano device comprises a substrate and a supporting beam. The base is provided with a cavity with an opening in the upper end. The supporting beam is arranged at an opening of the cavity, the supporting beam is suspended relative to the bottom end of the cavity, the supporting beam is provided with a first end part, a second end part and a third end part which are sequentially arranged in the circumferential direction of the supporting beam, the second end part is located between the first end part and the third end part in the first horizontal direction, and the third end part is located between the second end part and the third end part in the second horizontal direction. The first end portion and the third end portion are located on the same side of the second end portion in the vertical direction, and the substrate and the supporting beam are both monocrystalline silicon. According to the suspended micro-nano device, the strength of the supporting beam can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano devices, and in particular to a suspended micro-nano device and a method for forming the suspended micro-nano device. Background Art

[0002] The suspended structures formed based on micro-nano technology have a variety of applications in ultra-sensitive sensing, material property testing, cantilever resonant devices and microfluidics.

[0003] However, the suspended micro-nano structures in the prior art have low strength, which greatly limits their scope of use. Summary of the invention

[0004] The purpose of the present invention is to at least solve the problem of low strength of suspended micro-nano structures in the prior art. This purpose is achieved by:

[0005] The first aspect of the present invention proposes a suspended micro-nano device, comprising a substrate and a support beam. The substrate is provided with a cavity with an upper end opening. The support beam is arranged at the opening of the cavity, and the support beam is suspended relative to the bottom end of the cavity. The support beam has a first end, a second end, and a third end arranged in sequence in the circumferential direction of the support beam, the second end is located between the first end and the third end in the first horizontal direction, and the first end and the third end are located on the same side of the second end in the up-down direction, wherein the substrate and the support beam are both single crystal silicon.

[0006] In the suspended micro-nano device of the present invention, since the second end is located between the first end and the third end in the first horizontal direction, the first end and the third end are located on the same side of the second end in the vertical direction. The first end, the second end and the third end can disperse the external force, so that the support beam can avoid excessive local force, thereby improving the structural strength of the support beam. In addition, the support beam is single crystal silicon, which can further increase the structural strength of the support beam, and the substrate and the support beam are both single crystal silicon, which can reduce the difficulty of manufacturing the suspended micro-nano device of the embodiment of the present invention.

[0007] According to some embodiments of the present invention, a first end surface is defined between the first end and the third end, the first end surface is parallel to the upper surface of the substrate, and the first end and the third end are both located above the second end.

[0008] According to some embodiments of the present invention, a second end face is defined between the first end and the second end, a third end face is defined between the second end and the third end, and the second end face and the third end face are both arranged at an angle to the first end face.

[0009] According to some embodiments of the present invention, the support beam is provided with a trough body with an open upper end, the trough body having a first wall and a second wall connected to each other, the first wall is parallel to the second end surface, and the second wall is parallel to the third end surface.

[0010] According to some embodiments of the present invention, the support beam includes a first support portion, a second support portion and a suspended island, the first support portion and the second support portion both extend along a second horizontal direction, the first support portion and the second support portion are both provided with the groove body, the suspended island is located between the first support portion and the second support portion in the second horizontal direction, the first support portion and the second support portion are both connected to the suspended island, the width of the suspended island is greater than or equal to 50 microns, and the length of the suspended island is greater than or equal to 50 microns, wherein the first horizontal direction, the second horizontal direction and the up and down direction are perpendicular to each other.

[0011] According to some embodiments of the present invention, the support beam is further provided with a connecting groove, the upper end of which is connected to the groove body, and the lower end of which passes through the second end portion.

[0012] According to some embodiments of the present invention, the length of the support beam is greater than or equal to 100 micrometers and less than or equal to 3 millimeters; and / or the width of the support beam is greater than or equal to 50 millimeters.

[0013] According to some embodiments of the present invention, the first end surface is provided with a hard mask material layer.

[0014] The second aspect of the present invention proposes a method for forming a suspended micro-nano device, which is applied to the suspended micro-nano device as described in the first aspect above, and the method for forming the suspended micro-nano device includes: forming a hard mask material layer on the upper surface and the lower surface of a single crystal silicon substrate; removing the hard mask material layer in the etching area of ​​the single crystal silicon substrate; performing a preliminary etching on the etching area of ​​the single crystal silicon substrate through an etching process to form an intermediate etching body; adjusting the etching rate according to the anisotropy of the single crystal silicon substrate and further etching the intermediate etching body to form the suspended micro-nano device.

[0015] The method for forming a suspended micro-nano device of the present invention forms a hard mask material layer on the upper surface and the lower surface of the single crystal silicon substrate, and removes the hard mask material layer in the etching area of ​​the single crystal silicon substrate, so that the etching area on the single crystal silicon substrate can be exposed and etched, thereby improving the accuracy of etching. The single crystal silicon substrate is preliminarily etched and further etched according to the anisotropy of the single crystal silicon substrate to form a suspended micro-nano device. The method for forming a suspended micro-nano device of an embodiment of the present invention forms a suspended micro-nano device through the anisotropy of the hard mask material layer and the single crystal silicon, which can reduce the process complexity and can reduce the process cost.

[0016] According to some embodiments of the present invention, removing the hard mask material layer in the etched area of ​​the single crystal silicon substrate includes: forming a photoresist pattern on the hard mask material layer, wherein the photoresist pattern is adapted to the non-etched area; and etching the hard mask material layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. Among them:

[0018] Figure 1 A schematic diagram of a suspended micro-nano device according to an embodiment of the present invention;

[0019] Figure 2 A partial cross-sectional view of a suspended micro-nano device according to an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a suspended micro-nano device according to another embodiment of the present invention;

[0021] Figure 4 for Figure 3 A partial cross-sectional view of a portion of the structure of the suspended micro-nano device;

[0022] Figure 5 for Figure 2 A is an enlarged view of the middle figure;

[0023] Figure 6 A flow chart of a method for forming a suspended micro-nano device according to an embodiment of the present invention;

[0024] Figures 7 to 11 A schematic diagram of a formation process of a suspended micro-nano device according to an embodiment of the present invention;

[0025] Fig.12 FIG. 4 is a schematic diagram of a formation process of a suspended micro-nano device according to another embodiment of the present invention.

[0026] The reference numerals in the accompanying drawings represent the following:

[0027] 100. Suspended micro-nano device;

[0028] 1. base; 11. cavity;

[0029] 2. Support beam; 21. First end; 211. First end surface; 22. Second end; 221. Second end surface; 23. Third end; 231. Third end surface; 24. Slot body; 241. First wall surface; 242. Second wall surface; 25. First support portion; 26. Second support portion; 27. Suspended island; 28. Connecting slot;

[0030] 3. Hard mask material layer;

[0031] 200. Single crystal silicon substrate;

[0032] 300, intermediate etched body; 310, substrate; 311, protrusion; 320, support body; 321, first side surface; 322, second side surface; 323, third side surface;

[0033] a, first horizontal direction; b, up and down direction; c, second horizontal direction. DETAILED DESCRIPTION

[0034] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0035] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0036] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0037] For ease of description, spatial relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is rotated, then the elements described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." can include both above and below orientations.

[0038] In the description of the embodiments of the present invention, the orientations or positional relationships indicated by technical terms such as "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "circumferential", "height direction", "first direction", and "second direction" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed, operated or used in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0039] In the description of the embodiments of the present invention, the orientations or positional relationships indicated by technical terms such as "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "circumferential", "height direction", "first direction", and "second direction" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed, operated or used in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0040] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, they can be fixedly connected, detachably connected, or integrated; they can be mechanically connected, electrically connected, or able to communicate with each other; they can be directly connected, or indirectly connected through an intermediate medium, and they can be internally connected between two elements or an interactive relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the embodiments of the present invention, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship.

[0042] Micro-nano technology is a discipline involving the study of micron and nanoscale structures and devices. Micro-nano technology has shown broad application prospects in many fields. The core of micro-nano technology lies in micro-nano processing technology, which makes it possible to manufacture products with specific functions at the micron or nanometer scale. Micro-nano technology is a rapidly developing field that plays an important role in scientific research and industrial applications.

[0043] The suspended structures formed by micro-nano technology have a variety of applications in ultra-sensitive sensing, material property testing, thermoelectric performance testing, optical sensing, cantilever resonant devices and microfluidics.

[0044] As some examples, in terms of thermoelectric performance testing, micro-nano suspended structures can avoid parasitic heat loss and make measurements more accurate. For example, through a double suspended island structure, a single suspended island structure, or a suspended four-probe structure, the thermal conductivity, electrical conductivity, and Seebeck coefficient of micro-nano materials can be accurately measured. These structures are usually made of materials such as silicon or silicon nitride, and are prepared by micromachining technology. They can be tested in a vacuum or a specific atmosphere to reduce the impact of environmental factors.

[0045] As another example, in the field of optical sensing, the suspended structure of micro-nano optical fibers can achieve efficient light field confinement and transmission, thus playing a role in sensing and optical communications.

[0046] However, the suspended micro-nano structures in the prior art have low strength, which greatly limits their scope of use.

[0047] In order to at least solve the problem of low strength of suspended micro-nano structures in the prior art, an embodiment of the present invention proposes a suspended micro-nano device 100 that can improve the strength of the support beam 2.

[0048] The suspended micro-nano device 100 according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0049] Combination Figure 1 and Figure 2 As shown, the suspended micro-nano device 100 of the embodiment of the present invention comprises a substrate 1 and a support beam 2. The substrate 1 is provided with a cavity 11 with an opening at the upper end; the support beam 2 is arranged at the opening of the cavity 11, and the support beam 2 is suspended relative to the bottom end of the cavity 11. The support beam 2 has a first end 21, a second end 22 and a third end 23 arranged in sequence in the circumferential direction of the support beam, the second end 22 is located between the first end 21 and the third end 23 in the first horizontal direction a, and the first end 21 and the third end 23 are located on the same side of the second end 22 in the up-down direction b, wherein the substrate 1 and the support beam 2 are both single crystal silicon.

[0050] The bottom end of the cavity 11 may or may not have an opening.

[0051] The second end 22 is located between the first end 21 and the third end 23 in the first horizontal direction a, and the first end 21 and the third end 23 are located on the same side of the second end 22 in the up-down direction b. The first end 21, the second end 22, and the third end 23 can disperse the external force, so that the support beam 2 can avoid excessive local force, thereby improving the structural strength of the support beam 2.

[0052] In addition, the support beam 2 is made of single crystal silicon, which can further increase the structural strength of the support beam 2. Moreover, the substrate 1 and the support beam 2 are both made of single crystal silicon, which can reduce the manufacturing difficulty of the suspended micro-nano device 100 of the embodiment of the present invention.

[0053] Combination Figure 1 , Figure 2 and Figure 5As shown, in some embodiments, a first end surface 211 is defined between the first end 21 and the third end 23, and the first end surface 211 is parallel to the upper surface of the substrate 1. In other words, the first end surface 211 and the upper surface of the substrate 1 are both planes or inclined surfaces. The first end 21 and the third end 23 are both located above the second end 22. In other words, the second end 22 is located below the first end 21 and the third end 23.

[0054] By making the first end surface 211 of the support beam 2 parallel to the upper surface of the substrate 1 , the support beam 2 can be easily molded, thereby reducing the process difficulty of the suspended micro-nano device 100 according to the embodiment of the present invention.

[0055] A first end surface 211 is defined between the first end 21 and the third end 23, and both the first end 21 and the third end 23 are located above the second end 22. In other words, the first end surface 211 is the upper surface of the support beam 2. By making the upper surface of the support beam 2 a plane or an inclined surface, the use range of the suspended micro-nano device 100 of the embodiment of the present invention can be increased.

[0056] like Figure 2 As shown, further, the first end surface 211 is flush with the upper surface of the substrate 1 , thereby further reducing the process difficulty of the suspended micro-nano device 100 according to the embodiment of the present invention.

[0057] like Figure 2 As shown, optionally, the first end surface 211 is perpendicular to the up-down direction b. In other words, the first end surface 211 is a plane, thereby further increasing the application range of the suspended micro-nano device 100 of the embodiment of the present invention.

[0058] Combination Figure 2 and Figure 5 As shown, in some embodiments, a second end face 221 is defined between the first end 21 and the second end 22, and a third end face 231 is defined between the second end 22 and the third end 23. Both the second end face 221 and the third end face 231 are arranged at an angle to the first end face 211.

[0059] The second end surface 221 may be an inclined surface, a curved surface or a surface in other forms. The third end surface 231 may be an inclined surface, a curved surface or a surface in other forms.

[0060] It can be understood that since the second end 22 is located between the first end 21 and the third end 23 in the first horizontal direction a, and the first end 21 and the third end 23 are located on the same side of the second end 22 in the up and down direction b, the angles between the first end face 211, the second end face 221 and the third end face 231 are all less than 90°, so as to further increase the structural strength of the support beam 2.

[0061] The first end 21, the second end 22, the third end 23, the first end face 211, the second end face 221 and the third end face 231 can further disperse the external force, further enabling the support beam 2 to avoid excessive local force, thereby further improving the structural strength of the support beam 2.

[0062] like Figure 5 As shown, further, the second end surface 221 and the third end surface 231 are both inclined surfaces, so as to reduce the process difficulty of forming the support beam 2.

[0063] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, in some embodiments, the support beam 2 is provided with a slot body 24 with an upper end opening, the slot body 24 has a first wall surface 241 and a second wall surface 242 connected to each other, the first wall surface 241 is parallel to the second end surface 221, and the second wall surface 242 is parallel to the third end surface 231. In other words, the first wall surface 241, the second wall surface 242, the second end surface 221 and the third end surface 231 are all inclined surfaces.

[0064] Providing the groove body 24 can reduce the cross-sectional area of ​​at least part of the support beam 2 , thereby reducing the heat conduction path and improving the thermoelectric performance of the support beam 2 .

[0065] The first wall surface 241 of the trough body 24 is parallel to the second end surface 221, and the second wall surface 242 of the trough body is parallel to the third end surface 231. Therefore, when subjected to external force, the first wall surface 241 and the second wall surface 242 can disperse the external force, and the support beam 2 avoids excessive local force, thereby effectively improving the structural strength of the support beam 2 and reducing the probability of damage to the trough body 24.

[0066] The first wall 241 of the groove body 24 is parallel to the second end face 221, which can make the thickness between the first wall 241 and the second end face 221 uniform, so that the partial internal stress distribution between the first wall 241 and the second end face 221 on the support beam 2 can be as uniform as possible, thereby further improving the structural strength of the support beam 2.

[0067] The second wall 242 of the groove body 24 is parallel to the third end face 231, which can make the thickness between the second wall 242 and the third end face 231 uniform, so that the partial internal stress distribution between the second wall 242 and the third end face 231 on the support beam 2 can be as uniform as possible, thereby further improving the structural strength of the support beam 2.

[0068] like Figure 2As shown, in some embodiments, the support beam 2 includes a first support portion 25, a second support portion 26 and a suspended island 27, the first support portion 25 and the second support portion 26 both extend along the second horizontal direction c, the first support portion 25 and the second support portion 26 are both provided with a groove body 24, the suspended island 27 is located between the first support portion 25 and the second support portion 26 in the second horizontal direction c, the first support portion 25 and the second support portion 26 are both connected to the suspended island 27, the width of the suspended island 27 is greater than or equal to 50 microns, and the length of the suspended island 27 is greater than or equal to 50 microns, wherein the first horizontal direction a, the second horizontal direction c and the up and down direction b are perpendicular to each other.

[0069] The suspended island 27 plays an important role in the micro-nanoscale thermoelectric performance test. The suspended island 27 can provide an environment that is thermally isolated from the surrounding environment, so that the thermoelectric properties of micro-nano materials can be accurately measured through the suspended island 27, wherein the thermoelectric properties include thermal conductivity, electrical conductivity and Seebeck coefficient. By placing the micro-nano material on the suspended island, the thermal contact with the substrate can be reduced or eliminated, thereby reducing parasitic heat loss and improving the sensitivity and accuracy of the measurement.

[0070] The suspended island 27 can be supported by the first support portion 25 and the second support portion 26, so that the suspended island 27 can be suspended relative to the bottom end of the cavity 11. By providing the first support portion 25 and the second support portion 26 with a groove body 24, the heat conduction path of the first support portion 25 and the second support portion 26 can be reduced, thereby improving the thermoelectric performance of the first support portion 25, the second support portion 26 and the suspended island 27.

[0071] The width of the suspended island 27 is greater than or equal to 50 microns, and the length of the suspended island 27 is greater than or equal to 50 microns, so that the suspended island 27 can provide more space to accurately place the micro-nano material sample, thereby reducing the placement error and improving the accuracy of the thermoelectric performance test. Moreover, the suspended island 27 with the above size can also more effectively isolate the heat conduction between the sample and the substrate, reduce parasitic heat loss, and make the measurement result closer to the actual thermoelectric performance of the material. Moreover, the suspended island 27 with the above size can provide a larger surface area, thereby increasing the stability of the structure and reducing the impact of external factors (such as temperature changes, mechanical vibrations, etc.) on the test results. The suspended island 27 with the above size can provide more fixed points for the micro-nano material sample, which is convenient for the fixation and operation of the sample. The suspended island 27 with the above size can accommodate samples of different sizes, improves the flexibility of measurement, and allows the suspended island 27 to be used for thermoelectric performance tests of micro-nano materials of various sizes.

[0072] Combination Figure 3 and Figure 4As shown, in some embodiments, the support beam 2 is further provided with a connecting groove 28 , the upper end of the connecting groove 28 is communicated with the groove body 24 , and the lower end of the connecting groove 28 passes through the second end portion 22 .

[0073] By providing the connection groove 28 , the cross-sectional area of ​​at least a portion of the support beam 2 can be further reduced, thereby further reducing the heat conduction path, thereby further improving the thermoelectric performance of the support beam 2 .

[0074] In some embodiments, the length of the support beam 2 is greater than or equal to 100 micrometers and less than or equal to 3 millimeters.

[0075] The length of the support beam 2 being greater than or equal to 100 microns can make the force arm of the support beam 2 larger, thereby increasing the stability of the suspended island 27. In addition, the length of the support beam 2 being greater than or equal to 100 microns can reduce displacement caused by external vibration or thermal expansion.

[0076] The support beam 2 having a length less than or equal to 3 mm can have a higher natural frequency, and the suspended island 27 can respond to external stimuli more quickly.

[0077] In some embodiments, the width of the support beam 2 is greater than or equal to 50 mm.

[0078] The width of the support beam 2 being greater than or equal to 50 mm can enable the support beam 2 to have a larger section modulus, thereby increasing the overall stiffness of the suspended island 27 and reducing the probability of bending and deformation of the support beam 2 under external loads.

[0079] Combination Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in some embodiments, the first end surface 211 is provided with a hard mask material layer 3 .

[0080] The hard mask material layer 3 can facilitate the forming of the support beam 2 , thereby reducing the difficulty of the forming process of the support beam 2 .

[0081] In the prior art, a process flow mainly based on SOI substrate and DRIE etching is used to produce silicon-based suspended microstructures.

[0082] SOI (Silicon On Insulator) substrate is a special silicon-based material. SOI substrate consists of three layers: the top silicon film, the middle silicon dioxide insulating layer and the bottom silicon substrate. This structure gives SOI substrate significant advantages in integrated circuit manufacturing, such as reducing parasitic capacitance, increasing integration density, and reducing power consumption.

[0083] Deep reactive ion etching (DRIE) is a dry etching technology used in the manufacture of micro-electromechanical systems (MEMS) and integrated circuits. DRIE technology uses cations and free radicals in plasma to anisotropically etch materials, and can achieve micro-nano structures with high aspect ratios. DRIE technology is very important in the preparation of micro-nano suspended structures because DRIE technology can accurately etch the required structure on the silicon layer of the SOI substrate while maintaining the verticality of the sidewalls.

[0084] However, the production cost of SOI substrates is higher than that of traditional wafers, and the manufacturing process of SOI substrates is relatively complex. DRIE equipment is expensive and difficult to maintain, resulting in complex process flows and high process costs in the prior art.

[0085] In order to at least solve the problems of complicated process flow and high process cost in the prior art, an embodiment of the present invention provides a method for forming a suspended micro-nano device, which can reduce process complexity and process cost.

[0086] The following describes a method for forming a suspended micro-nano device according to an embodiment of the present invention in conjunction with the accompanying drawings.

[0087] like Figure 6 As shown, the method for forming a suspended micro-nano device according to an embodiment of the present invention is applied to the suspended micro-nano device 100 according to the above embodiment. The method for forming a suspended micro-nano device includes:

[0088] S100, forming a hard mask material layer 3 on the upper surface and the lower surface of the single crystal silicon substrate 200;

[0089] S200, removing the hard mask material layer 3 in the etching area of ​​the single crystal silicon substrate 200;

[0090] S300, performing preliminary etching on the etching area of ​​the single crystal silicon substrate 200 through an etching process to form an intermediate etching body 300;

[0091] S400 , adjusting the etching rate according to the anisotropy of the single crystal silicon substrate 200 and further etching the intermediate etched body 300 to form a suspended micro-nano device 100 .

[0092] Combination Figure 7 and Figure 8 As shown, S100 , a hard mask material layer 3 is formed on the upper surface and the lower surface of the single crystal silicon substrate 200 .

[0093] The hard mask material layer 3 can protect the single crystal silicon substrate 200 to prevent the single crystal silicon substrate 200 from being etched. The hard mask material layer 3 can prevent the single crystal silicon substrate 200 from being etched by a solution. For example, the hard mask material layer 3 can be silicon nitride.

[0094] The hard mask material layer 3 can be formed on the surface of the single crystal silicon substrate 200 by chemical vapor deposition, wherein the chemical vapor deposition method can be low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition or other forms of chemical vapor deposition. The hard mask material layer can also be formed by thermal oxidation.

[0095] The upper surface and the lower surface of the single crystal silicon substrate 200 are {100} crystal planes of the single crystal silicon substrate 200 .

[0096] On the {100} crystal plane, atoms have two dangling bonds and a higher surface activity. The {100} crystal plane is the plane with the closest atomic arrangement in silicon, so it usually exhibits a slower etching rate in wet etching.

[0097] Optionally, the thickness of the hard mask material layer 3 is greater than or equal to 100 nanometers and less than or equal to 1 micrometer.

[0098] When the hard mask material layer 3 is greater than 1 micron, the hard mask material layer 3 is too thick, resulting in more material to form the hard mask material layer 3, and it takes longer to form the hard mask material layer 3, resulting in reduced production efficiency. An overly thick hard mask material layer 3 may generate additional stress during the etching process, which may cause deformation or damage to the material.

[0099] When the hard mask material layer 3 is less than 100 nanometers, the hard mask material layer 3 is too thin, and the protection capability of the hard mask material layer 3 to the single crystal silicon substrate 200 is relatively poor.

[0100] like Fig. 9 As shown, S200 , the hard mask material layer 3 in the etched area of ​​the single crystal silicon substrate 200 is removed.

[0101] The etched area refers to the area on the single crystal silicon substrate 200 that needs to be etched by the solution. The hard mask material layer 3 in the etched area of ​​the single crystal silicon substrate 200 is removed so that the etched area on the single crystal silicon substrate 200 can be exposed and etched.

[0102] In some embodiments, S200, removing the hard mask material layer 3 in the etched area of ​​the single crystal silicon substrate 200, comprises:

[0103] forming a photoresist pattern on the hard mask material layer 3, wherein the photoresist pattern is adapted to the non-etched area;

[0104] The hard mask material layer 3 is etched.

[0105] The non-etching area refers to an area on the single crystal silicon substrate 200 that needs to be avoided from being etched by the solution.

[0106] The photoresist can protect the hard mask material layer 3 during the etching process of the hard mask material layer 3, so as to prevent the hard mask material layer 3 protected by the photoresist from being etched. After the photoresist pattern is formed on the hard mask material layer 3, the hard mask material layer 3 is etched to remove the hard mask material layer 3 in the etching area of ​​the single crystal silicon substrate 200, so that the single crystal silicon substrate 200 in the etching area is exposed and can be etched.

[0107] like Fig.10 As shown, S300 , the etching area of ​​the single crystal silicon substrate 200 is preliminarily etched by an etching process to form an intermediate etched body 300 .

[0108] Due to the anisotropy of the single crystal silicon substrate 200, the etching rate of the etching solution on the single crystal silicon substrate 200 is not the same. For example, in the first horizontal direction a and the second horizontal direction c, the etching rate of the etching solution is faster, and in the inclined direction, the etching rate of the etching solution is slower. Therefore, during the etching process of the single crystal silicon substrate 200, more substrate is etched at the upper and lower ends of the single crystal silicon substrate 200, and less substrate is etched in the middle part of the single crystal silicon substrate 200.

[0109] like Fig.10 As shown, specifically, the intermediate etching body 300 includes a base body 310 and a support body 320 connected to each other, the support body 320 is suspended relative to the bottom of the base body 310, and the two sides of the support body 320 are spaced relative to the base body 310. The support body 320 includes a first side surface 321, a second side surface 322 and a support body bottom surface 323, and the first side surface 321 and the second side surface 322 are both arranged at an angle with the support body bottom surface 323, wherein the angle is 54.7°.

[0110] The bottom surface 323 of the support body is a {100} crystal plane, and the first side surface 321 and the second side surface 322 are both {111} crystal planes.

[0111] The {111} crystal plane is the fastest etching plane in silicon because the surface atoms of the {111} crystal plane have only one dangling bond and a lower surface energy, making it easier to remove.

[0112] By preliminarily etching the single crystal silicon substrate 200 , the single crystal silicon substrate 200 can be preliminarily shaped.

[0113] Optionally, the etching solution is a potassium hydroxide solution or a tetramethylammonium solution.

[0114] Specifically, the etching process is a wet etching process.

[0115] Combination Fig.11 and Fig.12As shown, S400 , the etching rate is adjusted according to the anisotropy of the single crystal silicon substrate 200 and the intermediate etched body 300 is further etched to form the suspended micro-nano device 100 .

[0116] The first side surface 321 and the second side surface 322 are both arranged at an angle of 54.7° with the bottom surface 323 of the support body, that is, the bottom end of the support body 320 protrudes from the top end of the support body 320 in the first horizontal direction a.

[0117] The two sides of the support body 320 of the intermediate etched body 300 in the first horizontal direction a are spaced relative to the substrate 310, and the etching solution can etch through the space between the support body 320 and the substrate 310. In the further etching process of the intermediate etched body 300, since the bottom end of the support body 320 protrudes from the top end of the support body 320 in the first horizontal direction a, the etching solution etches the bottom of the support body 320 of the intermediate etched body 300 at a faster speed, so that the support beam 2 can be formed.

[0118] In addition, the substrate 310 has a protruding portion 31 protruding in the first horizontal direction a, and the etching rate of the etching solution on the protruding portion 311 of the substrate 310 is also relatively fast, so that the substrate 310 can be formed.

[0119] The anisotropically regulated etching rate of the single crystal silicon substrate 200 can make the substrate 1 and the support beam 2 more accurately formed.

[0120] The method for forming a suspended micro-nano device according to the embodiment of the present invention forms a hard mask material layer 3 on the upper and lower surfaces of a single crystal silicon substrate 200, and removes the hard mask material layer 3 in the etching area of ​​the single crystal silicon substrate 200, so that the etching area on the single crystal silicon substrate 200 can be exposed and etched, thereby improving the etching accuracy. The single crystal silicon substrate 200 is preliminarily etched and further etched according to the anisotropy of the single crystal silicon substrate 200 to form a suspended micro-nano device 100. The method for forming a suspended micro-nano device according to the embodiment of the present invention forms the suspended micro-nano device 100 through the anisotropy of the hard mask material layer 3 and single crystal silicon, which can reduce the process complexity and process cost.

[0121] like Fig.12 As shown, further, after adjusting the etching rate according to the anisotropy of the single crystal silicon substrate 200 and further etching the intermediate etched body 300 to form the suspended micro-nano device 100 in S400, the method for forming the suspended micro-nano device further includes:

[0122] The support beam 2 is further etched to form a connection groove 28 on the support beam 2 .

[0123] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A suspended micro-nano device, characterized in that: include: A base, wherein the base is provided with a cavity with an upper end opening; A support beam, wherein the support beam is disposed at the opening of the cavity, the support beam is suspended relative to the bottom end of the cavity, the support beam has a first end, a second end and a third end which are sequentially arranged in the circumferential direction of the support beam, the second end is located between the first end and the third end in the first horizontal direction, and the first end and the third end are located on the same side of the second end in the up-down direction, Wherein, the substrate and the support beam are both made of single crystal silicon.

2. The suspended micro-nano device according to claim 1, characterized in that: A first end surface is defined between the first end and the third end. The first end surface is parallel to the upper surface of the base. The first end and the third end are both located above the second end.

3. The suspended micro-nano device according to claim 2, characterized in that: A second end face is defined between the first end and the second end, a third end face is defined between the second end and the third end, and both the second end face and the third end face are arranged at an angle with the first end face.

4. The suspended micro-nano device according to claim 3, characterized in that: The support beam is provided with a groove body with an open upper end, wherein the groove body has a first wall surface and a second wall surface connected to each other, wherein the first wall surface is parallel to the second end surface, and the second wall surface is parallel to the third end surface.

5. The suspended micro-nano device according to claim 4, characterized in that: The support beam comprises a first support portion, a second support portion and a suspended island, the first support portion and the second support portion both extend along a second horizontal direction, the first support portion and the second support portion are both provided with the groove body, the suspended island is located between the first support portion and the second support portion in the second horizontal direction, the first support portion and the second support portion are both connected to the suspended island, the width of the suspended island is greater than or equal to 50 microns, and the length of the suspended island is greater than or equal to 50 microns, The first horizontal direction, the second horizontal direction and the up-down direction are perpendicular to each other.

6. The suspended micro-nano device according to claim 4, characterized in that: The support beam is further provided with a connecting groove, the upper end of which is communicated with the groove body, and the lower end of which passes through the second end portion.

7. The suspended micro-nano device according to any one of claims 1 to 6, characterized in that: The length of the support beam is greater than or equal to 100 micrometers and less than or equal to 3 millimeters; and / or, The width of the support beam is greater than or equal to 50 mm.

8. The suspended micro-nano device according to any one of claims 2 to 6, characterized in that: The first end surface is provided with a hard mask material layer.

9. A method for forming a suspended micro-nano device, applied to the suspended micro-nano device according to any one of claims 1 to 7, characterized in that: The method for forming the suspended micro-nano device comprises: forming a hard mask material layer on the upper surface and the lower surface of the single crystal silicon substrate; removing the hard mask material layer in the etching area of ​​the single crystal silicon substrate; Performing preliminary etching on the etching area of ​​the single crystal silicon substrate by an etching process to form an intermediate etching body; The etching rate is adjusted according to the anisotropy of the single crystal silicon substrate and the intermediate etched body is further etched to form the suspended micro-nano device.

10. The method for forming a suspended micro-nano device according to claim 9, characterized in that: The step of removing the hard mask material layer in the etching area of ​​the single crystal silicon substrate comprises: forming a photoresist pattern on the hard mask material layer, wherein the photoresist pattern is adapted to the non-etching area; The hard mask material layer is etched.

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