Overhanging micro-nano device and method for forming overhanging micro-nano device

Abstract

The application discloses a kind of overhanging micro-nano device and the forming method of overhanging micro-nano device, wherein, overhanging micro-nano device includes substrate and support beam.The substrate is provided with cavity of upper end opening.The support beam is arranged at the opening of the cavity, the support beam is suspended relative to the bottom end of the cavity, the support beam has first end portion, second end portion and third end portion sequentially arranged in the circumferential direction of the support beam, the second end portion is located between the first end portion and the third end portion in the first horizontal direction, and the first end portion and the third end portion are located on the same side of the second end portion in the up-down direction, wherein, the substrate and the support beam are both single crystal silicon.The overhanging micro-nano device of the application can improve the strength of the support beam.

Description

Technical Field

[0001] This invention relates to the field of micro-nano device technology, and in particular to a suspended micro-nano device and a method for forming such a device. Background Technology

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

[0003] However, the low strength of suspended micro- and nanostructures in existing technologies greatly limits their application. Summary of the Invention

[0004] The objective of this invention is to at least address the problem of low strength in suspended micro / nano structures in the prior art. This objective is achieved through the following means:

[0005] A first aspect of the present invention provides a suspended micro / nano device, comprising a substrate and a support beam. The substrate has a cavity with an opening at its upper end. The support beam is disposed at the opening of the cavity, and 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 sequentially in the circumferential direction of the support beam. The second end is located between the first end and the third end in a first horizontal direction. The first end and the third end are located on the same side of the second end in the vertical direction. Both the substrate and the support beam are made of monocrystalline silicon.

[0006] The suspended micro / nano device of the present invention has a second end located between the first and third ends in the first horizontal direction, and the first and third ends located on the same side of the second end in the vertical direction. The first, second, and third ends disperse the external forces acting upon the device, preventing excessive local stress on the support beam and thus improving its structural strength. Furthermore, the support beam is made of monocrystalline silicon, further increasing its structural strength. Moreover, the fact that both the substrate and the support beam are made of monocrystalline silicon reduces the manufacturing difficulty of the suspended micro / nano device according to the embodiments of the present invention.

[0007] According to some embodiments of the present invention, a first end face is defined between the first end and the third end, the first end face being parallel to the upper surface of the substrate, and both the first end and the third end being 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, and a third end face is defined between the second end and the third end, wherein both the second end face and the third end face are disposed at an angle to the first end face.

[0009] According to some embodiments of the present application, the support beam is provided with a groove which is open at the upper end, the groove has a first wall surface and a second wall surface which are connected to each other, the first wall surface is parallel to the second end surface, and the second wall surface is parallel to the third end surface.

[0010] According to some embodiments of the present application, the support beam comprises a first support part, a second support part and a suspended island, the first support part and the second support part each extend along a second horizontal direction, the first support part and the second support part are each provided with the groove, the suspended island is located between the first support part and the second support part in the second horizontal direction, the first support part and the second support part are 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-down direction are perpendicular to each other.

[0011] According to some embodiments of the present application, the support beam is further provided with a connecting groove, the upper end of the connecting groove is in communication with the groove, and the lower end of the connecting groove penetrates through the second end part.

[0012] According to some embodiments of the present application, the length of the support beam is greater than or equal to 100 microns 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 application, the first end surface is provided with a layer of hard mask material.

[0014] A second aspect of the present application provides a forming method of a suspended micro-nano device, applied to the suspended micro-nano device as described in the first aspect above, the forming method of the suspended micro-nano device comprising: forming a layer of hard mask material on the upper surface and the lower surface of a single-crystal silicon substrate; removing the layer of hard mask material 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; 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 forming method of the suspended micro-nano device can expose and etch the etching area on the single-crystal silicon substrate by forming a layer of hard mask material on the upper surface and the lower surface of the single-crystal silicon substrate and removing the layer of hard mask material in the etching area of the single-crystal silicon substrate, thereby improving the accuracy of etching. The preliminary etching and further etching of the single-crystal silicon substrate according to the anisotropy of the single-crystal silicon substrate can form the suspended micro-nano device. The forming method of the suspended micro-nano device according to the embodiments of the present application can reduce the process complexity and the process cost by using the layer of hard mask material and the anisotropy of the single-crystal silicon to form the suspended micro-nano device.

[0016] According to some embodiments of the present application, the removing the hard mask material layer of the etching region 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 region; etching the hard mask material layer. BRIEF DESCRIPTION OF DRAWINGS

[0017] Various other advantages and benefits will become apparent to those of ordinary skill in the art, upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not intended to be limiting of the application. In the drawings, like reference numerals refer to same components throughout the several views, of which:

[0018] Figure 1 A schematic view of a suspended micro / nano device according to an embodiment of the present application;

[0019] Figure 2 A partial sectional view of a part of the structure of the suspended micro / nano device according to an embodiment of the present application;

[0020] Figure 3 A schematic view of a suspended micro / nano device according to another embodiment of the present application;

[0021] Figure 4 A partial sectional view of a part of the structure of the suspended micro / nano device according to another embodiment of the present application; Figure 3

[0022] A partial sectional view of a part of the structure of the suspended micro / nano device according to another embodiment of the present application; Figure 5 Figure 2 A partial sectional view of a part of the structure of the suspended micro / nano device according to another embodiment of the present application;

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

[0024] Figures 7 to 11 A schematic view of a forming process of a suspended micro / nano device according to an embodiment of the present application;

[0025] Figure 12 A schematic view of a forming process of a suspended micro / nano device according to another embodiment of the present application.

[0026] The reference signs in the drawings represent the following items:

[0027] 100, a suspended micro / nano device;

[0028] 1, a substrate; 11, a cavity;

[0029] ​2, support beam; 21, first end portion; 211, first end surface; 22, second end portion; 221, second end surface; 23, third end portion; 231, third end surface; 24, groove body; 241, first wall surface; 242, second wall surface; 25, first support portion; 26, second support portion; 27, overhanging island; 28, connecting groove;

[0030] 3, hard mask material layer;

[0031] 200, single crystal silicon substrate;

[0032] 300, intermediate etching body; 310, base body; 311, protruding portion; 320, support body; 321, first side surface; 322, second side surface; 323, third side surface;

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

[0034] Exemplary embodiments of the present application will be described herein below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it is understood that the present application can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0035] It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order

[0036] Although the terms first, second, third, etc. can be used herein to describe various 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 be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first", "second", and other numerical terms when used herein do not connote an order or sequence unless specifically stated otherwise. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. In the description of the present application, the meaning of "a plurality" is at least two, for example, two, three or more, unless otherwise specifically defined.

[0037] For the convenience of description, spatial relative terms can be used herein to describe the relationship of one element or feature to another element or feature as shown in the drawings, such as "inner", "outer", "inward", "outward", "lower", "below", "upper", "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 figures. For example, if the device in the figures is turned over, an element described as "below" or "beneath" the other element or feature would then be oriented "above" or "over" the other element or feature. Thus, the example term "below" can include both the above and below orientations.

[0038] In the description of the embodiments of the present application, the orientations or positional relationships indicated by the technical terms "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "circumferential", "height direction", "first direction", "second direction", etc. are based on the orientations or positional relationships shown in the 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 device or element referred to must have a particular orientation, be constructed, operated or used in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0039] In the embodiments of the present application, unless specifically defined and limited otherwise, the terms "mount", "connect", "connection", "fix", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, or electrical connection or communication with each other; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] In the embodiments of the present application, the term "and / or" is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0041] Micro-nano technology is a discipline related to the study of micro and nano scale structures and devices. Micro-nano technology has shown wide application prospects in many fields. The core of micro-nano technology is 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 and plays an important role in scientific research and industrial applications.

[0042] The suspended structure formed by micro-nano process has various applications in ultra-sensitive sensing, material property testing, thermoelectric performance testing, optical sensing field, cantilever resonator devices and microfluidics, etc.

[0043] As some examples, in the aspect of thermoelectric performance testing, micro-nano suspended structure can avoid parasitic heat loss, making the measurement more accurate. For example, through double suspended island structure, single suspended island structure or 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, prepared by micro-processing technology, and can be tested in vacuum or specific atmosphere to reduce the influence of environmental factors.

[0044] As some other examples, in the field of optical sensing, the suspended structure of micro-nano optical fiber can realize efficient light field restriction and transmission, thereby playing a role in sensing and optical communication.

[0045] However, the suspended micro-nano structure in the prior art has low strength, which greatly limits its use range.

[0046] In order to at least solve the problem of low strength of the suspended micro-nano structure in the prior art, the embodiments of the present application propose a suspended micro-nano device 100, which can improve the strength of the support beam 2.

[0047] The embodiment of the application will be described below in conjunction with the drawings.

[0048] In conjunction with Figure 1 and Figure 2 shown, the embodiment of the application, the suspended micro-nano device 100, comprises a substrate 1 and a support beam 2. The substrate 1 is provided with a cavity 11 with an open 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, and the support beam 2 has a first end portion 21, a second end portion 22 and a third end portion 23 arranged in the circumferential direction of the support beam in sequence, the second end portion 22 is located between the first end portion 21 and the third end portion 23 in the first horizontal direction a, and the first end portion 21 and the third end portion 23 are located on the same side of the second end portion 22 in the up-down direction b, wherein the substrate 1 and the support beam 2 are both single crystal silicon.

[0049] The bottom end of the cavity 11 can form an opening, or can not form an opening.

[0050] The second end portion 22 is located between the first end portion 21 and the third end portion 23 in the first horizontal direction a, and the first end portion 21 and the third end portion 23 are located on the same side of the second end portion 22 in the up-down direction b. The first end portion 21, the second end portion 22 and the third end portion 23 can disperse the external force acting on them, so that the support beam 2 can avoid local overloading, thereby improving the structural strength of the support beam 2.

[0051] In addition, the support beam 2 is single crystal silicon, which can further increase the structural strength of the support beam 2, and the substrate 1 and the support beam 2 are both single crystal silicon, which can reduce the manufacturing difficulty of the embodiment of the suspended micro-nano device 100.

[0052] In conjunction with Figure 1 , Figure 2 and Figure 5 shown, in some embodiments, a first end surface 211 is defined between the first end portion 21 and the third end portion 23, and the first end surface 211 is parallel to the upper surface of the substrate 1. That is, the first end surface 211 and the upper surface of the substrate 1 are both planar or beveled. The first end portion 21 and the third end portion 23 are both located above the second end portion 22. That is, the second end portion 22 is located below the first end portion 21 and the third end portion 23.

[0053] 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 is easily formed, thereby reducing the process difficulty of the embodiment of the suspended micro-nano device 100.

[0054] The first end face 211 is defined between the first end portion 21 and the third end portion 23, and both the first end portion 21 and the third end portion 23 are above the second end portion 22. That is, the first end face 211 is an upper surface of the support beam 2. By making the upper surface of the support beam 2 a plane or an inclined plane, the use range of the suspended micro-nano device 100 of the embodiment of the present application can be increased.

[0055] As shown in Figure 2 , further, the first end face 211 is flush with the upper surface of the substrate 1, so that the process difficulty of the suspended micro-nano device 100 of the embodiment of the present application can be further reduced.

[0056] As shown in Figure 2 , optionally, the first end face 211 is perpendicular to the up-down direction b. That is, the first end face 211 is a plane, so that the use range of the suspended micro-nano device 100 of the embodiment of the present application can be further increased.

[0057] As shown in Figure 2 and Figure 5 , in some embodiments, a second end face 221 is defined between the first end portion 21 and the second end portion 22, and a third end face 231 is defined between the second end portion 22 and the third end portion 23, and both the second end face 221 and the third end face 231 are arranged at an angle with the first end face 211.

[0058] The second end face 221 can be an inclined plane, a curved surface or other forms of surface. The third end face 231 can be an inclined plane, a curved surface or other forms of surface.

[0059] It can be understood that, since the second end portion 22 is between the first end portion 21 and the third end portion 23 in the first horizontal direction a, and the first end portion 21 and the third end portion 23 are on the same side of the second end portion 22 in the up-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 that the structural strength of the support beam 2 can be further increased.

[0060] The first end portion 21, the second end portion 22, the third end portion 23, the first end face 211, the second end face 221 and the third end face 231 can further disperse the external force acting thereon, so that the support beam 2 can avoid local overloading, and thus the structural strength of the support beam 2 can be further improved.

[0061] As shown in Figure 5 , further, both the second end face 221 and the third end face 231 are inclined planes, so that the process difficulty of forming the support beam 2 can be reduced.

[0062] As shown in Figure 1 , Figure 2 , Figure 3 ,Figure 4 and Figure 5 As shown, in some embodiments, the support beam 2 is provided with a groove 24 with an opening at the top. The groove 24 has a first wall surface 241 and a second wall surface 242 that are 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. That is, 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.

[0063] The groove 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.

[0064] The first wall surface 241 of the tank 24 is parallel to the second end surface 221, and the second wall surface 242 of the tank is parallel to the third end surface 231. Therefore, when subjected to external forces, the first wall surface 241 and the second wall surface 242 can disperse the external force, preventing the support beam 2 from being subjected to excessive local stress, thereby improving the structural strength of the support beam 2 and reducing the probability of damage to the tank 24.

[0065] The first wall surface 241 of the groove 24 is parallel to the second end surface 221, which makes the thickness between the first wall surface 241 and the second end surface 221 uniform. This makes the distribution of internal stress between the first wall surface 241 and the second end surface 221 on the support beam 2 as uniform as possible, thereby further improving the structural strength of the support beam 2.

[0066] The second wall 242 of the groove 24 is parallel to the third end face 231, which makes the thickness between the second wall 242 and the third end face 231 uniform. This makes the distribution of internal stress between the second wall 242 and the third end face 231 on the support beam 2 as uniform as possible, thereby further improving the structural strength of the support beam 2.

[0067] like Figure 2 As shown, in some embodiments, the support beam 2 includes a first support portion 25, a second support portion 26, and a suspended island 27. Both the first support portion 25 and the second support portion 26 extend along a second horizontal direction c. Both the first support portion 25 and the second support portion 26 are provided with a groove 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. Both the first support portion 25 and the second support portion 26 are connected to the suspended island 27. The width of the suspended island 27 is greater than or equal to 50 micrometers, and the length of the suspended island 27 is greater than or equal to 50 micrometers. The first horizontal direction a, the second horizontal direction c, and the vertical direction b are perpendicular to each other.

[0068] Suspended islands 27 play a crucial role in the testing of thermoelectric properties at the micro- and nano-scale. They provide a thermally isolated environment, enabling precise measurement of the thermoelectric properties of micro- and nano-materials, including thermal conductivity, electrical conductivity, and the Seebeck coefficient. By placing the micro- and nano-materials on the suspended islands, thermal contact with the substrate can be reduced or eliminated, thereby minimizing parasitic heat loss and improving the sensitivity and accuracy of the measurements.

[0069] The first support part 25 and the second support part 26 can support the suspended island 27, so that the suspended island 27 can be suspended relative to the bottom of the cavity 11. By providing grooves 24 for both the first support part 25 and the second support part 26, the heat conduction path of the first support part 25 and the second support part 26 can be reduced, thereby improving the thermoelectric performance of the first support part 25, the second support part 26 and the suspended island 27.

[0070] The suspended island 27 has a width and length greater than or equal to 50 micrometers, providing more space for precise placement of micro / nanomaterial samples, thus reducing placement errors and improving the accuracy of thermoelectric performance testing. Furthermore, the suspended island 27 with these dimensions can more effectively isolate heat conduction between the sample and the substrate, reducing parasitic heat loss and making the measurement results closer to the true thermoelectric properties of the material. Moreover, the suspended island 27 with these dimensions provides a larger surface area, increasing structural stability and reducing the influence of external factors (such as temperature changes and mechanical vibrations) on the test results. The suspended island 27 with these dimensions provides more fixing points for micro / nanomaterial samples, facilitating sample fixation and manipulation. The suspended island 27 with these dimensions can accommodate samples of different sizes, improving measurement flexibility and enabling it to be used for thermoelectric performance testing of various micro / nanomaterials of different sizes.

[0071] Combination Figure 3 and Figure 4 As 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 connected to the groove body 24, and the lower end of the connecting groove 28 passes through the second end 22.

[0072] By providing the connecting groove 28, the cross-sectional area of ​​at least part of the support beam 2 can be further reduced, thereby further reducing the heat conduction path and further improving the thermoelectric performance of the support beam 2.

[0073] 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.

[0074] The length of the support beam 2 is greater than or equal to 100 microns, which can make the force arm of the support beam 2 larger, thereby increasing the stability of the overhanging island 27. In addition, the length of the support beam 2 is greater than or equal to 100 microns, which can reduce the displacement caused by external vibration or thermal expansion.

[0075] The length of the support beam 2 is less than or equal to 3 millimeters, which can have a higher natural frequency, and the overhanging island 27 can respond more quickly to external stimuli.

[0076] In some embodiments, the width of the support beam 2 is greater than or equal to 50 millimeters.

[0077] The width of the support beam 2 is greater than or equal to 50 millimeters, which can make the support beam 2 have a larger cross-sectional modulus, thereby increasing the overall stiffness of the overhanging island 27 and reducing the probability of bending and deformation of the support beam 2 under external load.

[0078] In combination with Figure 1 , Figure 2 , Figure 3 and Figure 4 , in some embodiments, the first end surface 211 is provided with a hard mask material layer 3.

[0079] By providing the hard mask material layer 3, the support beam 2 can be easily formed, thereby reducing the process difficulty of forming the support beam 2.

[0080] In the prior art, the SOI substrate and the DRIE etching process are mainly used to produce silicon-based overhanging microstructures.

[0081] The SOI (Silicon On Insulator) substrate is a special silicon-based material, which is composed of three layers: a top silicon film, a middle silicon dioxide insulating layer, and a bottom silicon substrate. This structure makes the SOI substrate have significant advantages in integrated circuit manufacturing, such as reducing parasitic capacitance, increasing integration density, and reducing power consumption.

[0082] Deep reactive ion etching (DRIE) is a dry etching technology used in micro-electro-mechanical systems (MEMS) and integrated circuit manufacturing. DRIE technology uses cations and free radicals in plasma to perform anisotropic etching on materials, which can achieve high-aspect-ratio micro-nano structures. DRIE technology is very important in the preparation of micro-nano overhanging structures, because DRIE technology can accurately etch the required structure on the silicon layer of the SOI substrate while maintaining the verticality of the sidewall.

[0083] However, the production cost of the SOI substrate is higher than that of the traditional wafer, and the manufacturing process of the SOI substrate is relatively complex, and the cost of the DRIE equipment is high, and the maintenance is complex, which leads to a complex process flow and high process cost in the prior art.

[0084] To at least solve the problems of complex process flow and high process cost in the prior art, embodiments of the present application provide a method for forming a suspended micro-nano device, which can reduce process complexity and process cost.

[0085] The method for forming a suspended micro-nano device according to the embodiments of the present application will be described below in combination with the drawings.

[0086] As shown in Figure 6 the method for forming a suspended micro-nano device according to the embodiments of the present application is applied to the suspended micro-nano device 100 according to the above embodiments, and the method for forming a suspended micro-nano device comprises the following steps.

[0087] S100, forming a hard mask material layer 3 on the upper surface and the lower surface of a single crystal silicon substrate 200;

[0088] S200, removing the hard mask material layer 3 of the etching area of the single crystal silicon substrate 200;

[0089] S300, performing preliminary etching on the etching area of the single crystal silicon substrate 200 by an etching process to form an intermediate etching body 300;

[0090] S400, adjusting the etching rate according to the anisotropy of the single crystal silicon substrate 200 and further etching the intermediate etching body 300 to form the suspended micro-nano device 100.

[0091] In combination with Figure 7 and Figure 8 S100, the hard mask material layer 3 is formed on the upper surface and the lower surface of the single crystal silicon substrate 200.

[0092] The hard mask material layer 3 can protect the single crystal silicon substrate 200 to avoid etching of the single crystal silicon substrate 200. The hard mask material layer 3 can avoid solution etching of the etched single crystal silicon substrate 200, for example, the hard mask material layer 3 can be silicon nitride.

[0093] The hard mask material layer 3 can be formed on the surface of the single crystal silicon substrate 200 by a chemical vapor deposition method, 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.

[0094] 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.

[0095] On the {100} crystal plane, the atoms have two dangling bonds, and the surface activity is high. The {100} crystal plane is the closest packed crystal plane in silicon, and therefore usually exhibits a slow etching rate in wet etching.

[0096] 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.

[0097] When the hard mask material layer 3 is larger than 1 micrometer, it becomes too thick, resulting in a larger amount of material being used to form the hard mask material layer 3 and requiring a longer formation time, thus reducing production efficiency. An excessively thick hard mask material layer 3 may also generate additional stress during etching, potentially leading to material deformation or damage.

[0098] When the hard mask material layer 3 is less than 100 nanometers, the hard mask material layer 3 is too thin, and the hard mask material layer 3 has poor protection ability for the single crystal silicon substrate 200.

[0099] like Figure 9 As shown, S200 is a hard mask material layer 3 that removes the etched area of ​​the single-crystal silicon substrate 200.

[0100] 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 of 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.

[0101] In some embodiments, S200, the hard mask material layer 3 for removing the etched area of ​​the single-crystal silicon substrate 200, includes:

[0102] A photoresist pattern is formed on the hard mask material layer 3, wherein the photoresist pattern is adapted to the non-etched area;

[0103] Etching is performed on the hard mask material layer 3.

[0104] The non-etched area refers to the area on the single-crystal silicon substrate 200 that needs to be avoided from being etched by the solution.

[0105] The photoresist protects the hard mask material layer 3 during the etching process, preventing the photoresist-protected hard mask material layer 3 from being etched. After forming a photoresist pattern on the hard mask material layer 3, etching is performed on the hard mask material layer 3 to remove the hard mask material layer 3 in the etched area of ​​the single-crystal silicon substrate 200, thereby exposing the single-crystal silicon substrate 200 in the etched area and making it available for etching.

[0106] like Figure 10 As shown, in S300, the etching area of ​​the single-crystal silicon substrate 200 is initially etched through an etching process to form an intermediate etched body 300.

[0107] 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, in the process of etching the single crystal silicon substrate 200, the upper end and the lower end of the single crystal silicon substrate 200 are etched more, and the middle part of the single crystal silicon substrate 200 is etched less.

[0108] As shown in Figure 10 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 end of the base body 310, and the two sides of the support body 320 are spaced apart 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, the first side surface 321 and the second side surface 322 are both arranged at an angle with the support body bottom surface 323, and the angle is 54.7°.

[0109] The support body bottom surface 323 is a {100} crystal surface, and the first side surface 321 and the second side surface 322 are both {111} crystal surfaces.

[0110] The {111} crystal surface is the fastest etching rate in silicon, because the {111} crystal surface has only one dangling bond, the surface energy is lower, and therefore it is easier to be removed.

[0111] Through the preliminary etching of the single crystal silicon substrate 200, the single crystal silicon substrate 200 can be initially formed.

[0112] Optionally, the etching solution is a potassium hydroxide solution or a tetramethylammonium solution.

[0113] Specifically, the etching process is a wet etching process.

[0114] As shown in Figure 11 and Figure 12 S400, according to the anisotropy of the single crystal silicon substrate 200, the etching rate is adjusted and the intermediate etching body 300 is further etched to form the suspended micro-nano device 100.

[0115] The first side surface 321 and the second side surface 322 are both arranged at an angle of 54.7° with the support body bottom surface 323, 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.

[0116] The support 320 of the intermediate etched body 300 is spaced apart from the substrate 310 on both sides in the first horizontal direction a, allowing the etching solution to etch through the gap between the support 320 and the substrate 310. During further etching of the intermediate etched body 300, because the bottom end of the support 320 protrudes beyond its top end in the first horizontal direction a, the etching solution etches the bottom of the support 320 of the intermediate etched body 300 at a faster rate, thus enabling the support beam 2 to be formed.

[0117] In addition, the substrate 310 has a protrusion 31 protruding in the first horizontal direction a, and the etching solution etches the protrusion 311 of the substrate 310 at a relatively fast rate, thereby enabling the substrate 310 to be formed.

[0118] The anisotropic adjustment of the etching rate of the single-crystal silicon substrate 200 enables higher accuracy in the forming of the substrate 1 and the support beam 2.

[0119] The method for forming a suspended micro / nano device according to an embodiment of the present invention involves forming a hard mask material layer 3 on the upper and lower surfaces of a single-crystal silicon substrate 200, and removing the hard mask material layer 3 from the etchable areas of the single-crystal silicon substrate 200. This exposes the etchable areas on the single-crystal silicon substrate 200 and allows them to be etched, thereby improving etching accuracy. Preliminary and further etching are performed on the single-crystal silicon substrate 200 based on its anisotropy to form the suspended micro / nano device 100. This method for forming a suspended micro / nano device, utilizing the hard mask material layer 3 and the anisotropy of single-crystal silicon to shape the suspended micro / nano device 100, reduces process complexity and costs.

[0120] like Figure 12 As shown, further, after 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 the suspended micro / nano device 100, the method for forming the suspended micro / nano device further includes:

[0121] The support beam 2 is further etched to form a connecting groove 28.

[0122] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A suspended micro- and nanodevice, characterized in that, include: A base, wherein the base has a cavity with an opening at the upper end; A support beam is provided at the opening of the cavity, and 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 sequentially in the circumferential direction. The second end is located between the first end and the third end in a first horizontal direction, and the first end and the third end are located on the same side of the second end in the vertical direction. Both the substrate and the supporting beam are made of monocrystalline silicon. The support beam is provided with a groove with an open top. The support beam includes a first support part, a second support part, and a suspended island. The first support part and the second support part both extend along a second horizontal direction. The first support part and the second support part are both provided with the groove. The suspended island is located between the first support part and the second support part in the second horizontal direction. The first support part and the second support part are both connected to the suspended island. The width of the suspended island is greater than or equal to 50 micrometers, and the length of the suspended island is greater than or equal to 50 micrometers. The first horizontal direction, the second horizontal direction, and the vertical direction are perpendicular to each other. The support beam is also 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. The suspended island provides a thermally isolated environment from the surrounding environment during micro-nano scale thermoelectric performance testing. Both the tank and the connecting groove can reduce the cross-sectional area of ​​at least part of the support beam to improve the thermoelectric performance of the support beam.

2. The levitated micro / nano device of claim 1, wherein A first end face is defined between the first end and the third end, the first end face being parallel to the upper surface of the substrate, and both the first end and the third end being located above the second end.

3. The levitated micro / nano device of claim 2, wherein, A second end face is defined between the first end and the second end, and a third end face is defined between the second end and the third end, with both the second end face and the third end face forming an angle with the first end face.

4. The levitated micro / nano device of claim 3, wherein The tank has a first wall and a second wall that are connected to each other. The first wall is parallel to the second end face, and the second wall is parallel to the third end face.

5. The levitated micro / nano device according to any one of claims 1 to 4, wherein 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.

6. The levitated micro / nano device according to any one of claims 2 to 4, wherein, The first end face is provided with a hard mask material layer.

7. A method for forming a suspended micro-nano device, applied to the suspended micro-nano device of any one of claims 1 to 5, characterized in that, The method for forming the suspended micro / nano device includes: Hard mask material layers are formed on the upper and lower surfaces of a single-crystal silicon substrate; Remove the hard mask material layer from the etched area of ​​the single-crystal silicon substrate; The etching region of the single-crystal silicon substrate is preliminarily etched using an etching process to form an intermediate etched 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.

8. The method of claim 7, wherein The hard mask material layer for removing the etched region of the single-crystal silicon substrate includes: A photoresist pattern is formed on the hard mask material layer, wherein the photoresist pattern is adapted to the non-etched area; The hard mask material layer is etched.

Images