CN116399495A - Variable-rigidity cantilever sensor structure, array and manufacturing method - Google Patents
Variable-rigidity cantilever sensor structure, array and manufacturing method Download PDFInfo
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Abstract
The invention discloses a variable-rigidity cantilever sensor structure, a variable-rigidity cantilever sensor array and a manufacturing method of the variable-rigidity cantilever sensor structure. The variable stiffness cantilever sensor structure comprises a supporting structure and a cantilever structure, wherein the cantilever structure is arranged on the supporting structure, the cantilever structure comprises a sensing part and a transmitting part, the sensing part and the transmitting part are sequentially arranged along the direction away from the supporting structure, the thickness of the sensing part is smaller than that of the transmitting part, and a piezoresistor is arranged on the sensing part. According to the variable-rigidity cantilever sensor structure, the local stress of the area where the piezoresistor is located under the same external force effect is improved through the variable-rigidity structural design, namely the different thicknesses of the transmission part and the sensing part, so that the sensitivity of the cantilever sensor is improved.
Description
Technical Field
The invention relates to the technical field of micro-nano equipment and devices, in particular to a variable-rigidity cantilever sensor structure, a variable-rigidity cantilever sensor array and a manufacturing method of the variable-rigidity cantilever sensor structure.
Background
Cantilever beam sensors are currently widely applied in the directions of environmental monitoring, underwater navigation, micro-force calibration and the like. Ultra-high sensitivity cantilever sensors are considered as an important tool for next generation physical, chemical and biological sensing. In order to develop a sensor with higher sensitivity and threshold detection limit, researchers learn the sensing principle, morphological geometry and design principle of a biological flow sensor in nature, and prepare a cantilever type artificial bionic whisker sensor. However, the current preparation methods of the cantilever bionic whisker sensor mainly focus on technologies such as 3D printing, ink-jet printing and self-adhesion, and the cantilever beams are generally composed of two different materials, so that the combination error between the two materials is large, the uniformity of the sensor is poor, and the large-scale production and further application of the cantilever bionic whisker sensor are limited. Microelectromechanical Systems (MEMS) technology is a traditional sensor technology, and cantilever sensors based on MEMS technology have the advantages of easy integration, easy miniaturization and easy mass production. However, most of the current MEMS bionic whisker sensors based on the bionic principle have complex preparation processes, and innovative process technologies are needed to prepare uniform, integrally formed and high-sensitivity cantilever bionic sensors.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.
Disclosure of Invention
The invention aims to provide a variable-rigidity cantilever sensor structure, a variable-rigidity cantilever sensor array and a manufacturing method of the variable-rigidity cantilever sensor structure, which can realize ultrasensitive sensing.
To achieve the above objective, an embodiment of the present invention provides a variable stiffness cantilever sensor structure, including a support structure and a cantilever structure, where the cantilever structure is disposed on the support structure, the cantilever structure includes a sensing portion and a transmitting portion that are sequentially disposed along a direction away from the support structure, and a thickness of the sensing portion is smaller than a thickness of the transmitting portion, and a varistor is disposed on the sensing portion.
In one or more embodiments of the present invention, the sensing part has a first surface parallel to the extension direction of the cantilever structure, and the varistor is disposed on the first surface; the transfer part is provided with a second surface parallel to the extending direction of the cantilever beam structure; the first surface is disposed parallel to the second surface.
In one or more embodiments of the invention, the support structure has a third surface parallel to the direction of extension of the cantilever structure, the third surface lying in the same plane as the first surface; and a metal lead is arranged on the third surface and is connected with the piezoresistor.
In one or more embodiments of the present invention, a ratio of a thickness of the sensing part to a thickness of the transmitting part is greater than or equal to 1/3 and less than 1, and preferably, a ratio of a thickness of the sensing part to a thickness of the transmitting part is 1/2.
In one or more embodiments of the invention, the aspect ratio of the transfer portion is 200-800.
In one or more embodiments of the invention, the aspect ratio of the transfer portion is 400-600.
In one or more embodiments of the invention, the support structure, the sensing portion of the cantilever structure, and the transfer portion of the cantilever structure are integrally formed.
The embodiment of the invention provides a variable-rigidity cantilever sensor array, which comprises a supporting structure and a plurality of groups of cantilever structures, wherein the groups of cantilever structures are arranged on the supporting structure in an arrayed manner, each group of cantilever structures comprises an induction part and a transmission part which are sequentially arranged along the direction far away from the supporting structure, the thickness of the induction part is smaller than that of the transmission part, and a piezoresistor is arranged on the induction part; wherein, there is at least one group of the cantilever structures, and the length-diameter ratio of the transfer part is different from that of other cantilever structures.
In one or more embodiments of the present invention, the length-diameter ratio of the plurality of groups of the cantilever structure transfer portions is different.
In one or more embodiments of the present invention, the sensing part has a first surface parallel to the extension direction of the cantilever structure, and the varistor is disposed on the first surface; the transfer part is provided with a second surface parallel to the extending direction of the cantilever beam structure; the support structure is provided with a third surface parallel to the extending direction of the cantilever structure, and a metal lead is arranged on the third surface and connected with the piezoresistor; the third surface and the first surface are positioned in the same plane, and the second surface is arranged in parallel with the first surface.
In one or more embodiments of the present invention, the support structure, the sensing portions of the plurality of sets of cantilever structures, and the transmitting portion are integrally formed.
The embodiment of the invention also provides a manufacturing method of the variable-rigidity cantilever sensor structure, which comprises the following steps: providing a wafer, wherein the wafer is provided with a first surface and a second surface which are oppositely arranged; forming a cantilever structure of the variable stiffness cantilever sensor structure on a first surface of a wafer; etching the sensing part of the cantilever structure from the second surface of the wafer to make the thickness of the sensing part smaller than that of the transmitting part; and a piezoresistor is arranged at the sensing part from the first surface of the wafer.
In one or more embodiments of the present invention, the step of etching the sensing portion of the cantilever structure from the second surface of the wafer includes: providing a die assembly, wherein the die assembly comprises a first die body and a second die body, and a slotted hole is formed in the second die body in a penetrating manner; placing a wafer between the first die body and the second die body and limiting, wherein the first surface of the wafer is attached to the first die body, and a slotted hole of the second die body exposes the sensing part of the cantilever structure; and etching the sensing part of the cantilever structure through the slotted hole.
In one or more embodiments of the present invention, there is provided a mold assembly comprising: providing a first die body, wherein a first limiting part for limiting a wafer is formed on the first die body, and a second limiting part for limiting the second die body is formed on the first die body; providing a second die body, wherein a protection part arranged in a protruding way is formed on the second die body, and the protruding height of the protection part is smaller than or equal to the thickness difference of the wafer and the cantilever structure; and the limiting piece is matched with the second limiting part to relatively limit the first die body and the second die body.
In one or more embodiments of the invention, the bump height of the guard is less than about 50-100 microns of the thickness difference between the wafer and the cantilever structure.
In one or more embodiments of the present invention, placing and spacing a wafer between the first mold body and the second mold body includes: attaching the first surface of the wafer to the first die body, and limiting through the first limiting part; placing a second die body on the wafer, wherein the protection part is arranged corresponding to the transmission part of the cantilever structure, and the slotted hole is arranged corresponding to the sensing part of the cantilever structure; the limiting piece is matched with the second limiting part to limit the first die body and the second die body.
In one or more embodiments of the present invention, the second mold body has the same shape as the wafer, and the second mold body has the same size as the wafer.
In one or more embodiments of the present invention, the first limiting portion may be a limiting post protruding from the surface of the first die body or a limiting groove formed on the surface of the first die body, the second limiting portion may be a limiting hole arranged in a circular shape, a radius of a circle where the limiting hole is located is equal to a radius of the wafer, and the limiting member may be a pin or a buckle.
Compared with the prior art, according to the variable stiffness cantilever sensor structure, the variable stiffness structural design, the different thicknesses of the transmission part and the sensing part are adopted, so that the local stress of the area where the piezoresistor is located under the same external force effect is improved, and the sensitivity of the cantilever sensor is improved.
The variable-rigidity cantilever sensor structure is provided based on a bionic principle, and the novel variable-rigidity piezoresistive bionic cantilever sensor based on the MEMS technology realizes ultrasensitive sensing.
According to the variable stiffness cantilever sensor array provided by the embodiment of the invention, a plurality of cantilever array structures are designed, and the detection limit and sensitivity of the variable stiffness cantilever sensor array are increased and the performance of the sensor is improved through integrating the cantilever structures with different length-diameter ratios of the transmission part.
According to the manufacturing method of the variable-rigidity cantilever sensor structure, provided by the embodiment of the invention, the process expansion of carrying out local etching on the back part (the surface corresponding to the first surface of the sensing part) of the cantilever structure is completed through the MEMS (micro electro mechanical system) process technology of the hard mask, so that the piezoresistor can be prepared in batches while being uniform.
According to the manufacturing method of the variable-rigidity cantilever sensor structure, disclosed by the embodiment of the invention, the mass production is easy, the flow sheet yield is improved, and the process steps are simplified through a specific die assembly.
Drawings
FIG. 1 is a schematic structural view of a variable stiffness cantilever sensor structure according to one embodiment of the present invention;
FIG. 2 is a flow chart of a method of fabricating a variable stiffness cantilever sensor structure according to one embodiment of the present invention;
fig. 3-6 are schematic structural diagrams illustrating steps of a method for fabricating a variable stiffness cantilever sensor structure according to an embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or components.
As described in the background art, the cantilever sensor has wide application in the directions of environmental monitoring, underwater navigation, micro force calibration and the like, and the ultra-high sensitivity cantilever sensor is regarded as an important tool for next generation physical, chemical and biological sensing. The cantilever beam sensor has very important application in micro-force detection, density detection and other aspects. The current effective method for improving the sensitivity of the cantilever beam sensor is based on a bionic principle and design, however, most cantilever type bionic whisker sensors are prepared based on 3D printing, self-pasting and other technologies, are not easy to prepare in batches, are difficult to ensure uniformity for different batches of devices, and are not easy to integrate. The mass production of integrated hypersensitive cantilever sensors using simple methods remains a significant challenge. Meanwhile, the current variable-rigidity cantilever beam sensor is mostly etched on the upper surface of the cantilever beam (the top surface of the sensor in the use state), the surface roughness of the device is increased due to the introduction of the etching process, the resistance value of the piezoresistor is non-uniform, and the performance of the device is affected. With the current increasing demand for sensitivity of cantilever sensors, further development of preparing high-sensitivity MEMS cantilever sensors has become particularly important.
In order to solve the problems, the invention creatively provides a variable-rigidity cantilever sensor structure, a variable-rigidity cantilever sensor array and a manufacturing method of the variable-rigidity cantilever sensor structure, which can ensure that piezoresistors are uniform and simultaneously are prepared in batches, and simultaneously can realize ultrasensitive sensing.
As shown in fig. 1, a variable stiffness cantilever sensor structure according to an embodiment of the present invention includes a support structure 10 and a cantilever structure 20, wherein the cantilever structure 20 is disposed on the support structure 10 by extending outwards from one end of the support structure 10. The cantilever structure 20 comprises a sensing portion 21 and a transmitting portion 22, which are arranged in sequence in a direction away from the support structure 10. The thickness of the sensing part 21 is smaller than that of the transmitting part 22, and the varistor 23 is provided on the sensing part 21.
Illustratively, the support structure 10 and the cantilever structure 20 may be integrally formed. The material of the support structure 10 and the cantilever structure 20 is preferably silicon.
The thickness of the support structure 10 is much greater than the overall thickness of the cantilever structure 20, and the support structure 10 is primarily used to constrain one end of the cantilever structure 20. The support structure 10 has a third surface 101 parallel to the extension direction of the cantilever structure 20, and a metal lead is disposed on the third surface 101.
The sensing portion 21 of the cantilever structure 20 has a first surface 211 parallel to the extension direction of the cantilever structure 20. The piezoresistor 23 is disposed on the first surface 211 and is electrically connected to a metal lead on the third surface 101, and the metal lead is responsible for leading out the signal sensed by the piezoresistor 23 on the sensing portion 21. The first surface 211 of the sensing portion 21 is located in the same plane as the third surface 101 of the support structure 10. The transfer portion 22 of the cantilever structure 20 has a second surface 221 parallel to the extension direction of the cantilever structure 20. The second surface 221 is disposed parallel to both the first surface 211 and the third surface 101 of the support structure 10. Preferably, the second surface 221, the first surface 211 and the third surface 101 of the support structure 10 lie in the same plane. After the first surface 211 of the sensing portion 21 and the second surface 221 of the transmitting portion 22 are on the same plane, the back portion (the other surface opposite to the first surface 211) of the sensing portion 21 may be locally etched by a hard mask-based technique, so as to increase the response of the piezo-resistor 23 under the same displacement deflection of the cantilever structure 20, while maintaining or even improving the stability, uniformity and homogeneity of the piezo-resistor 23 on the first surface 211 of the sensing portion 21.
The sensing portion 21 and the transmitting portion 22 form a cantilever structure 20. The cantilever structure 20 is arranged in a rectangular configuration. The transfer portion 22 has a relatively high aspect ratio (ratio of length to thickness) which may range from 200 to 800, preferably the aspect ratio of the transfer portion 22 ranges from 400 to 600. The transmission portion 22 is used for converting external micro force into deflection change of the sensing portion 21. Further, the aspect ratio of the transfer portion 22 is 500. The sensing portion 21 has a thinner thickness than the transmitting portion 22. Illustratively, the ratio of the thickness of the sensing portion 21 to the thickness of the transmitting portion 22 of the cantilever structure 20 is greater than or equal to 1/3 and less than 1. Preferably, the thickness of the sensing portion 21 is 1/2 of the thickness of the transmitting portion 22. The piezoresistor 23 is designed on the first surface 211 of the sensing part 21 (the same plane as the metal lead on the third surface 101 of the supporting structure 10), and forms a wheatstone bridge for sensing the deflection change of the transmitting part 22 caused by external force deflection.
In this embodiment, four piezoresistors 23 are disposed at the sensing portion 21 to form a wheatstone bridge. In other embodiments, the piezo-resistor 23 may not be arranged in this way, but only two piezo-resistors may be placed on the sensing portion 21. In yet another embodiment, the piezo-resistor 23 may be fabricated by injection on silicon (sensing portion 21), or other materials that sense deflection of the cantilever, such as graphite, may be used.
The variable-rigidity cantilever sensor structure is provided based on a bionic principle, and the novel variable-rigidity piezoresistive bionic cantilever sensor based on the MEMS technology realizes ultrasensitive sensing.
According to the variable stiffness cantilever sensor structure provided by the embodiment of the invention, the local stress of the area where the piezoresistor is located under the same external force effect is improved through the variable stiffness structural design-different thicknesses of the transmission part and the sensing part, so that the sensitivity of the cantilever sensor is improved.
In order to improve the measurement threshold of the variable stiffness cantilever beam sensor structure, a plurality of variable stiffness cantilever beam structure arrays with different sizes can be designed, and the detection limit of the sensor can be increased due to the fact that the response sensitivity and the threshold of each cantilever beam to external force are different due to the fact that the elastic coefficient of each cantilever beam is different.
Therefore, in order to increase the detection limit and sensitivity of the variable stiffness cantilever beam, the invention also provides a variable stiffness cantilever beam sensor array, which comprises a support structure 10 and a plurality of groups of cantilever beam structures 20. The support structure 10 and the plurality of sets of cantilever structures 20 may be integrally formed. The cantilever structures 20 are sequentially arranged on the support structure 10. Each group of cantilever beam structures 20 comprises a sensing part 21 and a transmitting part 22 which are sequentially arranged along the direction far away from the supporting structure 10, the thickness of the sensing part 21 is smaller than that of the transmitting part 22, and piezoresistors 23 are arranged on the sensing part 21. Wherein at least one group of cantilever structures 20 is present, the aspect ratio of the transfer portion 22 of which is different from the aspect ratio of the transfer portion 22 of the other cantilever structures 20.
In an exemplary embodiment, the aspect ratios of the transfer portions 22 of the plurality of sets of cantilever structures 20 are all different. Preferably, four arrays of cantilever structures 20 may be provided, with the aspect ratios of the transfer portions 22 of the four sets of cantilever structures 20 being 200, 400, 600, 800, respectively.
The thickness of the support structure 10 is much greater than the overall thickness of the cantilever structure 20, and the support structure 10 is primarily used to constrain one end of the cantilever structure 20. The support structure 10 has a third surface 101 parallel to the extension direction of the cantilever structure 20, and a metal lead is disposed on the third surface 101.
The sensing portion 21 of the cantilever structure 20 has a first surface 211 parallel to the extension direction of the cantilever structure 20. The piezoresistor 23 is disposed on the first surface 211 and is electrically connected to a metal lead on the third surface 101, and the metal lead is responsible for leading out the signal sensed by the piezoresistor 23 on the sensing portion 21. The first surface 211 of the sensing portion 21 is located in the same plane as the third surface 101 of the support structure 10. The transfer portion 22 of the cantilever structure 20 has a second surface 221 parallel to the extension direction of the cantilever structure 20. The second surface 221 is disposed parallel to both the first surface 211 and the third surface 101 of the support structure 10. Preferably, the second surface 221, the first surface 211 and the third surface 101 of the support structure 10 lie in the same plane. The design allows for localized batch etching of the backside (the other surface opposite the first surface 211) of the sensing portion 21 by a hard mask-based technique, improving the stability, uniformity, and responsiveness of the piezo-resistor 23 on the first surface 211 of the sensing portion 21, and deflection of the transmitting portion 22, while the first surface 211 of the sensing portion 21 and the second surface 221 of the transmitting portion 22 of the multi-set cantilever structure 20 are both coplanar.
The sensing portion 21 and the transmitting portion 22 form a cantilever structure 20. The cantilever structure 20 is arranged in a rectangular configuration. The transfer portion 22 has a relatively high aspect ratio (ratio of length to thickness) which may range from 200 to 800, preferably the aspect ratio of the transfer portion 22 ranges from 400 to 600. The transmission portion 22 is used for converting external micro force into deflection change of the sensing portion 21. The sensing portion 21 has a thinner thickness than the transmitting portion 22. Illustratively, the ratio of the thickness of the sensing portion 21 to the thickness of the transmitting portion 22 of the cantilever structure 20 is greater than or equal to 1/3 and less than 1. Preferably, the thickness of the sensing portion 21 is 1/2 of the thickness of the transmitting portion 22. The piezoresistor 23 is designed on the first surface 211 of the sensing part 21 (the same plane as the metal lead on the third surface 101 of the supporting structure 10), and forms a wheatstone bridge for sensing the deflection change of the transmitting part 22 caused by external force deflection.
According to the variable stiffness cantilever sensor array provided by the embodiment of the invention, a plurality of cantilever array structures are designed, and the detection limit and sensitivity of the variable stiffness cantilever sensor array are increased and the performance of the sensor is improved through integrating the cantilever structures with different length-diameter ratios of the transmission part.
Referring to fig. 2, the embodiment of the invention further provides a method for manufacturing the variable stiffness cantilever sensor structure, which comprises the following steps: s1, providing a wafer; the wafer has a first surface and a second surface disposed opposite to each other. And s2, forming a cantilever beam structure of the variable-rigidity cantilever beam sensor structure on the first surface of the wafer. And s3, etching the sensing part of the cantilever structure from the second surface of the wafer to make the thickness of the sensing part smaller than that of the transmitting part. And s4, arranging piezoresistors at the sensing part from the first surface of the wafer.
Fig. 3 to fig. 5 are schematic structural diagrams illustrating steps of a method for manufacturing a variable stiffness cantilever sensor structure according to an embodiment of the present invention. The method for manufacturing the variable stiffness cantilever sensor structure according to the present invention is described in detail below with reference to fig. 3 to 5.
In step s2, forming a cantilever structure of the variable stiffness cantilever sensor structure on a first surface of a wafer, specifically including: referring to fig. 3, a cantilever structure 20 of a variable stiffness cantilever sensor structure is formed and released on a first surface of wafer a. The cantilever structures 20 of the plurality of sets of variable stiffness cantilever sensor structures arranged in a row may be formed at one time on the first surface of the wafer a by etching. The etched region B is preferably a rectangular structure, and the cantilever structure 20 is located within the rectangular structure. When the cantilever structure 20 is released, the arrangement of the entire variable stiffness cantilever sensor structure on wafer a is as shown in fig. 3.
In step s3, etching the sensing portion of the cantilever structure from the second surface of the wafer to make the thickness thereof smaller than the thickness of the transfer portion, specifically including: s301, providing a mold assembly, wherein the mold assembly comprises a first mold body and a second mold body, and a slotted hole is formed on the second mold body in a penetrating manner. And S302, placing the wafer between the first die body and the second die body and limiting, wherein the first surface of the wafer is attached to the first die body, and the slot hole of the second die body exposes the sensing part of the cantilever structure. s303, etching the sensing part of the cantilever beam structure through the slot.
Referring to fig. 4, after the cantilever structure 20 is released, the first surface of the wafer a is attached to the first mold body 31 and placed on the first mold body 31. The first mold body 31 is configured as a wafer-shaped structure, the size of the first mold body 31 is slightly larger than that of the wafer a, and the radius of the first mold body 31 is about 1-2cm larger than that of the wafer a. The first die body 31 has a first stopper 311 for stopping the wafer a. The first die body 31 is formed with a second stopper 312 for being relatively limited with the second die body 32. The first limiting portion 311 may be a limiting post disposed in a protruding manner, and may be rectangular or circular in shape. The second limiting portion 312 may be a limiting hole, such as a drill hole, arranged in a circular shape. The number of the drilling holes can be multiple, and the radius of the circle where the center of the drilling holes is located is equal to the radius of the wafer A. The first limiting portion 311 and the second limiting portion 312 are mainly used for determining the position of the wafer a placed on the first mold body 31. The lateral edge cut on the wafer a (the edge cut is applied to the large-sized wafer) is to be tangent to the first limiting portion 311, and at the same time, the outer diameter of the wafer a is also tangent to the outer diameter of the second limiting portion 312.
The second mold body 32 is then placed over the wafer a, the second mold body 32 being shown in fig. 5. The shape of the second die body 32 is the same as that of the wafer a, and the size of the second die body 32 is the same as that of the wafer a, and the thickness is also equivalent to that of the wafer a, so that the second die body 32 is conveniently determined to be in position and is conveniently fixed. The second mold body 32 is formed with a protection portion 322 disposed in a protruding manner, and the protection portion 322 is preferably rectangular in shape, and has a length equal to the length of the etching area B on the wafer a and a width equal to the length of the transfer portion 22 of the cantilever structure 20. The protrusion height of the protection portion 322 is less than or equal to the thickness difference between the wafer a and the cantilever structure 20. Preferably, the protrusion height of the protecting portion 322 is less than about 50-100 micrometers of the thickness difference between the wafer a and the cantilever structure 20, so that when the second mold body 32 covers the wafer a, the protecting portion 322 can just cover the cantilever structure 20 to limit and protect it. The slot 321 on the second mold body 32 is opened at one side of the protecting portion 322 in the length direction, and is attached to the protecting portion 322. The width of the slot 321 is equal to the length of the sensing portion 21 of the cantilever structure 20, and the length of the slot 321 is equal to the length of the guard portion 322 and also equal to the length of the etched area B on the wafer a. The sum of the widths of the guard portion 322 and the slot 321 is equal to the width of the etching region B on the wafer a.
The second mold body 32 is placed over the wafer a, and the three are fixed by the stopper 33. The limiting member 33 cooperates with the second limiting portion 312 to relatively limit the first mold body 31 and the second mold body 32. The limiting member 33 may be a pin, and the structure shown in fig. 6 is obtained after limiting.
As shown in fig. 6, the second mold body 32 is placed above the wafer a, the protection portion 322 of the second mold body 32 is attached to the wafer a, the second mold body 32 is aligned with the outer contour of the wafer a, each point is tangent, and the three are fixed by pins, so that the subsequent overall etching can be performed. At this time, only the sensing portion 21 of the cantilever structure 20 may be partially etched, and simultaneously the variable stiffness cantilever sensor structure may be mass-fabricated.
The first mold body 31 has two main functions, one of which is to determine the placement position of the wafer a. And the second is to fix wafer a and second die body 32. In this embodiment, the first limiting portion 311 may be a rectangular protrusion, and the limiting member 33 is a pin. Similarly, in other embodiments, the first limiting portion 311 may be provided with a circular protrusion, or a limiting groove formed on the surface of the first mold body 31, where the limiting groove is the same as the outer frame of the wafer a, so as to determine the position of the wafer a. Meanwhile, the limiting member 33 may be replaced by a buckle, so long as the limiting locking of the first mold body 31, the wafer a and the second mold body 32 can be realized.
The second mold body 32 is used to protect the wafer a in a wide range and to partially expose the wafer a for etching process. Similarly, the material of the second mold body 32 is not limited, and the second mold body 32 may be silicon-based or glass-based. Meanwhile, the dimensions of the second die body 32 include, but are not limited to, the same size as the wafer a, and similarly, other sizes may be designed, so that the position fixing on the first die body 31 is convenient.
According to the manufacturing method of the variable-rigidity cantilever sensor structure, provided by the embodiment of the invention, the process expansion of carrying out local etching on the back part (the surface corresponding to the first surface of the sensing part) of the cantilever structure is completed through the MEMS (micro electro mechanical system) process technology of the hard mask, so that the piezoresistor can be prepared in batches while being uniform.
According to the manufacturing method of the variable-rigidity cantilever sensor structure, disclosed by the embodiment of the invention, the mass production is easy, the flow sheet yield is improved, and the process steps are simplified through a specific die assembly.
The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (13)
1. A variable stiffness cantilever sensor structure, comprising:
a support structure;
the cantilever beam structure is arranged on the supporting structure, the cantilever beam structure comprises an induction part and a transmission part, the induction part and the transmission part are sequentially arranged along the direction away from the supporting structure, the thickness of the induction part is smaller than that of the transmission part, and a piezoresistor is arranged on the induction part.
2. The variable stiffness cantilever sensor structure according to claim 1, wherein the sensing portion has a first surface parallel to the direction in which the cantilever structure extends, the varistor being disposed on the first surface;
the transfer part is provided with a second surface parallel to the extending direction of the cantilever beam structure;
the first surface is disposed parallel to the second surface.
3. The variable stiffness cantilever sensor structure of claim 2, wherein the support structure has a third surface parallel to the direction of extension of the cantilever structure, the third surface being in the same plane as the first surface;
and a metal lead is arranged on the third surface and is connected with the piezoresistor.
4. The variable stiffness cantilever sensor structure according to claim 1, wherein the ratio of the thickness of the sensing portion to the thickness of the transfer portion is greater than or equal to 1/3 and less than 1.
5. The variable stiffness cantilever sensor structure according to claim 1, wherein the aspect ratio of the transfer portion is 200-800.
6. The variable stiffness cantilever sensor structure according to claim 5, wherein the aspect ratio of the transfer portion is 400-600.
7. A variable stiffness cantilever sensor array, comprising:
a support structure;
the cantilever beam structures are arranged on the supporting structure, each cantilever beam structure comprises an induction part and a transmission part which are sequentially arranged along the direction far away from the supporting structure, the thickness of the induction part is smaller than that of the transmission part, and the induction parts are provided with piezoresistors;
wherein, there is at least one group of the cantilever structures, and the length-diameter ratio of the transfer part is different from that of other cantilever structures.
8. The variable stiffness cantilever sensor array according to claim 7, wherein the aspect ratios of the plurality of sets of cantilever structure transfer portions are all different.
9. The variable stiffness cantilever sensor array according to claim 7, wherein the sensing portion has a first surface parallel to the direction of extension of the cantilever structure, the piezoresistor being disposed on the first surface;
the transfer part is provided with a second surface parallel to the extending direction of the cantilever beam structure;
the support structure is provided with a third surface parallel to the extending direction of the cantilever structure, and a metal lead is arranged on the third surface and connected with the piezoresistor;
the third surface and the first surface are positioned in the same plane, and the second surface is arranged in parallel with the first surface.
10. A method of making a variable stiffness cantilever sensor structure according to any of claims 1 to 6, comprising:
providing a wafer, wherein the wafer is provided with a first surface and a second surface which are oppositely arranged;
forming a cantilever structure of the variable stiffness cantilever sensor structure on a first surface of a wafer;
etching the sensing part of the cantilever structure from the second surface of the wafer to make the thickness of the sensing part smaller than that of the transmitting part;
and a piezoresistor is arranged at the sensing part from the first surface of the wafer.
11. The method of fabricating a variable stiffness cantilever sensor structure according to claim 10, wherein etching the sensing portion of the cantilever structure from the second surface of the wafer comprises:
providing a die assembly, wherein the die assembly comprises a first die body and a second die body, and a slotted hole is formed in the second die body in a penetrating manner;
placing a wafer between the first die body and the second die body and limiting, wherein the first surface of the wafer is attached to the first die body, and a slotted hole of the second die body exposes the sensing part of the cantilever structure;
and etching the sensing part of the cantilever structure through the slotted hole.
12. The method of making a variable stiffness cantilever sensor structure according to claim 11, wherein providing a mold assembly comprises:
providing a first die body, wherein a first limiting part for limiting a wafer is formed on the first die body, and a second limiting part for limiting the second die body is formed on the first die body;
providing a second die body, wherein a protection part arranged in a protruding way is formed on the second die body, and the protruding height of the protection part is smaller than or equal to the thickness difference of the wafer and the cantilever structure;
and the limiting piece is matched with the second limiting part to relatively limit the first die body and the second die body.
13. The method of fabricating a variable stiffness cantilever sensor according to claim 12, wherein positioning and spacing a wafer between the first die body and the second die body comprises:
attaching the first surface of the wafer to the first die body, and limiting through the first limiting part;
placing a second die body on the wafer, wherein the protection part is arranged corresponding to the transmission part of the cantilever structure, and the slotted hole is arranged corresponding to the sensing part of the cantilever structure;
the limiting piece is matched with the second limiting part to limit the first die body and the second die body.
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| CN202310441444.8A CN116399495A (en) | 2023-04-23 | 2023-04-23 | Variable-rigidity cantilever sensor structure, array and manufacturing method |
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| CN202310441444.8A CN116399495A (en) | 2023-04-23 | 2023-04-23 | Variable-rigidity cantilever sensor structure, array and manufacturing method |
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