Piezoresistive chip, preparation method thereof and pressure sensor

Abstract

A piezoresistive chip includes a substrate, resistance leads and lead-out electrodes, the substrate has a support part, the support part includes a first support part and a second support part, the width of the lead-out electrodes is greater than the width of the first support part and less than the width of the second support part, the first support part is provided with only the resistance leads, and the second support part is provided with the lead-out electrodes. By arranging the resistance leads and the lead-out electrodes in different zones, the area occupied by the resistance leads can be reduced, thereby reducing the volume of the piezoresistive chip and the cost of the pressure sensor. The present disclosure also provides a pressure sensor including the piezoresistive chip.

Description

Technical Field

[0001] This disclosure relates to the field of microelectromechanical systems technology, and more specifically, to a piezoresistive chip and its fabrication method, and a pressure sensor. Background Technology

[0002] A pressure sensor is a device that converts pressure signals into electrical signals. The piezoresistive chip is the core component of a pressure sensor, converting the pressure signal of a medium into an electrical signal.

[0003] The main factor limiting the cost of pressure sensors is the cost of the piezoresistive chip, which in turn is limited by its size. Currently, piezoresistive chips are relatively large, leading to higher costs for pressure sensors.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the problem that the relatively large size of piezoresistive chips leads to high costs of pressure sensors, and to provide a piezoresistive chip, its fabrication method, and a pressure sensor.

[0006] According to one aspect of this disclosure, a piezoresistive chip is provided, comprising a substrate, a varistor, resistor leads, and lead-out electrodes. The substrate has a pressure-sensing portion and a support portion, the thickness of the substrate in the pressure-sensing portion being less than the thickness in the support portion. The support portion is disposed around the pressure-sensing portion, forming a pressure-sensing cavity. The varistor is disposed on the side of the pressure-sensing portion away from the pressure-sensing cavity. A varistor is connected to each end of the resistor leads. The lead-out electrodes are connected to the resistor leads. The support portion includes a first support portion and a second support portion, the width of the lead-out electrodes being greater than the width of the first support portion and less than the width of the second support portion. The first support portion only has resistor leads, and the second support portion has lead-out electrodes.

[0007] In one embodiment of this disclosure, the varistor includes a first varistor, a second varistor, a third varistor, and a fourth varistor. The first and third varistors are disposed opposite each other along a first direction, and the second and fourth varistors are disposed opposite each other along a second direction. The resistor lead includes a first resistor lead, a second resistor lead, a third resistor lead, and a fourth resistor lead. The two ends of the first resistor lead are connected to the first and second varistors. The two ends of the second resistor lead are connected to the second and third varistors. The two ends of the third resistor lead are connected to the third varistor and the fourth varistor. The four varistors are connected at both ends of the fourth resistor lead to the first varistor. The lead-out electrodes include a first lead-out electrode, a second lead-out electrode, a third lead-out electrode, and a fourth lead-out electrode. The first lead-out electrode is connected to the first resistor lead, the second lead-out electrode is connected to the second resistor lead, the third lead-out electrode is connected to the third resistor lead, and the fourth lead-out electrode is connected to the fourth resistor lead. The fourth lead-out electrode serves as the positive port of the power signal, the second lead-out electrode serves as the negative port of the power signal, the first lead-out electrode serves as the positive port of the output signal, and the third lead-out electrode serves as the negative port of the output signal.

[0008] In one embodiment of this disclosure, both the first support portion and the second support portion are located between the edge of the pressure-sensitive portion and the edge of the substrate.

[0009] In one embodiment of this disclosure, the pressure-sensing part is rectangular in shape, and the second support part includes two sub-second support parts located on opposite sides of the pressure-sensing part. Two lead-out electrodes are disposed on one sub-second support part, and the other two lead-out electrodes are disposed on the other sub-second support part.

[0010] In one embodiment of this disclosure, each of the four resistor leads includes a first lead segment, a second lead segment, and a third lead segment. The first lead segment and the third lead segment extend along a first direction, and one end of the first lead segment and the third lead segment are respectively connected to two adjacent piezoresists on the outer contour of the pressure sensing part. The second lead segment extends along a second direction, and both ends of the second lead segment are respectively connected to the other ends of the first lead segment and the third lead segment. The first lead segment is disposed on the first support part, and the second lead segment and the third lead segment are disposed on the second support part. The four lead electrodes are respectively connected to the second lead segment of the four resistor leads.

[0011] In one embodiment of this disclosure, the pressure-sensing part is rectangular in shape, the second support part is located on one side of the pressure-sensing part, and the four lead-out electrodes are all disposed on the second support part.

[0012] In one embodiment of this disclosure, the second lead electrode and the third lead electrode are disposed adjacent to each other, the first lead electrode is located on the side of the second lead electrode away from the third lead electrode, the fourth lead electrode is located on the side of the third lead electrode away from the second lead electrode, the first resistance lead includes a first extension segment, the first extension segment is located along a second direction on the side of the second resistance lead away from the pressure-sensing portion, and the first extension segment is connected to the first lead electrode, the fourth resistance lead includes a second extension segment, the second extension segment is located along a second direction on the side of the third resistance lead away from the pressure-sensing portion, and the second extension segment is connected to the fourth lead electrode.

[0013] In one embodiment of this disclosure, the pressure-sensing part is rectangular in shape, and the second support part includes three sub-second support parts. The three sub-second support parts are respectively located between the three sides of the pressure-sensing part and the corresponding three sides of the substrate. Two lead-out electrodes are located in one sub-second support part, and the other two lead-out electrodes are respectively located in the other two sub-second support parts.

[0014] In one embodiment of this disclosure, the pressure-sensing part is polygonal in shape, with notches at the four corners of the polygon. The second support part includes four sub-second support parts, which are respectively disposed in the four notches. Four lead-out electrodes are respectively disposed in the four sub-second support parts.

[0015] In one embodiment of this disclosure, the four resistor leads include a first lead segment and a second lead segment. The first lead segment extends along a first direction, and the second lead segment extends along a second direction. One end of the first lead segment and the second lead segment are connected to the same lead electrode, and the other end is respectively connected to two adjacent piezoresists on the outer contour of the pressure-sensing part.

[0016] In one embodiment of this disclosure, the extension direction of the edge of the pressure-sensing part intersects the extension direction of the edge of the substrate, and the edge of the substrate and the edge of the pressure-sensing part form a support part. The first support part includes four sub-first support parts, and the second support part includes four sub-second support parts. The sub-first support parts and the sub-second support parts are spaced apart, and four lead-out electrodes are disposed on the four sub-second support parts.

[0017] In one embodiment of this disclosure, each of the four resistor leads includes a first lead segment, a second lead segment, and a third lead segment. The first lead segment extends along a first direction, the second lead segment extends along a second direction, and the third lead segment is located on the side of the second lead segment away from the pressure-sensing part. The third lead segment extends in a direction away from the pressure-sensing part, and the four lead electrodes are connected to the third lead segment of each of the four resistor leads.

[0018] In one embodiment of this disclosure, the first support portion is located between the edge of the pressure-sensing portion and the edge of the substrate, the orthographic projection of the second support portion on the substrate is located within the orthographic projection of the pressure-sensing portion on the substrate, and all four lead-out electrodes are disposed on the second support portion.

[0019] In one embodiment of this disclosure, both the pressure-sensing part and the second support part are rectangular in shape, and the center of the orthographic projection of the second support part onto the substrate coincides with the center of the pressure-sensing part.

[0020] In one embodiment of this disclosure, the resistor lead includes a first lead segment, a second lead segment, and a third lead segment. The first lead segment extends along a first direction, the second lead segment extends along a second direction, one end of the first lead segment and the second lead segment are connected, and the other ends of the first lead segment and the second lead segment are respectively connected to two adjacent varistors on the outer contour of the pressure-sensing part. One end of the third lead segment is connected to the connection point of the first lead segment and the second lead segment, the third lead segment extends along the diagonal connection line between the pressure-sensing part and the second support part, and the other end of the third lead segment is connected to the lead-out electrode.

[0021] In one embodiment of this disclosure, the piezoresistive chip further includes a carrier portion disposed at the end of the first support portion away from the piezoresistive resistor, and the carrier portion extends toward the pressure-sensitive portion.

[0022] In one embodiment of this disclosure, the carrier portion and the support portion are made of different materials.

[0023] According to another aspect of this disclosure, a pressure sensor is provided, comprising a piezoresistive chip provided in one aspect of this disclosure.

[0024] The piezoresistive chip disclosed herein includes a substrate, resistor leads, and lead-out electrodes. The substrate has a support portion, which includes a first support portion and a second support portion. The width of the lead-out electrodes is greater than the width of the first support portion but less than the width of the second support portion. The first support portion only houses the resistor leads, while the second support portion houses the lead-out electrodes. By arranging the resistor leads and lead-out electrodes in separate sections, the area occupied by the resistor leads can be reduced, thereby reducing the size of the piezoresistive chip and lowering the cost of the pressure sensor.

[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0027] Figure 1 This is a schematic diagram of the structure of the pressure sensor involved in an embodiment of this disclosure.

[0028] Figure 2 This is a circuit schematic diagram of the Wheatstone bridge involved in the embodiments of this disclosure.

[0029] Figure 3 This is a planar schematic diagram of a piezoresistive chip according to an embodiment of the present disclosure, where the lead electrodes are located on the lines connecting the four corners of the substrate and the four corners of the pressure-sensing part.

[0030] Figure 4 This is a cross-sectional schematic diagram of a piezoresistive chip according to an embodiment of the present disclosure, where the lead electrodes are located on the lines connecting the four corners of the substrate and the four corners of the pressure-sensing part.

[0031] Figure 5 This is a cross-sectional schematic diagram of a piezoresistive chip when the two sub-first support portions are located on opposite sides of the pressure-sensing portion along the second direction.

[0032] Figure 6 A cross-sectional schematic diagram of a piezoresistive chip in this embodiment is provided, wherein two sub-first support portions are located on opposite sides of the pressure-sensing portion along the second direction, and no carrier portion is provided.

[0033] Figure 7 A cross-sectional schematic diagram of a piezoresistive chip is provided in this embodiment, wherein two sub-first support portions are located on opposite sides of the pressure-sensing portion along the second direction, and a carrier portion is provided at the end of the support portion away from the pressure-sensing portion.

[0034] Figure 8 When the second support portion is disposed on the other side of the pressure-sensing portion along the first direction, and all four lead-out electrodes are disposed on the second support portion, this disclosure relates to a planar schematic diagram of a piezoresistive chip.

[0035] Figure 9 When the second support portion is disposed on the other side of the pressure-sensing portion along the first direction, and all four lead-out electrodes are disposed on the second support portion, this disclosure relates to another planar schematic diagram of a piezoresistive chip.

[0036] Figure 10 When the second support portion includes three sub-second support portions, with two lead-out electrodes located in one sub-second support portion and the other two lead-out electrodes located in the other two sub-second support portions respectively, this disclosure relates to a planar schematic diagram of a piezoresistive chip.

[0037] Figure 11 With notches at the four corners of the pressure-sensing part and four sub-secondary supports respectively located at the four notches, this disclosure relates to a planar schematic diagram of a piezoresistive chip.

[0038] Figure 12 With notches at the four corners of the pressure-sensing part and four sub-secondary supports respectively located at the four notches, this disclosure relates to another planar schematic diagram of a piezoresistive chip.

[0039] Figure 13 for Figure 11 A schematic diagram of the BB cross section.

[0040] Figure 14 for Figure 13 A schematic diagram of the CC section.

[0041] Figure 15 This disclosure relates to a planar schematic diagram of a piezoresistive chip when the edge of the pressure-sensing part intersects with the edge of the substrate.

[0042] Figure 16 When the edge of the pressure-sensing part intersects with the edge of the substrate, this disclosure relates to another planar schematic diagram of a piezoresistive chip.

[0043] Figure 17 When the edge of the pressure-sensing part intersects with the edge of the substrate, this embodiment of the disclosure relates to a cross-sectional schematic diagram of a piezoresistive chip along the diagonal of the substrate.

[0044] Figure 18 This disclosure relates to a planar schematic diagram of a piezoresistive chip, wherein the first support portion is located between the edge of the pressure-sensing portion and the edge of the substrate, and the orthogonal projection of the second support portion on the substrate is located within the orthogonal projection of the pressure-sensing portion on the substrate.

[0045] Figure 19 When the first support portion is located between the edge of the pressure-sensing portion and the edge of the substrate, and the orthographic projection of the second support portion on the substrate is located within the orthographic projection of the pressure-sensing portion on the substrate, this disclosure relates to another planar schematic diagram of a piezoresistive chip.

[0046] Figure 20 This is a cross-sectional schematic diagram of a piezoresistive chip, where the first support portion is located between the edge of the pressure-sensing portion and the edge of the substrate, and the orthogonal projection of the second support portion on the substrate is located within the orthogonal projection of the pressure-sensing portion on the substrate.

[0047] Figure 21 This is a cross-sectional schematic diagram of a pressure-sensitive part and a support part formed on a substrate according to an embodiment of the present disclosure.

[0048] Figure 22 A schematic diagram of a cross-section for fabricating a varistor on the side of the substrate away from the pressure-sensing cavity.

[0049] Figure 23 This is a schematic cross-sectional view of a substrate on the side away from the pressure-sensing cavity, according to an embodiment of this disclosure, showing the fabrication of a resistor lead.

[0050] Figure 24 This is a cross-sectional schematic diagram of the carrier portion prepared according to an embodiment of this disclosure.

[0051] Figure 25This is a cross-sectional schematic diagram showing the support portion and the carrier portion of the substrate bonded together by anodizing in an embodiment of this disclosure.

[0052] Figure 26 This is a cross-sectional schematic diagram of a lead electrode fabricated on the side of the resistor lead away from the substrate, according to an embodiment of this disclosure.

[0053] In the diagram: 1-Base, 11-Pressure-sensing part, 111-Notch, 12-Support part, 121-First support part, 1211-Sub-first support part, 122-Second support part, 1221-Sub-second support part, 13-Pressure-sensing cavity, R-Varistor, R1-First varistor, R2-Second varistor, R3-Third varistor, R4-Fourth varistor, 3-Resistor lead, 31-First resistor lead, 32-Second resistor lead, 33-Third resistor lead. 34-Fourth resistor lead, 301-First lead segment, 302-Second lead segment, 303-Third lead segment, 304-First extension segment, 305-Second extension segment, 306-Third extension segment, 307-Fourth extension segment, 4-Lead electrode, 41-First lead electrode, 42-Second lead electrode, 43-Third lead electrode, 44-Fourth lead electrode, 5-Carrier portion, 100-Housing shell, 200-Pierre resistance chip, 300-Adhesive, 400-Circuit board. Detailed Implementation

[0054] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0055] Although relative terms such as "up" and "down" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples shown in the accompanying drawings. It is understood that if the device of the icon is flipped upside down, the component described as "up" will become the component described as "down." When a structure is "up" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0056] The terms “a,” “one,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first,” “second,” and “third,” etc., are used only as markers and are not a limitation on the number of objects.

[0057] A pressure sensor is a device that converts pressure signals into electrical signals. For example... Figure 1 As shown, the pressure sensor includes a housing 100, a piezoresistive chip 200, an adhesive 300, and a circuit board 400. The piezoresistive chip 200 is the core component of the pressure sensor, converting the medium pressure signal into an electrical signal. The adhesive 300 fixes the piezoresistive chip 200 to the circuit board 400 and achieves an airtight seal. The circuit board 400 serves as the signal input and output port of the pressure sensor. The housing 100 covers the outside of the piezoresistive chip 200 and is connected to the circuit board 400, providing physical protection and electromagnetic shielding for the piezoresistive chip 200. The piezoresistive chip 200 is the core component of the pressure sensor, converting the medium pressure signal into an electrical signal. The main factor limiting the cost of the pressure sensor is the cost of the piezoresistive chip 200, and the main factor limiting the cost of the piezoresistive chip 200 is its size.

[0058] like Figure 1 As shown, the piezoresistive chip 200 includes a substrate 1, a piezoresistive resistor R, a resistor lead 3, and a lead-out electrode 4. The substrate 1 has a pressure-sensing portion 11 and a support portion 12. The thickness of the substrate 1 in the pressure-sensing portion 11 is less than the thickness in the support portion 12. The support portion 12 is disposed around the pressure-sensing portion 11, forming a pressure-sensing cavity 13. The piezoresistive resistor R is disposed on the side of the pressure-sensing portion 11 away from the pressure-sensing cavity 13. The support portion 12 is located between the edge of the pressure-sensing portion 11 and the edge of the substrate 1. The resistor lead 3 and the lead-out electrode 4 are disposed in the support portion 12. A resistor lead 3 is connected between every two adjacent piezoresistive resistors R, and each resistor lead 3 has a lead-out electrode 4. The pressure-sensing portion 11 is used to sense the medium pressure and can convert the medium pressure signal into a signal of mechanical deformation of the piezoresistive chip 200. The medium can typically be air. The medium pressure can be transmitted from the pressure-sensing cavity 13 to the pressure-sensing portion 11. When the medium pressure P is greater than one atmosphere, the pressure-sensing portion 11 deforms upward.

[0059] like Figure 2As shown, the varistor R includes a first varistor R1, a second varistor R2, a third varistor R3, and a fourth varistor R4. The first varistor R1 and the third varistor R3 are arranged opposite each other along a first direction, and the second varistor R2 and the fourth varistor R4 are arranged opposite each other along a second direction. The resistor lead 3 includes a first resistor lead 31, a second resistor lead 32, a third resistor lead 33, and a fourth resistor lead 34. The two ends of the first resistor lead 31 are connected to the first varistor R1 and the second varistor R2. The two ends of the second resistor lead 32 are connected to the second varistor R2 and the third varistor R3. The two ends of the third resistor lead 33 are connected to the third varistor R3 and the fourth varistor R4. The two ends of the fourth resistor lead 34 are connected to the fourth varistor R4 and the first varistor R1.

[0060] The lead-out electrode 4 includes a first lead-out electrode 41, a second lead-out electrode 42, a third lead-out electrode 43, and a fourth lead-out electrode 44. The first lead-out electrode 41 is connected to the first resistor lead 31, the second lead-out electrode 42 is connected to the second resistor lead 32, the third lead-out electrode 43 is connected to the third resistor lead 33, and the fourth lead-out electrode 44 is connected to the fourth resistor lead 34. The fourth lead-out electrode 44 serves as the positive port of the power signal, the second lead-out electrode 42 serves as the negative port of the power signal, the first lead-out electrode 41 serves as the positive port of the output signal, and the third lead-out electrode 43 serves as the negative port of the output signal.

[0061] The measurement circuit of the piezoresistive chip 200 is based on the Wheatstone bridge principle. The input voltage of the Wheatstone bridge is Vin = Vin+ - Vin-, and the output voltage of the Wheatstone bridge is Vout = Vout+ - Vout-. The first piezoresistive resistor R1, the second piezoresistive resistor R2, the third piezoresistive resistor R3, and the fourth piezoresistive resistor R4 represent the resistances of the four arms of the Wheatstone bridge. Vout can be expressed by formula (1). The four arm resistances of the Wheatstone bridge are R1 = R2 = R3 = R4 = R. When external pressure is applied to the piezoresistive chip 200, the resistances of the first piezoresistive resistor R1 and the third piezoresistive resistor R3 decrease by ΔR, that is, their resistances become R-ΔR, and the resistances of the first piezoresistive resistor R1 and the fourth piezoresistive resistor R4 increase by ΔR, that is, their resistances become R+ΔR, causing Vout to change. The change in Vout is proportional to the pressure value applied to the piezoresistive chip 200, thereby converting the pressure signal into a voltage signal, which can be expressed by formula (2).

[0062]

[0063] like Figure 3As shown, the shape of the edge contour of the base 1 and the shape of the edge contour of the pressure-sensitive part 11 are both rectangular. The support part 12 is located between the four sides of the pressure-sensitive part 11 and the corresponding sides of the base 1. The first support part 121 includes two sub-first support parts 1211, which are located on opposite sides of the pressure-sensitive part 11 along the first direction. The second support part 122 includes two sub-second support parts 1221, which are located on opposite sides of the pressure-sensitive part 11 along the second direction.

[0064] There are four piezoresistors R, with two R arranged opposite each other along a first direction and the other two R arranged opposite each other along a second direction. The four resistor leads 3 are arranged as rectangular loops with notches, connecting to the piezoresistors R at the notches. The lead-out electrode 4 is located at a corner of the loop segment directly opposite the notch. It can be seen that this requires the widths of both the first sub-support 1211 and the second sub-support 1221 to be greater than the width of the lead-out electrode 4, resulting in a relatively large piezoresistor chip 200 and thus a higher cost for the pressure sensor. It should be noted that the width refers to the dimension of the support 12 along either the first or second direction.

[0065] Taking a 1000μm × 1000μm piezoresistive chip 200 as an example, the piezoresistive chip 200 has dimensions of 1000μm × 1000μm. The area of ​​the support portion 12, where the varistor R is located, is 600μm × 600μm, while the pressure-sensing portion 11 occupies only 36% of the chip area, and the support portion 12 occupies 64% of the chip area. Therefore, the proportion of the chip area occupied by the support portion 12 can be reduced, thereby reducing the volume of the piezoresistive chip 200. See also... Figure 4 The first support part 121 is the connection structure between the piezoresistive chip 200 and the circuit board 400 in the figure. In order to ensure the sealing effect, the width d1 of the first support part 1211 is generally greater than or equal to 200μm.

[0066] Based on this, this disclosure provides a piezoresistive chip 200. For example... Figures 5 to 26 As shown, the piezoresistive chip 200 includes a substrate 1, a piezoresistive resistor R, a resistor lead 3, and a lead-out electrode 4. The substrate 1 has a pressure-sensing portion 11 and a support portion 12. The thickness of the substrate 1 in the pressure-sensing portion 11 is less than the thickness in the support portion 12. The support portion 12 is disposed around the pressure-sensing portion 11, forming a pressure-sensing cavity 13. The piezoresistive resistor R is disposed on the side of the pressure-sensing portion 11 away from the pressure-sensing cavity 13. A piezoresistive resistor R is connected to each end of the resistor lead 3. The lead-out electrode 4 is connected to the resistor lead 3. The support portion 12 includes a first support portion 121 and a second support portion 122. The width of the lead-out electrode 4 is greater than the width of the first support portion 121 and less than the width of the second support portion 122. The first support portion 121 is only provided with the resistor lead 3, and the second support portion 122 is provided with the lead-out electrode 4.

[0067] The substrate 1 has a support portion 12, which includes a first support portion 121 and a second support portion 122. The width of the lead electrode 4 is greater than the width of the first support portion 121 but less than the width of the second support portion 122. The first support portion 121 only has resistor leads 3, while the second support portion 122 has lead electrodes 4. By arranging the resistor leads 3 and lead electrodes 4 in separate sections, the area occupied by the resistor leads 3 can be reduced, thereby reducing the volume of the piezoresistive chip 200 and lowering the cost of the pressure sensor.

[0068] The piezoresistive chip 200 involved in the embodiments of this disclosure will be described in detail below with reference to specific examples.

[0069] like Figure 5 As shown, the base 1 and the pressure-sensing part 11 are both rectangular. The first side of the pressure-sensing part 11 is parallel to the first side of the base 1. The first support part 121 is located between the first side of the pressure-sensing part 11 and the first side of the base 1. The second side of the pressure-sensing part 11 is parallel to the second side of the base 1. The second support part 122 is located between the second side of the pressure-sensing part 11 and the second side of the base 1. The first side of the pressure-sensing part 11 and the first side of the base 1 extend along a first direction. The second side of the pressure-sensing part 11 and the second side of the base 1 extend along a second direction. The second direction is perpendicular to the first direction.

[0070] The support portion 12 is a rectangular ring located between the edge of the base 1 and the edge of the pressure-sensing portion 11. The support portion 12 includes a first support portion 121 and a second support portion 122. The first support portion 121 includes two sub-first support portions 1211, which are located on opposite sides of the pressure-sensing portion 11 along a second direction. The second support portion 122 includes two sub-second support portions 1221, which are located on opposite sides of the pressure-sensing portion 11 along a first direction. The first support portion 121 is provided with only resistance leads 3, and the second support portion 122 is provided with lead-out electrodes 4.

[0071] Each of the first resistor leads 31 includes a first lead segment 301, a second lead segment 302, and a third lead segment 303 connected in sequence. The first lead segment 301 is located on the first support portion 121 and is connected to the first varistor R1. The first lead segment 301 extends along a first direction away from the first varistor R1. The second lead segment 302 extends along a second direction to the second support portion 122. The third lead segment 303 is connected to the end of the second lead segment 302 away from the first lead segment 301 and extends along the first direction to connect with the second varistor R2. The lead electrode 4 is connected to the second lead segment 302. The arrangement of the second resistor lead 32, the third resistor lead 33, and the fourth resistor lead 34 is basically the same as that of the first resistor lead 31, and will not be described in detail here.

[0072] The first support portion 121 has a smaller dimension along the second direction, therefore the dimension of the piezoresistive chip 200 along the second direction also decreases accordingly. Taking a piezoresistive chip 200 with W×L=1000μm×1000μm as an example, the dimension of the piezoresistive chip 200 is reduced from W×L=1000μm×1000μm to W×L=700μm×1000μm, a reduction of 30% in chip size. Figure 6 As shown, when the lead electrode 4 is placed on the two sub-secondary support portions 1221, the width d1 of the first support portion 121 is only 50μm, which is less than 200μm. This may cause the width d1 of the first support portion 121 to be less than 200μm, thereby reducing the sealing effect of the sensor and causing the pressure sensor to fail.

[0073] Therefore, as Figure 7 As shown, the piezoresistive chip 200 also includes a carrier portion 5, which is disposed at the end of the support portion 12 away from the pressure-sensing portion 11, and extends towards the pressure-sensing portion 11. The width d2 of the carrier portion 5 is greater than 200 μm, and in this embodiment, the width of the carrier portion 5 is 300 μm. To ensure sealing while ensuring that the structural strength of the piezoresistive chip 200 meets the usage requirements, the minimum width d1 of the first support portion 121 is set to be greater than or equal to 50 μm, and the minimum width d1 of the first support portion 121 is the minimum dimension along the second direction.

[0074] like Figure 8 and Figure 9 As shown, the base 1 and the pressure-sensing part 11 are both rectangular in shape. The support part 12 is a rectangular ring disposed between the edge of the base 1 and the edge of the pressure-sensing part 11. The first support part 121 includes three sub-first support parts 1211, of which two sub-first support parts 1211 are disposed on opposite sides of the pressure-sensing part 11 along the second direction, and the other sub-first support part 1211 is disposed on one side of the pressure-sensing part 11 along the first direction. The second support part 1221 is disposed on the other side of the pressure-sensing part 11 along the first direction. All four lead-out electrodes 4 are disposed on the second support part 122.

[0075] Four leads 4 are arranged sequentially along the second direction, wherein the second lead 42 and the third lead 43 are arranged adjacent to each other, the first lead 41 is located on the side of the second lead 42 away from the third lead 43, and the fourth lead 44 is located on the side of the third lead 43 away from the second lead 42. The first resistance lead 31 includes a first extension 304, which is located along the second direction on the side of the second resistance lead 32 away from the pressure sensing part 11 and is connected to the first lead 41. The fourth resistance lead 34 includes a second extension 305, which is located along the second direction on the side of the third resistance lead 33 away from the pressure sensing part 11 and is connected to the fourth lead 44. Since the second lead electrode 42 and the third lead electrode 43 are close to the third piezoresistive resistor, the second resistor lead 32 also includes a third extension 306 arranged along the first direction, which is connected to the second lead electrode 42. The third resistor lead 33 also includes a fourth extension 307 arranged along the first direction, which is connected to the third lead electrode 43.

[0076] The piezoresistive chip 200 has a second sub-support portion 1221 on only one side. The width of the first sub-support portion 1211 is half the width of the second sub-support portion 1221. For a piezoresistive chip 200 with W×L=1000μm×1000μm, the size of the piezoresistive chip 200 is reduced from W×L=1000μm×1000μm to W×L=700μm×850μm, a reduction of 41%. To ensure the sealing effect between the piezoresistive chip 200 and the circuit board 400, a carrier portion 5 is also provided at the end of the support portion 12 away from the pressure-sensing portion 11. The carrier portion 5 extends towards the pressure-sensing portion 11.

[0077] like Figure 10 As shown, the second support portion 122 can also be configured to include three sub-second support portions 1221, which are respectively located between the three sides of the pressure-sensing portion 11 and the corresponding three sides of the substrate 1. Two lead-out electrodes 4 are located in one sub-second support portion 1221, and the other two lead-out electrodes 4 are located in the other two sub-second support portions 1221. The size of the piezoresistive chip 200 is reduced from W×L=1000μm×1000μm to W×L=1000μm×850μm, representing a 15% reduction in size.

[0078] like Figures 11 to 14As shown, the pressure-sensing part 11 is polygonal in shape, with notches 111 at each of the four corners. The second support part 122 includes four sub-second support parts 1221, which are respectively located at the four notches 111. The four lead-out electrodes 4 are respectively located at the four sub-second support parts 1221. The sub-second support parts 1221 are located directly below the lead-out electrodes 4 and can support the lead-out electrodes 4 to prevent deformation when subjected to external force. The four resistance leads 3 include a first lead segment 301 and a second lead segment 302. The resistance leads 3 are parallel to the edge of the polygonal pressure-sensing part 11. The first lead segment 301 extends along a first direction, and the second lead segment 302 extends along a second direction. One end of the first lead segment 301 and the second lead segment 302 are connected to the same lead-out electrode 4, and the other end is respectively connected to two adjacent piezoresistors R on the outer contour of the pressure-sensing part 11.

[0079] The edge of the pressure-sensing part 11, excluding the notch, forms four sub-first support parts 1211 with the edge of the substrate 1. Therefore, the area of ​​the pressure-sensing chip can be further reduced. The size of the piezoresistive chip 200 is reduced from W×L=1000μm×1000μm to W×L=700μm×700μm, a reduction of 51%. See also... Figure 7 The width d1 of the first support portion 121 is 50 μm, see [reference]. Figure 13 The width d3 of the second support portion 122 is only 130μm. Therefore, a carrier portion 5 needs to be provided at the end of the first support portion 121 away from the piezoresistor R. The carrier portion 5 extends towards the pressure-sensing portion 11, and its width d2 is greater than 200μm, ensuring the reliability of the seal between the piezoresistive chip 200 and the circuit board 400. The width d1 of the first support portion 121 is the dimension of the first support portion 121 along the second direction. The width d2 of the carrier portion 5 is the dimension of the carrier portion 5 along the second direction, and the width of the second support portion 122 is the dimension of the second support portion 122 along the second direction.

[0080] like Figure 15 and Figure 16 As shown, the extension direction of the edge of the pressure-sensing part 11 intersects the extension direction of the edge of the base 1. The edge of the base 1 and the edge of the pressure-sensing part 11 form a support part 12. The first support part 121 includes four sub-first support parts 1211, and the second support part 122 includes four sub-second support parts 1221. The sub-first support parts 1211 and the sub-second support parts 1221 are spaced apart, and four lead-out electrodes are disposed on the four sub-second support parts 1221.

[0081] Specifically, the corner of the pressure-sensing part 11 is disposed opposite to the edge of the base 1. The edge of the base 1 and the edge of the pressure-sensing part 11 form a support part 12. The support part 12 includes a first support part 121 and a second support part 122. The first support part 121 includes four sub-first support parts 1211. The sub-first support parts 1211 are disposed on the vertical line connecting the corner of the pressure-sensing part 11 and the edge of the base 1. A second support part 1221 is disposed between every two adjacent sub-first support parts 1211. That is, the four sub-first support parts 1211 are located between the four corners of the pressure-sensing part 11 and the four sides of the base 1. The four sub-secondary support parts 12 are the corner areas formed by the two sides where the edge of the pressure-sensing part 11 intersects with the base 1. The four lead-out electrodes 4 are disposed on the four sub-secondary support parts 1221.

[0082] It should be noted that the base 1 is rectangular in shape, and the first support part 1211 can be arranged along the diagonal direction of the base 1.

[0083] Four resistance leads 3 are attached to the outer contour of the pressure sensing part 11. Each of the four resistance leads 3 includes a first lead segment 301 and a second lead segment 302. The first lead segment 301 extends along a first direction, and the second lead segment 302 extends along a second direction. Since the second lead segment 302 is closer to the varistor R, the four resistance leads 3 also include a third lead segment 303. The third lead segment 303 is located on the side of the second lead segment 302 away from the pressure sensing part 11, and extends in a direction away from the pressure sensing part 11. The four lead electrodes 4 are connected to the third lead segment 303 of each of the four resistance leads 3.

[0084] Since the side length of the pressure-sensing part 11 is 600μm, the angle between the edge of the pressure-sensing part 11 and the edge of the substrate 1 can be 45°, and the minimum distance between the edges of the substrate 1 corresponding to the four corners of the pressure-sensing part 11 is 50μm, the side length of the piezoresistive chip 200 can be calculated as W = 600 × √2 + 50 × 2 = 948μm. The size of the piezoresistive chip 200 is reduced from W × L = 1000μm × 1000μm to W × L = 948μm × 948μm, representing a 10% reduction in size.

[0085] like Figure 17As shown, although the width d3 of the second sub-support 1221 is greater than 200 μm, the width d1 of the first sub-support 1211 is only 50 μm. Therefore, a carrier portion 5 needs to be provided at the end of the first support 121 away from the varistor R. The carrier portion 5 extends towards the pressure-sensing portion 11, and the width d3 of the carrier portion 5 is greater than the width of the second sub-support 1221. In this embodiment, the dimension of the carrier portion 5 along the second direction can be 620 μm. The width d1 of the second sub-support 1221 is the dimension of the second sub-support 1221 along the second direction. The width d3 of the carrier portion 5 is the dimension of the carrier portion 5 along the second direction.

[0086] like Figures 18 to 20 As shown, the first support portion 121 is located between the edge of the pressure-sensing portion 11 and the edge of the base 1. The orthographic projection of the second support portion 122 on the base 1 lies within the orthographic projection of the pressure-sensing portion 11 on the base 1. All four lead-out electrodes 4 are disposed on the second support portion 122, which is directly below the lead-out electrodes 4, providing support and preventing deformation of the lead-out electrodes 4 under external force. Both the pressure-sensing portion 11 and the second support portion 122 are rectangular in shape, and the center of the orthographic projection of the second support portion 122 on the base 1 coincides with the center of the pressure-sensing portion 11.

[0087] The resistor lead 3 includes a first lead segment 301, a second lead segment 302, and a third lead segment 303. The first lead segment 301 extends along a first direction, and the second lead segment 302 extends along a second direction. One end of the first lead segment 301 and the second lead segment 302 are connected. The other ends of the first lead segment 301 and the second lead segment 302 are respectively connected to two adjacent piezoresistors R on the outer contour of a pressure sensing part 11. One end of the third lead segment 303 is connected to the connection point of the first lead segment 301 and the second lead segment 302. The third lead segment 303 extends along the diagonal connection line between the pressure sensing part 11 and the second support part 122. The other end of the third lead segment 303 is connected to the lead-out electrode 4.

[0088] The size of the piezoresistive chip 200 was reduced from W×L=1000μm×1000μm to W×L=700μm×700μm, a reduction of 51%. Similarly, a carrier portion 5 is provided at the end of the first support portion 121 away from the piezoresistive resistor R, and the carrier portion 5 extends toward the pressure-sensing portion 11.

[0089] It should be noted that the first direction is the y-direction in the diagram, and the second direction is the x-direction in the diagram.

[0090] The present invention also provides a method for fabricating a piezoresistive chip 200. This method may include:

[0091] In step S10, a pressure-sensitive part 11 and a support part 12 are formed on the substrate 1.

[0092] Step S20: Prepare a varistor R on the side of the substrate 1 away from the pressure-sensing cavity 13.

[0093] Step S30: Prepare a resistor lead 3 on the side of the substrate 1 away from the pressure-sensing cavity 13.

[0094] Step S40: Prepare an electrode 4 on the side of the resistor lead 3 away from the substrate 1.

[0095] Step S10, forming the pressure-sensitive part 11 and the support part 12 on the substrate 1, may include:

[0096] like Figure 21 As shown, N(100) silicon is used as substrate 1, and silicon nitride is grown on both sides of it as a mask layer. After the silicon nitride deposition is completed, the required shape of the pressure-sensing cavity 13 is photolithographically etched on the bottom of substrate 1. The substrate 1 is wet-etched using hot alkaline potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) solution. After etching, the silicon nitride mask layer is removed using hot phosphoric acid solution.

[0097] In step S20, a varistor R is prepared on the side of the substrate 1 away from the pressure-sensing cavity 13.

[0098] like Figure 22 As shown, the required pattern of the varistor R is prepared by photolithography. Ion implantation is performed using photoresist as a mask layer. After implantation, the photoresist is removed, and the implanted substrate 1 is annealed. The sheet resistance of the varistor R after annealing is required to be 100-1000Ω / square.

[0099] In step S30, a resistor lead 3 is prepared on the side of the substrate 1 away from the pressure-sensing cavity 13.

[0100] like Figure 23 As shown, the required pattern for resistor lead 3 is prepared by photolithography. Ion implantation is performed using photoresist as a mask layer. After implantation, the photoresist is removed, and the implanted silicon wafer is annealed. The required resistance of resistor lead 3 after annealing is 20-100Ω / square.

[0101] Between steps S30 and S40, the method may further include step S50, which prepares the carrier portion 5. Step S50 may include:

[0102] like Figure 24 As shown, glass is used as the carrier portion 5, and through holes are fabricated on the carrier portion 5 using photolithography and etching to serve as the air inlet for the piezoresistive chip 200. The diameter of the air inlet is 100 μm. If the air inlet is a square hole, then the side length of the air inlet is 100 μm × 100 μm.

[0103] Between steps S50 and S40, the method may further include step S60, which involves bonding the carrier portion 5 to the support portion 12. Step S60 may include:

[0104] like Figure 25 As shown, the support portion 12 of the substrate 1 and the carrier portion 5 are bonded together by anodic bonding. During the bonding process, the support portion 12 is connected to the positive terminal of the power supply, and the carrier portion 5 is connected to the negative terminal of the power supply. The voltage is 200-1000V, and the temperature is 100-500℃.

[0105] Step S40, which involves fabricating the lead electrode 4 on the side of the resistor lead 3 away from the substrate 1, may include:

[0106] like Figure 26 As shown, an adhesion layer and a lead electrode layer 4 are deposited on the resistor lead 3 using physical vapor deposition (PVD) or chemical vapor deposition (CVD) processes. The adhesion layer is made of titanium or chromium and has a thickness of 20–50 nm. The lead electrode layer 4 is made of aluminum or gold and has a thickness of 0.5–2 μm. After deposition, photolithography is performed to form the required lead electrode 4.

[0107] This disclosure also provides a pressure sensor, which may include the piezoresistive chip 200 mentioned above in this disclosure. The specific structure and beneficial effects of the pressure sensor can be found in the piezoresistive chip 200, whose specific structure and beneficial effects have been described in detail above and will not be repeated here.

[0108] It should be noted that, in addition to the piezoresistive chip 200, the pressure sensor also includes other necessary components and parts, such as the housing 100, the circuit board 400, etc. Those skilled in the art can make corresponding additions according to the specific usage requirements of the display device, which will not be elaborated here.

[0109] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A piezoresistive chip, characterized in that, include: A base having a pressure-sensing part and a support part, wherein the thickness of the base in the pressure-sensing part is less than the thickness in the support part, and the support part is disposed around the pressure-sensing part to form a pressure-sensing cavity; A varistor is disposed on the side of the pressure-sensing part away from the pressure-sensing cavity; A resistor lead, with each end of the resistor lead connected to a varistor; Lead-out electrodes are connected to the resistor leads; The support portion includes a first support portion and a second support portion. The width of the lead-out electrode is greater than the width of the first support portion and less than the width of the second support portion. The first support portion is only provided with the resistor lead, and the second support portion is provided with the lead-out electrode.

2. The piezoresistive chip according to claim 1, characterized in that, The varistor includes a first varistor, a second varistor, a third varistor, and a fourth varistor. The first varistor and the third varistor are arranged opposite each other along a first direction, and the second varistor and the fourth varistor are arranged opposite each other along a second direction. The resistor lead includes a first resistor lead, a second resistor lead, a third resistor lead, and a fourth resistor lead. The two ends of the first resistor lead are connected to the first varistor and the second varistor. The two ends of the second resistor lead are connected to the second varistor and the third varistor. The two ends of the third resistor lead are connected to the third varistor and the fourth varistor. The two ends of the fourth resistor lead are connected to the fourth varistor and the first varistor. The lead-out electrodes include a first lead-out electrode, a second lead-out electrode, a third lead-out electrode, and a fourth lead-out electrode. The first lead-out electrode is connected to the first resistor lead, the second lead-out electrode is connected to the second resistor lead, the third lead-out electrode is connected to the third resistor lead, and the fourth lead-out electrode is connected to the fourth resistor lead. The fourth lead-out electrode serves as a positive power signal port, the second lead-out electrode serves as a negative power signal port, the first lead-out electrode serves as a positive output signal port, and the third lead-out electrode serves as a negative output signal port.

3. The piezoresistive chip according to claim 2, characterized in that, Both the first support portion and the second support portion are located between the edge of the pressure-sensitive portion and the edge of the base.

4. The piezoresistive chip according to claim 3, characterized in that, The pressure-sensing part is rectangular in shape, and the second support part includes two sub-second support parts. The two sub-second support parts are located on opposite sides of the pressure-sensing part, wherein two lead-out electrodes are disposed in one sub-second support part and the other two lead-out electrodes are disposed in the other sub-second support part.

5. The piezoresistive chip according to claim 4, characterized in that, Each of the four resistor leads includes a first lead segment, a second lead segment, and a third lead segment. The first lead segment and the third lead segment extend along the first direction. One end of the first lead segment and the third lead segment are respectively connected to two adjacent varistors on the outer contour of the pressure-sensing part. The second lead segment extends along the second direction. Both ends of the second lead segment are respectively connected to the other ends of the first lead segment and the third lead segment. The first lead segment is located on the first support part, and the second lead segment and the third lead segment are located on the second support part. The four lead-out electrodes are respectively connected to the second lead segment of the four resistor leads.

6. The piezoresistive chip according to claim 3, characterized in that, The pressure-sensing part is rectangular in shape, the second support part is located on one side of the pressure-sensing part, and the four lead-out electrodes are all located on the second support part.

7. The piezoresistive chip according to claim 6, characterized in that, The second lead electrode and the third lead electrode are disposed adjacent to each other. The first lead electrode is located on the side of the second lead electrode away from the third lead electrode. The fourth lead electrode is located on the side of the third lead electrode away from the second lead electrode. The first resistance lead includes a first extension segment, which is located along the second direction on the side of the second resistance lead away from the pressure-sensing part. The first extension segment is connected to the first lead electrode. The fourth resistance lead includes a second extension segment, which is located along the second direction on the side of the third resistance lead away from the pressure-sensing part. The second extension segment is connected to the fourth lead electrode.

8. The piezoresistive chip according to claim 3, characterized in that, The pressure-sensing part is rectangular in shape, and the second support part includes three sub-second support parts. The three sub-second support parts are respectively located between the three sides of the pressure-sensing part and the corresponding three sides of the base. Two of the lead-out electrodes are located in one sub-second support part, and the other two lead-out electrodes are respectively located in the other two sub-second support parts.

9. The piezoresistive chip according to claim 3, characterized in that, The pressure-sensing part is polygonal in shape, with notches at the four corners of the polygon. The second support part includes four sub-second support parts, which are respectively located at the four notches. The four lead-out electrodes are respectively located at the four sub-second support parts.

10. The piezoresistive chip according to claim 9, characterized in that, The four resistor leads include a first lead segment and a second lead segment. The first lead segment extends along the first direction, and the second lead segment extends along the second direction. One end of the first lead segment and the second lead segment are connected to the same lead electrode, and the other end is respectively connected to two adjacent piezoresists on the outer contour of the pressure-sensing part.

11. The piezoresistive chip according to claim 3, characterized in that, The extension direction of the edge of the pressure-sensing part intersects the extension direction of the edge of the substrate. The edge of the substrate and the edge of the pressure-sensing part form the support part. The first support part includes four sub-first support parts, and the second support part includes four sub-second support parts. The sub-first support parts and the sub-second support parts are spaced apart. The four lead-out electrodes are disposed on the four sub-second support parts.

12. The piezoresistive chip according to claim 11, characterized in that, Each of the four resistor leads includes a first lead segment, a second lead segment, and a third lead segment. The first lead segment extends along the first direction, the second lead segment extends along the second direction, and the third lead segment is located on the side of the second lead segment away from the pressure-sensing part. The third lead segment extends in a direction away from the pressure-sensing part, and the four lead electrodes are connected to the third lead segment of each of the four resistor leads.

13. The piezoresistive chip according to claim 2, characterized in that, The first support portion is located between the edge of the pressure-sensing portion and the edge of the substrate, the orthographic projection of the second support portion on the substrate is located within the orthographic projection of the pressure-sensing portion on the substrate, and all four lead-out electrodes are disposed on the second support portion.

14. The piezoresistive chip according to claim 13, characterized in that, Both the pressure-sensing part and the second support part are rectangular in shape, and the center of the orthographic projection of the second support part onto the substrate coincides with the center of the pressure-sensing part.

15. The piezoresistive chip according to claim 13 or 14, characterized in that, The resistor lead includes a first lead segment, a second lead segment, and a third lead segment. The first lead segment extends along a first direction, and the second lead segment extends along a second direction. One end of the first lead segment and the second lead segment are connected. The other ends of the first lead segment and the second lead segment are respectively connected to two adjacent piezoresists on the outer contour of the pressure-sensing part. One end of the third lead segment is connected to the connection point of the first lead segment and the second lead segment. The third lead segment extends along the diagonal connecting line between the pressure-sensing part and the second support part. The other end of the third lead segment is connected to the lead-out electrode.

16. The piezoresistive chip according to claim 1, characterized in that, The piezoresistive chip also includes a carrier portion, which is located at the end of the first support portion away from the piezoresistor, and extends toward the pressure-sensing portion.

17. The piezoresistive chip according to claim 16, characterized in that, The carrier part and the support part are made of different materials.

18. A pressure sensor, characterized in that, Includes the piezoresistive chip according to any one of claims 1 to 17.

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