Preparation method of matrix pressure sensor

Abstract

The present invention provides a method for fabricating a matrix pressure sensor using an integrated circuit (IC) process. The method comprises: providing a first substrate and a second substrate; forming a first bonding medium on the surface of the first substrate; bonding the first substrate to the second substrate via the first bonding medium; forming a hole column on the surface of the second substrate, the hole column penetrating the second substrate and the first bonding medium; depositing an isolation layer on the sidewalls of the hole column; filling the hole column with a strain layer having a thickness greater than that of the first bonding medium; removing the isolation layer and the first bonding medium to form a cavity; and forming a hole plug at the location of the hole column on the second substrate to seal the cavity. The present invention has a reliable and stable manufacturing process, and the sensor array formed on the substrate has a high density, while also reducing the sensor space requirement.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a method for preparing a matrix pressure sensor. Background Art

[0002] Pressure sensors are commonly used in touch screens, robotic perception, medical equipment, and other fields. By arranging multiple pressure sensors in a matrix, pressure changes at multiple points can be detected simultaneously, providing a high-resolution pressure distribution map.

[0003] Current thin-film pressure sensors are manufactured using a printing process, with piercing cold-pressed terminals used for their interfaces. Due to the manufacturing process and interface constraints, multiple pressure sensor chips can only be packaged into a dot matrix on the back end. This results in large sensor space requirements and low dot matrix density, significantly limiting the application of thin-film pressure sensors.

[0004] Therefore, how to increase the density of sensor arrays while reducing sensor space requirements has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] The present invention provides a method for preparing a matrix pressure sensor, which solves the technical problem of how to increase the density of the sensor dot matrix while reducing the space requirement of the sensor.

[0006] According to a first aspect of the present invention, an embodiment of the present invention provides a method for preparing a matrix pressure sensor, comprising:

[0007] Step S1: providing a first substrate and a second substrate;

[0008] Step S2: forming a first bonding medium on the surface of the first substrate;

[0009] Step S3: bonding the first substrate and the second substrate via the first bonding medium;

[0010] Step S4: forming a hole column on the surface of the second substrate, wherein the hole column penetrates the second substrate and the first bonding medium;

[0011] Step S5: depositing an isolation layer on the sidewalls of the pore column;

[0012] Step S6: filling the pore column with a strain layer, wherein the thickness of the strain layer is greater than the thickness of the first bonding medium;

[0013] Step S7: removing the isolation layer and the first bonding medium to form a cavity;

[0014] Step S8: forming a hole plug at the position where the hole column is located in the second substrate to seal the cavity.

[0015] Optionally, step S5 includes:

[0016] Step S51: depositing an isolation material layer on the second substrate, wherein the isolation material layer covers the surface of the pore pillar and other areas of the second substrate;

[0017] Step S52: etching the isolation material layer on the surface of the second substrate and the isolation material layer at the bottom of the hole column to form the isolation layer.

[0018] Optionally, forming the hole plug in step S8 includes:

[0019] Epitaxial growth is performed on the second substrate at the hole column to form a first epitaxial layer, and the hole column is sealed to form a hole plug at the position where the hole column is located on the second substrate.

[0020] Optionally, after step S8, the method further includes:

[0021] The first mask layer is removed.

[0022] Optionally, step S6 includes:

[0023] Epitaxial growth is performed on the first substrate at the bottom of the hole column to form the strained layer.

[0024] Optionally, the material of the strain layer is different from the material of the isolation layer.

[0025] Optionally, the material of the strained layer includes single crystal silicon, silicon germanium and silicon phosphide.

[0026] Optionally, the cross-sectional length of the strain layer is 1 nm to 10 um.

[0027] Optionally, after step S8, the method further includes:

[0028] A first metal plate and a second metal plate are deposited on the first substrate and the second substrate respectively, wherein the first metal plate corresponds to the upper surface of the cavity, and the second metal plate corresponds to the lower surface of the cavity.

[0029] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0030] In the preparation method of the matrix pressure sensor of the technical solution of the present invention, the matrix pressure sensor is manufactured using an IC process, by providing a first substrate and a second substrate; forming a first bonding medium on the surface of the first substrate; bonding the first substrate and the second substrate through the first bonding medium; forming a hole column on the surface of the second substrate, the hole column penetrating the second substrate and the first bonding medium; depositing an isolation layer on the sidewall of the hole column; filling the hole column with a strain layer, the thickness of the strain layer being higher than the thickness of the first bonding medium; removing the isolation layer and the first bonding medium to form a cavity; forming a hole plug at the position where the hole column is located on the second substrate to seal the cavity, so that the manufacturing process of the present invention is reliable and stable, and the sensor dot density formed on the substrate is high, while taking into account the reduction of sensor space requirements.

[0031] Furthermore, the present invention utilizes the change in the cross-section of the strain layer when subjected to stress, or the deformation of the upper and lower plates of the cavity when subjected to stress, so that the matrix pressure sensor manufactured by the present invention can be used as both a resistive matrix pressure sensor and a capacitive matrix pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 1 is a flow chart of a method for preparing a matrix pressure sensor according to an embodiment of the present invention;

[0034] Figures 2 to 4 This is a structural diagram of the preparation process of a matrix pressure sensor according to an embodiment of the present invention. Figure 1 ;

[0035] Figure 5 is a schematic flow chart of a method for preparing a matrix pressure sensor in another embodiment of the present invention;

[0036] Figure 6 This is a structural diagram of the preparation process of a matrix pressure sensor according to an embodiment of the present invention. Figure 2 ;

[0037] Figure 7 1 is a flow chart of a method for preparing a matrix pressure sensor in another embodiment of the present invention;

[0038] Figures 8 to 15 This is a structural diagram of the preparation process of a matrix pressure sensor according to an embodiment of the present invention. Figure 2 ;

[0039] Figures 16 and 17 1 is a schematic diagram of the principle of a matrix pressure sensor according to an embodiment of the present invention;

[0040] Figures 18 to 20 This is a structural diagram of the preparation process of a matrix pressure sensor according to an embodiment of the present invention. Figure 3 ;

[0041] Description of reference numerals:

[0042] 101-first substrate;

[0043] 201- second substrate;

[0044] 301-first mask layer;

[0045] 401-isolating material layer;

[0046] 402-Isolation layer;

[0047] 501-hole column;

[0048] 502-strain layer;

[0049] 60-medium support beam;

[0050] 601-first dielectric support beam;

[0051] 602-second dielectric support beam;

[0052] 603- dielectric layer;

[0053] 701-first epitaxial layer;

[0054] 801-first metal plate;

[0055] 802- Second metal plate. DETAILED DESCRIPTION

[0056] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0057] The terms "first," "second," "third," "fourth," and the like (if any) in the description and claims of the present invention and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions, e.g., a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatus.

[0058] The technical solution of the present invention is described in detail below with reference to specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0059] As described in the background art, it is difficult to increase the sensor array density while reducing the sensor space requirement when manufacturing a pressure sensor in the prior art.

[0060] In light of this, the present invention provides a method for fabricating a matrix pressure sensor, comprising providing a first substrate and a second substrate; forming a first bonding medium on the surface of the first substrate; bonding the first substrate to the second substrate via the first bonding medium; forming a hole column on the surface of the second substrate, the hole column penetrating the second substrate and the first bonding medium; depositing an isolation layer on the sidewalls of the hole column; filling the hole column with a strain layer having a thickness greater than that of the first bonding medium; removing the isolation layer and the first bonding medium to form a cavity; and forming a hole plug at the location of the hole column on the second substrate to seal the cavity. The present invention utilizes an IC process to manufacture the matrix pressure sensor, achieving a reliable and stable process while also achieving a high density of sensor dots formed on the substrate and reducing sensor space requirements.

[0061] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0062] Please refer to Figure 1 The present invention proposes a method for preparing a matrix pressure sensor, comprising:

[0063] Step S1: providing a first substrate and a second substrate;

[0064] Step S2: forming a first bonding medium on the surface of the first substrate;

[0065] Step S3: bonding the first substrate and the second substrate via the first bonding medium;

[0066] Step S4: forming a hole column on the surface of the second substrate, wherein the hole column penetrates the second substrate and the first bonding medium;

[0067] Step S5: depositing an isolation layer on the sidewalls of the pore column;

[0068] Step S6: filling the pore column with a strain layer, wherein the thickness of the strain layer is greater than the thickness of the first bonding medium;

[0069] Step S7: removing the isolation layer and the first bonding medium to form a cavity;

[0070] Step S8: forming a hole plug at the position where the hole column is located in the second substrate to seal the cavity.

[0071] It can be seen that the present invention manufactures the matrix pressure sensor by utilizing the IC process. While the process is reliable and stable, the density of the sensor array formed on the substrate is relatively high, while also reducing the sensor space requirement.

[0072] Please refer to Figures 2 to 20 , which shows a structural schematic diagram of the preparation process of the matrix pressure sensor according to an embodiment of the present invention.

[0073] Please refer to Figure 2 , providing a first substrate 101 and a second substrate 201.

[0074] As an example, the first substrate 101 and the second substrate 201 can both be silicon substrates. Of course, the present invention is not limited to this, and SOI substrates, ceramic substrates, etc. can also be used. According to the needs of actual applications, the substrate materials used for the first substrate 101 and the second substrate 201 can also be different. Technicians in this field can use appropriate materials according to design requirements.

[0075] It should be understood that the thickness of the first substrate 101 and the thickness of the second substrate 201 in the embodiment of the present invention may be the same, or appropriate thicknesses may be selected according to needs.

[0076] Please refer to Figure 3 , a first bonding medium 102 is formed on the surface of the first substrate 101 .

[0077] In the embodiment of the present invention, the material of the first bonding medium 102 is silicon oxide, but the present invention is not limited thereto. Those skilled in the art can select a suitable material as the bonding medium as needed, such as silicon nitride, polysilicon, silicon carbide, etc.

[0078] Please refer to Figure 4The first substrate 101 and the second substrate 201 are bonded together through the first bonding medium 102 .

[0079] Please continue to refer to Figure 1 , executing step S4: forming a hole column on the surface of the second substrate, wherein the hole column penetrates the second substrate and the first bonding medium.

[0080] In one embodiment, please refer to Figure 5 , the step S4 includes:

[0081] Step S41: forming a first mask layer on the second substrate;

[0082] Step S42: performing a first patterning on the first mask layer to form a first patterned mask layer;

[0083] Step S43: using the first patterned mask layer as a mask and the interface between the first bonding medium and the first substrate as an etching stop layer, sequentially etching the second substrate and the first bonding medium to form the hole column.

[0084] Now combined Figure 6 Provide explanation.

[0085] Please refer to Figure 6 , a first mask layer 301 is formed on the second substrate 201, and the first mask layer 301 is patterned for the first time to form a first patterned mask layer. Using the first patterned mask layer as a mask and the interface between the first bonding medium 102 and the first substrate 101 as an etching stop layer, the second substrate 201 and the first bonding medium 102 are etched in sequence to form the hole column 501.

[0086] Please continue to refer to Figure 1 , executing step S5: depositing an isolation layer on the sidewall of the hole column.

[0087] In one embodiment, please refer to Figure 7 , the step S5 includes:

[0088] Step S51: depositing an isolation material layer on the second substrate, wherein the isolation material layer covers the surface of the pore pillar and other areas of the second substrate;

[0089] Step S52: etching the isolation material layer on the surface of the second substrate and the isolation material layer at the bottom of the hole column to form the isolation layer.

[0090] Now combined Figures 8 and 9 Provide explanation.

[0091] Please refer to Figure 8, an isolation material layer 401 is deposited on the second substrate 201 , and the isolation material layer 401 covers the surface of the pore column 501 and covers other areas of the second substrate 201 .

[0092] The isolation material layer 401 can be regarded as a thin film, and its material can be nitride, silicon oxynitride or silicon oxide, etc. The present invention is not limited to this, and those skilled in the art can select appropriate materials as needed.

[0093] Please refer to Figure 9 , the isolation material layer 401 on the surface of the second substrate 201 and the isolation material layer 401 at the bottom of the hole column 501 are etched to form the isolation layer 402.

[0094] In a specific embodiment, the isolation material layer 401 on the surface of the second substrate 201 and the isolation material layer 401 at the bottom of the hole column 501 are dry-etched to form the isolation layer 402.

[0095] Please refer to Figure 10 A strain layer 502 is filled in the pore column 501 , and the thickness of the strain layer 502 is greater than the thickness of the first bonding medium 102 .

[0096] In the embodiment of the present invention, the material of the strained layer 502 is different from the material of the isolation layer 402. For example, the material of the strained layer 502 can be single crystal silicon, silicon germanium, or phosphorus silicon.

[0097] Taking the strained layer 502 as an example, the material of the strained layer 502 is single crystal silicon. In one embodiment, the method of filling the strained layer in the pore column in step S6 includes:

[0098] Epitaxial growth is performed on the first substrate at the bottom of the hole column to form the strained layer.

[0099] In practical applications, the present invention can select a suitable cross-section of the single crystal silicon column according to the sensitivity to pressure. The smaller the cross-sectional area, the greater the deformation when receiving pressure and the higher the sensitivity. In a specific embodiment, the cross-sectional length of the strain layer 502 is 1nm~10um.

[0100] Please refer to Figure 11 , removing the isolation layer 402 and the first bonding medium 102 to form a cavity.

[0101] In one embodiment, the isolation layer 402 and the first bonding medium 102 may be removed by a dry etching process or a wet etching process.

[0102] After this process, the top view of the matrix pressure sensor can be as follows: Figure 12 As shown, the matrix pressure sensor further includes a dielectric support beam 60 , and the dielectric support beam 60 surrounds the periphery of the matrix pressure sensor.

[0103] In other embodiments, please refer to Figure 13 , the dielectric support beam 60 includes a first dielectric support beam 601, a dielectric layer 603 and a second dielectric support beam 602;

[0104] The dielectric layer 603 is located between the first dielectric support beam 601 and the second dielectric support beam 602 .

[0105] Of course, the present invention does not limit the top shape of the matrix pressure sensor, and those skilled in the art can select a suitable structure as needed.

[0106] Please continue to refer to Figure 1 , executing step S8: forming a hole plug at the position where the hole column is located in the second substrate to seal the cavity.

[0107] In one embodiment, the method for forming the hole plug in step S8 includes:

[0108] Epitaxial growth is performed on the second substrate at the hole column to form a first epitaxial layer, and the hole column is sealed to form a hole plug at the position where the hole column is located on the second substrate.

[0109] Now combined Figure 14 Provide explanation.

[0110] Please refer to Figure 14 , epitaxial growth is performed on the second substrate 201 at the hole column 501 to form a first epitaxial layer 701 , and the hole column 501 is sealed to form a hole plug at the position where the hole column 501 is located in the second substrate 201 .

[0111] It should be understood that the present invention does not limit whether the material of the first epitaxial layer 701 is the same as that of the second substrate 201 .

[0112] Please refer to Figure 15 , remove the first mask layer 301.

[0113] exist Figure 15 In the matrix pressure sensor formed by the example of , the pressure can be measured by resistance, that is, the deformation of the column of the strain layer 502 is controlled to change greatly during measurement, and the volume of the cavity changes slightly; its principle diagram can be shown as follows Figure 16 As shown, Figure 16 R in bodyThis can be understood as the resistance of the pillars in the strain layer 502. Specifically, when the sensor is subjected to an external force, the pillars in the strain layer 502 deform, their cross-sectional area increases, and the output resistance decreases. When the external force is removed, the pillars in the strain layer 502 regain their original shape, their cross-sectional area decreases, and the sensor output resistance increases.

[0114] In other application modes, pressure can also be measured by capacitance, that is, when measuring, the deformation change of the column of the strain layer 502 is controlled to be small, and the change of the cavity volume is large; its principle diagram can be shown as follows Figure 17 As shown. Figure 17 In the example, it can be seen that for the resistive array pressure sensor, the connection between adjacent rows and columns has the function of parallel capacitance in addition to the on-resistance.

[0115] In actual work, Figure 17 In the example, when a sensing unit is enabled, its parallel capacitor stores charge. When switching to another sensing unit, the corresponding capacitor charge requires time to discharge. This discharge time is determined by the RC network composed of resistors and capacitors. The specific design application depends on the product requirements.

[0116] In practical applications, if pressure is measured by capacitance, the thickness of the second substrate 201 can be appropriately reduced, or a metal layer can be deposited between the upper plate and the lower plate to enhance the capacitance change.

[0117] Specifically, please refer to Figure 18 A first metal plate 801 and a second metal plate 802 are deposited on the first substrate 101 and the second substrate 201 respectively, wherein the first metal plate 801 corresponds to the upper surface of the cavity, and the second metal plate 802 corresponds to the lower surface of the cavity.

[0118] In practical applications, the deposition of the first metal plate 801 and the second metal plate 802 can be completed after step S2 and before step S3 .

[0119] By controlling the thickness of the first metal plate, the sensitivity of the capacitive sensing can also be controlled. In a specific embodiment, the thickness of the first metal plate 801 can be controlled after the above-mentioned bonding process. For example, the thickness of the first metal plate 801 can be thinned by a CMP process.

[0120] Considering that the exposed second substrate 201 may be lost when etching the first metal plate 801, Figure 18 In the example, the surface of the strained layer 502 is flush with the surface of the second substrate 201, which does not affect the actual use effect.

[0121] The top view of the matrix pressure sensor that measures pressure by capacitance can be shown as follows: Figure 19 As shown, the matrix pressure sensor further includes a dielectric support beam 60 , and the dielectric support beam 60 surrounds the matrix pressure sensor.

[0122] In other embodiments, please refer to Figure 20 , the dielectric support beam 60 includes a first dielectric support beam 601, a dielectric layer 603 and a second dielectric support beam 602;

[0123] The dielectric layer 603 is located between the first dielectric support beam 60 and the second dielectric support beam 60 .

[0124] It can be seen that the present invention utilizes the change in the cross-section of the strain layer when subjected to force, or the deformation of the upper and lower plates of the cavity when subjected to force, so that the matrix pressure sensor manufactured by the present invention can be used as both a resistive matrix pressure sensor and a capacitive matrix pressure sensor.

[0125] In summary, the embodiment of the present invention utilizes an IC process to manufacture a matrix pressure sensor, by providing a first substrate and a second substrate; forming a first bonding medium on the surface of the first substrate; bonding the first substrate and the second substrate through the first bonding medium; forming a hole column on the surface of the second substrate, the hole column penetrating the second substrate and the first bonding medium; depositing an isolation layer on the sidewall of the hole column; filling the hole column with a strain layer, the thickness of the strain layer being higher than the thickness of the first bonding medium; removing the isolation layer and the first bonding medium to form a cavity; forming a hole plug at the position where the hole column is located on the second substrate to seal the cavity, so that the manufacturing process of the present invention is reliable and stable, and the sensor dot array formed on the substrate has a high density, while also reducing the sensor space requirement.

[0126] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A method for preparing a matrix pressure sensor, characterized in that: include: Step S1: providing a first substrate and a second substrate; Step S2: forming a first bonding medium on the surface of the first substrate; Step S3: bonding the first substrate and the second substrate via the first bonding medium; Step S4: forming a hole column on the surface of the second substrate, wherein the hole column penetrates the second substrate and the first bonding medium; Step S5: depositing an isolation layer on the sidewalls of the pore column; Step S6: filling the pore column with a strain layer, wherein the thickness of the strain layer is greater than the thickness of the first bonding medium; Step S7: removing the isolation layer and the first bonding medium to form a cavity; Step S8: forming a hole plug at the position where the hole column is located on the second substrate to seal the cavity; Step S9: depositing a first metal plate and a second metal plate on the surface of the first substrate facing away from the cavity and the surface of the second substrate facing away from the cavity, respectively, wherein the first metal plate corresponds to the upper surface of the cavity and the second metal plate corresponds to the lower surface of the cavity.

2. The method for preparing a matrix pressure sensor according to claim 1, wherein: The step S4 includes: Step S41: forming a first mask layer on the second substrate; Step S42: performing a first patterning on the first mask layer to form a first patterned mask layer; Step S43: using the first patterned mask layer as a mask and the interface between the first bonding medium and the first substrate as an etching stop layer, sequentially etching the second substrate and the first bonding medium to form the hole column.

3. The method for preparing a matrix pressure sensor according to claim 2, wherein: The step S5 includes: Step S51: depositing an isolation material layer on the second substrate, wherein the isolation material layer covers the surface of the pore pillar and other areas of the second substrate; Step S52: etching the isolation material layer on the surface of the second substrate and the isolation material layer at the bottom of the hole column to form the isolation layer.

4. The method for preparing a matrix pressure sensor according to claim 3, wherein: The forming of the hole plug in step S8 includes: Epitaxial growth is performed on the second substrate at the hole column to form a first epitaxial layer, and the hole column is sealed to form a hole plug at the position where the hole column is located on the second substrate.

5. The method for preparing a matrix pressure sensor according to claim 4, wherein: After step S8, the method further includes: The first mask layer is removed.

6. The method for preparing a matrix pressure sensor according to claim 1, wherein: Step S6 includes: Epitaxial growth is performed on the first substrate at the bottom of the hole column to form the strained layer.

7. The method for preparing a matrix pressure sensor according to claim 1, wherein: The material of the strain layer is different from that of the isolation layer.

8. The method for preparing a matrix pressure sensor according to claim 6, wherein: The material of the strained layer includes single crystal silicon, silicon germanium and silicon phosphide.

9. The method for preparing a matrix pressure sensor according to claim 6, wherein: The cross-sectional length of the strain layer is 1 nm to 10 um.

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