CN116735041A - Pressure sensor and preparation method thereof - Google Patents
Pressure sensor and preparation method thereof Download PDFInfo
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- CN116735041A CN116735041A CN202310459845.6A CN202310459845A CN116735041A CN 116735041 A CN116735041 A CN 116735041A CN 202310459845 A CN202310459845 A CN 202310459845A CN 116735041 A CN116735041 A CN 116735041A
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- 238000002360 preparation method Methods 0.000 title abstract description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 35
- 239000010703 silicon Substances 0.000 claims abstract description 35
- 229910002704 AlGaN Inorganic materials 0.000 claims abstract description 33
- 239000000758 substrate Substances 0.000 claims abstract description 28
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 238000005516 engineering process Methods 0.000 claims abstract description 7
- 239000004065 semiconductor Substances 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 22
- 238000005530 etching Methods 0.000 claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 16
- 239000002184 metal Substances 0.000 claims description 16
- 229920002120 photoresistant polymer Polymers 0.000 claims description 12
- 230000005533 two-dimensional electron gas Effects 0.000 claims description 10
- 238000004140 cleaning Methods 0.000 claims description 9
- 238000005229 chemical vapour deposition Methods 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 4
- 238000000576 coating method Methods 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 3
- SBEQWOXEGHQIMW-UHFFFAOYSA-N silicon Chemical compound [Si].[Si] SBEQWOXEGHQIMW-UHFFFAOYSA-N 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 abstract description 16
- 238000004088 simulation Methods 0.000 abstract description 7
- 229910002601 GaN Inorganic materials 0.000 description 50
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 34
- 230000008859 change Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 8
- 235000012431 wafers Nutrition 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000010408 film Substances 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 150000002739 metals Chemical class 0.000 description 5
- RNQKDQAVIXDKAG-UHFFFAOYSA-N aluminum gallium Chemical compound [Al].[Ga] RNQKDQAVIXDKAG-UHFFFAOYSA-N 0.000 description 4
- 230000010287 polarization Effects 0.000 description 4
- 238000000137 annealing Methods 0.000 description 3
- 230000004888 barrier function Effects 0.000 description 3
- CLOMYZFHNHFSIQ-UHFFFAOYSA-N clonixin Chemical compound CC1=C(Cl)C=CC=C1NC1=NC=CC=C1C(O)=O CLOMYZFHNHFSIQ-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
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- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000002269 spontaneous effect Effects 0.000 description 2
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 2
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- XPDWGBQVDMORPB-UHFFFAOYSA-N Fluoroform Chemical compound FC(F)F XPDWGBQVDMORPB-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000003637 basic solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
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- 238000003860 storage Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66409—Unipolar field-effect transistors
- H01L29/66446—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET]
- H01L29/66462—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET] with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/778—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface
- H01L29/7786—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with direct single heterostructure, i.e. with wide bandgap layer formed on top of active layer, e.g. direct single heterostructure MIS-like HEMT
- H01L29/7787—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with direct single heterostructure, i.e. with wide bandgap layer formed on top of active layer, e.g. direct single heterostructure MIS-like HEMT with wide bandgap charge-carrier supplying layer, e.g. direct single heterostructure MODFET
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Ceramic Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Computer Hardware Design (AREA)
- Manufacturing & Machinery (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The invention discloses a pressure sensor and a preparation method thereof, and belongs to the field of semiconductor technology and manufacturing. The pressure sensor of the invention comprises the following components from bottom to top: the device comprises a silicon substrate, a buffer layer, a GaN layer and an AlGaN layer, wherein a grid electrode, a source electrode and a drain electrode are arranged on the AlGaN layer; the silicon substrate includes: the substrate is provided with a first support body, a second support body and a third support body in sequence from left to right; the upper surfaces of the second supporting body and the third supporting body are attached to the lower surface of the buffer layer, and a cavity is formed between the second supporting body and the third supporting body; the first support body is smaller than the second support body in height, and a gap is reserved between the first support body and the buffer layer. According to the invention, the resistance of the current sensing channel in the drain electrode is increased when the pressure is applied, so that the current is reduced, further the pressure sensing is realized, and the simulation result proves that the pressure sensor has higher sensitivity and also has a larger measuring range.
Description
Technical Field
The invention relates to a pressure sensor and a preparation method thereof, belonging to the field of semiconductor technology and manufacturing.
Background
The basic principle of the gallium nitride pressure sensor is to utilize the good piezoresistive property of gallium nitride material, and when the material is subjected to external force, the resistance value can be changed. The change can be measured by an external circuit and converted into a pressure value.
Specifically, when a gallium nitride material is subjected to pressure, lattice distortion occurs, which causes a change in the difficulty level of movement of electrons inside the material, resulting in a change in the resistance value. This change in resistance value is proportional to the pressure applied and can be measured by an external circuit.
The gallium nitride pressure sensor can realize high-precision, high-speed and long-term stable pressure measurement, can help enterprises to find pressure abnormal conditions in equipment or products in time, avoids product quality problems and safety accidents, has the characteristics of high precision, high-temperature stability and the like, can reduce detection cost and equipment maintenance cost, and improves economic benefits of enterprises.
Currently, the sensitive element of gallium nitride pressure sensors generally uses a gallium nitride thin film, whose thickness is typically between several micrometers and several tens micrometers, and whose shape can be a diaphragm, a beam, a column, or the like. When an external force is applied, the gallium nitride film can be slightly deformed, so that the change of electrical properties is caused, and an electrical signal is output. However, the gallium nitride pressure sensor prepared by using the gallium nitride film as the sensitive element can measure the pressure ranging from several kilopascals to hundreds of megapascals, but has low sensitivity, and the actual measurement range cannot reach the range required by the actual engineering.
Disclosure of Invention
In order to solve the problems of low sensitivity and small measurement range of the existing gallium nitride pressure sensor, the invention provides a pressure sensor and a preparation method thereof, and the technical scheme is as follows:
a first object of the present invention is to provide a pressure sensor, comprising, in order from bottom to top: the semiconductor device comprises a silicon substrate, a buffer layer, a GaN layer and an AlGaN layer, wherein a grid electrode, a source electrode and a drain electrode are arranged on the AlGaN layer;
the silicon substrate includes: the substrate is provided with a first support body, a second support body and a third support body in sequence from left to right; the upper surfaces of the second supporting body and the third supporting body are attached to the lower surface of the buffer layer, and a cavity is formed between the second supporting body and the third supporting body; the height of the first supporting body is smaller than that of the second supporting body, and a gap is reserved between the first supporting body and the buffer layer.
Optionally, the thickness of the silicon substrate is: 350-1000um.
Optionally, a gap between the first support body and the buffer layer is: 10-130um.
Optionally, the thickness of the buffer layer is: 2-15um.
Optionally, the thickness of the GaN layer is: 1-5um.
Optionally, the thickness of the AlGaN layer is as follows: 10-20nm.
A second object of the present invention is to provide a pressure sensing method, implemented based on the pressure sensor described in any one of the above, comprising: when pressure is applied to the source electrode or the drain electrode, the left side of the pressure sensor is bent and deformed, so that the resistance of a current sensing channel between the source electrode and the drain electrode is increased, the current is reduced, and pressure sensing is realized, and the current sensing channel between the source electrode and the drain electrode is as follows: and the two-dimensional electron gas 2D-EDGE exists at the interface of the GaN layer and the AlGaN layer.
A third object of the present invention is to provide a method for manufacturing a pressure sensor, for manufacturing the pressure sensor described in any one of the above, comprising:
step 1: cleaning a silicon wafer;
step 2: growing a buffer layer on the cleaned silicon substrate;
step 3: preparing a GaN layer, and growing a GaN film on the buffer layer by a metal organic chemical vapor deposition method;
step 4: preparing an AlGaN layer, and growing a layer of AlGaN film on the GaN layer by a metal organic chemical vapor deposition method;
step 5: preparing a source electrode, a drain electrode and a grid electrode on the AlGaN layer;
step 6: etching and bonding a silicon substrate;
coating photoresist on the back of the pressure sensor at the position corresponding to the second support body, etching until 10-20um is reserved, and then washing off all the photoresist; coating photoresist on the position corresponding to the third support body, etching, and cleaning the photoresist after etching is finished;
bonding the matched silicon-based grinding column prepared in advance with the back surface of the pressure sensor by utilizing a silicon-silicon direct bonding technology;
optionally, the step 5 includes: source and drain electrodes are formed on the AlGaN layer using an ohmic contact principle, and then a gate electrode is formed by a schottky contact principle.
Optionally, the source electrode and the drain electrode are made of Ti/Al/Ni/Au 4 layer metal, and the grid electrode is made of Ni/Au two layer metal.
The invention has the beneficial effects that:
the pressure sensor is designed into a 'teeterboard structure', when pressure is applied to two places of a source electrode and a drain electrode, bending deformation can occur on two sides of the sensor, so that the resistance of a current sensing channel in the drain electrode is obviously increased, current is reduced, and pressure sensing is further realized.
In addition, due to the support of the bottom support body, damage to the gallium nitride pressure sensor caused by overlarge stress change due to suddenly increased pressure can be avoided. The measuring range of the invention is related to the size of the gap, the smaller the gap is, the larger the measuring range is, and the simulation result proves that the invention can measure the pressure of the MPa level.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a structural diagram of a pressure sensor of the present invention.
Fig. 2 is a flow chart of a process for manufacturing a pressure sensor according to the present invention.
FIG. 3 is a graph of sensor stress generation for a stress pressure of 500kpa in an embodiment of the present invention.
FIG. 4 is a graph of sensor stress generation for a stress pressure of 250kpa for an embodiment of the present invention.
FIG. 5 is a graph of sensor stress generation for a 50kpa stress pressure in an embodiment of the invention.
Fig. 6 is a sensitivity characteristic diagram of a conventional pressure sensor.
Fig. 7 is a sensitivity characteristic of the gallium nitride pressure sensor of the present invention.
Fig. 8 is a graph of maximum range versus gap size for a gallium nitride pressure sensor of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
Embodiment one:
this embodiment provides a pressure sensor, referring to fig. 1, the pressure sensor includes from bottom to top in order: the device comprises a silicon substrate, a buffer layer, a GaN layer and an AlGaN layer, wherein a grid electrode, a source electrode and a drain electrode are arranged on the AlGaN layer;
the silicon substrate includes: the substrate is provided with a first support body, a second support body and a third support body in sequence from left to right; the upper surfaces of the second supporting body and the third supporting body are attached to the lower surface of the buffer layer, and a cavity is formed between the second supporting body and the third supporting body; the first support body is smaller than the second support body in height, and a gap is reserved between the first support body and the buffer layer.
Embodiment two:
this embodiment provides a pressure sensor, referring to fig. 1, the pressure sensor includes from bottom to top in order: the device comprises a silicon substrate, a buffer layer, a GaN layer and an AlGaN layer, wherein a grid electrode, a source electrode and a drain electrode are arranged on the AlGaN layer;
the silicon substrate includes: the substrate is provided with a first support body, a second support body and a third support body in sequence from left to right; the upper surfaces of the second supporting body and the third supporting body are attached to the lower surface of the buffer layer, and a cavity is formed between the second supporting body and the third supporting body; the first support body is smaller than the second support body in height, and a gap is reserved between the first support body and the buffer layer.
The thickness of the silicon substrate is: 350-1000um. The clearance between the first support body and the buffer layer is: 10-130um. The thickness of the buffer layer is as follows: 2-15um. The thickness of the GaN layer is as follows: 1-5um. The thickness of the AlGaN layer is as follows: 10-20nm.
The thickness of the silicon substrate obtained by the simulation experiment of this embodiment is 500um, the gap between the first support and the buffer layer is 130um, and the thickness of the buffer layer is: 7um, gaN layer thickness is: 3um, the thickness of the AlGaN layer is: 10nm. The width of the whole pressure sensor is 100um and the length is 2000um.
When the pressure sensor is provided at the left side (the area is only 0.02mm 2 ) When 0.01N (500 kPa) is applied, 2830Mpa of stress is generated in the middle, and the embodiment of the invention realizes pressure sensing by resistance change caused by two-dimensional electron gas change at the gallium nitride/aluminum gallium nitride interface under the condition of pressure, wherein the specific sensing process is analyzed as follows:
the change in lattice constant is obtained by the formula Δa/a0= (1/E) σ, where Δa is the change in lattice constant, a is the lattice constant when unstressed, σ is stress, E is the elastic modulus, and the elastic modulus of gallium nitride is 280Gpa, where Δa/a0= 12.1×10 can be known from the formula -3 /280
And then calculating the polarization charge density according to a formula:
a(x)＝(-0.077x+3.189)10 -10 m
c 13 (x)＝(5x+103)*10^9Pa
c 33 (x)＝(-32x+405)10^9Pa
e 31 (x)＝(-0.11x-0.49)C/m 2
e 33 (x)＝(0.73x+0.73)C/m 2
wherein Δδ (x) is the polarization charge density, c 13 And c 33 Is the elastic constant, e 31 、e 33 Is a piezoelectric constant, x is the Al component ratio in the AlGaN barrier layer, generally 20% -30%,is AlGaN spontaneous polarization charge density, ">For GaN spontaneous polarization charge density, a0 is GaN lattice constant.
The two-dimensional electron gas surface density formula is:
q＝1.6*10 -19 C
wherein ε 0 ＝8.85*10 -12 F/m (dielectric constant in air), ε r (x) =4.82F/m (dielectric constant of 30% aluminum gallium nitride), d AlGaN For the thickness of the barrier layer d AlGaN ＝17nm＝17*10 -6 m，Barrier heights for AlGaN, ranging from a few hundred milli-electron volts to a few electron volts (1.5 electron volts); e (E) F (x) The fermi level in the GaN material at equilibrium is 1.7 ev.
The gallium nitride material is doped with aluminum element to realize the forbidden band width of 3.4-6.2 eV, the forbidden band width of the gallium nitride of the embodiment is 3.4eV, and the forbidden band width of 30% of aluminum-nitrogen-gallium is 3.96eV; ΔE C (x) =0.56 eV, indicating the conduction of gallium nitride and aluminum gallium nitrideThe band difference.
Two-dimensional electron gas surface density n s (x) The relationship between (unit of areal density and bulk density) and resistance r (sheet resistance) can be expressed by the following formula:
r＝1/(eμn)
where n is the two-dimensional electron gas surface density, e is the meta-charge, and μ is the mobility of the two-dimensional electron flow. In gallium nitride, the mobility μ is typically around 0.2m 2/Vs.
The resistance R of the gallium nitride pressure sensor is calculated as follows:
where L is the length of the gallium nitride pressure sensor, d is the width of the gallium nitride pressure sensor, and R is approximately 320 Ω, 20=6400 Ω under 0N pressure.
The structure of the sensor of this embodiment is similar to a seesaw, the metal has ductility similar to rubber strips, when pressure is applied to two places of the source electrode and the drain electrode, bending deformation occurs to two sides of the sensor, so that the resistance of a current sensing channel (two-dimensional electron gas 2D-EDGE exists at the gallium nitride/aluminum gallium nitride interface) inside the drain electrode is obviously increased, conductivity is realized, but the resistivity of the two-dimensional electron gas is related to the stress of the surface of the two-dimensional electron gas, so that current is reduced, and pressure sensing is realized.
According to the stress, when the source is subjected to a small force, the source has a certain speed, the source can be contacted with the lower support body quickly because the middle slit is small, the drain is connected with the silicon-based column, the lower support column of the grid electrode, the source, the drain and the grid electrode are deformed (compared with the common gallium nitride pressure sensor which is stressed and only deforms at the source and the drain, the deformation is more, the sensitivity is higher), the two-dimensional electron gas is greatly changed, the resistance is quickly changed, namely, the sensor has high sensitivity characteristic, and the force can be always increased because of the support of the bottom support body, so that the measuring range of the pressure sensor is large.
The simulation experiment of the measurement range of the pressure sensor of this embodiment is as follows:
simulation 1: namely, the range is (0-0.01N), as shown in FIG. 3, when the pressure is 0.01N (500 kPa), the gallium nitride intermediate stress generates 2.83Gpa, and the resistance reaches 3200Ω, ΔR≡3200Ω, and the sensitivity is high: deltaR/R is approximately 0.50.
Simulation 2: at a pressure of 0.005N (250 kPa), the gallium nitride intermediate stress produced a sensitivity of 1.41Gpa as shown in FIG. 4: deltaR/R is approximately 0.33.
Simulation 3: at a pressure of 0.001N (50 kPa), as shown in FIG. 5, the gallium nitride intermediate stress produced 0.28Gpa, sensitivity: deltaR/R is approximately equal to 0.08.
Comparative example: flexible piezoresistance type pressure sensor CN201911277053.7 with adjustable measuring range and sensitivity of invention patent of Nanjing university of technology "
Fig. 6 is an effect diagram of the invention patent of university of south Beijing technology, and as shown in fig. 6, the maximum sensitivity is about 0.23, 0.16, and 0.1 when the pressure is 500kpa, 250kpa, and 50kpa, respectively.
As shown in fig. 7, the relationship between the sensitivity and the pressure of the pressure sensor in this embodiment is shown in fig. 7, and compared with the prior art, the maximum sensitivity is 0.50, 0.33, and 0.08 under the conditions of 500kpa, 250kpa, and 50kpa, and the sensitivity is larger.
Fig. 8 is a graph showing the relationship between the maximum range and the gap size of the gallium nitride pressure sensor according to the present embodiment.
As can be seen from fig. 8, the smaller the gap, the larger the measuring range of the pressure sensor, and it can be seen that the measuring range of the pressure sensor in this embodiment can reach MPa level, and the measuring range of the comparative example patent can only reach Kpa level, so this embodiment significantly enlarges the measuring range of the pressure sensor while improving sensitivity.
Embodiment III:
the embodiment provides a method for manufacturing a pressure sensor, which includes:
step 1: cleaning a silicon wafer;
new wafer cleaning is the first step in the sensor process flow of this embodiment, with the aim of removing organic and oxide from the heterojunction surface. The cleaning of organic matters on the surface of the heterojunction mainly uses acetone, isopropanol and oxygen plasma. The oxide is primarily cleaned by acidic and basic solutions such as HF, HCL, NH OH, (NH 4) 2S, TMAH, stripper, etc.
Step 2: preparing a buffer layer; the effect of this layer is to make gallium nitride and Si lattice more matched, and to improve the growth quality.
Step 3: preparing a GaN layer;
preheating a reaction furnace: the reactor is preheated to a proper temperature (generally 1000 ℃ -1100 ℃), so as to ensure the temperature stability and the reaction rate of the growth process.
Preparing a growth gas: raw material gases such as high-purity nitrogen, trimethylgallium and the like are injected into a reaction furnace, and the flow and the proportion are regulated by a flow controller so as to control the stability and the components of the reaction atmosphere in the growth process.
Gallium nitride growth: placing the cleaned substrate into a reaction furnace, performing certain pretreatment (such as high-temperature drying), and then growing a layer of gallium nitride film on the substrate by a Metal Organic Chemical Vapor Deposition (MOCVD) method and the like.
Step 4: preparing an AlGaN layer;
preheating a reaction furnace: the reactor is preheated to a proper temperature (generally 800-1000 ℃) to ensure the temperature stability and the reaction rate of the growth process.
Preparing a growth gas: high-purity nitrogen, trimethylaluminum, trimethylgallium and other raw material gases are injected into a reaction furnace, and the flow and the proportion are regulated by a flow controller so as to control the stability and the components of the reaction atmosphere in the growth process.
AlGaN growth: placing the cleaned substrate into a reaction furnace, carrying out certain pretreatment (such as high-temperature drying), and then growing a layer of AlGaN film on the substrate by a Metal Organic Chemical Vapor Deposition (MOCVD) method and the like.
Step 5: preparing a source electrode, a drain electrode and a grid electrode;
and growing a source electrode and a drain electrode on the AlGaN layer by utilizing an ohmic contact principle (a high-temperature thermal annealing method (adopting electron beam evaporation, four layers of metals (Ti/Al/Ni/Au 4 layers of metals in sequence) and rapidly annealing for 35s in a nitrogen atmosphere at 850 ℃), and then growing a grid electrode by Schottky contact (adopting electron beam evaporation, two layers of metals (grid metals are Ni/Au two layers of metals in sequence) and annealing for 5min in a nitrogen atmosphere at 400 ℃).
Step 6: preparing a silicon substrate;
and protecting Si of the support column to be protected by using photoresist on the back surface of the sensor, etching by using a deep silicon etching method (plasma Si generated by SF6/O2/CHF3 mixed gas is used for etching a buffer which is a gallium nitride material, chlorine is needed for etching the gallium nitride, SF6 gas cannot be used for etching the gallium nitride), etching until 10-20um is reserved (enough space is reserved for bonding with the silicon support column), washing out all the photoresist, protecting the right silicon support column by using the photoresist, and using the deep silicon etching method again to finish etching and then cleaning the photoresist.
The last step is also the most important, the matched silicon-based grinding columns are prepared in advance, a certain interval is reserved, then the silicon-silicon direct bonding technology (two silicon wafers can be directly bonded together through high-temperature treatment without any adhesive or external electric field, and the process is simple) is utilized (1) the three lower silicon wafers are polished (oxidized or not oxidized), and firstly, the three lower silicon wafers are subjected to proper surface cleaning and activation (OH-solution or plasma); (2) Bonding the polished surfaces of the three parts of silicon wafers together at room temperature; (3) The bonded silicon wafer is subjected to high temperature treatment for several hours in an oxygen or nitrogen environment, so that good bonding is formed.
Some steps in the embodiments of the present invention may be implemented by using software, and the corresponding software program may be stored in a readable storage medium, such as an optical disc or a hard disk.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (10)
1. A pressure sensor, characterized in that the pressure sensor includes from bottom to top in proper order: the semiconductor device comprises a silicon substrate, a buffer layer, a GaN layer and an AlGaN layer, wherein a grid electrode, a source electrode and a drain electrode are arranged on the AlGaN layer;
the silicon substrate includes: the substrate is provided with a first support body, a second support body and a third support body in sequence from left to right; the upper surfaces of the second supporting body and the third supporting body are attached to the lower surface of the buffer layer, and a cavity is formed between the second supporting body and the third supporting body; the height of the first supporting body is smaller than that of the second supporting body, and a gap is reserved between the first supporting body and the buffer layer.
2. The pressure sensor of claim 1, wherein the silicon substrate has a thickness of: 350-1000um.
3. The pressure sensor of claim 1, wherein the gap between the first support and the buffer layer is: 10-130um.
4. The pressure sensor of claim 1, wherein the buffer layer has a thickness of: 2-15um.
5. The pressure sensor of claim 1, wherein the GaN layer has a thickness of: 1-5um.
6. The pressure sensor of claim 1, wherein the AlGaN layer has a thickness of: 10-20nm.
7. A method of pressure sensing, characterized in that the method is implemented on the basis of a pressure sensor according to any one of claims 1-6, comprising: when pressure is applied to the source electrode or the drain electrode, the left side of the pressure sensor is bent and deformed, so that the resistance of a current sensing channel between the source electrode and the drain electrode is increased, the current is reduced, and pressure sensing is realized, and the current sensing channel between the source electrode and the drain electrode is as follows: and the two-dimensional electron gas 2D-EDGE exists at the interface of the GaN layer and the AlGaN layer.
8. A method of manufacturing a pressure sensor according to any one of claims 1-6, comprising:
step 1: cleaning a silicon wafer;
step 2: growing a buffer layer on the cleaned silicon substrate;
step 3: preparing a GaN layer, and growing a GaN film on the buffer layer by a metal organic chemical vapor deposition method;
step 4: preparing an AlGaN layer, and growing a layer of AlGaN film on the GaN layer by a metal organic chemical vapor deposition method;
step 5: preparing a source electrode, a drain electrode and a grid electrode on the AlGaN layer;
step 6: etching and bonding a silicon substrate;
coating photoresist on the back of the pressure sensor at the position corresponding to the second support body, etching until 10-20um is reserved, and then washing off all the photoresist; coating photoresist on the position corresponding to the third support body, etching, and cleaning the photoresist after etching is finished;
and bonding the matched silicon-based grinding columns prepared in advance with the back surface of the pressure sensor by utilizing a silicon-silicon direct bonding technology.
9. The method of manufacturing a pressure sensor according to claim 8, wherein the step 5 comprises: source and drain electrodes are formed on the AlGaN layer using an ohmic contact principle, and then a gate electrode is formed by a schottky contact principle.
10. The method of manufacturing a pressure sensor according to claim 8, wherein the source and drain electrodes are made of Ti/Al/Ni/Au 4 layer metal, and the gate electrode is made of Ni/Au two layer metal.
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| CN117889998A (en) * | 2024-03-13 | 2024-04-16 | 成都凯天电子股份有限公司 | Sensor chip with stress amplifying structure and preparation method |
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