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CN-122016951-A - Hydrogen sensor and preparation method thereof

CN122016951ACN 122016951 ACN122016951 ACN 122016951ACN-122016951-A

Abstract

The invention discloses a hydrogen sensor and a preparation method thereof, wherein the hydrogen sensor comprises bonding glass; the bonding glass is bonded with the bottom of the SOI substrate to form a whole, the top surface of the SOI substrate is covered with a strain diaphragm, a palladium alloy film is arranged on the strain diaphragm, and a Wheatstone bridge for detecting the concentration of hydrogen is integrated on a working crystal face of the strain diaphragm. The hydrogen sensor provided by the invention has the advantages of good selectivity, long service life, good long-term stability, high sensitivity and low measurement lower limit of a conventional palladium alloy film resistance sensor.

Inventors

  • LIU YOUQING
  • JING TAO

Assignees

  • 苏州海卓赛思科技有限公司

Dates

Publication Date
20260512
Application Date
20260129

Claims (10)

  1. 1. A hydrogen sensor comprises bonding glass, and is characterized in that the bonding glass is bonded with the bottom of an SOI substrate to form a whole, the top surface of the SOI substrate is covered with a strain diaphragm, a palladium alloy film is arranged on the strain diaphragm, and a Wheatstone bridge for detecting hydrogen concentration is integrated on a working crystal face of the strain diaphragm.
  2. 2. The hydrogen sensor of claim 1 wherein the wheatstone bridge has a resistance that is a single crystal silicon thin film resistance.
  3. 3. The hydrogen sensor of claim 1, wherein the strain membrane is further provided with a heating resistor and a temperature measuring resistor.
  4. 4. A hydrogen sensor according to claim 3, wherein a temperature measuring resistance value is collected in real time, the temperature measuring resistance value is differed from a set value, the difference value is used as an input of a PID controller, an output value positively correlated with current is obtained, and the output value is applied to the heating resistance, so that the constant temperature control of the hydrogen sensor is realized.
  5. 5. A hydrogen sensor according to claim 3, wherein the thickness of the heating resistor and the temperature measuring resistor is 50nm-500nm.
  6. 6. The hydrogen sensor of claim 1 wherein each resistance of the wheatstone bridge has a rate of change of resistance of: ; Wherein, the y , x The longitudinal pressure and the transverse pressure at the strain diaphragm measuring point are respectively, R 1 、R 2 、R 3 、R 4 is four resistors of a Wheatstone bridge, the connecting point of R 1 、R 3 is connected with the power supply anode, the connecting point of R 2 、R 4 is connected with the power supply cathode, and pi 44 is the pressure group coefficient of monocrystalline silicon.
  7. 7. The hydrogen sensor according to any one of claims 1 to 6, wherein the SOI substrate has a thickness of 300um to 1000um.
  8. 8. The hydrogen sensor according to any one of claims 1 to 6, wherein the thickness of the strain gauge is 20um to 100um.
  9. 9. A method of manufacturing a hydrogen sensor according to any one of claims 1 to 8, comprising: Selecting an SOI wafer, and carrying out high-concentration B doping on the top monocrystalline silicon by adopting an ion implantation technology to obtain an SOI substrate; Etching the resistor strip by using an inductively coupled plasma dry etching technology to form a piezoresistor strip taking the monocrystalline silicon layer as a strain resistor, and exposing an SiO 2 insulating layer in a region except the piezoresistor strip; Photoetching a hydrogen sensitive graph on the SiO 2 insulating layer, and depositing a palladium alloy film as a hydrogen sensitive graph block; photoetching a lead groove and a bonding pad, and depositing a Ni-Au film as an electrode; etching a window on the back of the SOI substrate by photoetching, and etching a silicon cup by a dry method; and carrying out electrostatic sealing and scribing on the SOI substrate and Pyrex7740 glass to obtain the hydrogen sensor.
  10. 10. The method of manufacturing according to claim 6, further comprising: Photoetching a temperature measuring resistor strip on the SiO 2 insulating layer, and depositing a Ni film as a temperature measuring resistor; And photoetching a heating resistor strip on the SiO 2 insulating layer, and depositing an Au film as a heating resistor.

Description

Hydrogen sensor and preparation method thereof Technical Field The invention relates to a hydrogen sensor, in particular to a hydrogen sensor and a preparation method thereof. Background Currently, the technical principles of hydrogen sensors mainly include catalytic combustion, electrochemistry, metal oxide semiconductor, thermal conductivity, palladium alloy thin film resistance, and the like, and the advantages and disadvantages are shown in the following table 1. As can be seen from the table, the conventional hydrogen sensor has the advantages of poor selectivity, short service life, poor long-term stability, small sensitivity and insufficient measurement lower limit. Compared with other hydrogen sensors based on the conventional principle, the palladium alloy hydrogen sensor has the advantages of long service life, good selectivity, good long-term stability and the like, but has small sensitivity, is not suitable for low-concentration measurement, and has slower response time. The principle of the conventional palladium alloy thin film resistor sensor is that a palladium alloy thin film resistor strip is plated on a substrate, when hydrogen appears in a measuring medium, the hydrogen can be decomposed into hydrogen atoms and absorbed into internal lattices of the palladium alloy thin film resistor strip, so that the volume of the palladium alloy thin film resistor strip expands, the resistivity of the resistor strip changes, the higher the hydrogen concentration is, the more the lattice expands, the larger the resistivity changes, and the change of the hydrogen concentration is identified by measuring the change of the resistivity. However, at low concentration, the hydrogen atoms absorbed into the internal crystal lattice of the palladium alloy thin film resistor strip are few, the expansion of the crystal lattice is small, the change of the resistivity of the alloy is small, the response time is slow, and the low concentration test requirement cannot be met. Disclosure of Invention Aiming at the defects of the prior art, the invention provides the hydrogen sensor with the advantages of good selectivity, long service life, good long-term stability, high sensitivity and low measurement lower limit of the conventional palladium alloy thin film resistance sensor and the preparation method thereof. The technical scheme includes that the hydrogen sensor comprises bonding glass and is characterized in that the bonding glass is bonded with the bottom of an SOI substrate to form a whole, the top surface of the SOI substrate is covered with a strain membrane, a palladium alloy film is arranged on the strain membrane, and a Wheatstone bridge for detecting hydrogen concentration is integrated on a working crystal face of the strain membrane. The resistance of the Wheatstone bridge adopts a monocrystalline silicon thin film resistor. And the strain diaphragm is also provided with a heating resistor and a temperature measuring resistor. And acquiring a temperature measuring resistance value in real time, making a difference between the temperature measuring resistance value and a set value, taking the difference value as input of a PID controller, obtaining an output value positively correlated with current, and applying the output value to the heating resistance to realize constant temperature control of the hydrogen sensor. The thickness of the heating resistor and the temperature measuring resistor is 50nm-500nm. The change rate of the resistance values of the resistors of the Wheatstone bridge is as follows: ; Wherein, the y,x The longitudinal pressure and the transverse pressure at the strain diaphragm measuring point are respectively, R 1、R2、R3、R4 is four resistors of a Wheatstone bridge, the connecting point of R 1、R3 is connected with the power supply anode, the connecting point of R 2、R4 is connected with the power supply cathode, and pi 44 is the pressure group coefficient of monocrystalline silicon. The thickness of the SOI substrate is 300um-1000um. The thickness of the strain membrane is 20um-100um. A method of manufacturing a hydrogen sensor according to any one of claims 1 to 8, comprising: Selecting an SOI wafer, and carrying out high-concentration B doping on the top monocrystalline silicon by adopting an ion implantation technology to obtain an SOI substrate; Etching the resistor strip by using an inductively coupled plasma dry etching technology to form a piezoresistor strip taking the monocrystalline silicon layer as a strain resistor, and exposing an SiO 2 insulating layer in a region except the piezoresistor strip; Photoetching a hydrogen sensitive graph on the SiO 2 insulating layer, and depositing a palladium alloy film as a hydrogen sensitive graph block; photoetching a lead groove and a bonding pad, and depositing a Ni-Au film as an electrode; etching a window on the back of the SOI substrate by photoetching, and etching a silicon cup by a dry method; And carrying out electrostatic seal