阅读说明：本技术 一种基于硅导电的mems电化学振动传感器敏感电极及其制造方法 (MEMS electrochemical vibration sensor sensitive electrode based on silicon conduction and manufacturing method thereof ) 是由 陈德勇 陈明惟 王军波 刘博文 梁天 齐文杰 钟安详 段语默 于 2021-09-08 设计创作，主要内容包括：本发明公开一种基于硅导电的MEMS电化学振动传感器敏感电极及其制造方法。所述电极包括：基底；基底正背面绝缘层；正面绝缘层包括绝缘设置的第一区域和第二区域；背面绝缘层包括绝缘设置的第三区域和第四区域；第一区域和第三区域包括阳极接入面,每个阳极接入面上有阳极电压接入处和至少一个阳极接入孔；第一阴极形成于第二区域上；多个流道孔位于第二区域内；阳极接入孔和流道孔贯穿正背面绝缘层和基底；第二阴极,形成于第四区域上；流道孔侧壁阳极,形成于流道孔的内侧壁上,分别与第一阴极、第二阴极绝缘设置。使用硅导电的引线方式,无需占用硅片表面面积将每一个流孔侧壁的阳极引出,增加硅片表面的阴极面积,提高器件灵敏度。(The invention discloses a sensitive electrode of a silicon-conduction-based MEMS (micro-electromechanical system) electrochemical vibration sensor and a manufacturing method thereof. The electrode includes: a substrate; a substrate front and back insulating layer; the front insulating layer comprises a first area and a second area which are arranged in an insulating mode; the back insulating layer comprises a third area and a fourth area which are arranged in an insulating mode; the first area and the third area comprise anode access surfaces, and each anode access surface is provided with an anode voltage access position and at least one anode access hole; the first cathode is formed on the second region; a plurality of flow channel holes are located in the second region; the anode access hole and the flow passage hole penetrate through the front and back insulating layers and the substrate; a second cathode formed on the fourth region; and the anode of the side wall of the runner hole is formed on the inner side wall of the runner hole and is respectively arranged in an insulating way with the first cathode and the second cathode. By using a silicon conductive lead mode, the anode of the side wall of each flow hole is led out without occupying the surface area of the silicon wafer, the cathode area of the surface of the silicon wafer is increased, and the sensitivity of a device is improved.)

1. The sensitive electrode of the MEMS electrochemical vibration sensor based on silicon conduction is characterized by comprising a substrate, a first insulating layer, a second insulating layer, a plurality of flow channel holes, a first cathode, a flow channel hole side wall anode, a second cathode, an anode access hole and an anode voltage access position;

the substrate has a first surface and a second surface opposite to each other;

a first insulating layer formed on the first surface;

a second insulating layer formed on the second surface;

the first insulating layer is divided into a first area and a second area which are arranged in an insulating mode; the first region comprises a plurality of anode access surfaces;

the second insulating layer is divided into a third area and a fourth area which are arranged in an insulating mode; the third region comprises a plurality of anode access faces;

each anode access surface is provided with an anode voltage access part;

in the first region, each anode access surface is provided with at least one anode access hole penetrating to the anode access surface of the third region, and the anode access hole penetrates through the first insulating layer, the substrate and the second insulating layer;

the first cathode is formed on the second area, and an insulating ring distributed along the periphery of the runner hole is arranged between the first cathode and the runner hole;

a plurality of flow channel holes in the second region, the flow channel holes penetrating through the first insulating layer, the substrate and the second insulating layer, the flow channel holes being in the fourth region at an exit of the second insulating layer;

the second cathode is formed on the fourth area, and an insulating ring distributed along the periphery of the runner hole is arranged between the second cathode and the runner hole;

and the anode of the side wall of the runner hole is formed on the inner side wall of the runner hole and is respectively arranged in an insulating way with the first cathode and the second cathode.

2. The sensing electrode of claim 1, wherein the interior sidewall of the anode access hole is sputtered with metal.

3. The sensing electrode of claim 1, wherein the metal is Pt.

4. The sensing electrode of claim 1, wherein the insulating layer material is selected from silicon oxide or silicon nitride.

5. The sensing electrode of claim 1, wherein the flow channel aperture distribution is circular or square.

6. The sensing electrode of claim 1, wherein the substrate is a silicon wafer; preferably, the silicon wafer is selected from N-type silicon or P-type silicon.

7. The sensing electrode of claim 1, wherein the anode access surface has a metal layer thereon; the inner side wall of the anode access hole is provided with a metal layer; and the metal on the inner side wall of the anode access hole is connected with the metal on the surface of the anode voltage access position.

8. A method for manufacturing a sensing electrode according to any of claims 1-7, comprising the steps of:

step (1): selecting and cleaning a substrate;

step (2): respectively forming a first insulating layer and a second insulating layer on the first surface and the second surface of the substrate;

and (3): photoresist is used, photoresist spinning, prebaking, exposure and development are carried out on the first insulating layer, and a first area and a second area which are separated by an insulating tape and a plurality of anode access surfaces which are arranged on the first area in an insulating mode are formed;

and (4): growing a first cathode metal layer on the second region of the first insulating layer; simultaneously growing metal layers on a plurality of anode access surfaces of the first region respectively;

and (5): removing the metal on the photoresist and the glue to form a first cathode and an anode access surface with a metal layer;

and (6): photoresist is used, spin coating, prebaking, alignment and development are carried out on the second surface of the substrate, the technological parameters are consistent with those in the step (3), and a third area and a fourth area which are separated by an insulating tape and a plurality of anode access surfaces which are arranged on the third area in an insulating mode are formed;

and (7): growing a second cathode metal layer on a fourth region on the second insulating layer; simultaneously growing metal layers on the plurality of anode access surfaces of the third area respectively;

and (8): removing the metal on the photoresist and the glue to form a second cathode and an anode access surface with a metal layer;

and (9): photoresist is used, spin coating, prebaking, front alignment and developing are carried out on the first insulating layer;

step (10): etching the first insulating layer by taking the photoresist in the step (9) as a mask, then etching the substrate, and finally etching the second insulating layer to form a flow channel hole and an anode access hole;

step (11): exposing and developing on the first insulating layer by using a dry film, and covering the first cathode pattern and the position of the insulating arrangement; the anode access hole and the anode access position need to be completely exposed, so that metal on the side wall of the anode access hole and the surface of the anode access position are fully connected during sputtering;

step (12): sputtering metal from the first insulating layer using a sputtering process;

step (13): removing the dry film and the metal to form a runner hole side wall anode; and simultaneously, completing the metal connection from the anode access position to the substrate to form a passage from the voltage access position to the anode of the electrolyte for reaction.

9. The method of claim 8, wherein the insulating layer is fabricated using a thermal oxygen process or deposited using a PECVD method; preferably, in step (8), the second cathode metal pattern is identical to the first cathode metal pattern.

10. A MEMS electrochemical vibration sensor based on silicon conduction, comprising a sensing electrode according to any of claims 1 to 7 or manufactured by the method according to any of claims 8 to 9.

Technical Field

The invention relates to the field of MEMS sensors and the field of low-frequency vibration measurement, in particular to the field of MEMS process manufacturing, and specifically relates to a sensitive electrode of an MEMS electrochemical vibration sensor based on silicon conduction and a manufacturing method thereof.

Background

Vibration sensors based on various principles have been developed. According to different working principles, the vibration sensors can be divided into a piezoelectric accelerometer, an optical fiber sensor, an electrochemical vibration sensor and the like, except the electrochemical vibration sensor, the vibration sensing units of the vibration sensors use precision mechanical parts as inertial mass, and the problems of large volume, heavy weight and the like of devices exist.

The core unit of the electrochemical vibration sensor consists of a sensitive electrode, electrolyte and the like. The sensitive electrode mainly adopts an anode-cathode-anode arrangement mode, and the electrolyte contains KI and I₂In which I^-Loss of electron generation at the anode I₃ ^-And I is₃ ^-Electron generation I at the cathode^-. When the external vibration is carried out, ions flow relative to the electrodes, so that the ions between the two positive and negative electrodes are unbalanced, the output current is unbalanced, the amplitude and the frequency of the vibration can be obtained by detecting the unbalanced current, and the working principle of the electrochemical vibration sensor is realized. Therefore, the manufacturing quality of the sensitive electrode of the electrochemical vibration sensor is related to important performances such as sensitivity of the device.

At present, MEMS (Micro-Electro-Mechanical-System) sensitive electrode structures mainly comprise two types, namely an ACCA (anode collector and cathode collector) four-electrode structure and a CAC three-electrode structure, and the sensitivity of the sensor is improved by changing the distance between the anode and the cathode of the MEMS sensitive electrode, increasing the area of the cathode and the like. The electrode aligns two-layer chips from the early manual alignment of seven layers of porous plates to the wafer-level bonding, and finally monolithic integration is realized, so that the integration level of the electrode is improved.

How the electrodes are wired is an important issue while reducing the number of chips. Each layer of platinum electrode of the multilayer chip covers the surfaces of different chips, and voltage can be conveniently connected from leads on the surfaces of the chips. A pair of anode and cathode of the ACCA structure sensitive electrode integrated on a chip need to be manufactured on the same surface, and the anode surrounds the cathode (or the cathode surrounds the anode), so that a complex metal line needs to be sputtered on the surface of the chip to connect the surrounded electrode to a peripheral voltage access point lead; the CAC structure sensitive electrode integrated on a chip is an arrangement form of a front cathode, a middle anode and a back cathode, the anodes are distributed on the side walls of independent runner holes, and complex metal lines are sputtered on the surfaces to connect the anode of each runner hole to the surface of the chip and lead wires outside. The method of sputtering complicated metal lines on the surface of the chip to connect the dispersed electrodes for leading increases the complexity of the process and reduces the utilization rate of the surface area of the chip. Therefore, the invention provides a lead mode of using the support layer for silicon conduction, the electrode does not need to be led from the surface, the process is simplified, and the effective electrode area on the surface of the chip is increased.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to provide a sensitive electrode of an MEMS (micro-electromechanical system) electrochemical vibration sensor based on silicon conduction and a manufacturing method thereof, which solve the problem of an integrated sensitive electrode lead, reduce the process steps, increase the cathode area, optimize the size parameters of the electrode and improve the sensitivity of the sensor.

The invention adopts the following technical means:

a sensitive electrode of a silicon-conduction-based MEMS (micro-electromechanical system) electrochemical vibration sensor comprises a substrate, a first insulating layer, a second insulating layer, a plurality of flow channel holes, a first cathode, a flow channel hole side wall anode, a second cathode, an anode access hole and an anode voltage access position.

The substrate has a first surface and a second surface opposite to each other;

a first insulating layer formed on the first surface;

a second insulating layer formed on the second surface;

the first insulating layer is divided into a first area and a second area which are arranged in an insulating mode; wherein the first region comprises a plurality of anode access faces.

The second insulating layer is divided into a third area and a fourth area which are arranged in an insulating mode; the third region includes a plurality of anode access faces. And the plurality of anode access surfaces on the third area are arranged in an insulated manner or not.

Each anode connection surface has an anode voltage connection.

In the first region, each anode access surface is provided with at least one anode access hole penetrating to the anode access surface of the third region, and the anode access hole penetrates through the first insulating layer, the substrate and the second insulating layer.

The first cathode is formed on the second area, and an insulating ring distributed along the periphery of the runner hole is arranged between the first cathode and the runner hole;

and the flow channel holes are positioned in the second area, penetrate through the first insulating layer, the substrate and the second insulating layer, and are positioned in the fourth area at the outlet of the second insulating layer.

And the second cathode is formed on the fourth area, and an insulating ring distributed along the periphery of the runner hole is arranged between the second cathode and the runner hole.

And the anode of the side wall of the runner hole is formed on the inner side wall of the runner hole and is respectively arranged in an insulating way with the first cathode and the second cathode.

Preferably, the anode access surface of the first region and the anode access surface of the third region are patterned in a uniform manner.

Furthermore, the anode on the side wall of the runner hole is respectively arranged with the first cathode and the second cathode in an insulating way through insulating rings distributed along the periphery of the runner hole.

Further, the mutual insulation arrangement is realized by an insulation tape. The insulating tape is a silicon oxide or silicon nitride insulating tape. The first and second regions of the first insulating layer are insulated from each other by an insulating tape, for example. The third area and the fourth area of the second insulating layer are mutually insulated by an insulating tape. The first region includes a plurality of anode access faces spaced apart by insulating tape which provides surface insulation between the plurality of anode access faces, the anode access faces being connected to the silicon substrate by an anode access hole metal.

The third region comprises two anode access faces separated by an insulating strip, which provides surface insulation between the plurality of anode access faces.

Further, the inner side wall of the anode access hole is sputtered with metal; preferably, the metal is Pt.

Further, the insulating layer material is selected from silicon oxide or silicon nitride.

Further, the distribution of the flow passage holes is circular or square.

Further, the substrate is a silicon wafer; preferably, the silicon wafer is selected from N-type silicon or P-type silicon.

Further, the anode voltage connection is located on the anode connection surface. The anode access surface is provided with a metal layer; the inner side wall of the anode access hole is provided with a metal layer. And the metal on the inner side wall of the anode access hole is connected with the metal on the surface of the anode voltage access position. Preferably, the metal of the inner wall of the anode access hole is directly connected with the metal of the surface of the anode voltage access. For example, the metal layer is a Pt layer, preferably, the Pt layer has a thickness ofThe metal layer can also be a Pt layer and a Ti or Cr layer sandwiched between the Pt layer and the anode access surface, and the Pt layer is preferably as thick asThe thickness of the Ti or Cr layer is

Furthermore, the anode and the first cathode on the side wall of the runner hole are insulated by the insulating ring coated around the runner hole.

Furthermore, the anode and the second cathode on the side wall of the runner hole are insulated by the insulating ring coated around the runner hole.

Further, the insulating ring material is selected from silicon oxide or silicon nitride.

A method for manufacturing a sensing electrode as described in any one of the above, comprising the steps of:

step (1): selecting and cleaning a substrate;

step (2): respectively forming a first insulating layer and a second insulating layer on the first surface and the second surface of the substrate;

and (3): photoresist is used, photoresist spinning, prebaking, exposure and development are carried out on the first insulating layer, and a first area and a second area which are separated by an insulating tape and a plurality of anode access surfaces which are arranged on the first area in an insulating mode are formed;

and (4): growing a first cathode metal layer on the second area of the first insulating layer, and simultaneously growing metal layers on the plurality of anode access surfaces of the first area respectively;

and (5): removing the metal on the photoresist and the glue to form a first cathode and an anode access surface with a metal layer;

and (6): photoresist is used, spin coating, prebaking, alignment and development are carried out on the second surface of the substrate, the technological parameters are consistent with those in the step (3), and a third area and a fourth area which are separated by an insulating tape and a plurality of anode access surfaces which are arranged on the third area in an insulating mode are formed;

and (7): growing a second cathode metal layer on a fourth region on the second insulating layer; simultaneously growing metal layers on the plurality of anode access surfaces of the third area respectively;

and (8): removing the metal on the photoresist and the glue to form a second cathode and an anode access surface with a metal layer;

and (9): photoresist is used, spin coating, prebaking, front alignment and developing are carried out on the first insulating layer;

step (10): etching the first insulating layer by taking the photoresist in the step (9) as a mask, then etching the substrate, and finally etching the second insulating layer to form a flow channel hole and an anode access hole;

step (11): exposing and developing on the first insulating layer by using a dry film, and covering the first cathode pattern and the position of the insulating arrangement; the anode access hole and the anode access position need to be completely exposed, so that metal on the side wall of the anode access hole and the surface of the anode access position are fully connected during sputtering;

step (12): a sputtering process is used to sputter metal from the first insulating layer. Preferably, a Ti or Cr layer is sputtered first, followed by a Pt layer; preferably, the Ti or Cr layer has a thickness ofPreferably, the Pt layer is thick

Step (13): removing the dry film and the metal to form a runner hole side wall anode; and simultaneously, completing the metal connection from the anode access position to the substrate to form a passage from the voltage access position to the anode of the electrolyte for reaction.

Further, the insulating layer is fabricated using a thermal oxygen process or deposited using a PECVD method.

Further, the first cathode metal layer grown in the step (4) and the second cathode metal layer grown in the step (7) are respectively subjected to an electron beam evaporation process.

Further, in the step (8), the second cathode metal pattern is identical to the first cathode metal pattern.

Further, the shape of the flow passage hole is square or circular.

The invention also provides a silicon conduction-based MEMS electrochemical vibration sensor, which comprises the sensitive electrode or the sensitive electrode manufactured by the method.

The invention has the beneficial effects that:

(1) the structure of cathode-anode-cathode is used, the mode of integrating all electrodes by using a single silicon chip is adopted, and multiple pairs of electrodes do not need to be aligned manually when devices are assembled later, so that the assembly difficulty is reduced.

(2) The consistency error of the electrode structure is only generated during the MEMS process, and the consistency of the device is improved.

(3) By using a silicon conductive lead mode, the anode of the side wall of each flow hole is led out without occupying the surface area of the silicon wafer, the cathode area of the surface of the silicon wafer is increased, and the sensitivity of a device is improved.

(4) By using the lead wire mode of silicon conduction, complicated metal lines do not need to be sputtered on the surface, the problem that part of anode flow holes are not utilized due to the fact that the lead wire part on the surface is not led out possibly in the process manufacturing is solved, the complexity of process patterns is reduced, the process steps are reduced, and the sheet forming rate is improved.

(5) The present invention demonstrates the feasibility of using silicon for the introduction of electrode voltage, providing a means for the lead problem in the design of electrode structures to follow.

Drawings

FIG. 1 is a MEMS sensitive electrode structure based on silicon conduction;

figure 2 is a process flow diagram of a MEMS sensitive electrode structure based on silicon conduction.

In the figure, 101: an anode access hole; 102: anode voltage access 1; 103: an anode voltage access 2; 104: a front cathode; 105: an insulating layer; 106 sensitive unit flow channel holes; 107: anode on the side wall of the flow channel; 108 low resistance silicon; 109: a back cathode; 110: and a flow passage.

Detailed Description

The invention is described in detail below with reference to the figures and the embodiments. The following examples are only for explaining the present invention, the scope of the present invention shall include the full contents of the claims, and the full contents of the claims of the present invention can be fully realized by those skilled in the art through the following examples.

Fig. 1 is a general schematic and cross-sectional view of a silicon-based conductive sensing electrode as proposed by the present invention. As shown in fig. 1, the present invention provides a MEMS sensitive electrode structure based on silicon conduction, which includes a substrate, a first insulating layer, a second insulating layer, a plurality of sensitive unit flow channel holes 106, a front cathode 104, a flow channel sidewall anode 107, a back cathode 109, an anode access hole 101, an anode voltage access point 1102, and an anode voltage access point 2103. The substrate may be a silicon wafer. In one embodiment of the invention, the substrate is low resistivity silicon 108. The insulating layer 105 includes a first insulating layer and a second insulating layer. Preferably, the insulating layer material is selected from silicon oxide or silicon nitride.

The first insulating layer is formed on the front surface of the substrate, and the second insulating layer is formed on the back surface of the substrate. The number of the sensing unit flow channel holes 106 is plural, and the sensing unit flow channel holes 106 penetrate through the first insulating layer, the substrate and the second insulating layer. The sensing unit flow channel hole 106 is an anode hole.

The first insulating layer is divided into a first region and a second region which are arranged to be insulated from each other. The first and second regions of the first insulating layer are separated by an insulating tape.

Wherein the first region comprises two anode access faces separated by an insulating tape, wherein one of the anode access faces has an anode voltage access 1102 and at least one anode access hole 101; the other anode access face has an anode voltage access 2103 and at least one anode access hole 101.

The second insulating layer is divided into a third region and a fourth region which are arranged in an insulating manner, and the third region and the fourth region are separated by an insulating tape. The third region comprises two anode connection surfaces separated by an insulating strip, each anode connection surface having an anode voltage connection. Preferably, the anode access surface pattern on the first area and the anode access surface pattern on the third area coincide.

In the first region, the anode access hole 101 penetrates to the third region anode access surface. The anode access hole 101 penetrates the first insulating layer, the substrate, and the second insulating layer.

Each anode access surface has a metal layer thereon; the anode access hole 101 has a metal layer on its sidewall. The metal of the anode access hole 101 side wall in the same anode access plane is connected to the metal of the anode voltage access surface. For example, the metal layer on the anode access face is the same as the metal layer on the sidewall of the anode access hole 101, and the metal layer is a Pt layer, preferably the Pt layer has a thickness of The metal layer can also be a Pt layer and a Ti or Cr layer sandwiched between the Pt layer and the anode access surface, and the Pt layer is preferably as thick asThe thickness of the Ti or Cr layer is

The second region is provided with a front cathode 104, and an insulating ring distributed along the periphery of the flow channel hole 106 is arranged between the front cathode 104 and the sensitive unit flow channel hole 106.

The runner sidewall anode 107 is formed on the inner sidewall of the sensing unit runner hole 106 and is separated from the front cathode 104 and the back cathode 109 by an insulating ring. The insulating ring is wrapped around the sensitive unit flow channel hole 106, and the radial width of the insulating ring is 20 um.

A back cathode 109 formed on the fourth region of the second insulating layer and spaced apart from the runner sidewall anode 107 by an insulating ring.

The sensing unit flow channel hole 106 is a flow channel of the electrolyte solution. Preferably, the front cathode 104 and the back cathode 109 are patterned identically.

The first insulating layer, the second insulating layer, the insulating tape, and the insulating ring may be made of silicon oxide or other materials such as silicon nitride.

The sensing electrode is mainly composed of three electrodes arranged in the form of cathode 104-anode 107-cathode 109 and insulating layer 105 between the electrodes, and the electrodes are Pt electrodes fixed in the flow channel 110 filled with electrolyte solution. The flow channel 110 refers to the flow channel 110 where the sensing electrode is located when being packaged, as shown in fig. 1. The electrolyte solution fills the anode pores and is distributed over the surface of the front cathode 104, the surface of the back cathode 109 and the surface of the anode 107. According to the invention, 0.3V voltage is connected to an anode voltage connection part 1(102), the voltage is introduced into low-resistance silicon 108 through Pt sputtered on the side wall of an anode connection hole 101, the low-resistance silicon 108 conducts electricity and is transmitted to an anode 107 on the side wall of a flow channel, and two cathodes are directly led out from the front side and the back side respectively. By measuring the resistance between the anode voltage tap 1(102) and tap 2(103), the input resistance of the 0.3V voltage from tap to anode 107 can be approximately characterized.

By the method for connecting the supporting layer silicon to the anode voltage, the problem that the electrode needs to be provided with patterns from the surface and sputter metal leads is solved, the complexity of the process is reduced, meanwhile, the surface does not need to occupy the area of the cathode, the utilization rate of the surface area is increased, and the area of the cathode is increased. When a voltage difference exists between the anode and the cathode, ions in the electrolyte solution respectively react at the anode and the cathode, and the charge transfer between the anode and the cathode is completed. When the electrolyte solution has mechanical motion, the ion distribution around the electrode is unbalanced, so that the current output of the two cathodes is unbalanced, and the electric signal proportional to the external input motion signal can be obtained by calculating the differential current output by the cathodes.

Fig. 2 is a MEMS process flow diagram of the sensing unit of the electrochemical vibration sensor proposed by the present invention. The method comprises the following specific steps:

step (1): selecting four inches of silicon wafer with resistivity of 0.0015 omega-cm and thickness of 200 μm, boiling acid and water, and cleaning the silicon wafer. The silicon wafer is low-resistance silicon 108.

Step (2): silicon oxide with a thickness of 700nm is grown on the surface of the silicon wafer as the insulating layer 105 by a thermal oxygen method.

And (3): and after the silicon wafer is cleaned by oxygen, a positive photoresist AZ1500 is used, and spin coating, prebaking, exposure and development are carried out on the front side of the silicon wafer. A first region, a second region and a plurality of anode access surfaces are formed on the first region, the anode access surfaces are separated by an insulating tape.

And (4): growing Ti on the front surface of a silicon wafer by using an electron beam evaporation processPt

And (5): a lift-off process using acetone removes the metal from the photoresist and the photoresist, leaving the metal as the front cathode 104 and the anode access surface with the metal layer.

And (6): and after the silicon wafer is cleaned by oxygen, a positive photoresist AZ1500 is used, spin coating, prebaking, back alignment and developing are carried out on the back of the silicon wafer. The technological parameters are the same as those in the step (3). Forming a third area, a fourth area separated by an insulating tape, and a plurality of anode access surfaces arranged on the third area and insulated from each other.

And (7): growing Ti on the back of a silicon wafer by using an electron beam evaporation processPt

And (8): and (3) removing the metal on the photoresist and the metal on the photoresist by using acetone, leaving the metal as the back cathode 109, wherein the metal pattern is completely consistent with the front side, and the consistency of the structures of the two cathodes is ensured. Simultaneously, an anode access face with a metal layer is formed.

And (9): and (3) using a positive photoresist AZ4620 to spin on the front surface of the silicon wafer, prebaking, etching the front surface and developing.

Step (10): and (4) taking the photoresist in the step (9) as a mask, etching the silicon oxide on the front side by using a Reactive Ion Etching (RIE) process, etching the silicon by using a Deep Reactive Ion Etching (DRIE) process, and finally etching the silicon oxide on the back side by using the RIE process to form a sensitive unit flow channel hole (106) and an anode access hole. The remaining photoresist was removed using acetone.

Step (11): and exposing and developing the front surface of the silicon wafer by using a dry film, and covering the pattern of the front cathode 104 and the position of the insulating ring. The anode access hole 101 and the anode voltage access points (102, 103) need to be fully exposed so that the metal of the anode access hole 101 sidewall and the access voltage surface (102, 103) is fully connected during sputtering.

Step (12): sputtering Ti from the front side of a silicon wafer using a sputtering processPt

Step (13): stripping with NaOH solution removes the dry film and metal, leaving the anode 107 on the side wall of the sensitive cell flow channel hole 106. And metal connection of anode voltage access points (102, 103) to the low-resistance silicon 108 is completed at the same time, and a path from the voltage access point 102 to an anode 107 where the electrolyte reacts is formed.

In some embodiments of the present invention, the insulating layer material may be silicon nitride or other materials;

in some embodiments of the present invention, the silicon oxide of the insulating layer may be formed using a thermal oxidation process or may be deposited using a PECVD method.

In some embodiments of the present invention, the shape of the flow channel holes may be square, and the distribution of the flow channel holes in the flow channel portion of the chip may be circular or square. In some embodiments of the present invention, the transition electrode material Ti may also use other metals that are not easily released from the silicon surface, such as Cr, etc.

In some embodiments of the present invention, the silicon wafer used may be either N-type silicon or P-type silicon.

The invention has not been described in detail and is part of the common general knowledge of a person skilled in the art. The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and the preferred embodiments are not exhaustive and do not limit the invention to the precise embodiments described. Various modifications and improvements of the technical solution of the present invention may be made by those skilled in the art without departing from the spirit of the present invention, and the technical solution of the present invention is to be covered by the protection scope defined by the claims.