CN114572930A

CN114572930A - Micro-scale flow heat exchange high-precision integrated test method based on MEMS (micro-electromechanical systems) process

Info

Publication number: CN114572930A
Application number: CN202210206942.XA
Authority: CN
Inventors: 徐天彤; 李海旺; 方卫东; 陶智; 吴瀚枭; 李沐润
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2022-06-03
Anticipated expiration: 2042-03-03
Also published as: CN114572930B

Abstract

The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process comprises the following steps: processing an experimental part based on an MEMS (micro-electromechanical system) process; integrating a test system; according to the invention, the in-situ extraction measurement of the pressure measurement point is completed by glass laser drilling and a plasma etching technology of a silicon wafer, so that the local pressure loss is avoided; the temperature coefficient characteristic of the metal resistor is utilized, the temperature of the current thin film thermal resistor is measured through the resistance change, and the thin film thermal resistor is arranged above the heating film, so that the thin film thermal resistor is closer to the wall surface of the channel, and the obtained temperature data is more accurate; through multilayer wafer bonding technology, the glass sheet with the pressure measuring hole, the upper silicon wafer with the microchannel and the temperature measuring thermal resistor and the lower silicon wafer with the heating film are sequentially bonded with multiple wafers respectively, the tightness of the microchannel and the accurate alignment bonding of the silicon surface with the metal film are guaranteed, and the integrated design of pressure measuring, temperature measuring, heating and visualization is finally realized by combining the integration of a test system.

Description

Micro-scale flow heat exchange high-precision integrated test method based on MEMS (micro-electromechanical systems) process

Technical Field

The invention relates to a testing method, in particular to a micro-scale flow heat exchange high-precision integrated testing method based on an MEMS (micro-electromechanical systems) process.

Background

Technological progress brings the development of integration, microminiaturization and compaction of various devices, and a micro electro mechanical system becomes a new technical field and shows great superiority, and is widely applied to the aspects of energy power, biomedical treatment, information communication and the like. In order to meet the requirements of efficient heat transfer, mass transfer and various chemical reactions, a great deal of research is carried out on various effects of the micro-channel, such as hydraulic diameter, aspect ratio, roughness, surface structure, surface modification and the like by a plurality of scholars, but the different research results have great difference, and the conclusions of the scholars even have contradictions.

This phenomenon is due to the fact that the test method in the field of micro-scale flow heat exchange is not perfect enough, and the traditional test method has large errors in the experimental test of micro-flow. Therefore, the development and establishment of a set of micro-scale flow heat exchange integrated test technology based on the MEMS process are very important, and the standard test technology with complete standards can bring standardized experimental data, obtain a unified research conclusion according with scientific laws, and generate advanced and practical scientific achievements.

The common micro-scale flow pressure drop test method is that pressure measuring pipelines are led out from inlet and outlet pipelines, and the additional pressure difference caused by the turning possibly existing in the fluid inlet and outlet and the sudden expansion and the sudden contraction of a channel is corrected according to the traditional empirical relational expression. For example, Ling et al (Ling W, Zhou W, Yu W, et al. Experimental experimental on thermal and hydraulic performance of microchannel with interconnected configuration [ J ]. Energy Conversion and Management,2018,174(OCT.): 439) 452) in the Experimental study of flow Heat transfer Performance for microchannels in staggered configuration the pressure testing method used is shown in FIG. 1, where the pressure points are placed on the piping at the inlet and outlet, which results in a pressure drop measured by the differential pressure transmitter comprising the following parts: (1) frictional losses within the microchannels. (2) Pressure loss due to sudden contraction and expansion of the inlet/outlet manifold channels. (3) Local pressure losses due to the bending of the inlet/outlet manifold channels. The pressure loss of the second and third parts is caused by the inevitable installation of the pipeline, but the pressure loss is not in the research range of the article, and the author corrects the pressure loss by using the traditional empirical relation.

Spizzichino M et al (Spizzichino M, Sinibaldi G, Romano G P. Experimental Investigation on Fluid Mechanics of Micro-Channel Heat Transfer Devices [ J ]. Experimental Thermal and Fluid Science (EXP THERM FLUID SCI),2020,118:110141.) place the sensors at the same location on each cell on the liquid delivery tubing to measure the pressure loading of microchannels of different configurations as the resistance of the syringe pump, as shown in FIG. 2. And finally, obtaining the required micro-channel flow resistance by using an empirical relation.

The common micro-scale heat exchange test method mainly comprises two parts, namely a heating part and a temperature measuring part. For a heating part, the constant heat flow heating scheme can be divided into a constant heat flow scheme and a constant wall temperature scheme, the constant heat flow heating scheme is still found in the temperature measurement scheme of Spizzichino M, a hot plate Stuart US-150 is adopted to maintain the constant heat flow of the temperature measurement scheme, an experiment is in an open environment, temperature measurement points are arranged at the position of 0.5mm in depth of an aluminum plate, three measurement points are used in total, and a K-type thermocouple is used for collecting the temperature measurement points, as shown in figure 3. A constant wall temperature heating scheme is found in Hsieh S (Hsieh S, Lin C Y. structural Heat Transfer in required microchannels with hydro-phobic and hydro-graphical surfaces [ J ]. International Journal of Heat and Mass Transfer,2009,52(1-2):260 plus 270.), where a heater is a 10mm by 20mm aluminum tape micro-heater located on the upper surface of a channel, the lower surface of the channel is cooled with ice blocks as the constant wall temperature, and a single channel is heated with 10 points along the path, as shown in FIG. 4.

The conventional visual measurement of the Micro flow is mainly based on a Micro-PIV test, the Micro-PIV can be directly used for auxiliary observation when the Micro flow condition is only considered, and if the Micro flow heat exchange aspect is involved, an experimental heat loss correction method is generally adopted for calibration.

In the existing micro-scale flow heat exchange test scheme, the four test methods are adopted in large quantity and are respectively used for measuring different parameters required to be obtained by experiments, and through the test methods, numerous scholars obtain many research conclusions to analyze various mechanisms of micro-scale flow heat exchange. However, the integrated test schemes using the above four test methods are rare, and the widely accepted high-precision test schemes are still to be further developed and explored.

The prior art has the following defects

In the current micro-scale flow heat exchange test scheme, two major problems exist. Firstly, the testing precision is not enough, the experimental data is corrected by the traditional empirical relational expression, and certain deviation of the testing is caused. Secondly, integrated measurement is difficult to realize, in a certain experimental test, at most two to three test means are realized, and the integrated measurement of the four schemes mentioned in the above section simultaneously is not realized, so that the information quantity obtained by the experiment is insufficient.

In the existing micro-flow pressure drop experiment, a pressure measuring point of the traditional pressure measuring scheme is generally positioned at a pipeline joint, and the pressure measuring point is led out by utilizing a three-way joint or other connecting means. In the scheme, the pressure measuring point is always away from the inlet of the micro-channel by a certain distance, and even the structure of inevitable turning, sudden expansion, sudden contraction and the like exists between the pressure measuring point and the micro-channel due to the design of sealing connection of the inlet and the outlet. The indirect pressure measurement method causes the pressure drop measured by the differential pressure transmitter to have local pressure losses such as turning, sudden expansion, sudden contraction, pipeline connection and the like besides the concerned friction loss in the micro-channel, and the local pressure losses are irrelevant to a research object and need to be corrected according to a traditional empirical relational expression. The correction relation for micro-scale flow is not clear, and the empirical correction relation has certain error, so that the pressure measurement in the micro-flow at present has the defects of indirect measurement and fuzzy correction.

In current little flow heat transfer experiment, the design of experiment boundary and temperature monitoring is especially important, according to the latest literature research, the test method of current little flow heat transfer experiment still falls into the nest mortar of traditional test method. The method is characterized in that experimental boundary design is firstly carried out, and the experimental boundary design is mainly divided into two parts, wherein the first part is the selection of the experimental boundary. In order to facilitate data processing and rule exploration, a constant heat flow and constant wall temperature boundary is usually adopted in an experiment, the constant heat flow boundary is mainly a heating film on the market, and an ice block or other constant temperature object is usually used as a wall surface of the constant wall temperature boundary. For a heating film purchased in the market, such as a common PI electric heating film, the heating film is formed by compounding a high-temperature environment-friendly flame-retardant material and a heating core made of metal platinum, and the temperature of the heating film has certain nonuniformity. The heating resistance wire of the heating film is generally arranged in a snake-shaped winding manner, and meanwhile, due to the fact that the heat conductivity coefficients of the insulating material and the conductive material are different and the resistance temperature coefficient of metal exists, the heating film has certain temperature nonuniformity inevitably. If a constant temperature object is used as a constant wall temperature boundary, the absolute uniformity of the temperature of the object is difficult to ensure due to factors such as environmental heat exchange and physicochemical property change. The second part is the arrangement of experiment boundaries, the constant heat flow and constant wall temperature boundaries in the experiment are often not directly positioned on the lower surface of the channel and have a certain distance with the testing channel, and the combined action of the temperature redistribution, the longitudinal heat flow and the heat exchange with the surrounding environment and other factors caused by the distance can cause the problems of uneven heat flow distribution and uneven temperature distribution of the constant heat flow boundaries. Secondly, the design of temperature monitoring, the existing temperature measurement is mainly a thermocouple sold in the market and directly arranged on the bottom surface of an experimental part. The main error of the temperature monitoring test scheme is that the temperature measured by the thermocouple is not the wall temperature of the channel, and the arrangement position of the thermocouple is often away from the bottom surface of the channel, so that a certain difference exists between the measured temperature and the real wall temperature, which is one of the important reasons that the experimental data and the numerical simulation result are difficult to unify.

In the existing Micro-flow visualization experiment, Micro-PIV is an important component of visualization measurement, and can measure the instantaneous velocity field of fluid at a Micro scale and display the instantaneous velocity field visually in an image mode. The Micro-PIV extracts fluid velocity field information in the Micro-channel by means of displacement of tracer particles uniformly distributed in a flow field. Compared with the traditional laser Doppler velocimeter and the hot-wire anemometer, the Micro-PIV technology can realize the simultaneous measurement and display of global and local details of the velocity field under the condition of not disturbing the measured flow field. However, the Micro-PIV visual measurement relates to the construction of a light path and the design of a special experiment table, so that the Micro-PIV technology is often subjected to an experiment test independently and is difficult to be carried out simultaneously with other test technologies, and certain difficulty is caused in ensuring the real-time performance and the uniformity of the experiment working condition and in-situ measurement.

Disclosure of Invention

Compared with the existing testing method, the invention provides the micro-scale flow heat exchange testing technology with higher integration degree and higher testing precision, and meets the requirements of integration, in-situ, synchronization, real-time and standardized measurement of the micro-scale flow heat exchange test. By means of a laser cutting technology, in-situ extraction of pressure measuring points is achieved, and additional local pressure loss in a traditional test scheme is eliminated. By means of the MEMS processing technology of the current MEMS, the precision of the arrangement of the heating film and the temperature measuring thermal resistor from the traditional millimeter level is increased to the micron level, the arrangement mode is more reasonable, the accurate heating and in-situ measurement of the channel are realized, and the process design scheme of the MEMS processing is provided. Independently design vacuum heat preservation laboratory bench, optimize traditional Micro-PIV experiment overall arrangement to give the overall arrangement of integrated test laboratory bench, make visual measurement and pressure measurement, temperature measurement go on together, realize the real-time synchronous measurement of each item of test technique, fall to all kinds of unpredictable errors to minimum, its technical scheme as follows:

the micro-scale flow heat exchange high-precision integrated test method based on the MEMS process is characterized in that: the method comprises the following steps:

a first part: processing an experimental part based on an MEMS (micro-electromechanical system) process;

a second part: and (6) testing the integration of the system.

The invention also discloses a micro-scale flow heat exchange high-precision integrated test method based on the MEMS process, which is applied to the micro-scale single-channel flow heat exchange test process.

Has the advantages that:

according to the invention, heating, temperature measurement, pressure measurement and Micro-PIV visual measurement systems in the Micro-channel are organically combined to obtain a high-precision integrated test technology, wherein the vacuum system is used for reducing the heat loss of the surrounding environment while introducing the Micro-PIV visual measurement system.

The invention completes the in-situ extraction measurement of the pressure measuring point by the laser drilling technology of glass and the plasma etching technology of silicon wafers, and avoids local pressure loss such as turning, sudden expansion, sudden shrinkage, pipeline connection and the like.

The invention realizes high coincidence with an ideal constant wall temperature heating mode through the integrated arrangement and the accurate arrangement of the film thermal resistor and the heating film. The temperature of the current thin film thermal resistor is measured through the change of the resistance by utilizing the temperature coefficient characteristic of the resistance of metal, the thin film thermal resistor is arranged above the heating film, so that the thin film thermal resistor is closer to the wall surface of the channel, and the obtained temperature data is more accurate.

According to the invention, through a multilayer wafer bonding technology, polycrystalline circles of two bonding modes of anodic bonding and auxiliary bonding are sequentially bonded on a glass sheet with a pressure measuring hole, an upper silicon sheet with a microchannel and a temperature measuring thermal resistor and a lower silicon sheet with a heating film, wherein the high bonding strength of anodic bonding ensures the sealing property of the microchannel, the low surface unevenness of the auxiliary bonding requires the alignment bonding of the silicon surface with a metal film, and the integration of the two bonding modes ensures the integrated standardized measurement of pressure measuring, temperature measuring and heating of an experimental part.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a staggered configuration microchannel pressure measurement scheme of Ling et al;

FIG. 2Spizzichino M et al's serpentine microchannel manometry scheme;

FIG. 3Spizzichino M et al snakelike microchannel temperature measurement scheme;

FIG. 4Lin C Y. et al, array microchannel thermometry protocol;

FIG. 5 is a schematic diagram illustrating the design of a micro-scale flow heat exchange high-precision integration test technology;

FIG. 6 is a side view of the MEMS-based high-precision integrated heating temperature measurement experimental part according to the present invention;

FIG. 7 is a conceptual diagram illustrating a MEMS-based high-precision integrated heating temperature measurement experimental part according to the present invention;

FIG. 8 is a flow chart of a process for processing a glass sheet of a test piece according to an embodiment of the present invention;

FIG. 9 is a top view of a portion of a processing step one of a glass sheet in an example provided by an embodiment of the invention;

FIG. 10 is a flowchart of a process for processing a silicon wafer on a test piece according to an embodiment of the present invention;

FIG. 11 is a bottom view of a portion of a wafer processing step on a test piece according to an embodiment of the present invention;

FIG. 12 is a bottom view of a portion of a second step of processing a silicon wafer on a test piece according to an embodiment of the present invention;

FIG. 13 is a bottom view of a portion of a silicon wafer on a test piece processed in a three step process in accordance with an embodiment of the present invention;

FIG. 14 is a bottom view of a silicon wafer step on a test piece, illustrating a processing operation according to an embodiment of the present invention;

FIG. 15 is a flowchart of a process for processing a lower silicon wafer of a test piece according to an embodiment of the present invention;

FIG. 16 is a top view of a portion of the front and back side processing steps of the lower silicon wafer of the test piece in accordance with one embodiment of the present invention;

FIG. 17 is a top view of a portion of a second silicon wafer processing step under a test piece in an example provided by an embodiment of the invention;

FIG. 18 is a top view of a portion of a silicon wafer from a test piece during a three step process in accordance with an embodiment of the present invention;

FIG. 19 is a bottom view of a silicon wafer step annealing section of a test piece according to an embodiment of the present invention;

FIG. 20 is a top view of a portion of a lower silicon wafer processing step six of a test piece according to an embodiment of the present invention;

FIG. 21 illustrates anodic bonding of upper silicon and glass layers in accordance with an embodiment of the present invention;

FIG. 22 illustrates an example of an upper silicon-glass layer and a lower silicon layer with auxiliary bonding according to embodiments of the present invention;

FIG. 23 is a schematic diagram of a Honeywell STD820 differential pressure transmitter of an example embodiment of the present invention;

FIG. 24 is a diagram of a self-grinding joint engineering in an example provided by an embodiment of the present invention, where a is a front view, b is a bottom view, c is a top view, and d is an isometric view;

FIG. 25 is a schematic view of a partial installation of a pressure measurement system in an example provided by an embodiment of the invention;

FIG. 26 illustrates an example of a selected microfluidic Coriolis flowmeter BFS3 in accordance with an embodiment of the present invention;

fig. 27 is a schematic view illustrating an overall installation of a pressure measurement system and a mass flow system in an example provided by the embodiment of the present invention;

FIG. 28 is a schematic diagram of a heating portion lead of a test piece in an example provided by an embodiment of the invention;

FIG. 29 is a schematic view of a lead of a temperature measuring portion of a test piece according to an embodiment of the present invention;

FIG. 30 is a schematic view of an entire experimental part heating and temperature measuring system according to an embodiment of the present invention;

FIG. 31 is a schematic view of an entire thermal insulating system for a test piece according to an embodiment of the present invention;

FIG. 32 is a schematic illustration of a laboratory test piece visualization system installation in an example provided by an embodiment of the present invention;

reference numeral 5:

1-high precision pressure pump;

2-a liquid storage tank;

3-mass flow meter;

4-a MicroPIV system;

5-experimental part;

6-precision power supply

7-a vacuum system;

8-a differential pressure transmitter;

9-a data acquisition system;

10-liquid draining pool

11-multichannel low-power precision resistance tester

12-data processing terminal

Reference numeral 6:

1-a glass cover plate;

2-an upper silicon wafer;

3-thin film thermal resistance;

4-thin film thermal resistance-Au lead Pad;

5-lower layer silicon wafer;

6-thin film thermal resistor-lead through hole;

7-pressure measuring hole

8-a microchannel;

9-heating the film;

10-heating film-Au lead Pad;

11-heating film-Au lead through hole

Reference numeral 7:

1-heating film-Au lead Pad;

2-inlet of micro-channel;

3-a microchannel;

4-pressure measuring hole;

5-thin film thermal resistance-Au lead Pad;

6-microchannel outlet;

reference numeral 9:

1-heating film-Au lead through hole;

2-inlet of micro-channel;

3-microchannel outlet;

4-pressure measuring hole;

reference numeral 11

1: patterning and removing the back lead through hole oxide layer;

reference numeral 12

1: ti adhesion layer/Pt thin film thermal resistor

Reference numeral 13

1: thin-film thermal resistor Au lead Pad

Reference numeral 14

1-front side channel;

2-lead through holes;

FIG. 16 labels

1: patterned removal of front and back via oxide layers

FIG. 17 marks

1: ti adhesion layer/Pt heating film

FIG. 18 label

1: heating film Au lead Pad

FIG. 19 label

1: lower silicon wafer lead through hole

FIG. 20 labels

1: PECVD uncovered part

Reference numeral 25

1-self-lapping joints;

2-silica gel ring;

3-experimental part;

4-microchannel inlet;

5-pressure cell (high pressure);

6-pressure tap (low pressure);

7-microchannel outlet;

reference numeral 27

1-mass flow meter;

2-experimental part;

3-3 mm of outer diameter hose;

4-soft and hard butt luer joint;

5-Honeywell STD820 differential pressure transmitter;

6-cutting sleeve straight reducing joint with outer diameter of 3mm to 4 mm;

reference numeral 28

1-a PCB circuit board;

2-heating film-Au lead Pad;

3-a bonding pad on the PCB;

4-external connection of a lead;

5-wire bonding wire;

reference numeral 29

1-a PCB circuit board;

2-thin film thermal resistance-Au lead Pad;

3-a bonding pad on the PCB;

4-external connection of a lead;

5-wire bonding wire;

reference numeral 31

1-a vacuum box;

2-an air extraction pipeline;

3-external wire guide hole;

4-external pipeline hole and sealing element thereof;

5, putting the box body;

6, discharging the box body;

reference numeral 32

1-an object stage;

2-a vacuum box;

3-experimental part;

4-self-lapping joints;

5-bottom microscope objective;

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to the patent invention scheme, an example of a micro-scale flow heat exchange high-precision integrated test technology design scheme based on an MEMS process is provided, and respective corresponding processing schemes are provided. In terms of design, the test technique consists of two parts, the first part is the experimental piece processing based on the MEMS process (as shown in fig. 5), and the second part is the integration of the test system (as shown in fig. 6).

The processing design of the experimental part is completed by bonding three layers of wafers, wherein the three layers of wafers are a glass sheet (shown as 1 in fig. 5), an upper silicon sheet (shown as 2 in fig. 5) and a lower silicon sheet (shown as 5 in fig. 5) from top to bottom, and the bonding modes are silicon-glass anodic bonding (shown as fig. 21) and silicon-silicon auxiliary bonding (shown as fig. 22). Laser drilling (as shown in fig. 9) is mainly performed in the glass sheet, the upper silicon sheet is mainly provided with an upper micro-channel (as shown in 8 in fig. 5), a lead through hole (as shown in 11 in fig. 5) and a bottom magnetron sputtering thin film thermal resistor (as shown in 3 in fig. 5), and the lower silicon sheet is mainly provided with an upper magnetron sputtering heating film (as shown in 9 in fig. 5). The resistivity of platinum is 10.7 mu omega cm and the resistivity of gold is 2.26 mu omega cm by consulting the data; platinum Temperature Coefficient of Resistance (TCR) of 3.9 x 10^-3/° c; gold Temperature Coefficient of Resistance (TCR) of 8.3 x 10^-3V. C. The size of the micro-channel in the upper silicon chip is 300 micrometers multiplied by 3.5cm, the substrate of the thin film thermal resistor adopts Ti as an adhesion layer, the thickness is 70nm, the line width parameter is 16 micrometers, the length of the serpentine loop is 564 micrometers, the thickness is 600nm, the size of the thin film thermal resistor is about 80 micrometers multiplied by 100 micrometers, the estimated resistance value is 6.3 omega, in a lead part (Pad), metal gold is subjected to magnetron sputtering again, the thickness of the thin film is 600nm, the number of the thermal resistors in the example is 8, and the number of the lead parts is 16. The heating film substrate in the lower silicon wafer adopts a first layer which adopts Ti as an adhesion layer, the thickness is 70nm, a magnetron sputtering platinum film is 300 mu m multiplied by 35mm multiplied by 300nm, the expected heating film is 13.8 omega, the number is 3, and the main reason for dividing the heating film into three sections is to reduce the deviation from the constant heat flow heating hypothesis caused by the change of the resistance of the heating film along with the temperature. The above parameters can control the size of the micro-channel and the sputtering parameters of the thin film thermal resistance and the heating film according to the specific needs of the experiment. The silicon-glass anodic bonding mode (as shown in fig. 21) is adopted between the glass sheet and the upper silicon sheet, the sealing of the micro-channel is mainly realized, and the silicon-silicon auxiliary bonding mode (as shown in fig. 22) is adopted between the upper silicon sheet and the lower silicon sheet, and the precise arrangement of the heating film is mainly realized. In the aspect of processing process flow, the experimental part designed by the patent needs to be processed for the upper layer structure, the middle layer structure and the lower layer structure respectively, then silicon-glass anodic bonding and silicon-silicon auxiliary bonding are carried out, and finally the experimental part is cut into single experimental parts. After the processing technology of the experimental part is completed, the integration of a test system is carried out, the connection from a pressure measuring point to a differential pressure transmitter is realized through the switching of pipelines such as a 3D printed self-grinding joint, the connection from a microchannel inlet to a mass flow meter and the connection from a microchannel outlet to a liquid storage tank, the circuit connection of a heating film and a thin film thermal resistor is realized through the mode of lead bonding and PCB circuit board lead welding, the integration of a heat preservation system and other test systems is realized through the design of a vacuum box, the installation of a visual system is realized through the design and the installation of an objective table, the integration of the test system is finally realized through equipment installation and debugging, pipeline connection and the like, and the example design of the micro-scale flow heat exchange high-precision integrated test technology based on the MEMS technology is completed.

The first part of the micro-scale flow heat exchange high-precision integrated test method based on the MEMS process is the processing of an experimental piece based on the MEMS process, and the method specifically comprises the following steps:

1. glass sheet processing flow (as in figure 8)

A 4-inch glass sheet with the thickness of 200 μm (shown in fig. 8) is subjected to laser cutting and punching, lead through holes (1 in fig. 8 and 1 in fig. 9), micro-channel inlets and outlets (2 and 3 in fig. 9) and pressure taps (2 in fig. 8 and 4 in fig. 9) of a lower silicon wafer are processed, the processed glass sheet is subjected to deionized water-acetone-isopropanol-alcohol ultrasonic cleaning (5min) -deionized water, and cutting residual particles, dust and organic matters on the surface of the glass sheet are cleaned.

2. Processing flow of upper silicon wafer (as in FIG. 10)

The method comprises the following steps: a 4 inch 340 μm thick double polished oxidized intrinsic high resistance silicon wafer (as shown in fig. 10) was oxidized to a thickness of 2 um. Cleaning dust and organic matters on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water; coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 2 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; using BOE solution to completely remove the silicon wafer front oxide layer and selectively removing the back through hole and the oxide layer at the alignment mark (as shown in step one and mark 3 in FIG. 10 and as shown in step 1 in FIG. 11); and cleaning the photoresist, dust and organic matters on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-Piranha solution-deionized water on a wet bench.

Step two: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning a magnetron sputtering Ti adhesion layer with the thickness of 70nm to enhance the adhesion of the Pt thin film, and patterning a magnetron sputtering Pt thin film with the thickness of 600nm (as shown in step two and mark 4 in FIG. 10 and as shown in 1 in FIG. 12) as a thin film thermal resistance of the lower surface of the upper silicon wafer (as shown in step two and mark 5 in FIG. 10 and as shown in 1 in FIG. 12); completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

Step three: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning a magnetron sputtering Au thin film with the thickness of 600nm as a lead part of the thin film thermal resistor (as shown in step three and mark 6 in FIG. 10, as shown in 1 in FIG. 13); completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

Step four: annealing at high temperature in a low vacuum or nitrogen environment, wherein the heating rate is 300 ℃/h, the temperature is 600 ℃, the heat preservation time is 4h, natural cooling is carried out, and the electrical property of the film is more stable through metal recrystallization, and meanwhile, the stress of the film is reduced.

Step five: cleaning dust and a natural oxide layer on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-BOE solution for 30 s-deionized water on a wet bench; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; plasma etching is carried out for 300 μm, etching of a front channel is completed (as shown in step five and a mark 7 in fig. 10, and as shown in 1 in fig. 14), and then a lead through hole structure is etched (as shown in step five and a mark 8 in fig. 10, and as shown in 2 in fig. 14); acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

3. Processing flow of lower silicon wafer (as in FIG. 15)

The method comprises the following steps: a 4 inch 500 μm thick double polished oxide intrinsic high resistance silicon wafer (as shown in fig. 15) was oxidized to a thickness of 2 um. Cleaning dust and organic matters on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water; coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 2 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; selectively removing the oxide layer at the front side, the back side through hole and the alignment mark of the silicon wafer by using BOE solution (as shown in step one and mark 3 in FIG. 15, and as shown in step 1 in FIG. 16); and cleaning the photoresist, dust and organic matters on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-Piranha solution-deionized water on a wet bench.

Step two: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning the magnetron-sputtered Ti adhesion layer to a thickness of 70nm (as shown in step two and labeled 4 in FIG. 15 and shown in 1 in FIG. 17) to enhance the adhesion of the Pt thin film, and patterning the magnetron-sputtered Pt thin film to a thickness of 600nm (as shown in step two and labeled 5 in FIG. 15 and shown in 1 in FIG. 17) as a heating film portion of the upper surface of the lower silicon wafer; completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

Step three: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning a magnetron sputtering Au thin film with the thickness of 600nm as a lead part of the heating film (as shown in step three and mark 6 in FIG. 15, as shown in 1 in FIG. 18); completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

Step five: cleaning dust and a natural oxide layer on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-BOE solution for 30 s-deionized water on a wet bench; spin-coating photoresist 8 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; plasma etching the through hole to complete the etching of the lead through hole (as shown in step five and labeled 7 in FIG. 15, as shown in 1 in FIG. 19); acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

Step six: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; PECVD patterned deposited oxide layer SiO₂(shown as step six in fig. 15 and reference numeral 8, and as shown in fig. 20, 1), reducing the parasitic capacitance between the heating film and the thin film thermal resistance during testing, acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

4. Multilayer wafer sequential bonding

The method comprises the following steps: after the structural processing of the glass sheet, the upper silicon wafer and the lower silicon wafer is finished, cleaning dust and a natural oxide layer on the surface of the upper silicon wafer by using alcohol-acetone-alcohol-deionized water-BOE solution for 30 s-deionized water on a wet bench; cleaning dust on the surface of the glass sheet by using alcohol-acetone-alcohol-deionized water; and (3) carrying out silicon-glass anodic bonding on the upper silicon wafer and the glass by using a bonding machine (as shown in figure 21).

Step two: cleaning dust on the surface of the lower silicon wafer by using alcohol-acetone-alcohol-deionized water on a wet bench; performing auxiliary bonding on the glass-upper silicon wafer and the lower silicon wafer by using a bonding machine (as shown in FIG. 22); and cutting the wafer after the processing is finished to obtain a single experimental piece.

The second part of the testing technology of the present invention is the integration of the testing system (as shown in fig. 6), which is divided according to the functions of the testing system, and specifically includes the following contents:

1. installation process of pressure measuring system

The main body of the pressure measuring system consists of a differential pressure transmitter (in this example, Honeywell STD820 is selected, as shown in FIG. 23), a self-grinding joint (as shown in FIG. 24, the processing mode is high-temperature-resistant photosensitive resin 3D printing), a single experimental piece (as shown in FIG. 22, as shown in 3 in FIG. 25) and related pipelines, wherein the single experimental piece is processed.

The method comprises the following steps: the silica gel ring (shown as 2 in fig. 25) purchased from the self-grinding adapter sleeve is respectively bonded with the inlet (shown as 4 in fig. 25), the pressure measuring hole (high pressure) (shown as 5 in fig. 25), the pressure measuring hole (low pressure) (shown as 6 in fig. 25) and the outlet (shown as 7 in fig. 25) of the micro-channel by using epoxy resin system adhesive, and the connection mode is shown in fig. 25.

Step two: the above-mentioned connected experimental part (as shown in fig. 25), differential pressure transmitter (as shown in fig. 23) and mass flowmeter (as shown in fig. 26, as shown in fig. 27, 1) are connected by pipeline, wherein the process joint of the differential pressure transmitter is quickly inserted by converting 1/4NPT into a hard pipe with an outer diameter of 4mm, the pipeline connection between the experimental part adopts a self-grinding joint-a hose with an outer diameter of 3mm (as shown in fig. 27, 3) -a soft-hard butt luer joint with an outer diameter of 3mm, hard pipe-a straight-through reducing joint with an outer diameter of 3mm, hard pipe-a clamping sleeve with an outer diameter of 4mm (as shown in fig. 27, 4), 6) -a hard pipe-differential pressure transmitter with an outer diameter of 3mm, and the pipeline connection part of the self-grinding joint is a standard pagoda joint, so that the above-mentioned hose with an outer diameter of 3mm can be used.

2. Installation process of mass flow system

The method comprises the following steps: the process connection of the mass flow meter (in this example, the microfluidic coriolis flow meter BFS3 is selected, as shown in fig. 26, and as shown in fig. 27, 1) is a 3mm ferrule connection, so that the pipeline connection is a mass flow meter-a 3mm outer diameter hard tube-a 3mm outer diameter soft tube-a 3mm outer diameter hard tube-a soft and hard butt luer connection (as shown in fig. 27, 4) -a 3mm soft tube (as shown in fig. 27, 3) -a self-grinding connection, thereby completing the pipeline installation of the mass flow system.

3. Installation process of heating temperature measurement system

The method comprises the following steps: in the first part of the experimental part processing, the precise heating film and the thermometric thermal resistance are already arranged at the bottom of the single channel, and the Pad of the lead is given (as shown in 2 in fig. 28), so the experimental part is firstly installed on the PCB circuit board (as shown in 1 in fig. 28) and is leaded to the front side, the Pad (as shown in 3 in fig. 28) on the PCB circuit board and the heating film-Au lead Pad (as shown in 2 in fig. 28) on the front side of the experimental part are connected by using the lead bonding method (as shown in 5 in fig. 28), and then the external lead (as shown in 4 in fig. 28) is welded to the adjacent Pad (the corresponding Pad in the designed PCB circuit board is conducted to ensure that the external lead is conducted with the corresponding heating film-Au lead Pad), and the positive and negative poles are totally three groups, as shown in fig. 28.

Step two: after the front side is leaded, the back side is leaded to the installed experimental part, a bonding Pad (shown as 3 in fig. 29) on a PCB (shown as 1 in fig. 29) and a thin film thermal resistor-Au lead Pad (shown as 2 in fig. 29) on the back side of the experimental part are connected by using a lead bonding method (shown as 5 in fig. 29), and then an external lead (shown as 4 in fig. 29) is welded on an adjacent bonding Pad (the corresponding bonding Pad in the designed PCB is conducted to ensure that the external lead is conducted with the corresponding thin film thermal resistor-Au lead Pad), wherein the external lead is divided into eight groups, the positive and negative poles are shown in fig. 29, and the overall schematic diagram is shown in fig. 30 after the installation is finished.

4. Installation process of heat preservation system

The method comprises the following steps: firstly, putting an experimental part which is preliminarily installed into a vacuum box (shown as 1 in figure 31), wherein an upper box body (shown as 5 in figure 31) of the vacuum box is a transparent box body and can transmit laser of a Micro-PIV system, a lower box body (shown as 6 in figure 31) of the vacuum box is an opaque box body, interference of an external light source on an image is reduced to a certain extent, then the upper box body and the lower box body are folded, an external lead is placed in an external lead hole (shown as 3 in figure 31), a self-grinding joint is placed in an external pipeline hole (shown as 4 in figure 31), a pipeline hole sealing piece is installed (the pipeline hole is sealed by a left sealing piece and a right sealing piece), an aviation joint required by a lead of the vacuum box is used at a connection part, an ultrahigh vacuum sealing glue (an Agilent vacuum AB vacuum sealing glue is selected in the example), and the vacuum box is subjected to low vacuum pumping through a pumping pipeline (shown as 2 in figure 31) before an experiment, after the installation is completed, as shown in fig. 31.

5. Installation flow of visualization system

The method comprises the following steps: after the experiment piece and the accessories of each system are basically installed, as shown in fig. 31, the experiment piece is installed on the stage (as shown in 1 in fig. 32) of the bottom microscope of the Micro-PIV system, and the stage may need to be re-designed in size in consideration of the diversity of sizes among different experiment pieces and the interference of the accessories such as pipeline joints, and will not be described again here. Note that the light-transmitting portion faces downward when mounted so that the bottom objective lens (as shown in fig. 32, 5) can observe the flow conditions in the channel, completing the mounting of the visualization system, as shown in fig. 32.

6. Integrated test system integral installation process

The method comprises the following steps: the method comprises the steps of placing a test piece and the position of each device (such as a pressure pump (shown as 1 in fig. 6), a flowmeter (shown as 3 in fig. 6), a differential pressure transmitter (shown as 8 in fig. 6), a Micro-PIV system (shown as 4 in fig. 6), a vacuum system (shown as 7 in fig. 6), a precision power supply (shown as 6 in fig. 6), a multi-channel low-power precision resistance tester (shown as 11 in fig. 6), a data acquisition system (shown as 9 in fig. 6) and a data processing terminal (shown as 12 in fig. 6), connecting a pipeline through which fluid flows through the test piece, fixing the positions of the test piece and the pipeline, vacuumizing the closed environment of the test piece by using the vacuum system (shown as 7 in fig. 6), and opening a power supply to carry out an experiment after the construction of the test system is completed.

Step two: the processed experimental part and various devices (such as a pressure pump (shown as 1 in FIG. 6), a flowmeter (shown as 3 in FIG. 6), a differential pressure transmitter (shown as 8 in FIG. 6), a Micro-PIV system (shown as 4 in FIG. 6), a vacuum system (shown as 7 in FIG. 6), a precision power supply (shown as 6 in FIG. 6), a multi-channel low-power precision resistance tester (shown as 11 in FIG. 6), a data acquisition system (shown as 9 in FIG. 6) and a data processing terminal (shown as 12 in FIG. 6) are arranged at proper positions, a fluid pipeline is connected, the position of the pipeline is fixed, the experimental part is vacuumized in a closed environment by using the vacuum system, and during the process, the pipeline and a circuit pass through a vacuum box, so that corresponding joints which can be subjected to vacuum sealing by using an aerial joint and the like are required to be connected, and in order to be integrated with the Micro-PIV visualization system, the vacuum box is designed to be partially transparent (a visualization system is excited by fluorescent particles and laser of a Micro-PIV system, so that the interference of an external light source on an image is reduced, and meanwhile, the light transmittance of an observation area is ensured, so that the vacuum box is partially transparent), and an experiment is performed after the connection of an internal pipeline and an external pipeline of the vacuum box and a circuit is completed (as shown in fig. 6).

In summary, the present invention embodies the experimental piece processing flow and the test system installation flow required for implementing the micro-scale flow heat exchange high-precision integrated test method based on the MEMS process through the above examples. In the experimental piece processing process, the plasma dry etching technology is adopted to realize the precise processing of the micro-channel, the patterning magnetron sputtering method is adopted to realize the precise arrangement of the heating film and the high-precision control of the size and the position of the temperature measuring point, the laser cutting punching technology is adopted to realize the in-situ extraction of the pressure measuring point, the auxiliary bonding and the silicon-glass anodic bonding are adopted to realize the integral packaging of the experimental piece, and the like, and finally the experimental piece processing required by the micro-scale flow heat exchange high-precision integrated testing method in the patent is completed. In the integration of the test system, the in-situ leading-out of a pressure measuring point is realized by the aid of a 3D printed self-grinding joint, the circuit connection of heating and temperature measurement is realized by the aid of lead bonding and welding technologies, the design of a heat insulation system and a visual system is realized by the aid of the autonomous design of a vacuum box, and the integration of the test system is realized by means of equipment installation, pipeline connection and the like. Therefore, the embodiment of the invention realizes the micro-scale flow heat exchange high-precision integrated test method based on the MEMS process through the processing of the first part of experimental pieces and the integration of the second part of test systems.

In the layout of the Micro-scale flow heat exchange integral experiment table, the scheme of the invention adopts a vacuum experiment table based on a microscope optical test system, because the integration of a Micro-PIV visual measurement system makes contact type heat preservation (such as heat preservation material wrapping and the like) not available, a vacuum system is introduced to play a role of heat preservation, external outputs of pressure measurement, temperature measurement, graphic signals and the like and external inputs of signals of voltage, current and the like can be connected with corresponding circuits in a vacuum joint mode, and whether the vacuum experiment table is placed in the vacuum experiment table or not can be selected according to the convenience of instrument and equipment control under the vacuum condition

In the micro-flow pressure measurement technology, the scheme of the invention adopts an in-situ extraction type pressure measurement technology, a small hole is cut on the glass cover plate on the upper side of the channel by utilizing a laser drilling technology to serve as a pressure measurement point, the size of the hole can be determined according to the channel size, experimental conditions and the like, and the processed hole is subjected to anodic alignment bonding with a silicon wafer on the channel part. The pressure measuring point is connected to the differential pressure transmitter through a pipeline, and the pipeline is incompressible fluid and responds to the propagation of pressure pulsation in real time. Meanwhile, when in measurement, the fluid is in a static state, sudden expansion, sudden contraction, turning and the like in the pressure measuring pipeline cannot cause additional pressure loss, high-precision in-situ measurement can be realized, and experimental data and a theoretical model are well matched.

On the micro-flow heating temperature measurement technology, an MEMS (micro electro mechanical systems) integrated heating temperature measurement technology is adopted, a Pt thin film thermal resistor is subjected to magnetron sputtering on the lower surface of a channel, the distance from the bottom surface of the channel is in the micron order, according to the latest bonding and magnetron sputtering technology, the integrated arrangement of the thin film thermal resistor can be directly realized even on the bottom surface of the channel, high-precision in-situ measurement is realized, an ICP (inductively coupled plasma) plasma etching technology is utilized to process a micro-channel with a complex structure, and meanwhile, a through hole is etched to reserve a lead point of a heating film. Meanwhile, a heating film is arranged on the lower surface of the channel by utilizing a bonding technology and a magnetron sputtering film process, the distance between the heating film and the bottom surface of the channel is in a micron order, and a lead point of a film temperature measuring thermal resistor is reserved by utilizing an ICP plasma etching technology, so that a given constant thermal current boundary condition in a theoretical model is realized, and a standardized experiment boundary design is realized.

In the Micro-flow visual measurement technology, according to the overall layout and the pipeline connection of the experiment table, the Micro-PIV optical path system and the temperature and pressure measurement technology are integrated in the vacuum experiment table, and finally, the integrated, in-situ, synchronous, real-time and standardized Micro-scale flow heat exchange test technology is realized.

The foregoing shows and describes the general principles, principal features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process is characterized in that: the method comprises the following steps:

a second part: and (6) testing the integration of the system.

2. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process, as claimed in claim 1, is characterized in that: the experimental part comprises three layers of wafer bonding, wherein the three layers of wafers are a glass sheet, an upper silicon wafer and a lower silicon wafer from top to bottom in sequence, and the bonding modes are silicon-glass anodic bonding and silicon-silicon auxiliary bonding respectively.

3. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process, as claimed in claim 2, is characterized in that: the glass sheet is subjected to laser drilling; the upper silicon wafer is provided with a micro-channel, a lead through hole and a bottom magnetron sputtering film thermal resistor; the lower silicon wafer is mainly provided with a heating film with the upper part being subjected to magnetron sputtering.

4. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process, as claimed in claim 3, wherein: the size of the micro-channel in the upper silicon chip is 300 micrometers multiplied by 3.5cm, the substrate of the thin film thermal resistor adopts Ti as an adhesion layer, the thickness is 70nm, the line width parameter is 16 micrometers, the length of the snake-shaped surrounding is 564 micrometers, the thickness is 600nm, the size of the thin film thermal resistor is about 80 micrometers multiplied by 100 micrometers, the estimated resistance value is 6.3 omega, and metal gold is subjected to magnetron sputtering again at a lead bonding Pad (Pad) part, and the thickness of the thin film is 600 nm.

5. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process, which is characterized by comprising the following steps of: the heating film substrate in the lower silicon wafer adopts a first layer which adopts Ti as an adhesion layer, the thickness is 70nm, a magnetron sputtering platinum film is 300 mu m multiplied by 35mm multiplied by 300nm, the expected heating film is 13.8 omega, the number is 3, and the main reason for dividing the heating film into three sections is to reduce the deviation from the constant heat flow heating hypothesis caused by the change of the resistance of the heating film along with the temperature.

6. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process as claimed in claim 2, wherein: the experimental piece is firstly processed for the upper layer structure, the middle layer structure and the lower layer structure respectively, then silicon-glass anodic bonding and silicon-silicon auxiliary bonding are carried out, and finally the experimental piece is cut into single experimental pieces.

7. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process, as claimed in claim 1, is characterized in that: the processing of the test piece comprises the following steps: processing flow of the glass sheet; processing flow of upper silicon chip; processing flow of the lower silicon wafer; sequentially bonding the multiple layers of wafers;

the processing flow of the glass sheet comprises the following contents:

laser cutting and punching a glass sheet, processing a lead through hole, a micro-channel inlet/outlet and a pressure measuring hole of a lower silicon wafer, and cleaning cutting residual particles, dust and organic matters on the surface of the glass sheet by using deionized water, acetone, isopropanol, alcohol ultrasonic cleaning and deionized water;

the processing flow of the upper silicon wafer comprises the following contents:

the method comprises the following steps: cleaning dust and organic matters on the surface of a double-polishing oxidation intrinsic high-resistance silicon wafer with the thickness of 2um by using alcohol-acetone-alcohol-deionized water; coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 2 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; using BOE solution to completely remove the oxide layer on the front surface of the silicon wafer and selectively removing the oxide layer on the through hole on the back surface and the alignment mark; cleaning photoresist, dust and organic matters on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-Piranha solution-deionized water on a wet bench;

step two: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning a magnetron sputtering Ti adhesion layer with the thickness of 70nm to enhance the adhesion of the Pt film, and patterning a magnetron sputtering Pt film with the thickness of 600nm to serve as a film thermal resistor on the lower surface of the upper silicon wafer; completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and impurities on the surface of the silicon wafer;

step three: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning a magnetron sputtering Au thin film with the thickness of 600nm to be used as a lead part of the thin film thermal resistor; completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer;

step four: annealing at high temperature in a low vacuum or nitrogen environment at the heating rate of 300 ℃/h and the temperature of 600 ℃, keeping the temperature for 4h, naturally cooling, and recrystallizing metal to ensure that the electrical property of the film is more stable and the stress of the film is reduced;

step five: cleaning dust and a natural oxidation layer on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-BOE solution for 30 s-deionized water on a wet bench; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; etching 300 microns by using plasma, finishing the etching of the front channel, and then etching the lead through hole structure; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer.

The processing flow of the lower silicon wafer comprises the following contents:

the method comprises the following steps: and (3) performing double-polishing oxidation on the intrinsic high-resistance silicon wafer, wherein the thickness of an oxide layer is 2 um. Cleaning dust and organic matters on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water; coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 2 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; selectively removing through holes on the front surface and the back surface of the silicon wafer and an oxide layer at the alignment mark by using a BOE solution; cleaning photoresist, dust and organic matters on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-Piranha solution-deionized water on a wet bench;

step two: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning a magnetron sputtering Ti adhesion layer with the thickness of 70nm to enhance the adhesion of the Pt film, and patterning a magnetron sputtering Pt film with the thickness of 600nm to be used as a heating film part on the upper surface of the lower silicon chip; completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and impurities on the surface of the silicon wafer;

step three: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; patterning a magnetron sputtering Au thin film with the thickness of 600nm to be used as a lead part of a heating film; completing metal patterning by a Lift-off process; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer;

step five: cleaning dust and a natural oxide layer on the surface of the silicon wafer by using alcohol-acetone-alcohol-deionized water-BOE solution for 30 s-deionized water on a wet bench; spin-coating photoresist 8 μm on the back of the silicon wafer, performing prebaking and back exposure, developing with a developing solution on a wet bench, and performing postbaking; etching the through hole by using the plasma to complete the etching of the lead through hole; acetone-alcohol-deionized water to clean the photoresist and other impurities on the surface of the silicon wafer;

step six: coating the cleaned silicon wafer with a tackifier to enhance the adhesion of the photoresist; spin-coating photoresist 8 μm on the front surface of the silicon wafer, performing prebaking and front surface exposure, developing with a developing solution on a wet bench, and performing postbaking; PECVD patterned deposited oxide layer SiO₂Reducing parasitic capacitance between a heating film and a thin film thermal resistor during testing, and cleaning photoresist and other impurities on the surface of the silicon wafer by using acetone-alcohol-deionized water;

the multilayer wafer sequentially bonded comprises the following contents:

the method comprises the following steps: after the structural processing of the glass sheet, the upper silicon wafer and the lower silicon wafer is finished, cleaning dust and a natural oxide layer on the surface of the upper silicon wafer by using alcohol-acetone-alcohol-deionized water-BOE solution for 30 s-deionized water on a wet bench; cleaning dust on the surface of the glass sheet by using alcohol-acetone-alcohol-deionized water; carrying out silicon-glass anodic bonding on the upper silicon chip and the glass by adopting a bonding machine;

step two: cleaning dust on the surface of the lower silicon wafer by using alcohol-acetone-alcohol-deionized water on a wet bench; carrying out auxiliary bonding on the glass-upper silicon wafer and the lower silicon wafer by adopting a bonding machine; and cutting the wafer after the processing is finished to obtain a single experimental piece.

8. The micro-scale flow heat exchange high-precision integrated test method based on the MEMS process, which is characterized by comprising the following steps of: the second portion further comprises the following: the experimental part that will process the completion and including the force pump, the flowmeter, differential pressure transmitter, the Micro-PIV system, vacuum system, accurate power, the accurate resistance tester of multichannel low power, data acquisition system and data processing terminal are put according to suitable position, connect the fluid pipeline, the position of fixed pipeline, utilize vacuum system to carry out the evacuation of experimental part confined environment, in the meantime, pipeline and circuit can pass through the vacuum box, utilize the aviation to connect and carry out the corresponding joint of vacuum seal and connect, in order to integrate with the visual system of Micro-PIV, the vacuum box design is local printing opacity, accomplish the interior outer pipeline of vacuum box, experiment after the connection of circuit.

9. A micro-scale flow heat exchange high-precision integrated test method based on an MEMS process is applied to a micro-scale single-channel flow heat exchange test process.