阅读说明：本技术 一种真空封装结构差压谐振压力敏感芯片探头及封装方法 (Differential pressure resonance pressure sensitive chip probe of vacuum packaging structure and packaging method ) 是由 尹延昭 张鹏 孙权 于洋 周志炜 李修钰 于 2021-08-25 设计创作，主要内容包括：一种真空封装结构差压谐振压力敏感芯片探头及封装方法,它涉及一种探头及其封装方法。本发明为了解决现有的谐振压力敏感芯片存在Q值偏低,测量精度和长期稳定性下降的问题。本发明的可伐合金引脚安在引线孔上,硅谐振压力敏感芯片安在芯片粘接面上,硅谐振压力敏感芯片和可伐合金引脚通过电极键合引线连接；波纹膜片安在波纹膜片接触面上,压环压装在波纹膜片上,隔离介质填充在间隙、探头介质传递通道、波纹膜片和密封管座之间形成的密闭空腔内,硅谐振压力敏感芯片通过谐振层中的两个压力谐振器实现差压测量。封装方法：对谐振层进行二次封装,使硅谐振压力敏感芯片处于隔离介质中工作。本发明用于压力的测量以及压力芯片探头的封装。(A differential pressure resonance pressure sensitive chip probe with a vacuum packaging structure and a packaging method relate to a probe and a packaging method thereof. The invention aims to solve the problems of low Q value, low measurement precision and low long-term stability of the conventional resonant pressure sensitive chip. The Kovar alloy pin is arranged on the lead hole, the silicon resonance pressure sensitive chip is arranged on the chip bonding surface, and the silicon resonance pressure sensitive chip and the Kovar alloy pin are connected through an electrode bonding lead; the corrugated diaphragm is arranged on the contact surface of the corrugated diaphragm, the press ring is pressed on the corrugated diaphragm, the isolation medium is filled in a closed cavity formed among the gap, the probe medium transmission channel, the corrugated diaphragm and the sealing tube seat, and the silicon resonance pressure sensitive chip realizes differential pressure measurement through two pressure resonators in the resonance layer. The packaging method comprises the following steps: and carrying out secondary packaging on the resonance layer to enable the silicon resonance pressure sensitive chip to work in an isolation medium. The invention is used for measuring pressure and packaging the pressure chip probe.)

1. The utility model provides a vacuum packaging structure differential pressure resonance pressure sensitive chip probe which characterized in that: the device comprises a sealing cover plate (1), a silicon resonance pressure sensitive chip (2), a kovar alloy pin (3), an electrode bonding lead (4), a probe medium transfer channel (5) and a sealing tube seat (6);

the upper end face of the sealing tube seat (6) is a sealing cover plate contact face (601), a three-level stepped groove is formed in the sealing cover plate contact face (601), the middle stepped face of the stepped groove is a lead hole face (604), the lower stepped face of the stepped groove is a chip bonding face (602), the probe medium transfer channel (5) is formed in the chip bonding face (602), a plurality of lead holes (603) are vertically formed in the lead hole face (604), an annular sealing groove (605) is formed in the middle of the outer cylindrical face of the sealing tube seat (6), and a pressure buffer groove (606) is formed in the lower portion of the outer cylindrical face of the sealing tube seat (6);

the Kovar alloy pin (3) is vertically arranged on a lead hole (603) of the sealing tube seat (6) in a glass sintering mode, the silicon resonance pressure sensitive chip (2) is arranged on a chip bonding surface (602) of the sealing tube seat (6) in an adhesive mode, a gap is reserved between the silicon resonance pressure sensitive chip (2) and the side wall of the stepped groove, and the silicon resonance pressure sensitive chip (2) is connected with the Kovar alloy pin (3) through an electrode bonding lead (4); the sealing cover plate (1) is arranged on a contact surface (601) of the sealing cover plate, and a closed cavity for protecting the resonant pressure sensitive chip (2) is formed between the probe medium transfer channel (5) and the three-stage stepped groove of the sealing tube seat (6);

the silicon resonance pressure sensitive chip (2) realizes differential pressure measurement through two pressure resonators in the resonance layer (202).

2. The differential pressure resonance pressure sensitive chip probe of the vacuum packaging structure of claim 1, characterized in that: the silicon resonance pressure sensitive chip (2) comprises an upper chip cover (201), a resonance layer (202), a first pressure silicon-based substrate (2021-1), a second silicon-based substrate (2022-1) and a stress isolation layer (203), wherein the upper chip cover (201), the resonance layer (202), the first pressure silicon-based substrate (2021-1), the second silicon-based substrate (2022-1) and the stress isolation layer (203) are sequentially connected from top to bottom and are manufactured into a whole,

the resonance layer (202) comprises a first pressure resonator (2021) and a second pressure resonator (2022), the first pressure resonator (2021) and the second pressure resonator (2022) are horizontally arranged on a first pressure silicon-based substrate (2021-1) and a second silicon-based substrate (2022-1) from right to left,

the lower end faces of the first pressure silicon-based substrate (2021-1) and the second pressure silicon-based substrate (2022-1) are respectively provided with an inverted trapezoidal pressure sensing groove, wherein an absolute pressure chamber is formed between the chip upper cover (201) and the first pressure silicon-based substrate (2021-1) as well as between the chip upper cover and the second pressure silicon-based substrate (2022-1), and the resonance layer (202) is positioned in the absolute pressure chamber.

3. The differential pressure resonance pressure sensitive chip probe of the vacuum packaging structure of claim 2, wherein: a first pressure sensing through hole (2031) is arranged right below the first pressure silicon-based substrate (2021-1), and a second pressure sensing through hole (2032) is arranged right below the second silicon-based substrate (2022-1).

4. The differential pressure resonance pressure sensitive chip probe of the vacuum packaging structure of claim 3, wherein: the first pressure resonator (2021) and the second pressure resonator (2022) have the same structure, wherein the first pressure resonator (2021) comprises four extraction electrodes (3050), two driving electrodes (3023), a spare electrode (3024), two sensitive comb-tooth electrodes (3025), two stabilizing beams (3026), two transverse tie beams (3027), an anchor block (3028) and an electrode path (3029),

two drive electrodes (3023) are arranged in parallel from top to bottom, a leading-out electrode (3050) is respectively installed on the left side and the right side of each drive electrode (3023), a sensitive comb-tooth electrode (3025) is installed on the opposite side of each drive electrode (3023), a stabilizing beam (3026) is respectively installed on the inner sides of the two sensitive comb-tooth electrodes (3025), a transverse tie beam (3027) is respectively installed on the inner sides of the two stabilizing beams (3026), an anchor block (3028) is installed between the two transverse tie beams (3027), and the anchor block (3028) is connected with a spare electrode (3024) through an electrode passage (3029).

5. The differential pressure resonance pressure sensitive chip probe of the vacuum packaging structure of claim 4, wherein: the end part of each transverse pulling beam (3027) is of a Y-shaped beam structure.

6. The differential pressure resonance pressure sensitive chip probe of the vacuum packaging structure of claim 5, wherein: each stabilizing beam (3026) comprises two stabilizing units which are symmetrical left and right,

each stabilizing unit comprises a first connecting support beam (901), a first inclined-pulling beam parallel support beam (901-1), a first inclined-pulling beam vertical support beam (901-2), a first parallel support beam vertical beam (901-3), a first inclined-pulling beam stabilizing beam (901-4) and a second inclined-pulling beam stabilizing beam (901-5),

a trapezoid structure is formed among the first inclined-pulling beam parallel supporting beam (901-1), the first inclined-pulling beam stabilizing beam (901-4), the second inclined-pulling beam stabilizing beam (901-5) and the sensitive comb electrode (3025), the first inclined-pulling beam vertical supporting beam (901-2) and the first parallel supporting beam vertical beam (901-3) are perpendicular to the first inclined-pulling beam parallel supporting beam (901-1), and a right-angled triangle is formed among the first inclined-pulling beam vertical supporting beam (901-2) and the first parallel supporting beam vertical beam (901-3), the first inclined-pulling beam stabilizing beam (901-4), the second inclined-pulling beam stabilizing beam (901-5) and the first inclined-pulling beam parallel supporting beam (901-1),

one end of the first connecting support beam (901) is superposed with the intersection of the first diagonal beam vertical support beam (901-2) and the first diagonal beam parallel support beam (901-1), and the other end of the first connecting support beam (901) is superposed with the intersection of the first parallel support beam vertical beam (901-3) and the second diagonal beam stabilizing beam (901-5).

7. The differential pressure resonance pressure sensitive chip probe of the vacuum packaging structure of claim 6, wherein: the probe medium transfer channel (5) comprises two channel units which are symmetrically arranged, each channel unit comprises a pressure guide hole (501), an external pressure hole (502) and an internal pressure pipeline (503),

the pressure guide hole (501) is formed in the chip bonding surface (602) and communicated with the silicon-based substrate (2021), the external pressure hole (502) is formed in the annular sealing groove (605), the pressure guide hole (501) and the external pressure hole (502) are connected through the internal pressure pipeline (503), and the horizontal sections of the internal pressure pipelines (503) of the two channel units are not communicated.

8. The differential pressure resonance pressure sensitive chip probe of the vacuum packaging structure of claim 7, wherein: the sealing cover plate (1) comprises a T-shaped table (101), a vacuumizing hole (102), a round boss (103) and a notch (104),

circular boss (103) are embedded in the upper end face groove of T shape platform (101), and vacuum hole (102) have been seted up to T shape platform (101) in vertical direction, evenly seted up four openings (104) on circular boss (103).

9. A packaging method for a vacuum packaging structure differential pressure resonance pressure sensitive chip probe according to any one of claims 1 to 8, characterized in that: it comprises the following steps:

the method comprises the following steps: manufacturing and cleaning a sealing pipe seat (6);

sintering a lead hole (603) in the sealing tube seat (6) and the upper pin and the lower pin together by using glass slurry to form a sealing pin structure, wherein the sealing tube seat (6) is made of stainless steel;

respectively clamping silk fabrics adhered with acetone and absolute ethyl alcohol by using stainless steel tweezers with heads coated with polytetrafluoroethylene to clean a sealing tube seat (6), then cleaning the sealing tube seat for more than 20 seconds by using absolute ethyl alcohol, and putting the sealing tube seat into a drying oven for drying; sequentially putting the silicon resonance pressure sensitive chip (2) into acetone and absolute ethyl alcohol, respectively carrying out ultrasonic cleaning on the sealing tube seat (6) and the silicon resonance pressure sensitive chip (2) for 15min, and sequentially putting the special fixture ceramic ring into acetone and absolute ethyl alcohol for ultrasonic cleaning for 15 +/-3 min;

step two: gluing and bonding;

fixing a sealing tube seat (6) on a clamp, uniformly dispensing 6 spots on the sealing tube seat (6) by using a toothpick 730 adhesive or using an automatic dispenser according to the shape of a silicon resonance pressure sensitive chip (2), then embedding the silicon resonance pressure sensitive chip (2) therein, pressing the upper part of a chip upper cover (201) of the silicon resonance pressure sensitive chip (2) by using a ceramic rod, ensuring that an external pressure hole on the sealing tube seat (6) corresponds to a first pressure sensing through hole (2031) and a second pressure sensing through hole (2032) of a stress isolation layer (203), then continuously dispensing 730 adhesive by using the toothpick or using the automatic dispenser, protecting a Kovar alloy pin (3) corresponding to a through hole of a special clamp ceramic ring, and taking out the ceramic ring after the adhesive is coated;

step three: curing the glue;

curing the sealing tube seat (6) bonded with the silicon resonance pressure sensitive chip (2) in the second step in a constant temperature and humidity environment for 20-30 hours;

step four: pressure welding of the electrode bonding lead (4);

step four, firstly: fixing the sealing pipe seat (6) on a clamp, and welding the electrode bonding lead (4) and the extraction electrode (3050) together at the position of the distance from the top of the cleaver to the surface of the extraction electrode (3050) and the diameter of the electrode bonding lead (4) being 2.5 times;

step four and step two: the other end of the electrode bonding lead (4) is welded on the kovar alloy pin (3) through a hot welding pen, and the length of the electrode bonding lead (4) is automatically formed when two points are pressure-welded;

step four and step three: carrying out a breaking force test on the electrode bonding lead (4) until the breaking force meets the design requirement;

step five: performing insulation test on the kovar alloy pin (3) and the sealing tube seat (6);

testing the insulation resistance between each pin of the kovar alloy pin (3) and the sealing tube seat (6) by using an insulation resistance tester, wherein the resistance is greater than a design limit value;

step six: testing the basic performance of the silicon resonance pressure sensitive chip (2);

the water absorption ball is adopted to blow and lead the pressure hole, the pressure change is less than hundreds of hertz, and the temperature frequency is not changed; at the moment, the silicon resonance pressure sensitive chip (2) meets the design requirement;

step seven: welding the sealing cover plate (1) on the sealing pipe seat (6);

placing the sealing cover plate (1) on the sealing pipe seat (6), utilizing argon arc welding or electron beam welding, and then carrying out a penetration test; repeating the step five;

step eight: plugging the sealing pipe seat (6);

sealing the vacuumized hole 102 with the diameter of 1.3mm by using a phi 2 steel ball, and then sealing and welding the vacuumized sealed cavity by adopting electron beam welding;

thus, the packaging of the resonant pressure sensitive chip probe of the vacuum packaging structure is completed;

step nine: electrically testing the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;

the electrical test is carried out under the constant normal pressure condition, and when the resonance pressure sensitive chip probe does not generate the frequency hopping phenomenon and the frequency changes towards one direction, the resonance pressure sensitive chip probe is stable and qualified within the time of less than 3 seconds;

step ten: carrying out pressure fatigue and aging tests on the resonance pressure sensitive chip probe of the packaged vacuum packaging structure;

the resonance pressure sensitive chip probe is arranged on a clamp and is connected with an air pressure fatigue machine or a hydraulic fatigue machine, the fatigue times are 5000/10000 times, and the resonance pressure sensitive chip probe is placed in a high-low temperature test box for temperature aging tests to release the internal stress of the resonance pressure sensitive chip probe together, so that the output stability of the resonance pressure sensitive chip of the vacuum packaging structure is improved;

step eleven: performing air tightness detection on a resonance pressure sensitive chip probe of the packaged vacuum packaging structure;

connecting the resonance pressure sensitive chip probe with a pressure controller, and carrying out air tightness detection, wherein the pressure change value is not more than +/-2 Pa, and at the moment, the air tightness of the resonance pressure sensitive chip probe is qualified;

step twelve: and carrying out laser marking and screening on the resonance pressure sensitive chip probe of the packaged vacuum packaging structure, and switching to the next production stage.

Technical Field

The invention relates to a differential pressure resonance pressure sensitive chip probe and a packaging method, in particular to a differential pressure resonance pressure sensitive chip probe with a vacuum packaging structure and a packaging method, and belongs to the field of MEMS (micro-electromechanical systems) resonance type pressure sensors.

Background

The silicon resonance pressure sensor indirectly measures pressure by measuring the natural frequency of silicon, the precision is 1-2 orders of magnitude higher than that of a common pressure sensor, the operation is reliable, and the stability and the repeatability are better. The traditional silicon resonance pressure transmission realizes pressure measurement by directly contacting with the measured pressure, and can be suitable for high-precision pressure measurement of clean gas; when the pressure environment to be measured is in the pressure measurement of highly corrosive liquid or gas environment (seawater, oil circuit, etc.), the traditional silicon resonance pressure sensor works in a corrosion state for a long time, which easily causes structural damage of the silicon resonance pressure probe and corrosion of the pressure chip, resulting in performance reduction or sensor failure.

Meanwhile, the core part of the silicon resonance pressure sensor is a resonator, the Q value is a core index for evaluating the resonator, and the performance of the resonator is better when the Q value is larger. The stable packaging environment can ensure that the resonator works with a fixed Q value, thereby ensuring that the silicon resonance pressure sensor has high stability. The leakage rate is an important parameter for the stability of the resonant pressure sensor chip. The most common pressure absolute pressure measurement die-sealed cavities are prepared by silicon-silicon bonding, silicon-glass bonding, and other crystalline material bonding.

The support beam of the conventional resonant pressure sensitive chip has low strength and rigidity, and the resonant frequency is low, so that the Q value of a core index is low, and the measurement precision and the application range of the chip are influenced. Meanwhile, the existing packaging method generally adopts the structure that the absolute pressure cavity is exposed in the atmospheric pressure range, so that the leakage rate of the high-precision absolute pressure sensor sealing cavity is increased, the pressure in the vacuum cavity is increased, the signal output value of the sensor chip is directly influenced, and the problem that the measurement precision and the long-term stability of the sensor chip are reduced is caused.

In summary, the conventional resonant pressure sensitive chip has the problems that the Q value is low and the measurement accuracy and the application range are affected, and the conventional packaging method has the problems that the measurement accuracy and the long-term stability are reduced.

Disclosure of Invention

The invention aims to solve the problems that the measurement precision and the application range of the conventional resonant pressure sensitive chip are influenced by the low Q value, and the measurement precision and the long-term stability of the conventional packaging method are reduced. Further provides a differential pressure resonance pressure sensitive chip probe of a vacuum packaging structure and a packaging method.

The technical scheme of the invention is as follows: a differential pressure resonance pressure sensitive chip probe with a vacuum packaging structure comprises a sealing cover plate, a silicon resonance pressure sensitive chip, a kovar alloy pin, an electrode bonding lead, a probe medium transfer channel and a sealing tube seat; the upper end face of the sealing tube seat is a sealing cover plate contact face, three stages of stepped grooves are formed in the sealing cover plate contact face, the middle stepped face of each stepped groove is a lead hole face, the lower stepped face of each stepped groove is a chip bonding face, a probe medium transfer channel is formed in the chip bonding face, a plurality of lead holes are vertically formed in the lead hole face, an annular sealing groove is formed in the middle of the outer cylindrical face of the sealing tube seat, and a pressure buffer groove is formed in the lower portion of the outer cylindrical face of the sealing tube seat;

the Kovar alloy pin is vertically arranged on a lead hole of the sealing tube seat in a glass sintering mode, the silicon resonance pressure sensitive chip is arranged on a chip bonding surface of the sealing tube seat in an adhesive mode, a gap is reserved between the silicon resonance pressure sensitive chip and the side wall of the stepped groove, and the silicon resonance pressure sensitive chip and the Kovar alloy pin are connected through an electrode bonding lead; the sealing cover plate is arranged on the contact surface of the sealing cover plate, and a closed cavity for protecting the resonant pressure sensitive chip is formed between the probe medium transfer channel and the three-stage stepped groove of the sealing tube seat;

the silicon resonance pressure sensitive chip realizes differential pressure measurement through two pressure resonators in the resonance layer.

The invention also provides a packaging method, which comprises the following steps:

the method comprises the following steps: manufacturing and cleaning a sealing pipe seat;

sintering a lead hole and upper and lower pins in a sealing tube seat together by using glass slurry to form a sealing pin structure, wherein the sealing tube seat is made of stainless steel;

respectively clamping the silk fabric cleaning sealing tube seat stuck with acetone and absolute ethyl alcohol by using stainless steel tweezers with heads coated with polytetrafluoroethylene, cleaning the silk fabric cleaning sealing tube seat by using absolute ethyl alcohol for more than 20s, and drying the silk fabric cleaning sealing tube seat in a drying oven; sequentially putting the silicon resonance pressure sensitive chip into acetone and absolute ethyl alcohol, respectively carrying out ultrasonic cleaning on the sealing tube seat and the silicon resonance pressure sensitive chip for 15min, and sequentially putting the special fixture ceramic ring into acetone and absolute ethyl alcohol for ultrasonic cleaning for 15 +/-3 min;

step two: gluing and bonding;

fixing a sealing tube seat on a clamp, uniformly dotting 6 points on the sealing tube seat according to the shape of a silicon resonance pressure sensitive chip by using a toothpick 730 adhesive or using an automatic dispenser, then embedding the silicon resonance pressure sensitive chip into the silicon resonance pressure sensitive chip, pressing the upper part of an upper cover of the chip of the silicon resonance pressure sensitive chip by using a ceramic rod to ensure that an external pressure hole on the sealing tube seat corresponds to a first pressure sensing through hole and a second pressure sensing through hole of a stress isolation layer, then continuously picking 730 adhesive by using the toothpick or using the automatic dispenser for dispensing, enabling a kovar alloy pin to correspond to a through hole of a special clamp ceramic ring, protecting the kovar alloy pin, and taking out the ceramic ring after the adhesive is coated;

step three: curing the glue;

curing the sealing tube seat bonded with the silicon resonance pressure sensitive chip in the second step in a constant temperature and humidity environment for 20-30 hours;

step four: pressure welding of the electrode bonding lead;

step four, firstly: fixing the sealing tube seat on a clamp, and welding an electrode bonding lead and an extraction electrode together at the position of the distance from the tip of a cleaver to the diameter of the electrode bonding lead on the surface of the extraction electrode, which is 2.5 times of the diameter of the electrode bonding lead;

step four and step two: welding the other end of the electrode bonding lead on the kovar alloy pin by a hot welding pen, wherein the length of the electrode bonding lead is automatically formed when two points are pressure-welded;

step four and step three: carrying out a breaking force test on the electrode bonding lead until the breaking force meets the design requirement;

step five: performing insulation test on the kovar alloy pin and the sealing tube seat;

testing the insulation resistance between each pin of the kovar alloy pin and the sealing tube seat by using an insulation resistance tester, wherein the resistance is greater than a design limit value;

step six: testing the basic performance of the silicon resonance pressure sensitive chip;

the water absorption ball is adopted to blow and lead the pressure hole, the pressure change is less than hundreds of hertz, and the temperature frequency is not changed; at the moment, the silicon resonance pressure sensitive chip meets the design requirement;

step seven: welding a sealing cover plate on the sealing pipe seat;

placing the sealing cover plate on the sealing tube seat, utilizing argon arc welding or electron beam welding, and then carrying out a penetration test; repeating the step five;

step eight: plugging the sealing pipe seat;

sealing a vacuumized hole with the diameter of 1.3mm by using a phi 2 steel ball, and then sealing and welding the vacuumized sealed cavity by adopting electron beam welding;

thus, the packaging of the resonant pressure sensitive chip probe of the vacuum packaging structure is completed;

step nine: electrically testing the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;

the electrical test is carried out under the constant normal pressure condition, and when the resonance pressure sensitive chip probe does not generate the frequency hopping phenomenon and the frequency changes towards one direction, the resonance pressure sensitive chip probe is stable and qualified within the time of less than 3 seconds;

step ten: carrying out pressure fatigue and aging tests on the resonance pressure sensitive chip probe of the packaged vacuum packaging structure;

the resonance pressure sensitive chip probe is arranged on a clamp and is connected with an air pressure fatigue machine or a hydraulic fatigue machine, the fatigue times are 5000/10000 times, and the resonance pressure sensitive chip probe is placed in a high-low temperature test box for temperature aging tests to release the internal stress of the resonance pressure sensitive chip probe together, so that the output stability of the resonance pressure sensitive chip of the vacuum packaging structure is improved;

step eleven: performing air tightness detection on a resonance pressure sensitive chip probe of the packaged vacuum packaging structure;

connecting the resonance pressure sensitive chip probe with a pressure controller, and carrying out air tightness detection, wherein the pressure change value is not more than +/-2 Pa, and at the moment, the air tightness of the resonance pressure sensitive chip probe is qualified;

step twelve: and carrying out laser marking and screening on the resonance pressure sensitive chip probe of the packaged vacuum packaging structure, and switching to the next production stage.

Compared with the prior art, the invention has the following effects:

1. the invention adopts the vacuum packaging technology, and the silicon resonance pressure chip is isolated from the external environment, so that the silicon resonance pressure sensor can also realize the measurement of high-precision pressure in the severe environment, and the working reliability of the sensor in the complex environment is improved; silicon resonance pressure chip package has fixed higher Q value in stable vacuum environment, the chip has very low leak rate, improve the long-term stability of sensor, silicon resonance pressure chip adopts the design of dual resonator simultaneously, dual resonator has the same operational environment, can effectively reduce the temperature, influence such as acceleration, realize the independent real-time pressure measurement of double-circuit, can handle alone on dual resonator's signal processing, obtain the pressure differential signal, also can carry out signal processing through the difference mode, obtain differential signal, obtain higher pressure measurement precision.

2. The chip of the invention adopts an integrated double-resonator design to realize multi-pressure differential pressure measurement, and the secondary packaging method of the resonator can reduce the working environment pressure of the sealed cavity, thereby reducing the pressure difference value between the sealed cavity and the external environment, reducing the pressure change in the sealed cavity caused by the leakage rate, and improving the stability of the sensor. The vacuum packaging structure can isolate the differential pressure type silicon resonance pressure sensitive chip 2 from the external atmospheric environment in a sealing mode, so that the differential pressure type silicon resonance pressure sensitive chip 2 works in a low-pressure environment, and the stability is improved; meanwhile, the double resonators are arranged in the same working environment for pressure detection, so that the measurement error caused by environmental interference such as temperature, acceleration and the like can be reduced, and the accuracy of the sensor is improved.

3. The pressure value outside the chip sealing cavity of the differential pressure type silicon resonance pressure sensitive probe prepared by the invention is 100Pa-1000Pa, and the chip sealing cavity in the traditional packaging mode is directly exposed under the atmospheric pressure environment, generally about 100000 Pa. Because the leak rate of the sealed cavity is in direct proportion to the pressure difference between the sealed cavity and the outside, the pressure of the sealed cavity is generally below 100Pa after bonding. Thus, by adopting the secondary vacuum packaging method, the chip leakage rate can be reduced by two orders of magnitude under the condition of the same chip bonding process, and the stability of the sensor can be improved.

Drawings

FIG. 1 is a full sectional view of a differential pressure resonant pressure sensitive chip probe of the vacuum packaging structure of the present invention;

FIG. 2 is a front cross-sectional view of a silicon resonant pressure sensitive chip;

FIG. 3 is a front cross-sectional view of the sealing cover plate;

FIG. 4 is a top view of the sealing cover plate;

FIG. 5 is a front cross-sectional view of a kovar pin;

FIG. 6 is a front cross-sectional view of the sealing stem;

FIG. 7 is a left side cross-sectional view of the sealing stem;

fig. 8 is a top view of a pressure resonator.

Detailed Description

The technical scheme of the invention is not limited to the specific embodiments listed below, and any reasonable combination of the specific embodiments is included.

The first embodiment is as follows: the present embodiment is described with reference to fig. 1 to 8, and the differential pressure resonance pressure sensitive chip probe with a vacuum package structure of the present embodiment includes a sealing cover plate 1, a silicon resonance pressure sensitive chip 2, a kovar alloy pin 3, an electrode bonding lead 4, a probe medium transmission channel 5, and a sealing tube seat 6;

the upper end face of the sealing tube seat 6 is a sealing cover plate contact face 601, a three-level stepped groove is formed in the sealing cover plate contact face 601, the middle stepped face of the stepped groove is a lead hole face 604, the lower stepped face of the stepped groove is a chip bonding face 602, the probe medium transfer channel 5 is formed in the chip bonding face 602, a plurality of lead holes 603 are vertically formed in the lead hole face 604, an annular sealing groove 605 is formed in the middle of the outer cylindrical face of the sealing tube seat 6, and a pressure buffer groove 606 is formed in the lower portion of the outer cylindrical face of the sealing tube seat 6; the Kovar alloy pin 3 is vertically arranged on a lead hole 603 of the sealing tube seat 6 in a glass sintering mode, the silicon resonance pressure sensitive chip 2 is arranged on a chip bonding surface 602 of the sealing tube seat 6 in an adhesive mode, a gap is reserved between the silicon resonance pressure sensitive chip 2 and the side wall of the stepped groove, and the silicon resonance pressure sensitive chip 2 is connected with the Kovar alloy pin 3 through an electrode bonding lead 4; the sealing cover plate 1 is arranged on a contact surface 601 of the sealing cover plate, and a closed cavity for protecting the resonant pressure sensitive chip 2 is formed between the probe medium transfer channel 5 and the three-stage stepped groove of the sealing tube seat 6;

the silicon resonant pressure sensitive die 2 achieves differential pressure measurement through two pressure resonators in the resonant layer 202.

The second embodiment is as follows: referring to fig. 2, the silicon resonant pressure sensitive chip 2 of this embodiment includes a chip upper cover 201, a resonant layer 202, a first pressure silicon-based substrate 2021-1, a second silicon-based substrate 2022-1 and a stress isolation layer 203, the chip upper cover 201, the resonant layer 202, the first pressure silicon-based substrate 2021-1, the second silicon-based substrate 2022-1 and the stress isolation layer 203 are sequentially connected from top to bottom and are formed into a whole, the resonant layer 202 includes a first pressure resonator 2021 and a second pressure resonator 2022, the first pressure resonator 2021 and the second pressure resonator 2022 are horizontally mounted on the first pressure silicon-based substrate 2021-1 and the second silicon-based substrate 2022-1 from right to left, the lower end surfaces of the first pressure silicon-based substrate 2021-1 and the second silicon-based substrate 2022-1 are both provided with inverted trapezoidal pressure-sensitive slots, wherein a gap is formed between the chip upper cover 201 and the first pressure silicon-based substrate 2021-1 and the second silicon-based substrate 2022-1 A pressure-insulated chamber in which the resonant layer 202 is located. With such arrangement, the lower end faces of the first pressure silicon-based substrate 2021-1 and the second pressure silicon-based substrate 2022-1 are both provided with inverted trapezoidal pressure sensing grooves for accurately sensing the pressure of the medium and transmitting the pressure to the resonance layer 202, and meanwhile, an absolute pressure chamber formed between the chip upper cover 201 and the first pressure silicon-based substrate 2021-1 and the second pressure silicon-based substrate 2022-1 is used for protecting the resonance layer 202 and preventing the resonance layer 202 from being subjected to resistance of other media when in a working state, thereby further affecting the measurement accuracy of the probe. Other components and connections are the same as those in the first embodiment.

The third concrete implementation mode: referring to fig. 2, the embodiment is described, wherein a first pressure sensing via 2031 is formed directly below the first pressure silicon-based substrate 2021-1, and a second pressure sensing via 2032 is formed directly below the second pressure silicon-based substrate 2022-1. The arrangement is convenient for transmitting the pressure to the first pressure silicon-based substrate 2021-1 and the second pressure silicon-based substrate 2022-1, and further to the resonance layer 202, thereby achieving the purpose of pressure sensing. Other components and connection relationships are the same as those in the first or second embodiment.

The fourth concrete implementation mode: in the present embodiment, the first pressure resonator 2021 and the second pressure resonator 2022 of the present embodiment have the same structure as each other, wherein, the first pressure resonator 2021 comprises four extraction electrodes 3050, two driving electrodes 3023, a spare electrode 3024, two sensitive comb-teeth electrodes 3025, two stabilizing beams 3026, two cross-tie beams 3027, an anchor block 3028 and an electrode path 3029, the two driving electrodes 3023 are arranged in parallel up and down, and the left side and the right side of each driving electrode 3023 are respectively provided with one leading-out electrode 3050, the opposite sides of the two driving electrodes 3023 are provided with one sensitive comb-tooth electrode 3025, the inner sides of the two sensitive comb-tooth electrodes 3025 are respectively provided with one stabilizing beam 3026, the inner sides of the two stabilizing beams 3026 are respectively provided with one transverse tie beam 3027, an anchor block 3028 is arranged between the two transverse tie beams 3027, and the anchor block 3028 is connected with the spare electrode 3024 through an electrode passage 3029.

So set up, electrode path 3029 constitutes triangle-shaped stable structure, under the assurance signal transmission prerequisite, promotes the intensity that the electrode was propped admittedly, can effectively promote the stability on resonance layer to be applicable to the deformation range that vibration and pressure variation of higher frequency arouse. Meanwhile, the anchor block 3028 is arranged, so that the side length of the force arm is increased, the torque generated by the stress of the anchor block 3028 can be effectively improved, and the deformation of the rear end connected with the related stress beam is improved. Thereby improving the resonant frequency and increasing the resolution of the sensor. Other components and connection relations are the same as those of any one of the first to third embodiments.

The fifth concrete implementation mode: the present embodiment is described with reference to fig. 8, and the end portion of each tie beam 3027 of the present embodiment is a "Y" beam structure. So set up, "Y" type beam structure of two fixed fulcrums forms triangle-shaped stable structure, can promote rigidity intensity, improves the reliability of sensor. Other components and connection relations are the same as those of any one of the first to fourth embodiments.

The sixth specific implementation mode: describing the present embodiment with reference to fig. 8, each of the stabilizing beams 3026 of the present embodiment includes two stabilizing units that are bilaterally symmetric,

each stabilizing unit comprises a first connecting support beam 901, a first inclined-pulling beam parallel support beam 901-1, a first inclined-pulling beam vertical support beam 901-2, a first parallel support beam vertical beam 901-3, a first inclined-pulling beam stabilizing beam 901-4 and a second inclined-pulling beam stabilizing beam 901-5,

a trapezoid structure is formed among the first diagonal beam parallel support beam 901-1, the first diagonal beam stabilizing beam 901-4, the second diagonal beam stabilizing beam 901-5 and the sensitive comb electrodes 3025, the first diagonal beam vertical support beam 901-2 and the first parallel support beam vertical beam 901-3 are perpendicular to the first diagonal beam parallel support beam 901-1, and the first diagonal beam vertical support beam 901-2 and the first parallel support beam vertical beam 901-3, the first diagonal beam stabilizing beam 901-4, the second diagonal beam stabilizing beam 901-5 and the first diagonal beam parallel support beam 901-1 form a right triangle,

one end of the first connecting support beam 901 coincides with the intersection of the first diagonal beam vertical support beam 901-2 and the first diagonal beam parallel support beam 901-1, and the other end of the first connecting support beam 901 coincides with the intersection of the first parallel support beam vertical beam 901-3 and the second diagonal beam stabilizing beam 901-5. So set up, can form triangular supports structure, the intensity of each supporting beam of increase resonance layer and sensitive broach electrode 3025 draw to one side to increase mechanics vibration transmission intensity, improve chip vibration frequency, and then can effectively increase the measurement range, and reduced external disturbance, thereby promote stability. Other components and connection relations are the same as those of any one of the first to fifth embodiments.

The seventh embodiment: the present embodiment is described with reference to fig. 6 and 7, the probe medium transmission channel 5 of the present embodiment includes two channel units symmetrically formed, each channel unit includes a pressure guide hole 501, an external pressure hole 502, and an internal pressure pipeline 503, the pressure guide hole 501 is formed on the chip bonding surface 602 and is communicated with the silicon-based substrate 2021, the external pressure hole 502 is formed on the annular sealing groove 605, the pressure guide hole 501 and the external pressure hole 502 are connected by the internal pressure pipeline 503, and horizontal segments of the internal pressure pipelines 503 of the two channel units are not communicated.

So set up, the shutoff of sealed tube socket 6 of being convenient for, silicon resonance pressure sensitive chip 3 is in vacuum environment for external medium pressure accurately transmits to silicon resonance pressure sensitive chip 3, plays to reduce silicon resonance pressure sensitive chip 3's leak rate, and effectively protects it. Other components and connection relations are the same as those of any one of the first to sixth embodiments.

The specific implementation mode is eight: the present embodiment is described with reference to fig. 6 and 7, the sealing cover plate 1 of the present embodiment includes a T-shaped platform 101, a vacuuming hole 102, a circular boss 103, and notches 104, the circular boss 103 is embedded in a groove on an upper end surface of the T-shaped platform 101, the vacuuming hole 102 is vertically formed in the T-shaped platform 101, and four notches 104 are uniformly formed in the circular boss 103.

So set up, sealed apron 1 arranges the topmost of vacuum packaging structure in, generally adopts the preparation of weldable metal material, and the overall dimension of sealed apron 1 and the contact surface upper end size of sealed tube socket 6 need be joined in marriage and do, and sealed apron 1 and sealed tube socket 6 are welding material each other simultaneously. The front surface of the sealing cover plate 1 is provided with the vacuumizing hole 102, vacuumizing is carried out through the vacuumizing hole 102, the vacuumizing hole 102 is welded after the requirement of the vacuum degree is met, and the vacuum degree in the vacuum packaging structure is guaranteed. Other components and connection relations are the same as those of any one of the first to seventh embodiments.

The specific implementation method nine: the present embodiment is described with reference to fig. 1 to 8, and the encapsulation method of the present embodiment includes the following steps:

the method comprises the following steps: manufacturing and cleaning a sealing pipe seat 6;

sintering a lead hole 603 in the sealing tube seat 6 and the upper and lower pins together by using glass slurry to form a sealing pin structure, wherein the sealing tube seat 6 is made of stainless steel;

respectively clamping the silk fabric with acetone and absolute ethyl alcohol to clean the sealing pipe seat 6 by using stainless steel tweezers with heads coated with polytetrafluoroethylene, cleaning for more than 20 seconds by using absolute ethyl alcohol, and drying in a drying oven; sequentially putting the silicon resonance pressure sensitive chip 2 into acetone and absolute ethyl alcohol, respectively carrying out ultrasonic cleaning on the sealing tube seat 6 and the silicon resonance pressure sensitive chip 2 for 15min, and sequentially putting the special fixture ceramic ring into acetone and absolute ethyl alcohol for ultrasonic cleaning for 15 +/-3 min;

step two: gluing and bonding;

fixing a sealing tube seat 6 on a clamp, uniformly dotting 6 points on the sealing tube seat 6 according to the shape of a silicon resonance pressure sensitive chip 2 by using a toothpick 730 adhesive or using an automatic dispenser, then embedding the silicon resonance pressure sensitive chip 2 therein, pressing the upper part of a chip upper cover 201 of the silicon resonance pressure sensitive chip 2 by using a ceramic rod, ensuring that an external pressure hole on the sealing tube seat 6 corresponds to a first pressure sensing through hole 2031 and a second pressure sensing through hole 2032 of a stress isolation layer 203, then continuously picking 730 adhesive by using the toothpick or using the automatic dispenser for dispensing, ensuring that a Kovar alloy pin 3 corresponds to a through hole of a special clamp ceramic ring, protecting the Kovar alloy pin 3, and taking out the ceramic ring after the adhesive is coated;

step three: curing the glue;

curing the sealing tube seat 6 bonded with the silicon resonance pressure sensitive chip 2 in the step two in a constant temperature and humidity environment for 20-30 hours;

step four: pressure welding of the electrode bonding lead 4;

step four, firstly: fixing the sealing tube seat 6 on a clamp, and welding the electrode bonding lead 4 and the extraction electrode 3050 together at the position of the distance from the tip of the cleaver to the diameter of the electrode bonding lead 4 on the surface of the extraction electrode 3050, which is 2.5 times of the diameter;

step four and step two: the other end of the electrode bonding lead 4 is welded on the kovar alloy pin 3 through a hot welding pen, and the length of the electrode bonding lead 4 is automatically formed when two points are welded;

step four and step three: carrying out a breaking force test on the electrode bonding lead 4 until the breaking force meets the design requirement;

step five: performing insulation test on the kovar alloy pin 3 and the sealing tube seat 6;

testing the insulation resistance between each pin of the kovar alloy pin 3 and the sealing tube seat 6 by using an insulation resistance tester, wherein the resistance is greater than a design limit value;

step six: testing the basic performance of the silicon resonance pressure sensitive chip 2;

the water absorption ball is adopted to blow and lead the pressure hole, the pressure change is less than hundreds of hertz, and the temperature frequency is not changed; at this time, the silicon resonance pressure sensitive chip 2 meets the design requirements;

step seven: welding the sealing cover plate 1 on the sealing pipe seat 6;

placing the sealing cover plate 1 on the sealing pipe seat 6, utilizing argon arc welding or electron beam welding, and then carrying out a penetration test; repeating the step five;

step eight: plugging the sealing pipe seat 6;

sealing the vacuumized hole 102 with the diameter of 1.3mm by using a phi 2 steel ball, and then sealing and welding the vacuumized sealed cavity by adopting electron beam welding;

thus, the packaging of the resonant pressure sensitive chip probe of the vacuum packaging structure is completed;

step nine: electrically testing the resonance pressure sensitive chip probe of the vacuum packaging structure after packaging;

the electrical test is carried out under the constant normal pressure condition, and when the resonance pressure sensitive chip probe does not generate the frequency hopping phenomenon and the frequency changes towards one direction, the resonance pressure sensitive chip probe is stable and qualified within the time of less than 3 seconds;

step ten: carrying out pressure fatigue and aging tests on the resonance pressure sensitive chip probe of the packaged vacuum packaging structure;

the resonance pressure sensitive chip probe is arranged on a clamp and is connected with an air pressure fatigue machine or a hydraulic fatigue machine, the fatigue times are 5000/10000 times, and the resonance pressure sensitive chip probe is placed in a high-low temperature test box for temperature aging tests to release the internal stress of the resonance pressure sensitive chip probe together, so that the output stability of the resonance pressure sensitive chip of the vacuum packaging structure is improved;

step eleven: performing air tightness detection on a resonance pressure sensitive chip probe of the packaged vacuum packaging structure;

connecting the resonance pressure sensitive chip probe with a pressure controller, and carrying out air tightness detection, wherein the pressure change value is not more than +/-2 Pa, and at the moment, the air tightness of the resonance pressure sensitive chip probe is qualified;

step twelve: and carrying out laser marking and screening on the resonance pressure sensitive chip probe of the packaged vacuum packaging structure, and switching to the next production stage.

The working principle of the invention is as follows:

the invention can reduce the pressure difference between the chip sealing cavity and the external working environment based on the double-resonator chip probe secondary vacuum packaging, and meanwhile, the double-pressure resonator realizes multi-path pressure measurement through the probe pipeline. The invention designs a special probe pressure transmission structure, and respectively transmits two paths of pressures to be measured to the pressure sensing surfaces of the double pressure resonators to respectively realize double-path pressure measurement.