A kind of chip of 6H-SiC high-temp pressure sensor
Technical field
The present invention's design relates to the chip structure of MEMS sensor, relates in particular to a kind of employing 6H-SiC material and makes, and for the chip structure of high temperature pressure measurement, belongs to the sensor construction design field.
Background technology
SiC, than traditional silicon materials, at high temperature has more stable physicochemical property, is to be hopeful very much to be applied to the semiconductor material under the high temperature mal-condition.Achievements in research more both domestic and external show, the electron device that SiC material, particularly 6H-SiC material are made do not need cooling just can on-line operation in the environment of 600 ℃.At present existing, utilize the high-temperature device that the SiC material makes, the pressure resistance type high-temp pressure sensor is because it is simple in structure, and range of application has more extensively obtained research widely.And in the process of design 6H-SiC chip of high-temp pressure sensor, must carry out structural design according to the characteristics of piezoresistive pressure sensor and the material behavior of 6H-SiC self, comprise following some:
One, need the variation of the responsive ambient pressure of specific structure.
Two, sensitive resistance will be arranged according to the isotropic characteristic of 6H-SiC piezoresistance coefficient.
Three, along with the rising of temperature, the coefficient of strain of 6H-SiC can change, and the coefficient of strain is being radially different with tangential temperature variant trend.
Only have the structural design of carrying out the 6H-SiC chip of high-temp pressure sensor according to main points as above, could farthest utilize the pressure-sensitive character of sensitive resistance, improve the sensitivity of device, guarantee device is worked under hot environment performance.
Summary of the invention
The objective of the invention is to propose a kind of structure of 6H-SiC chip of high-temp pressure sensor, guaranteeing that the 6H-SiC pressure transducer at high temperature on the basis of steady operation, farthest utilizes the pressure-sensitive character of sensitive resistance, improve device sensitivity at high temperature.
Technical scheme of the present invention is as follows:
A kind of chip of 6H-SiC high-temp pressure sensor, this chip structure comprise responsive diaphragm and form needed four sensitive resistance of bridge diagram: the first long pressure drag, the second long pressure drag, the 3rd long pressure drag and the 4th long pressure drag; Above-mentioned four long pressure drags are all to obtain in the 6H-SiC epitaxial loayer etching through overdoping, and after sputter, the graphical circuit that forms couples together these four long pressure drags, form complete bridge diagram, it is characterized in that: the described first long pressure drag and the second long pressure drag are arranged in responsive diaphragm center, both are parallel to each other, and radially both sides alignment; The 3rd long pressure drag and the 4th long pressure drag radially are arranged in responsive diaphragm marginal position, and are arranged symmetrically with about the first long pressure drag and the second long pressure drag, and with the first long pressure drag and the second long pressure drag on same straight line.
Above-mentioned 6H-SiC chip of high-temp pressure sensor is characterised in that: the 3rd long pressure drag is formed by bonding jumper one series connection by the first short pressure drag and the second short pressure drag, and both are equal in length, be parallel to each other, and the both sides alignment; The 4th long pressure drag is formed by bonding jumper two series connection by the 3rd short pressure drag and the 4th short pressure drag, and both are equal in length, be parallel to each other, and the both sides alignment.
Above-mentioned 6H-SiC chip of high-temp pressure sensor is characterised in that: the first short pressure drag, the 3rd short pressure drag and the first long pressure drag are on the same straight line; The second short pressure drag, the 4th short pressure drag and the second long pressure drag are on the same straight line.
The present invention has the following advantages and the high-lighting effect: one, responsive diaphragm distribution of force is even, stress is concentrated less, thereby the work upper limit is higher; Two, due to the piezoresistance coefficient isotropy of 6H-SiC, therefore the sensitive resistance that is arranged in responsive diaphragm center and marginal position can obtain maximum piezoresistive effect, responsive diaphragm center is opposite with the stress direction that marginal position is subject to simultaneously, said structure can guarantee the difference output of bridge diagram, the sensitivity that has further improved the 6H-SiC chip of high-temp pressure sensor; Three, under hot environment, the tangential strain coefficient of 6H-SiC wafer is faster than radially descending, therefore the sensitive resistance of radial arrangement is conducive to improve the sensitivity that chip is at high temperature worked, and has also guaranteed the stability that the 6H-SiC pressure transducer is at high temperature worked.
The accompanying drawing explanation
Fig. 1 is the chip structure principle schematic of 6H-SiC high-temp pressure sensor provided by the invention.
Fig. 2 is the long pressure drag structural representation that is arranged in diaphragm edge.
Fig. 3 is the long pressure drag structural representation that is arranged in the diaphragm center.
In figure: the long pressure drag of 1-first; The long pressure drag of 2-second; 3-bonding jumper one; The short pressure drag of 4-first; The short pressure drag of 5-second; 6-bonding jumper two; 7-the 3rd short pressure drag; 8-the 4th short pressure drag; The responsive diaphragm of 9-; 10-the 3rd long pressure drag; 11-the 4th long pressure drag.
Embodiment
Below in conjunction with the drawings and specific embodiments, structure of the present invention, principle and the course of work are described further.
Fig. 1 is the chip structure principle schematic of a kind of 6H-SiC high-temp pressure sensor provided by the invention, comprise responsive diaphragm and form needed four sensitive resistance of full bridges circuit: responsive diaphragm structure stress is evenly distributed, stress is concentrated less, thereby the work upper limit is higher; The first long pressure drag 1 and the second long pressure drag 2 are arranged in responsive diaphragm center, and both are parallel to each other, and radially both sides alignment; The 3rd long pressure drag 10 and the 4th long pressure drag 11 radially are arranged in responsive diaphragm marginal position, and are arranged symmetrically with about the first long pressure drag 1 and the second long pressure drag 2, and with the first long pressure drag 1 and the second long pressure drag 2 on same straight line.Due to the piezoresistance coefficient isotropy of 6H-SiC, therefore center and the marginal position of responsive diaphragm are the zones of piezoresistive effect maximum, and chip structure as above can obtain maximum sensitivity.Simultaneously, under hot environment, 6H-SiC wafer tangential strain coefficient is faster than radially descending, therefore four sensitive resistance are radially arranged and can be guaranteed that larger piezoresistive effect is still arranged under very high working temperature, and then improve the sensitivity that the 6H-SiC pressure sensor chip is at high temperature worked.
Fig. 2 is the long pressure drag structural representation that a kind of 6H-SiC chip of high-temp pressure sensor provided by the invention is arranged in diaphragm edge, the first short pressure drag 4 and the second short pressure drag 5 are by bonding jumper one 3 series connection, make the first long pressure drag 10 of final formation as far as possible near responsive diaphragm marginal position, and the first short pressure drag 4 and the second short pressure drag 5 have also improved all along the diaphragm radial arrangement sensitivity that the 6H-SiC pressure sensor chip is at high temperature worked.
Fig. 3 is the long pressure drag structural representation of a kind of 6H-SiC chip of high-temp pressure sensor provided by the invention in the diaphragm center, wherein the first long pressure drag 1 and the second long pressure drag 2 are arranged in responsive diaphragm center, both are parallel to each other, and radially both sides alignment.