MEMS electric heating bicrystal actuator
Technical field:
What the present invention relates to is a kind of bimetallic electric heating actuator of working under "on" position, the processing of a kind of specifically employing MEMS (MEMS) processing technology, the beam type structure of forming by the different material of the two-layer coefficient of expansion, when energising, electric heating layer produces Joule heat, thereby making bimetallic actuator produce the outer buckling deformation of sheet, is a kind of actuator that recycle, low-power consumption, that respond fast.
Background technology:
Along with the continuous development of society and and the continual renovation of technology, people improve constantly for the requirement of product, this makes that reducing its cost when product function is preeminent becomes the conflicting requirement that people must face.One of method that solves this difficult problem is exactly to adopt MEMS (MEMS, Micro Electromechanical System).It makes system and product develop towards miniaturization, intellectuality and integrated direction, can predict: MEMS can bring another time technological revolution to human society, it will exert far reaching influence to science and technology, the mode of production and the human being's production quality of 21 century, is to be related to national science and technology development, national defense safety and a key technology of prosperous economy.
Micro-actuator had obtained paying attention to widely and constantly development as an important branch of MEMS device in recent years.The micro element of various different active principle emerges in an endless stream, and in numerous active principle, electromagnetism and piezoelectric element have high energy density and be suitable for high frequency, stepping control, but control system is big than complexity and energy consumption, and manufacturing cost is big, and element stability is poor; Static drives simple the actuating apart from being restricted; The destruction that the problem that supersonic speed activates is then mainly brought in mesomerism; Because component size dwindles, dimensional effect make mechanical strain that thermal expansion caused become very considerable and active force big; Developed a kind of electric heating actuator that utilizes Joule heat to produce buckling deformation thus, characteristics such as it has, and distortion is big, low-power consumption, reaction are fast.
Summary of the invention:
The purpose of this invention is to provide a kind of based on MEMS (MEMS) body processing and surface processing technique, the distortion of working under "on" position is big, power consumption is little, swift bimetallic electric heating actuator.
The object of the present invention is achieved like this: the electric heating actuator is made of the main body trilaminate material, the material that two-layer up and down thermal expansion coefficient difference is bigger and a kind of middle electric heating layer material of the big material of thermal coefficient of expansion that is clipped in.In conjunction with MEMS technology, and further raise the efficiency, so the less bigger metal aluminium lamination-silicon nitride dielectric layer-doping of undoped polysilicon-thermal coefficient of expansion of passivation layer-thermal coefficient of expansion of actuator deposit-deposit successively-evaporation/sputter-deposit-deposit from bottom to top and doping-deposit-evaporation/sputter makes the bigger metal aluminium lamination of polysilicon layer-silicon nitride dielectric layer-thermal coefficient of expansion of its resistance decreasing.It is characterized in that: a kind of under the energising situation electric heating layer produce Joule heat, the overall structure that Joule heat is formed up and down two-layer materials having different thermal expansion coefficient produces the electric heating actuator of buckling deformation.At silicon chip upper surface oxidation passivation layer, deposit polysilicon on passivation layer then, evaporation/splash-proofing sputtering metal aluminium, the deposit silicon nitride insulating barrier, the deposit polysilicon layer also mixes, and the polysilicon chip after mixing is carried out photoetching form required form, deposition insulating layer silicon nitride on this layer polysilicon layer again, cut into required figure together with substrate with above six layers, again second half metal aluminium lamination of evaporation/sputter and make the shape of this layer by lithography.Finish above institute and the bottom substrate silicon layer bear the photoresist photoetching after in steps, remove the silica-based lamella of part actuator bottom, the formation required form.The present invention can also comprise some architectural features like this:
1, the base material of described electric heating actuator is silicon-based semiconductor material<100〉or silicon-based semiconductor material<110;
2, the bigger material of thermal coefficient of expansion can be that aluminium also can be MEMS common metal materials such as copper or gold in the described electric heating actuator;
3, the thermal coefficient of expansion materials with smaller can be that polysilicon also can be silicon or silica in the described electric heating actuator;
MEMS (MEMS) processing technology uses technology such as photoetching, etching and chemical vapour deposition (CVD) to have a clear superiority on the micro-structural of making micro-system in batches.The present invention passes through the electric heating actuator material is selected, and the design of structure manufacturing process can make the electric heating actuator respond the certain buckling deformation of generation fast by applying external voltage, reaches the actuating purpose.This structural entity thickness less than the 200um surface size less than 1 * 1mm
2The electric heating actuator of making by the MEMS processes can be integrated on same silicon base simultaneously, to reach the purpose of the system integration.The major advantage of this kind actuator can be summed up as:
1. electric heating actuator power consumption is very little
2. the electric heating actuator response is fast
3. realize the sheet outer displacement
4. distortion is bigger, and actuation force is bigger
5. simple in structure, can be repeatedly used
6. can be used for the optical path signal blocking and wait other occasions
7. avoid signal voltage to disturb
8. can under the very low state of ambient temperature, work
The difference that the output displacement of electric heating actuator can be selected with material, the variation of overall dimensions and changing is so can adjust flexibly at needs when the MEMS entire system is established.
Description of drawings:
Fig. 1, bimetallic electric heating actuator structure graphics;
Fig. 2, electric heating layer structure three-dimensional figure;
Specific embodiments:
For example the present invention is done more detailed description below in conjunction with accompanying drawing: in conjunction with Fig. 1,2, the composition of the electric heating actuator embodiment among the present invention comprises polysilicon (6), the insulating passivation layer silicon nitride (7) of electric heating layer upper surface, the metallic aluminium (8) after insulating passivation layer silicon nitride (5), the electric heating layer of the lower surface of silicon base (1), silicon dioxide passivation layer (2), non-impurity-doped polysilicon (3), metallic aluminium (4), electric heating layer promptly mix.At first in silicon chip<100 of twin polishing〉go up growth silicon dioxide passivation layer (2), purpose is the corrosion that stops in the subsequent step, wherein the oxidation furnace temperature is 1150 ℃, 95~97 ℃ of bath temperatures, oxygen flow 1L/min; Next step is deposit one deck polysilicon on passivation layer, as that less one deck of thermal coefficient of expansion; The processing of the big one deck of the thermal coefficient of expansion that is about to begin then, also useful therebetween insulating barrier parcel electric heating layer.Evaporation on polysilicon/splash-proofing sputtering metal aluminium lamination; The silicon nitride dielectric layer of deposit electric heating layer lower surface on the metal aluminium lamination then; Deposit polysilicon once more afterwards, and, make it reach required resistance value to its doping, and utilize method to form the electric heating layer shape to polysilicon electric heating layer gluing, photoetching, reaction ion deep etching.Photolithography process: gluing〉preceding baking〉exposure〉develop post bake corrosion remove photoresist, so because mask and the photoetching of the consistent selection of the figure of formation positive photoetching rubber.Under the protection of undeveloped photoresist, utilize the mode of reaction ion deep etching to form required electric heating layer shape; The last silicon nitride dielectric layer of deposit electric heating layer upper surface once more; Above (1) (2) (3) (4) (5) (6) (7) layer is cut, and purpose is the rectangular strip that forms as shown in the figure; Last evaporation/sputter is half metal aluminium lamination in addition, and the means by photoetching, gluing, reaction ion deep etching are with the shape of its formation as figure again.Reserve a position and carry out the hole opening technology of standard, purpose is to apply voltage.At last bottom substrate silicon layer (1) is born the photoresist photoetching, remove the silica-based lamella of part actuator bottom.So just form final bimetallic electric heating actuator.
The course of work of electric heating actuator is as follows: under peacetime state; under the state that does not promptly power on; the electric heating actuator does not produce distortion; even interfering signal voltage is arranged, and also avoided voltage directly to be loaded into producing big calorimetric on the bigger metal level of thermal coefficient of expansion making its fusing also because there is the protection of insulating barrier silicon nitride to make it avoid producing abnormal working position.In the time of in working order, it is applied voltage, the electric heating layer polysilicon is in "on" position, produces Joule heat, because the official post total of the thermal coefficient of expansion of two layers of material is finished actuating because Joule heat responds the generation buckling deformation rapidly up and down.