CN102401840A - Si based HEMT embedded micro accelerator and production method thereof - Google Patents
Si based HEMT embedded micro accelerator and production method thereof Download PDFInfo
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- CN102401840A CN102401840A CN2011103597453A CN201110359745A CN102401840A CN 102401840 A CN102401840 A CN 102401840A CN 2011103597453 A CN2011103597453 A CN 2011103597453A CN 201110359745 A CN201110359745 A CN 201110359745A CN 102401840 A CN102401840 A CN 102401840A
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Abstract
The invention provides an Si based HEMT (High Electron Mobility Transistor) embedded micro accelerator, which comprises an Si substrate; the Si substrate comprises a micro accelerator structure composed of a peripheral base formed by etching, a cantilever beam and a mass block; the Si substrate has an HEMT material layer film at the processing position of the HEMT, and the HEMT material layer film comprises a GexSil-x buffer layer and other HEMT material layers; and the HEMT is processed on the HEMT material layer film. The invention further provides a production method for the Si based HEMT embedded micro accelerator. The accelerator provided by the invention solves the problems that a GaAS based microstructure has poorer elasticity, easy breakage in application process, higher test working difficulty, and the like.
Description
Technical field
The present invention relates to the micro-acceleration gauge technical field, more specifically, relate to embedded micro-acceleration gauge of a kind of Si based hemts and working method thereof.
Background technology
Along with the development of micro-electromechanical technology, the application in market is had higher requirement to accelerometer, such as high precision, and high linearity, high stability.MEMS sensor traditional detection method mainly contains pressure resistance type detection, condenser type detection etc.; Pressure resistance type detects with voltage dependent resistor (VDR) as sensing unit; Mainly utilize resistance interval with the linear response of ambient pressure, because the temperature of voltage dependent resistor (VDR) is floated effect, piezoresistance coefficient is restricted; Therefore be difficult to further improve response sensitivity, these drawbacks limit the application of this type of accelerometer at the high sensitivity sensory field.Detect for condenser type, because the restriction of micro-nano structure yardstick, the increase of capacity area also is restricted, and its detection sensitivity and resolution also are difficult to improve, and can't satisfy the application demand that further develops.
For satisfying application, be necessary to explore the restriction that breaks through traditional detection method based on the novel micro nanometer mechanical detection structure of new principle, new effect to the pressing for of highly sensitive micro-acceleration gauge.In recent years, the field effect transistor that has an e indicial response has caused various countries scientists' extensive concern.HEMT (High Electronic Mobility Transistor; Be called for short HEMT) be one of the most rising high-speed electronic components of generally acknowledging; Have hypervelocity, low-power consumption, low noise characteristics (especially at low temperatures), can satisfy purposes such as very-high speed computer and signal Processing, satellite communication.Wherein the GaAs based hemts is of greatest concern, and N-AlGaAs and GaAs lattice constant match can form heterojunction (energy gap of AlGaAs is greater than GaAs).Because the fermi level position of heterojunction two layers of material is different; Electronics will be transferred to lower low bandgap material one side from higher relatively wide bandgap material one side of Fermi level, make electronics and alms giver's ionized impurity apart in the raceway groove, and the motion on vertical interface direction (z direction) is to be limited in the very narrow trap; (x on the direction of parallel interface; The y direction) but is freely, therefore, in raceway groove, forms two-dimensional electron gas (2DEG).Because the output characteristics of HEMT is the e exponential form; The various extraneous parameter of this characteristic relation to causing that carrier transport properties (like two-dimensional electron gas) changes; Response like the variation of optics, calorifics, mechanical quantity is extremely sensitive; And on the I-V characteristic, show significantly, on suitable working point, realize the highly sensitive detection of external parameter.Utilize above character, can realize with GaAs being the micro-acceleration gauge detection means of substrate.
But because the GaAs material is more crisp; Elasticity is less; There is certain defective in the micro-acceleration gauge of substrate that traditional with GaAs is in application process, because the elasticity of material is less, the semi-girder root ruptures easily in sensitive direction stress application process; And in the stress test process of Raman pressurization, causing the Raman frequency shift difference disorderly, change direction is inconsistent.Based on above reason, must explore new material structure and technology, to break through the application limitation of conventional micro-acceleration gauge, to satisfy growing demand.
Monocrystalline silicon has favorable mechanical physical property and electrical property, in the MEMS manufacturing, is used widely.Because it has following major advantage: (1) stable mechanical property, electron device is integrated on the same substrate easily.(2) intensity of silicon, hardness and Young modulus and iron phase are worked as, but density is similar to aluminium, and high Young's modulus can keep the linear relationship of load and distortion well, therefore have the favorable mechanical performance.(3) fusing point is higher, and thermal expansivity is less, makes it under high-temperature condition, still can keep the stable of size.(4) silicon does not have mechanical hysteresis, is suitable for the Design of Sensor manufacturing.(5) silicon substrate has greater flexibility in manufacturing and designing, and the manufacturing process comparative maturity.Based on above reason, if can adopt the Si substrate to realize Si base micro-acceleration gauge, must solve the restriction of traditional GaAs base micro-acceleration gauge in application, remedy the defective of prior art.
Summary of the invention
To the demand of the prior art; The present invention adopts the Si substrate; Utilize the embedded micro-acceleration gauge of method processing Si based hemts of heterogenous junction epitaxy,, can reach highly sensitive detection to solve the restriction of traditional GaAs base micro-acceleration gauge in application; Realized the application of power coupling effect on micro-acceleration gauge of HEMT (HEMT), satisfied the demand of application micro-acceleration gauge.
The embedded micro-acceleration gauge of Si based hemts provided by the present invention comprises the Si substrate, and said Si substrate comprises the micro-acceleration gauge structure that the peripheral pedestal, semi-girder and the mass that are formed by etching constitute; It is characterized in that:
Said Si substrate has HEMT material layer film at the Working position place of HEMT (HEMT), and said HEMT material layer film comprises Ge
xSi
1-xCushion and other HEMT material layer; On said HEMT material layer film, be processed with HEMT (HEMT).
Preferably, the Ge of said HEMT material layer film
xSi
1-xCushion is that the multilayer Ge composition of on the Si substrate, growing increases progressively until all being the Ge of Ge successively
xSi
1-xCushion.Further preferably, said HEMT material layer film is at Ge
xSi
1-xSaid other HEMT material layer on the cushion comprises superlattice layer, separation layer, channel layer, barrier layer, etch stop layer, transition bed and cap layer.Wherein, said channel layer is the i-InGaAs layer of high-purity and smoothness; Said etch stop layer is to be used to the i-InGaP layer that makes following process be convenient to control, said transition bed be used to increase two-dimensional electron gas (2DEG) concentration have Si doped n-GaASn layer.
Preferably, the conducting channel direction of the source of said HEMT (HEMT), drain electrode and said semi-girder are 0 °, 45 ° and/or 90 ° of angles.
Preferably, said HEMT (HEMT) comprising: through the Ohmic contact figure of employing photoetching source electrode, drain electrode on said HEMT material layer film and source electrode and the drain electrode that the evaporation deposition alloy forms; Groove with etching formation between source electrode, drain electrode; The grid groove of in the middle of the bottom land of groove, processing along groove direction; The grid that the depositing metal overlayer forms at grid groove place; Between source electrode and drain electrode and source electrode and drain electrode over against the Si of the edge deposit formation of side
3N
4Passivation layer; The metal A u layer of sputter on source electrode, drain and gate.
In order to realize the embedded micro-acceleration gauge of above-mentioned Si based hemts, the present invention further provides the working method of the embedded micro-acceleration gauge of a kind of Si based hemts, it is characterized in that, may further comprise the steps:
Step 1, applied molecular beam epitaxy technology generate HEMT material layer film on the Si substrate, increase progressively successively until all being the Ge of Ge comprising the multilayer Ge composition of at first on the Si substrate, growing
xSi
1-xCushion; Then at said Ge
xSi
1-xOther HEMT material layer of growth on the cushion;
Step 2; Processing HEMT (HEMT) and micro-acceleration gauge structure; Specifically comprise: step a; According to the layout of micro-acceleration gauge structure to be processed, utilize etching technics, at other film that removes on the said HEMT material layer membrane structure of Si substrate growth except the table top part of needs processing HEMTs (HEMT); Step b processes HEMT (HEMT) respectively in each table top part of said reservation film; Step c; Use etching technics the Si substrate etching is become by peripheral pedestal, semi-girder and through semi-girder to prop up the micro-acceleration gauge structure that the mass that is suspended from peripheral pedestal central authorities constitutes, and make the said film that is processed with HEMT (HEMT) be positioned at the junction of semi-girder and peripheral pedestal.
Preferably, in step 1, said Ge
xSi
1-xOther HEMT material layer of growth comprises superlattice layer, separation layer, channel layer, barrier layer, etch stop layer, transition bed and cap layer on the cushion.Wherein, said channel layer is the i-InGaAs layer of high-purity and smoothness; Said etch stop layer is to be used to the i-InGaP layer that makes following process be convenient to control, said transition bed be used to increase two-dimensional electron gas (2DEG) concentration have Si doped n-GaASn layer.
Preferably, said step b specifically comprises:
B1, at first adopt photoetching process to process the source electrode of HEMT (HEMT) and the Ohmic contact figure of drain electrode on the ohmic contact layer n-GaAs surface of said film; Adopt electron beam evaporation process to form the Au/Ge/Ni metal level then on ohmic contact layer n-GaAs surface; After after peeling off cleaning; With 400 ℃ of high temperature quick alloy in 60s; Realize source electrode, the drain metallization of transistor HEMT, make between the ohmic contact layer n-GaAs surface of source electrode, drain electrode and said film of transistor HEMT and form good Ohmic contact;
B2, on the film between source electrode and the drain electrode, process and drain parallel and run through the groove of whole film, and groove is a groove bottom with the schottky contact layer n-AlGaAs surface of film with etching technics; In the middle of the bottom land of groove, process the grid groove with photoetching process then along groove direction; And in grid groove process; Detection resources is leaked the saturation current of two interpolars in real time, and the saturation current that leaks two interpolars until the source reaches required value, obtains required grid groove; Adopt electron beam evaporation process in groove surfaces, grid groove, to form the Ti/Pt/Au overlayer subsequently; Form grid at grid groove place to peel off method, realize gate metalized, make the good Schottky barrier of formation between the schottky contact layer n-AlGaAs of grid and said film;
B3, with the PECVD sedimentation on the film of source electrode, drain electrode, grid with 230 ℃ of temperature deposit Si
3N
4Passivation layer is then with the said Si of photoetching process etching
3N
4Passivation layer makes Si
3N
4The passivation layer zone only covers between source electrode and the drain electrode and the edge of source electrode and drain electrode offside; Use the certain thickness metal A u layer of sputtering unit sputter then, with three electrode thickenings.
Preferably, among the step a, direction and said semi-girder that order is used to process the table top part of said HEMT (HEMT) are 0 °, 45 ° and/or 90 ° of angles.
Principal feature of the present invention comprises: 1.Ge
xSi
1-xCushion has played the effect that reduces the disorderly density of mispairing.2. channel layer is as the core of HEMT device, and high-purity and smoothness can well avoid in growth course, introducing new impurity and defective.3. the etch stop layer can become to follow-up processing technology and control easily; Concentration .4. high electron mobility transistor (HEMT) and semi-girder that transition bed can increase 2DEG are multiple angles; Through to different HEMT dynamic tests; Can better understand the relation in orientation of sensitivity and the sensing unit of accelerometer, to increase the sensitivity of accelerometer.
Problems such as micro-acceleration gauge according to the invention mainly is that to solve the elasticity of GaAs base microstructure relatively poor, and fracture easily in the application process, test job difficulty are bigger have proposed a kind of application heterogenous junction epitaxy technology processing Si based hemts micro-acceleration gauge structure.When this accelerometer is sensed the acceleration of sensitive direction; Mass produces skew; Drive the semi-girder bending that deforms; Can make in the high electron mobility transistor (HEMT) raceway groove of semi-girder root setting and produce STRESS VARIATION, multiple physical mechanism interacts and causes channel resistance to change, and wherein a kind of mechanism is because the variation of electron effective mass causes the variation of carrier mobility; Another physical mechanism is under stress, because the variation of phase pair potential, electronics can transit to from the level structure with high carrier mobility the low carrier mobility energy level; The 3rd physical mechanism is different from other mechanism, and it mainly is because the piezoelectric effect under the stress causes the variation of channel resistance.In sum,, compare, produce bigger piezoresistance coefficient and higher sensitivity with voltage dependent resistor (VDR) because the combined action of pressure drag and piezoelectric effect causes the variation of two-dimensional electron gas.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the present invention is done further detailed explanation:
Fig. 1 is the HEMT material layer membrane structure synoptic diagram of the embodiment of the invention;
Fig. 2 is a HEMT table position synoptic diagram described in the accelerometer of the embodiment of the invention;
Fig. 3 is the process for machining and manufacturing schematic flow sheet of the embodiment of the invention;
Fig. 4 A-C is the SEM synoptic diagram of the HEMT (HEMT) of the embodiment of the invention;
Fig. 5 is the embedded micro-acceleration gauge one-piece construction of the Si based hemts figure of the embodiment of the invention.
Embodiment
In order to make those skilled in the art person understand technical scheme of the present invention better, and make above-mentioned purpose of the present invention, feature and advantage can be more obviously understandable, below in conjunction with embodiment and embodiment accompanying drawing the present invention done further detailed explanation.
Micro-acceleration gauge according to the invention mainly is to realize the detection to mechanical signal through HEMT (HEMT).Utilize the power coupling effect of HEMT to design the micro-acceleration gauge of embedded HEMT micro-cantilever-mass block structure.When microstructure received acceleration movement, the mass forced vibration made semi-girder crooked, thereby causes the HEMT channel stress on the semi-girder to change.Respective change will take place in the band structure affected by force of semiconductor material among the HEMT, thereby cause the two-dimensional electron gas restriction to change, and have influence on the concentration of channel electrons, finally reflect the I-V characteristic variations of HEMT.
Introduce the working method of the embedded micro-acceleration gauge of Si based hemts of the present invention below.Key step of the present invention comprises the design generation and the manufacturing of micro-acceleration structure Design of membrane structure, promptly may further comprise the steps: step 1, applied molecular beam epitaxy technology generate HEMT material layer film on the Si substrate; Step 2, processing HEMT (HEMT) and micro-acceleration gauge structure.
Step 1: applied molecular beam epitaxy technology generates HEMT material layer film on the Si substrate
Because the Si substrate is different with the grating constant of epitaxial film materials, it is disorderly that epitaxial loayer and substrate interface place produce mispairing.In order to reduce the disorderly density between epitaxial loayer and the substrate, can take following method in the prior art: the substrate orientation error, cushion adopts the superlattice layer with strain, and heterojunction or selective growth zone are taked the aftertreatment of annealing.
Yet in patent of the present invention, it is disorderly to take a kind of improved new method to prevent with the mispairing of Si substrate: the Ge that growth multilayer Ge composition increases progressively with 10%Ge/um successively on the Si substrate
xSi
1-xCushion all is Ge until at last, utilizes other structure of heterogenous junction epitaxy technology growth HEMT material layer film afterwards on this basis.Concrete HEMT material layer membrane structure and correlation parameter are as shown in table 1 below:
Table 1
The key component of listed HEMT material layer film is as shown in Figure 1 in the table 1.Successively introduce the key component of said HEMT material layer film below in conjunction with Fig. 1:
Semi-insulated Si substrate: the structural sheet of HEMT device utilizes molecular beam epitaxy technique on semi-insulating substrate, to form; The quality quality of Si substrate directly affects the growth of subsequent thin film material and the electric property of device; Performance index to sensing unit play a part can not be ignored; Therefore, the selection of substrate and subsequent treatment seem particularly important.For reducing the influence of substrate to technology, the Si substrate that the present invention adopted must have the characteristics of high polishing degree and low-dislocation-density.
Ge
xSi
1-xCushion and GaAs/Al
xGa
1-xThe As superlattice layer: because substrate is different with the grating constant of epitaxial film materials, it is disorderly that epitaxial loayer and substrate interface place produce mispairing.In the present invention, Ge
xSi
1-xTo be the multilayer Ge composition of on the Si substrate, growing increase progressively until all being the Ge of Ge with 10%Ge/um cushion successively
xSi
1-xCushion has played the effect that reduces the disorderly density of mispairing.Be employed in the GaAs/Al that grows on the cushion
xGa
1-xThe method of As superlattice layer can be avoided extending to channel layer from the various defect and impurities of substrate, influences the transport mechanism of charge carrier.
Separation layer: in HEMT, because the existence of quantum well channel makes charge carrier and donor ion be separated, this will reduce the ionized impurity scattering in the carrier moving process greatly, greatly improve the low field mobility and the saturated velocity of charge carrier.The existence of separation layer makes impurity spatially separate with two-dimensional electron gas (2DEG), has reduced impurity scattering greatly.The thickness of separation layer could guarantee neither can introduce impurity to channel layer within the specific limits the time, also not can the time channel layer two-dimensional electron gas very low.As shown in table 1, said HEMT material layer film comprises a plurality of separation layers, and planar isolated layer shown in Figure 1.
Channel layer: channel layer is the i-InGaAs layer of high-purity and smoothness as the core of HEMT device, and its purity and smoothness are had very high requirement, and high-purity and smoothness can well avoid in growth course, introducing new impurity and defective.
Barrier layer: barrier layer has two main effects, and the one, for two-dimensional electron gas provides electronics, the one, the Schottky contacts of realization grid.In order effectively to suppress low electron mobility effect, the depletion region of grid should be greater than Al
xGa
1-xAs/2DEG depletion region at the interface.
Etch stop layer and transition bed: the etch stop layer is to be used to the i-InGaP layer that makes following process be convenient to control; Said transition bed be used to increase two-dimensional electron gas (2DEG) concentration have Si doped n-GaASn layer.
Highly doped cap layer: be used to realize the HEMT source, leak Ohmic contact.As shown in Figure 1, the upper surface of cap layer forms the n-GaAs ohmic contact layer.
Fig. 3 is the process for machining and manufacturing schematic flow sheet of the embodiment of the invention.Shown in Fig. 3 A, the HEMT material layer film of on the superficial growth of Si substrate 1, introducing 2 as shown in table 1.
Step 2: use the method that microelectronic technique and MEMS body processing technology combine, process HEMT (HEMT) and micro-acceleration gauge structure as follows.Specifically comprise:
Step a, according to topology layout that designs in advance and relative dimensions; Utilize etching technics on the HEMT material layer membrane structure 2 of long Si substrate 1 well, to etch the table top part that to process HEMT (HEMT), remove all films except the film 2 of needs processing HEMT (HEMT) position.As shown in Figure 2; If Design and Machining four beams---mass micro-acceleration gauge; Then need keep four table top membrane structures, and be positioned at the root of the semi-girder of " ten " font, be " ten " word distribute (i.e. four table tops partly lay respectively at " ten " word four summits); Two table tops are wherein arranged perpendicular to semi-girder, a table top is parallel to semi-girder, one with semi-girder be 45 ° of angles, as shown in Figure 2.The direction of table top part and reason that semi-girder is 0 °, 45 ° and/or 90 ° angle are: in the HEMT that machines afterwards (HEMT); Make the conducting channel direction and the said semi-girder of transistorized source, drain electrode be 0 °, 45 ° and/or 90 ° of angles; Thereby pass through different HEMT dynamic tests; Can better understand the relation in orientation of sensitivity and the sensing unit of accelerometer, to increase the sensitivity of accelerometer.On the other hand, if the work sheet cantilever beam structure, the table top that then on the Si substrate, only keeps monolithic films 2 gets final product, shown in B among Fig. 3.
Step b processes HEMT (HEMT) respectively in each table top part of said reservation film 2, specifically comprises:
Step b1: shown in C among Fig. 3; At first adopt photoetching process to process the source electrode 3 of high electron mobility transistor (HEMT) and the Ohmic contact figure of drain electrode 4 on the ohmic contact layer n-GaAs surface of said film 2; Adopt electron beam evaporation process to form
thick Au/Ge/Ni overlayer then on ohmic contact layer n-GaAs surface; After after peeling off cleaning; With 400 ℃ of high temperature quick alloy in 60s; Realize source electrode 3, drain electrode 4 metallization of transistor HEMT, make between the ohmic contact layer n-GaAs surface of source electrode 3, drain electrode 4 and said film of transistor HEMT and form good Ohmic contact.
Step b2: on source electrode 3 and the film 2 between 4 of draining, process and drain parallel and run through the groove 7 of whole film with etching technics, and groove 7 is groove bottom with the schottky contact layer n-AlGaAs surface (as shown in Figure 1) of film 2, shown in D among Fig. 3; In the middle of groove 7 bottom lands, process grid groove 6 with photoetching process then along groove 7 directions; And in grid groove 6 process, detection resources is leaked the saturation current of two interpolars in real time, and the saturation current that leaks two interpolars until the source reaches required value; Obtain required grid groove 6, shown in E among Fig. 3; Adopt electron beam evaporation process in groove 7 surfaces, grid groove 6, to form
thick Ti/Pt/Au metal level subsequently; Form grid 5 at grid groove place to peel off method; Realize the gate metalized of transistor HEMT; Shown in F among Fig. 3, make between the schottky contact layer n-AlGaAs (as shown in Figure 1) of grid and said film of transistor HEMT and form good Schottky barrier.
B3, processing on high electron mobility transistor (HEMT) source electrode 3, drain electrode 4, the film of grid 5 with 230 ℃ of temperature deposits with the PECVD sedimentation
Thick Si
3N
4Passivation layer 8 is then with the said Si of photoetching process etching
3N
4Passivation layer 8 makes Si
3N
4Passivation layer 8 zones only cover source electrode 3 and drain between 4 and the source electrode 3 and 4 edges over against side that drain, shown in G among Fig. 3; Use the certain thickness metal A u layer 9 of sputtering unit sputter then, with three electrode thickenings, shown in H among Fig. 3.Accomplished the processing of each HEMT 12 like this.
Step c, use the micro electro mechanical device process technology and process the micro-acceleration gauge structure as follows: (1) shown in I among Fig. 3, application controls hole lithographic technique carries out positive etching on Si substrate 1, and the degree of depth of etching is thick 20 of semi-girder 10---20um; (2) back-etching: back-etching is accomplished through two parts, at first shown in J among Fig. 3, and the part of etching mass 11, etching depth is 75um, makes mass 11 and frame form difference in height, under the effect of microgravity, mass 11 can move up and down.Then shown in K among Fig. 3, utilize the control punch technology to continue back-etching, till the control punch in front was punched, then having obtained thickness was the semi-girder of 20um; The outermost of Si substrate is peripheral pedestal 13.Formed semi-girder through said method---mass micro-acceleration gauge structure.
Pass through aforementioned production method; Realized the embedded micro-acceleration gauge of a kind of Si based hemts of the present invention; Fig. 5 is the embedded micro-acceleration gauge overall construction drawing of Si based hemts of the present invention; Show Si substrate 1, semi-girder 10, mass 11, peripheral pedestal 13, HEMT material layer film 2 and HEMT (HEMT) 12.As shown in Figure 5, this micro-acceleration gauge comprises Si substrate 1, and said Si substrate 1 comprises the micro-acceleration gauge structure that the peripheral pedestal 13, semi-girder 10 and the mass 11 that are formed by etching constitute; Said Si substrate 1 has HEMT material layer film 2 in the corresponding position of HEMT (HEMT) 12, and the concrete layer structure of this HEMT material layer film 2 is introduced in the table 1 of preceding text and Fig. 1 in detail.Processing realizes HEMT (HEMT) 12 on HEMT material layer film 2.HEMT (HEMT) 12 comprises: the source electrode 3 that Ohmic contact figure through on said HEMT material layer film 2, adopting photoetching source electrode, drain electrode and evaporation deposition alloy form and drain 4; Groove 7 with etching formation between source electrode 3, drain electrode 4; The grid groove of in the middle of the bottom land of groove 7, processing 6 along groove direction; Grid 5 in the 6 places depositing metal overlayers formation of grid groove; At source electrode 3 with drain between 4 and Si that source electrode 3 and drain electrode 4 form over against the edge deposit of side
3N
4Passivation layer 8; The metal A u layer 9 of sputter on source electrode, drain and gate.Wherein, conducting channel direction and the said semi-girder between the source electrode 3 of high electron mobility transistor (HEMT) 12, the drain electrode 4 is 0 °, 45 ° and/or 90 ° of angles.As shown in Figure 4, wherein Fig. 4 A shows source electrode 3, drain electrode 4 and grid 5, and source electrode 3 and the conducting channel direction and the said semi-girder that drain between 4 are 0 °; Similar ground, Fig. 4 B and Fig. 4 C show the form that conducting channel direction and said semi-girder are 45 ° and 90 ° respectively.With the HEMT (HEMT) of different angles, through to different HEMT dynamic tests, can better understand the relation in orientation of sensitivity and the sensing unit of accelerometer, to increase the sensitivity of accelerometer.
Problems such as micro-acceleration gauge according to the invention mainly is that to solve the elasticity of GaAs base microstructure relatively poor, and fracture easily in the application process, test job difficulty are bigger, thus a kind of application heterogenous junction epitaxy technology processing Si based hemts micro-acceleration gauge structure has been proposed.When this accelerometer is sensed the acceleration of sensitive direction; Mass produces skew; Drive the semi-girder bending that deforms; Can make in the high electron mobility transistor (HEMT) raceway groove of semi-girder root setting and produce STRESS VARIATION, multiple physical mechanism interacts and causes channel resistance to change, and wherein a kind of mechanism is because the variation of electron effective mass causes the variation of carrier mobility; Another physical mechanism is under stress, because the variation of phase pair potential, electronics can transit to from the level structure with high carrier mobility the low carrier mobility energy level; The 3rd physical mechanism is different from other mechanism, and it mainly is because the piezoelectric effect under the stress causes the variation of channel resistance.In sum,, compare, produce bigger piezoresistance coefficient and higher sensitivity with voltage dependent resistor (VDR) because the combined action of pressure drag and piezoelectric effect causes the variation of two-dimensional electron gas.
The above is merely embodiment of the present invention, and the present invention can also be applied in other opertaing device.Protection scope of the present invention is not limited thereto, and any technician who is familiar with the present technique field is in the technical scope that the present invention discloses, and the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain that claim was defined.
Claims (10)
1. the embedded micro-acceleration gauge of Si based hemts comprises the Si substrate, and said Si substrate comprises the micro-acceleration gauge structure that the peripheral pedestal, semi-girder and the mass that are formed by etching constitute; It is characterized in that:
Said Si substrate has HEMT material layer film at the Working position place of HEMT (HEMT), and said HEMT material layer film comprises Ge
xSi
1-xCushion and other HEMT material layer; On said HEMT material layer film, be processed with HEMT (HEMT).
2. the embedded micro-acceleration gauge of Si based hemts according to claim 1 is characterized in that, the Ge of said HEMT material layer film
xSi
1-xCushion is that the multilayer Ge composition of on the Si substrate, growing increases progressively until all being the Ge of Ge successively
xSi
1-xCushion.
3. the embedded micro-acceleration gauge of Si based hemts according to claim 2 is characterized in that, said HEMT material layer film is at Ge
xSi
1-xSaid other HEMT material layer on the cushion comprises superlattice layer, separation layer, channel layer, barrier layer, etch stop layer, transition bed and cap layer.
4. the embedded micro-acceleration gauge of Si based hemts according to claim 3 is characterized in that, said channel layer is the i-InGaAs layer of high-purity and smoothness; Said etch stop layer is to be used to the i-InGaP layer that makes following process be convenient to control, said transition bed be used to increase two-dimensional electron gas (2DEG) concentration have Si doped n-GaASn layer.
5. the embedded micro-acceleration gauge of Si based hemts according to claim 1 is characterized in that, the source of said HEMT (HEMT), the conducting channel direction of drain electrode and said semi-girder are 0 °, 45 ° and/or 90 ° of angles.
6. the embedded micro-acceleration gauge of Si based hemts according to claim 1; It is characterized in that said HEMT (HEMT) comprising: through the Ohmic contact figure of employing photoetching source electrode, drain electrode on said HEMT material layer film and source electrode and the drain electrode that the evaporation deposition alloy forms; Groove with etching formation between source electrode, drain electrode; The grid groove of in the middle of the bottom land of groove, processing along groove direction; The grid that the depositing metal overlayer forms at grid groove place; Between source electrode and drain electrode and source electrode and drain electrode over against the Si of the edge deposit formation of side
3N
4Passivation layer; The metal A u layer of sputter on source electrode, drain and gate.
7. the working method of the embedded micro-acceleration gauge of Si based hemts is characterized in that, may further comprise the steps:
Step 1, applied molecular beam epitaxy technology generate HEMT material layer film on the Si substrate, increase progressively successively until all being the Ge of Ge comprising the multilayer Ge composition of at first on the Si substrate, growing
xSi
1-xCushion; Then at said Ge
xSi
1-xOther HEMT material layer of growth on the cushion;
Step 2; Processing HEMT (HEMT) and micro-acceleration gauge structure; Specifically comprise: step a; According to the layout of micro-acceleration gauge structure to be processed, utilize etching technics, at other film that removes on the said HEMT material layer membrane structure of Si substrate growth except the table top part of needs processing HEMTs (HEMT); Step b processes HEMT (HEMT) respectively in each table top part of said reservation film; Step c; Use etching technics the Si substrate etching is become by peripheral pedestal, semi-girder and through semi-girder to prop up the micro-acceleration gauge structure that the mass that is suspended from peripheral pedestal central authorities constitutes, and make the said film that is processed with HEMT (HEMT) be positioned at the junction of semi-girder and peripheral pedestal.
8. working method according to claim 7 is characterized in that, in step 1, and said Ge
xSi
1-xOther HEMT material layer of growth comprises superlattice layer, separation layer, channel layer, barrier layer, etch stop layer, transition bed and cap layer on the cushion.
9. working method according to claim 7 is characterized in that, said step b specifically comprises:
B1, at first adopt photoetching process to process the source electrode of HEMT (HEMT) and the Ohmic contact figure of drain electrode on the ohmic contact layer n-GaAs surface of said film; Adopt electron beam evaporation process to form the Au/Ge/Ni metal level then on ohmic contact layer n-GaAs surface; After after peeling off cleaning; With 400 ℃ of high temperature quick alloy in 60s; Realize source electrode, the drain metallization of transistor HEMT, make between the ohmic contact layer n-GaAs surface of source electrode, drain electrode and said film of transistor HEMT and form good Ohmic contact;
B2, on the film between source electrode and the drain electrode, process and drain parallel and run through the groove of whole film, and groove is a groove bottom with the schottky contact layer n-AlGaAs surface of film with etching technics; In the middle of the bottom land of groove, process the grid groove with photoetching process then along groove direction; And in grid groove process; Detection resources is leaked the saturation current of two interpolars in real time, and the saturation current that leaks two interpolars until the source reaches required value, obtains required grid groove; Adopt electron beam evaporation process in groove surfaces, grid groove, to form the Ti/Pt/Au overlayer subsequently; Form grid at grid groove place to peel off method, realize gate metalized, make the good Schottky barrier of formation between the schottky contact layer n-AlGaAs of grid and said film;
B3, with the PECVD sedimentation on the film of source electrode, drain electrode, grid with 230 ℃ of temperature deposit Si
3N
4Passivation layer is then with the said Si of photoetching process etching
3N
4Passivation layer makes Si
3N
4The passivation layer zone only covers between source electrode and the drain electrode and the edge of source electrode and drain electrode offside; Use the certain thickness metal A u layer of sputtering unit sputter then, with three electrode thickenings.
10. working method according to claim 7 is characterized in that, among the step a, direction and said semi-girder that order is used to process the table top part of said HEMT (HEMT) are 0 °, 45 ° and/or 90 ° of angles.
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| CN110887977A (en) * | 2019-11-28 | 2020-03-17 | 上海应用技术大学 | Nanoscale piezoresistive acceleration sensor and preparation method thereof |
| CN111983257A (en) * | 2020-08-22 | 2020-11-24 | 范绪阁 | Acceleration sensor based on suspension two-dimensional material and heterogeneous layer suspension mass block |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104599957A (en) * | 2013-11-01 | 2015-05-06 | 中航（重庆）微电子有限公司 | Semiconductor device and manufacturing method thereof |
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| CN110887977A (en) * | 2019-11-28 | 2020-03-17 | 上海应用技术大学 | Nanoscale piezoresistive acceleration sensor and preparation method thereof |
| CN110887977B (en) * | 2019-11-28 | 2021-12-07 | 上海应用技术大学 | Nanoscale piezoresistive acceleration sensor and preparation method thereof |
| CN111983257A (en) * | 2020-08-22 | 2020-11-24 | 范绪阁 | Acceleration sensor based on suspension two-dimensional material and heterogeneous layer suspension mass block |
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