CN106158693A - Etching self-stopping technology realizes the system and method for recessed grid enhancement mode HEMT device - Google Patents
Etching self-stopping technology realizes the system and method for recessed grid enhancement mode HEMT device Download PDFInfo
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- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- 239000010931 gold Substances 0.000 claims description 8
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- 238000000137 annealing Methods 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 238000001259 photo etching Methods 0.000 claims description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
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- 235000006408 oxalic acid Nutrition 0.000 claims description 4
- 239000001117 sulphuric acid Substances 0.000 claims description 4
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67017—Apparatus for fluid treatment
- H01L21/67063—Apparatus for fluid treatment for etching
- H01L21/67075—Apparatus for fluid treatment for etching for wet etching
- H01L21/67086—Apparatus for fluid treatment for etching for wet etching with the semiconductor substrates being dipped in baths or vessels
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66409—Unipolar field-effect transistors
- H01L29/66446—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET]
- H01L29/66462—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET] with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
Abstract
Present invention is disclosed a kind of self-stopping technology that etches and realize the system of recessed grid enhancement mode HEMT device, it includes broad spectrum light source, wave filter, etching power supply, etching solution, minus plate, between etching solution, minus plate, etching power supply and etching sample, series connection forms etching loop, and etching sample is positioned at the barrier layer Al of device gate electrode lower endxGa(1‑x)N is all etched by the method for electrochemistry, weaken the polarity effect of barrier layer thus two-dimensional electron gas is exhausted, realize HEMT device and be off state zero gate bias when, reach by open type HEMT device to the transformation of normally-off HEMT device, and by using the wavelength of wave filter regulation light source, it is achieved the self-stopping technology of electrochemical etching barrier layer.Present invention further teaches and a kind of etch the method that self-stopping technology realizes recessed grid enhancement mode HEMT device.The present invention have effectively achieved enhancement mode HEMT, and it has technique simply, etches self-stopping technology, and repeatability is high, and with low cost, etching injury is little, it is easy to carry out the features such as large-scale production.
Description
Technical field
The present invention relates to a kind of enhancement mode HEMT device, especially relate to a kind of etching self-stopping technology and realize recessed grid enhancement mode HEMT
The system and method for device.
Background technology
HEMT device be make full use of quasiconductor heterojunction structure formed two-dimensional electron gas and make, with III-VI race (as
AlGaAs/GaAs HEMT device) to compare, III group-III nitride semiconductor is due to piezoelectric polarization and spontaneous polarization effect, heterogeneous
In structure (Heterostructure), such as: AlGaN/GaN, it is possible to form the two-dimensional electron gas of high concentration.So using III
In the HEMT device that group-III nitride is made, barrier layer is typically made without doping.III group-III nitride have big energy gap,
The features such as higher saturated electron drift velocity, high critical breakdown electric field and extremely strong capability of resistance to radiation, it is possible to full electricity of future generation
The requirement to the work of power device greater power, higher frequency, smaller volume and higher temperature of the power electronic system.
When existing III group-III nitride semiconductor HEMT device uses as high-frequency element or high voltage switch device, special
When not being as device for power switching, enhancement mode HEMT device be favorably improved system safety, reduce device loss and
Simplify design circuit.Realize the main method of enhancement mode HEMT device at present and have thin barrier layer, recessed grid structure, p-type block
The technology such as layer and F process, but all there is the deficiency of self in each technology.Such as, the most first enhancement mode HEMT device
Part is to use relatively thin barrier layer to realize, and this method does not use etching technics, so the damage brought is little, but due to
Relatively thin barrier layer, the saturation current of device is less；P-type cap need not etching technics, but produces the most serious boundary
Face state, affects the stability of device；F plasma treatment also can realize enhancement mode HEMT device, and need not etching, but
Be F plasma inject during also can etch barrier layer, cause the reduction of device performance.
In these realize the method for enhancement mode HEMT device, owing to GaN material has preferable etch resistant characteristic, generally
Acids such as sulphuric acid, hydrochloric acid, nitric acid etc. and common bases such as potassium hydroxide, sodium hydroxide etc. all GaN can not be carried out effectively
Etching, and up to now, also do not have one to be capable of AlxGa(1-x)N (0 < x≤1) and GaN bi-material height select
The solution of etching ratio.In traditional recessed grid structure-forming process, the barrier layer under grid is mainly (main by plasma
It being chlorine based plasma) method that etches realizes, and general HEMT device barrier layer only has 20～30nm, thus recessed
The etching of grid is faced with the problem such as the control of etch thicknesses and the reparation of etching injury, uses etching technics to form the work of recessed grid structure
Skill is difficult to control, and repeatability is poor.
Summary of the invention
A kind of self-stopping technology that etches of offer is provided and realizes the system and method for recessed grid enhancement mode HEMT device,
To overcome defect of the prior art.
For achieving the above object, the present invention proposes following technical scheme:
A kind of self-stopping technology that etches realizes the system of recessed grid enhancement mode HEMT device, comprising:
In order to provide the etching power supply of etching electric current and in order to the etching solution as electrolyte and etching liquid, work in described system
Time, etching sample and minus plate be impregnated in described etching solution, the anode of described etching power supply and negative electrode respectively with etching sample
The electrode of product and minus plate connect, thus series connection is formed between described etching solution, minus plate, etching power supply and etching sample
One etching loop, wherein said etching sample includes epitaxial layer structure, is formed with two-dimensional electron gas, institute in described epitaxial layer structure
The electrode stating etching sample is connected with described two-dimensional electron gas；And
Etching light source, in order to provide the etching light with setting wavelength to irradiate described etching sample when described system works, makes
During the recessed grid structure needed for being formed that is etched on proper described etching sample, it is achieved the self-stopping technology of etching.
Further, described etching light source includes:
Broad spectrum light source,
And, wave filter, in order to be filtered by the some light in light emitted for described broad spectrum light source line, thus obtain described tool
There is the etching light setting wavelength.
Further, described system also includes the ammeter being connected between described etching power anode and etching sample electrode.
A kind of etch the method that self-stopping technology realizes recessed grid enhancement mode HEMT device, comprise the following steps:
S1, offer etching sample, described etching sample includes epitaxial layer structure, is formed with Two-dimensional electron in described epitaxial layer structure
Gas；
S2, the electrode that making is connected with described two-dimensional electron gas on etching sample；
S3, surface to described etching sample are patterned process, thus expose etching surface,；
S4, etching sample and minus plate are immersed etching solution, make described etching surface be directly exposed in etching solution, and will
The etching anode of power supply and negative electrode are connected with electrode and the minus plate of etching sample respectively, thus described etching solution, minus plate,
Etching power supply and etching sample between series connection formed one etching loop, and the most also with have set wavelength etching light irradiate institute
State etching sample, thus on etching sample, form required recessed grid structure, and realize etching while forming described recessed grid structure
Self-stopping technology.
Further, step S2 includes: by the surface of described etching sample deposition indium metal formed or by titanium deposition,
Carry out annealing after aluminum, nickel, gold multiple layer metal and make the described electrode of formation.
Further, described electrode is preferably provided at the edge part of described etching sample.
Further, graphic processing method described in step S2 includes photoetching or laser direct-writing or electron beam exposure.
Further, the method includes: the part or all of barrier layer etching in the epitaxial structure layer of etching sample is formed institute
State recessed grid structure.
Further, aforesaid etching solution uses the etching liquid of the barrier layer that can effectively etch described etching sample, described quarter
Erosion liquid is at least selected from electrochemical etching liquid such as sulphuric acid, potassium hydroxide and oxalic acid, and the material of described barrier layer includes AlxGa(1-x)N,
0<x≤1。
Further, the energy of aforesaid etching light be enough to assist described etching solution to etch described barrier layer but can not etch institute
Stating the space layer of etching sample, the material of described space layer includes aluminium nitride.
Among an embodiment, the electrochemical etching equipment employed in the system of the present invention include etch power supply, etching solution,
Light source, ammeter etc., wherein etching power supply provides etching electric current, and etching solution serves as the effect of electrolyte and etching liquid, light source
Transition for vitalizing semiconductor electronics, it is achieved the etching of barrier layer.And by regulating the wavelength of light source, it is possible to achieve electrification
Learn the self-stopping technology of etching barrier layer.Ammeter is for monitoring during etching reaction the variation tendency of electric current in loop.
Further, during electrochemical etching, it is contemplated that some etching solutions only could etch gesture in the case of illumination
Barrier layer, thus by arranging external light source in etching process, the wavelength of regulation etching light source, make the energy of light source to assist
Etching barrier layer (material such as AlxGa(1-x)N, 0 < x≤1), but can not etched volume layer (material such as aluminium nitride AlN), real
The self-stopping technology on space layer surface now.
Further, the wavelength of regulation etching light source can be, but not limited to be realized by filter plate, when a broad spectrum light source leads to
After crossing filtering system, the light source of specific wavelength will be absorbed, and part light source passes through, and the energy of light source passed through is less than etched volume layer
The energy of aluminium nitride (AlN), it is therefore an objective to realize self-stopping technology.
Further, for needing to carry out the etching sample of recessed grid etching, electrode should be made before etching on the surface of sample,
The position of electrode can (preferably, electrode be arranged on the edge of sample, it is therefore an objective to save the face of sample in any position of sample
Long-pending, improve the utilization rate of sample), electrode should be connected with two-dimensional electron gas, and the manufacture method of electrode can select but be not limited to
Carry out quickly after sample surfaces deposition indium forms electrode or passes through the multiple layer metals such as titanium deposition/aluminum/ni au (Ti/Al/Ni/Au)
Annealing makes electrode, and wherein later approach can form the most stable Ohmic contact.
Further, in order to monitor at barrier layer, such as AlxGa(1-x)In N (0 < x≤1) etching process, electric current is with etch period
Change curve, it is therefore intended that can estimate etching effect by the change curve of electric current, improve the repeatability of etching, ammeter should
This is connected in the loop of electrochemical etching, it is recommended to use current monitoring, but can not also use in the present invention.
Further, in etching process, the electrode on sample should be connected with the anode of power supply, and the negative electrode of power supply should pass through
Minus plate is connected with solution, and the flowing through channel of electric current should be power anode, ammeter.Etching is needed under two-dimensional electron gas, grid
The negative electrode of barrier layer, etching solution and power supply.
Among an embodiment of the present invention, additionally providing a kind of recessed grid enhancement mode HEMT device, it includes source, leakage, grid
Electrode, gate medium, grid low groove and heterojunction structure, source, drain electrode are by the Two-dimensional electron pneumoelectric being formed in heterojunction structure
Connecting, heterojunction structure is mainly by GaN and AlxGa(1-x)N (0 < x≤1) quasiconductor forms, and source, drain electrode are positioned at gallium nitride table
Face and being connected with two-dimensional electron gas by Ohmic contact, gate electrode is located between source, drain electrode, at gate electrode metal and nitrogen
Change and between gallium cap surface, there is gate medium, form MISHEMT structure.Wherein, the Al below gate electrodexGa(1-x)N gesture
Barrier layer is partly or entirely etched by electrochemical method and is formed grid low groove, exhausts the two-dimensional electron gas under grid.
In the HEMT device of the present invention, by weakening the polarity effect of barrier layer, two-dimensional electron gas is exhausted, it is achieved HEMT
Device is off state zero gate bias when, reaches by open type HEMT device turning to normally-off HEMT device
Become.Al further, when grid is zero-bias, under described HEMT device gridxGa(1-x)N (0 < x≤1) barrier layer quilt
All or part of etching, two-dimensional electron gas is depleted, and device is off, and when adding forward voltage at grid, described
HEMT device holds accumulation electronics under the gate electrode, and device is at opening.
Further, described source electrode and drain electrode are connected with electronegative potential and the high potential of power supply respectively.
Further, for the recessed grid structural region of HEMT device of the present invention, its barrier layer etching depth is about 10nm-20nm,
The thickness of etching depends on the component of aluminum in barrier layer and the gross thickness of barrier layer, and etching should stop at and exhaust two-dimensional electron gas and be
Only, it is achieved device when the duty of zero gate bias, the disconnection of source-drain electrode.
Compared with prior art, the beneficial effect comprise that
1, the present invention is by using electrochemical method by the barrier layer Al of gate electrode lower endxGa(1-x)N completely or partially etches, permissible
Effectively weaken the polarity effect of barrier layer, thus two-dimensional electron gas exhausted, it is achieved HEMT device zero gate bias when at
In off state, reach by open type HEMT device to the transformation of normally-off HEMT device, effectively achieve enhancement mode
HEMT, overcomes in traditional recessed grid etching process, uses the damage that device is caused by dry etching, plasma, electrification
The method learned belongs to wet etching, can effectively control damage, it is to avoid or the mobility weakening device causes by etching injury
Reduction, meanwhile, the present invention effective can also realize etching self-stopping technology by the wavelength of regulation etching light source；
2, the present invention is by series current table in etching loop, also can monitor whole etching process, improves what making devices made
Repeatability, meanwhile the etching technics of device is simple, reproducible, and it is big that etching controls window, with low cost, etching injury
Little, it is not necessary to introduce the toxic gas (such as chlorine etc.) during dry etching, it is easy to carry out the features such as large-scale production.
Accompanying drawing explanation
Fig. 1 is the partial structurtes schematic diagram of common HEMT device；
Fig. 2 is the theory structure signal etching the method that self-stopping technology realizes recessed grid enhancement mode HEMT device in the embodiment of the present invention
Figure；
Fig. 3 is the method etching barrier layer Al using electrochemistry in the embodiment of the present inventionxGa(1-x)The enhancement mode that N realizes
The cross-sectional view of MIS-HEMT.
Description of reference numerals: 1-substrate, 2-gallium nitride, 3-two-dimensional electron gas, 4-barrier layer, 5-recessed grid etch mask, under 6-grid
Barrier layer, 7-electrochemical etching electrode, 8-ammeter, 9-light source, 10-etching solution, 11-power supply, 12-minus plate, 13-carves
Erosion container, 14-source electrode, 15-drain electrode, 16-gate electrode, 17-gate dielectric layer, 18-width spectrum light, 19-wave filter, 20-
Etching light, 21-space layer, 22-cap, 23-barrier layer etch areas.
Detailed description of the invention
Below in conjunction with the accompanying drawing of the present invention, the technical scheme of the embodiment of the present invention is carried out clear, complete description.
As it is shown in figure 1, for common HEMT device (as a example by AlGaN/GaN device), it is however generally that, when at gate electrode
16 apply zero-bias or when not having biasing, source electrode 14 is all connected with two-dimensional electron gas 3 with drain electrode 15, so
The source electrode 14 of HEMT device and drain electrode 15 are conductings, and HEMT device is in opening, the most this HEMT
Device is depletion type HEMT device, it is also possible to be referred to as open type HEMT device.In order to make HEMT device be in disconnection shape
State, it is necessary to make the two-dimensional electron gas 3 between source electrode 14 and drain electrode 15 exhaust or the two-dimensional electron gas in certain region exhausts.
Can realize by applying certain voltage at gate electrode 16, when gate electrode 16 add back bias voltage reach grid voltage Vg < during Vth,
Vth is the threshold voltage of device, and Vth general for common HEMT device is negative value, can exhaust the two dimension electricity in region under grid
Edema of the legs during pregnancy, so that HEMT device is off state.This HEMT device in side circuit application process due to only
When grid 16 applies back bias voltage, HEMT device could turn off, and compared with enhancement mode HEMT device, adds common HEMT
The power consumption of device, and the safety of system is poor.
The defect that safety grid poor, the recessed etching existed in view of above-mentioned common HEMT device difficult controls, repeatability is poor etc.,
A kind of self-stopping technology that etches that the present invention proposes realizes the system and method for recessed grid enhancement mode HEMT device, by the method for electrochemistry
Barrier layer 4Al by the lower end of gate electrode 16xGa(1-x)N (0 < x≤1) all etches, weaken barrier layer 4 polarity effect thus
Two-dimensional electron gas is exhausted, it is achieved HEMT device is closed zero gate bias when, reaches by open type HEMT
Device is to the transformation of normally-off HEMT device.And by the method regulating electrochemical etching optical source wavelength, reach to etch recessed grid
Self-stopping technology.
As in figure 2 it is shown, a kind of self-stopping technology that etches that the present invention proposes realizes the system of recessed grid enhancement mode HEMT device and includes electric current
Table 8, etching power supply 11, minus plate 12, etching solution 10, broad spectrum light source 18 and wave filter, wherein etching power supply 11 is used
In providing etching electric current, etching solution 10 serves as the effect of electrolyte and etching liquid, and broad spectrum light source 18 is for vitalizing semiconductor
The transition of electronics, it is achieved the etching of barrier layer 4.
Etching sample includes the epitaxial layer structure on substrate 1 and substrate, and epitaxial layer structure includes the space layer 21 on substrate 1, gesture
Barrier layer 4 and cap 22, actual epitaxial layer structure may also include other epitaxial structures, such as nucleating layer, resistive formation and transition zone etc.
Structure.Epitaxial layer structure is formed two-dimensional electron gas 3.
For needing to carry out the sample of recessed grid etching, first make electrode 7, electrode 7 on the surface of sample epitaxial layer
It is connected with two-dimensional electron gas 3.The manufacture method of electrode 7 can select but be not limited to form electricity at sample surfaces deposition indium metal
Pole or make electrode 7, latter side by carrying out short annealing after the multiple layer metal such as titanium deposition/aluminum/ni au (Ti/Al/Ni/Au)
Method can form the most stable Ohmic contact.It addition, the position of electrode 7 can be in any position of sample, it is preferable that electricity
Pole 7 may be provided at the edge of sample, it is therefore an objective to saves the area of sample, improves the utilization rate of sample.
Then, being patterned process at device surface, the method for process can select but be not limited to photoetching, laser direct-writing and electricity
Son bundle exposure etc., it would be desirable to the barrier layer 6 of gate electrode 16 lower end of etching is exposed in etching solution 10, and remainder uses
Mask 5 can select as protection, the mask 5 of etching but be not limited to photoresist, silicon dioxide and silicon nitride etc..
Secondly, being connected with ammeter 8 by the etching electrode 7 of sample, ammeter 8 is connected with the anode of etching power supply 11, etching
The negative electrode of power supply 11 is connected with minus plate 12, adds etching solution 10 in etching container 13, by minus plate 12 and etching sample
Product contact with etching solution 10, so, and etching solution 10, minus plate 12, etching power supply 11, ammeter 8 and etching sample
Between series connection formed one etching loop.The flowing through channel of electric current is under power supply 11 anode, ammeter 8, two-dimensional electron gas 3, grid
Need the Al of etchingxGa(1-x)N barrier layer 6, etching solution 10 and the negative electrode of power supply 11.Etching solution 10 can select but not
It is limited to the etch liquids such as sulphuric acid, potassium hydroxide and oxalic acid.
Preferably, the present invention is series current table 8 in etching loop, for monitoring at AlxGa(1-x)N barrier layer 6 etching process
Middle electric current is with the change curve of etch period, it is therefore intended that estimate etching effect by the change curve of electric current, etching is carried out reality
Time monitoring, improve etching repeatability, certainly, ammeter can not also be used in the present invention.
During electrochemical etching, it is contemplated that some etching solutions 10 only could etch barrier layer 4 in the case of illumination,
So by arranging external light source 9 in etching process, the wavelength of regulation light source 18, make the energy of light source 18 can etch gesture
Barrier layer 6 (material such as AlxGa(1-x)N), but can not etched volume layer 21 (material such as aluminium nitride AlN), it is achieved in space
The self-stopping technology on layer surface.
In order to realize the self-stopping technology of etching, need to be filtered by the light source of the part wavelength of broad spectrum light source 18 by wave filter 19,
The most remaining etching light source 20, wave filter 19 can be, but not limited to be realized by filter plate.In general HEMT device extension
In structure, energy gap Eg22 of cap 22, energy gap Eg4 of barrier layer 4, energy gap Eg21 of space layer 21
There is a kind of relation in the energy gap of these three material: Eg22 < Eg4 < Eg21, it is possible to selected by wave filter 19
The light source 20 of specific wavelength, the energy of light source 20 is E20, and meets the requirement of Eg22 < Eg4 < E20 < Eg21, so
Just can set and suitably etch voltage so that electrochemistry can only etch barrier layer 4 and cap 22 in etching process, and does not has
There are enough energy etched volume layers 21, it is achieved the purpose of self-stopping technology.Whole etching process can use constant current etch mode or perseverance
Pressure etch mode, grid lower barrierlayer 6 needs the thickness of etching about 10～30nm, and concrete thickness depends on the barrier layer of sample
The component of aluminum and barrier layer 4 thickness in 4.
When being embodied as, space layer 21 generally aluminium nitride (AlN), barrier layer 4 generally Al0.25Ga0.75The ternary of N is partly led
Body material, cap 22 typically chooses GaN material, and under room temperature environment, the energy gap of AlN is about 6.2eV, corresponding light
The wavelength of spectrum is 200nm, Al0.25Ga0.75The energy gap of N barrier layer 4 is 4.1eV according to the computing formula of linear component, right
The wavelength answered be the energy gap of 302nm, GaN be 3.4eV, corresponding optical wavelength is 365nm, it is possible to by filter
Wavelength in broad spectrum light source 18 is filtered by ripple device 19 less than 200nm or the light source near 200nm, is only left to carve
Erosion barrier layer 4Al0.25Ga0.75N and there is no the light source of enough energy etched volume layers 21, when etching arrive AlN space layer time,
Realize self-stopping technology state.
Etching is clean by sample clean after terminating, and makes source electrode 14 and drain electrode 15 on the surface of sample, first at sample table
Face spin coating photoresist, then by design mask plate and photoetching technique sample surfaces formed source, drain electrode graphical, so
Rear redeposited metal, be typically chosen titanium deposition, aluminum, nickel, gold (Ti, Al, Ni, Au, thickness be respectively 20nm, 130nm,
50nm, 150nm) etc. multiple layer metal, after metal deposit, the metal-stripping outside source, drain electrode is clean, the most quickly move back
Fire, condition is 890 DEG C and anneals 30 seconds, and after annealing, source electrode 14 is connected with two-dimensional electron gas 3 with drain electrode 15.
Then growing one layer of dielectric layer 17 at sample surfaces, growth pattern can be, but not limited to plasma reinforced chemical vapour deposition
(PECVD), ald (ALD), low-pressure chemical vapor deposition (LPCVD) and inductively coupled plasma chemistry gas
The semiconductor deposition techniques that deposition etc. are conventional mutually.The medium of deposition is optional but is not limited to aluminium oxide, aluminium nitride, silicon oxide and nitridation
Dielectric film conventional in the quasiconductors such as silicon.
Formed the figure of grid metal again by the method for photoetching after having deposited, heavy above the barrier layer etch areas 23 of sample
Long-pending grid metal and stripping technology, form gate electrode 16, finally etched by the dielectric layer on source, drain electrode clean.Grid metal is general
Selecting Ni, Au, thickness is respectively 50nm, 150nm,
Therefore, with reference to shown in Fig. 3, the enhancement mode HEMT device finally making realization includes source, leakage, gate electrode, gate medium
17, grid low groove and heterojunction structure, source, drain electrode are electrically connected by the two-dimensional electron gas being formed in heterojunction structure, heterogeneous
Structure is by GaN and AlxGa(1-x)N quasiconductor forms, and source, drain electrode are positioned at gallium nitride 2 surface and by Ohmic contact and two
Dimensional electron gas 3 is connected, and gate electrode 16 is located between source, drain electrode, at gate electrode metal and AlxGa(1-x)N deposits between surface
At gate medium 17, form enhancement mode MISHEMT structure, and contact with semiconductor surface formation Xiao Jite, gate electrode 16
The barrier layer Al of lower endxGa(1-x)N is all etched by the method for electrochemistry.
The operation principle of enhancement mode HEMT that the present invention realizes is: illustrate with reference to Fig. 3, in enhancement mode HEMT device,
Threshold voltage vt h be on the occasion of, when adding zero-bias or not biasing at gate electrode 16, gate voltage Vg < Vth, due to gesture under grid
Barrier layer 6 is partially etched or all etches, so the two-dimensional electron gas in the lower end of etch areas is depleted, at this moment due under grid
There is no conducting channel, so source electrode 14 and drain electrode 15 are in disconnection, so device is off.When adding at grid
During forward voltage, gate voltage Vg > Vth, at this moment under grid, region can accumulate electronics, accumulation electronically form new communication channel, make
Source electrode 14 and drain electrode 15 turn on, and device is in opening.HEMT device is transformed into increasing from original depletion device
Strong type device.
The technology contents of the present invention and technical characteristic have revealed that as above, but those of ordinary skill in the art are still potentially based on this
Bright teaching and announcement and make all replacements without departing substantially from spirit of the present invention and modification, therefore, scope should be not limited to
Content disclosed in embodiment, and the various replacement without departing substantially from the present invention and modification should be included, and be present patent application claim
Contained.
Claims (10)
1. one kind etches self-stopping technology and realizes the system of recessed grid enhancement mode HEMT device, it is characterised in that including:
In order to provide the etching power supply of etching electric current and in order to the etching solution as electrolyte and etching liquid, work in described system
Time, etching sample and minus plate be impregnated in described etching solution, the anode of described etching power supply and negative electrode respectively with etching sample
The electrode of product and minus plate connect, thus series connection is formed between described etching solution, minus plate, etching power supply and etching sample
One etching loop, wherein, described etching sample includes epitaxial layer structure, is formed with two-dimensional electron gas in described epitaxial layer structure,
The electrode of described etching sample is connected with described two-dimensional electron gas；And
Etching light source, in order to provide the etching light with setting wavelength to irradiate described etching sample when described system works, makes
During the recessed grid structure needed for being formed that is etched on proper described etching sample, it is achieved the self-stopping technology of etching.
Etching self-stopping technology the most according to claim 1 realizes the system of recessed grid enhancement mode HEMT device, it is characterised in that institute
State etching light source to include:
Broad spectrum light source,
And, wave filter, in order to be filtered by the some light in light emitted for described broad spectrum light source line, thus obtain described tool
There is the etching light setting wavelength.
Etching self-stopping technology the most according to claim 1 realizes the system of recessed grid enhancement mode HEMT device, it is characterised in that also
Including the ammeter being connected between the anode of described etching power supply and the electrode of etching sample.
Etching self-stopping technology the most according to claim 1 and 2 realizes the system of recessed grid enhancement mode HEMT device, and its feature exists
Use the etching liquid of the barrier layer that can effectively etch described etching sample in described etching solution, described etching liquid is at least selected from sulfur
Acid, potassium hydroxide and oxalic acid；The energy of described etching light be enough to assist described etching solution to etch described barrier layer but can not carve
Losing the space layer of described etching sample, the material of described barrier layer includes AlxGa(1-x)N, 0 < x≤1, the material of described space layer
Including aluminium nitride.
5. one kind etches the method that self-stopping technology realizes recessed grid enhancement mode HEMT device, it is characterised in that comprise the following steps:
S1, offer etching sample, described etching sample includes epitaxial layer structure, is formed with Two-dimensional electron in described epitaxial layer structure
Gas；
S2, the electrode that making is connected with described two-dimensional electron gas on etching sample；
S3, surface to described etching sample are patterned process, thus expose etching surface；
S4, etching sample and minus plate are immersed etching solution, make described etching surface be directly exposed in etching solution, and will
The etching anode of power supply and negative electrode are connected with electrode and the minus plate of etching sample respectively, thus described etching solution, minus plate,
Etching power supply and etching sample between series connection formed one etching loop, and the most also with have set wavelength etching light irradiate institute
State etching sample, thus on etching sample, etch required recessed grid structure, and realize carving while forming described recessed grid structure
The self-stopping technology of erosion.
Etching self-stopping technology the most according to claim 5 realizes the method for recessed grid enhancement mode HEMT device, it is characterised in that step
Rapid S2 includes: by being formed or by titanium deposition, aluminum, nickel, gold multilamellar gold at the surface of described etching sample deposition indium metal
Carry out after genus annealing and make the described electrode of formation.
Etching self-stopping technology the most according to claim 6 realizes the method for recessed grid enhancement mode HEMT device, it is characterised in that
Described electrode is arranged on the edge part of described etching sample.
Etching self-stopping technology the most according to claim 5 realizes the method for recessed grid enhancement mode HEMT device, it is characterised in that step
Graphic processing method described in rapid S2 includes photoetching, laser direct-writing or electron beam exposure.
Etching self-stopping technology the most according to claim 5 realizes the method for recessed grid enhancement mode HEMT device, it is characterised in that bag
Include: the part or all of barrier layer etching in the epitaxial structure of etching sample is formed described recessed grid structure.
Etching self-stopping technology the most according to claim 5 realizes the method for recessed grid enhancement mode HEMT device, it is characterised in that
Described etching solution uses the etching liquid of barrier layer that can effectively etch described etching sample, described etching liquid at least selected from sulphuric acid,
Potassium hydroxide and oxalic acid；The energy of described etching light be enough to assist described etching solution to etch described barrier layer but can not etch institute
Stating the space layer of etching sample, the material of described barrier layer includes AlxGa(1-x)N, 0 < x≤1, the material of described space layer includes
Aluminium nitride.
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| CN109841520A (en) * | 2019-03-06 | 2019-06-04 | 北京大学深圳研究生院 | A kind of notched gates lithographic method preparing enhanced GaN HEMT device |
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