CN106158693B - Etching self-stopping technology realizes the system and method for the enhanced HEMT device of recessed grid - Google Patents
Etching self-stopping technology realizes the system and method for the enhanced HEMT device of recessed grid Download PDFInfo
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- CN106158693B CN106158693B CN201510160921.9A CN201510160921A CN106158693B CN 106158693 B CN106158693 B CN 106158693B CN 201510160921 A CN201510160921 A CN 201510160921A CN 106158693 B CN106158693 B CN 106158693B
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- 230000008021 deposition Effects 0.000 claims description 7
- 239000010931 gold Substances 0.000 claims description 7
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- 229910052737 gold Inorganic materials 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 238000001259 photo etching Methods 0.000 claims description 5
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
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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 discloses a kind of systems that etching self-stopping technology realizes the enhanced HEMT device of recessed grid, it includes broad spectrum light source, filter, etching power supply, etching solution, cathode plate, etching solution, cathode plate etch series connection formation etching circuit between power supply and etching sample, and etching sample is located to 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 to exhaust two-dimensional electron gas, realize that HEMT device is in an off state when zero gate bias, reach the transformation from open type HEMT device to normally-off HEMT device, and the wavelength of light source is adjusted by using filter, realizes the self-stopping technology of electrochemical etching barrier layer.Present invention further teaches a kind of methods that etching self-stopping technology realizes the enhanced HEMT device of recessed grid.The present invention has effectively achieved enhanced HEMT, and it etches self-stopping technology, repeatability is high, and low in cost, etching injury is small, is easy to the features such as being mass produced with simple process.
Description
Technical field
The present invention relates to a kind of enhanced HEMT devices, realize that recessed grid are enhanced more particularly, to a kind of etching self-stopping technology
The system and method for HEMT device.
Background technique
HEMT device is the two-dimensional electron gas for making full use of the heterojunction structure of semiconductor to be formed and manufactured, with III-VI
Race's (such as AlGaAs/GaAs HEMT device) compares, III group-III nitride semiconductor due to piezoelectric polarization and spontaneous polarization effect,
On heterojunction structure (Heterostructure), such as: AlGaN/GaN is capable of forming the two-dimensional electron gas of high concentration.So making
In the HEMT device made of III group-III nitride, barrier layer does not need generally to be doped.III group-III nitride has big forbidden band
The features such as width, higher saturated electron drift velocity, high critical breakdown electric field and extremely strong capability of resistance to radiation, under capable of expiring
Generation power electronic system is more high-power to power device, the requirement of the work of higher frequency, smaller volume and higher temperature.
Existing III group-III nitride semiconductor HEMT device is used as high-frequency element or high voltage switch device
When, when especially as device for power switching, enhanced HEMT device helps to improve the safety of system, reduces the damage of device
Consumption and simplified design circuit.Realize that the main method of enhanced HEMT device has thin barrier layer, recessed grid structure, p-type lid at present
The technologies such as cap layers and F processing, but all there is the deficiency of itself in each technology.For example, the enhanced HEMT device of first branch in the world
Part is realized using relatively thin barrier layer, and this method does not use etching technics, so bring damage is small, but due to
The saturation current of relatively thin barrier layer, device is smaller；P-type cap does not need etching technics, but generates more serious boundary
Face state influences the stability of device；F plasma treatment is also able to achieve enhanced HEMT device, and does not need to etch, but F
Plasma barrier layer can be also etched during injection, cause the reduction of device performance.
In the method that these realize enhanced HEMT device, since GaN material has preferable etch resistant characteristic, usually
Acids such as sulfuric acid, hydrochloric acid, nitric acid etc. and common bases such as potassium hydroxide, sodium hydroxide etc. GaN cannot all be carried out it is effective
Etching, and up to now, there are no one kind can be realized AlxGa(1-x)Two kinds of material high selections of N (0 < x≤1) and GaN are carved
Lose the solution of ratio.In traditional recessed grid structure forming process, barrier layer under grid mainly pass through plasma (important is
Chlorine based plasma) method of etching realizes that and general HEMT device barrier layer only has 20~30nm, so recessed grid
The problems such as etching the reparation of the control and etching injury that are faced with etch thicknesses, the technique that recessed grid structure is formed using etching technics
It is difficult to control, it is less reproducible.
Summary of the invention
The main purpose of the present invention is to provide it is a kind of etching self-stopping technology realize the enhanced HEMT device of recessed grid system and
Method, to overcome defect in the prior art.
To achieve the above object, the following technical solutions are proposed by the present invention:
A kind of system that etching self-stopping technology realizes the enhanced HEMT device of recessed grid comprising:
To provide the etching power supply of etching electric current and to the etching solution as electrolyte and etching liquid, in the system
When system work, etching sample and cathode plate are impregnated in the etching solution, the anode and cathode difference of the etching power supply
It is connect with the electrode of etching sample and cathode plate, thus between the etching solution, cathode plate, etching power supply and etching sample
Series connection forms an etching circuit and is formed with two dimension in the epitaxial layer structure wherein the etching sample includes epitaxial layer structure
The electrode of electron gas, the etching sample is connected with the two-dimensional electron gas；And
Light source is etched, to provide in system work there is the etching light of setting wavelength to irradiate the etching sample
Product, so that realizing the self-stopping technology of etching when being etched to form required recessed grid structure on the etching sample.
Further, the etching light source includes:
Broad spectrum light source,
And filter, to filter out some light in the light emitted line of the broad spectrum light source, to obtain institute
State the etching light with setting wavelength.
Further, the system also includes be connected on the etching power anode and etch the electric current between sample electrode
Table.
A method of etching self-stopping technology realizes the enhanced HEMT device of recessed grid, comprising the following steps:
S1, etching sample is provided, the etching sample includes epitaxial layer structure, is formed with two dimension in the epitaxial layer structure
Electron gas；
S2, the electrode being connected with the two-dimensional electron gas is made on etching sample；
S3, processing is patterned to the surface of the etching sample, so that etching surface is exposed,；
S4, sample and cathode plate immersion etching solution will be etched, and will be directly exposed to the etching surface in etching solution,
And by the anode and cathode for etching power supply respectively with etching sample electrode and cathode plate connect, thus the etching solution,
Series connection forms an etching circuit between cathode plate, etching power supply and etching sample, and simultaneously also to have the etching of setting wavelength
Light irradiates the etching sample, thus recessed grid structure needed for being formed on etching sample, and forming the recessed grid structure
The self-stopping technology of etching is realized simultaneously.
Further, step S2 includes: to be formed or by depositing indium metal on the surface of the etching sample by heavy
It is annealed after product titanium, aluminium, nickel, golden multiple layer metal and makes to form the electrode.
Further, the electrode is preferably provided at the edge part of the etching sample.
Further, graphic processing method described in step S2 includes photoetching or laser direct-writing or electron beam exposure.
Further, this method comprises: by some or all of in the epitaxial structure layer for etching sample barrier layer etching and
Form the recessed grid structure.
Further, etching solution above-mentioned uses the etching liquid that can effectively etch the barrier layer of the etching sample,
The etching liquid is at least selected from the electrochemical etchings liquid such as sulfuric acid, potassium hydroxide and oxalic acid, and the material of the barrier layer includes
AlxGa(1-x)N, 0 < x≤1.
Further, the energy of etching light above-mentioned is enough to assist the etching solution to etch the barrier layer but cannot
The space layer of the etching sample is etched, the material of the space layer includes aluminium nitride.
Among an embodiment, electrochemical etching equipment employed in system of the invention includes etching power supply, carves
Solution, light source, ammeter etc. are lost, wherein etching power supply provides etching electric current, etching solution serves as the work of electrolyte and etching liquid
With light source is used for the transition of vitalizing semiconductor electronics, realizes the etching of barrier layer.And it, can be with by the wavelength for adjusting light source
Realize the self-stopping technology of electrochemical etching barrier layer.The variation that ammeter is used to monitor electric current in circuit during etching reaction becomes
Gesture.
Further, during electrochemical etching, it is contemplated that some etching solutions only could in the case where illumination
Barrier layer is etched, so adjusting the wavelength of etching light source by setting external light source in etching process, making the energy of light source can
With auxiliary etch barrier layer (material such as AlxGa(1-x)N, 0 < x≤1), but it is unable to etched volume layer (material such as aluminium nitride
AlN), the self-stopping technology in space layer surface is realized.
Further, the wavelength for adjusting etching light source can be, but not limited to realize by filter plate, when a wide spectrum
Light source pass through filtering system after, the light source of specific wavelength will be absorbed, and part light source passes through, by energy of light source be less than etching
The energy of space layer aluminium nitride (AlN), it is therefore an objective to realize self-stopping technology.
It further, before etching should be in the surface system of sample for needing to carry out the etching sample of recessed grid etching
Make electrode, electrode position can (preferred, the edge of sample be arranged in electrode, it is therefore an objective to save in any position of sample
The area of sample improves the utilization rate of sample), electrode should be connected with two-dimensional electron gas, and the production method of electrode can be selected
It selects but is not limited to deposit indium formation electrode in sample surfaces or by multilayers such as deposition titanium/aluminium/ni aus (Ti/Al/Ni/Au)
Short annealing is carried out after metal and makes electrode, and wherein later approach can form well stable Ohmic contact.
Further, in order to monitor in barrier layer, such as AlxGa(1-x)When electric current is with etching in N (0 < x≤1) etching process
Between change curve, it is therefore intended that can by the change curve of electric current estimate etching effect, improve the repeatability of etching, electric current
Table should be connected in the circuit of electrochemical etching, it is recommended to use current monitoring, but can also not use in the present invention.
Further, in etching process, the electrode on sample should be connect with the anode of power supply, and the cathode of power supply should
It is connect by cathode plate with solution, the flowing through channel of electric current should be power anode, ammeter.It is needed under two-dimensional electron gas, grid
The cathode of the barrier layer of etching, etching solution and power supply.
Among an embodiment of the invention, additionally provide a kind of enhanced HEMT device of recessed grid comprising source, leakage,
Gate electrode, gate medium, grid lower groove and heterojunction structure, source, drain electrode pass through the two-dimensional electron gas that is formed in heterojunction structure
Electrical connection, heterojunction structure is mainly by GaN and AlxGa(1-x)N (0 < x≤1) semiconductor group is at source, drain electrode are located at gallium nitride surface
And it is connected by Ohmic contact with two-dimensional electron gas, gate electrode is set between source, drain electrode, in gate electrode metal and nitridation
There are gate mediums between gallium nut cap layer surface, form MISHEMT structure.Wherein, the Al below gate electrodexGa(1-x)N barrier layer quilt
It partly or entirely etches to form grid lower groove by electrochemical method, exhausts the two-dimensional electron gas under grid.
In HEMT device of the invention, two-dimensional electron gas is exhausted by weakening the polarity effect of barrier layer, is realized
HEMT device is in an off state when zero gate bias, reaches and turns from open type HEMT device to normally-off HEMT device
Become.Further, the Al when grid is zero-bias, under the HEMT device gridxGa(1-x)N (0 < x≤1) barrier layer is by whole
Or partial etching, two-dimensional electron gas are depleted, device is in an off state, and when grid adds forward voltage, the HEMT
Device holds accumulation electronics under the gate electrode, and device is at open state.
Further, the source electrode and drain electrode is connect with the low potential of power supply and high potential respectively.
Further, for the recessed grid structure region of HEMT device of the present invention, barrier layer etching depth is about 10nm-
The thickness of 20nm, etching depend on the component of aluminium and the overall thickness of barrier layer in barrier layer, and etching, which should stop at, exhausts two dimension
Until electron gas, realization device is in the working condition 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 is completely or partially carved
Erosion, can effectively weaken the polarity effect of barrier layer, so that two-dimensional electron gas be exhausted, realize HEMT device in zero gate bias
When it is in an off state, reach the transformation from open type HEMT device to normally-off HEMT device, effectively realize enhanced
HEMT is overcome in the recessed grid etching process of tradition, is damaged caused by device using dry etching, plasma, electrochemistry
Method belong to wet etching, can effectively control damage, the mobility for avoiding or weakening device is caused by etching injury
Reduction, meanwhile, the present invention can also pass through the wavelength for adjusting etching light source, effective to realize etching self-stopping technology；
2, the present invention can also monitor entire etching process, improve making devices by the series electrical flow table in etching circuit
The repeatability of production, the etching technics of device is simple at the same time, reproducible, and etching control window is big, low in cost, etching
Damage it is small, do not need introduce dry etching during toxic gas (such as chlorine), be easy to the features such as being mass produced.
Detailed description of the invention
Fig. 1 is the partial structural diagram of common HEMT device；
Fig. 2 is to etch self-stopping technology in the embodiment of the present invention to realize that the theory structure of the method for the enhanced HEMT device of recessed grid shows
It is intended to；
Fig. 3 is the method etching barrier layer Al in the embodiment of the present invention using electrochemistryxGa(1-x)N is realized enhanced
The schematic diagram of the section structure of MIS-HEMT.
Description of symbols: 1- substrate, 2- gallium nitride, 3- two-dimensional electron gas, 4- barrier layer, the recessed grid etch mask of 5-, 6-
Grid lower barrierlayer, 7- electrochemical etching electrode, 8- ammeter, 9- light source, 10- etching solution, 11- power supply, 12- cathode plate, 13-
Etching container, 14- source electrode, 15- drain electrode, 16- gate electrode, 17- gate dielectric layer, 18- wide spectrum light, 19- filter,
20- etches light, 21- space layer, 22- cap, 23- barrier layer etch areas.
Specific embodiment
Below in conjunction with attached drawing of the invention, clear, complete description is carried out to the technical solution of the embodiment of the present invention.
As shown in Figure 1, for common HEMT device (by taking AlGaN/GaN device as an example), it is however generally that, when in gate electrode 16
When applying zero-bias or not having biasing, source electrode 14 and drain electrode 15 are all connected with two-dimensional electron gas 3, so HEMT device
The source electrode 14 and drain electrode 15 of part are conductings, and HEMT device is in the open state, and this HEMT device is generally referred to as to exhaust
Type HEMT device may also be referred to as open type HEMT device.In order to be in an off state HEMT device, it is necessary to make source electrode 14
Two-dimensional electron gas 3 between drain electrode 15 exhausts or the two-dimensional electron gas in some region exhausts.It can be by gate electrode
16, which apply certain voltage, realizes, when gate electrode 16 adds back bias voltage to reach grid voltage Vg < Vth, Vth is the threshold value electricity of device
Pressure, Vth general for common HEMT device are negative value, the two-dimensional electron gas in region under grid can be exhausted, to make HEMT device
It is in an off state.This HEMT device in actual circuit application process due to only grid 16 apply back bias voltage when,
HEMT device could turn off, and compared with enhanced HEMT device, increase the power consumption of common HEMT device, and the safety of system
Property is poor.
Poor in view of safety existing for above-mentioned common HEMT device, recessed grid etching it is difficult to control, less reproducible etc.
A kind of defect, system and method for etching self-stopping technology and realizing the enhanced HEMT device of recessed grid proposed by the present invention, passes through electrochemistry
Method by the barrier layer 4Al of the lower end of gate electrode 16xGa(1-x)N (0 < x≤1) is all etched, and weakens the polarization effect of barrier layer 4
It should realize that HEMT device is in close state when zero gate bias to exhaust two-dimensional electron gas, reach by open type
Transformation of the HEMT device to normally-off HEMT device.And the method by adjusting electrochemical etching optical source wavelength, reaches etching
The self-stopping technology of recessed grid.
As shown in Fig. 2, a kind of system that etching self-stopping technology realizes the enhanced HEMT device of recessed grid proposed by the present invention includes
Ammeter 8, etching power supply 11, cathode plate 12, etching solution 10, broad spectrum light source 18 and filter, wherein etching power supply 11 is used
Electric current is etched in providing, etching solution 10 serves as the effect of electrolyte and etching liquid, and broad spectrum light source 18 is used for vitalizing semiconductor
The etching of barrier layer 4 is realized in the transition of electronics.
Etching sample includes the epitaxial layer structure on substrate 1 and substrate, and epitaxial layer structure includes the space layer on substrate 1
21, barrier layer 4 and cap 22, practical epitaxial layer structure may also include other epitaxial structures, such as nucleating layer, resistive formation and transition
The structures such as layer.Two-dimensional electron gas 3 is formed in epitaxial layer structure.
For needing to carry out the sample of recessed grid etching, electrode 7 is made on the surface of sample epitaxial layer first before etching,
Electrode 7 is connected with two-dimensional electron gas 3.The production method of electrode 7 can choose but be not limited to deposit indium metal in sample surfaces
It forms electrode or makes electrode by carrying out short annealing after the multiple layer metals such as deposition titanium/aluminium/ni au (Ti/Al/Ni/Au)
7, later approach can form well stable Ohmic contact.In addition, the position of electrode 7 can in any position of sample,
Preferably, electrode 7 may be provided at the edge of sample, it is therefore an objective to which the area for saving sample improves the utilization rate of sample.
Then, it is patterned processing in device surface, the method for processing can choose but be not limited to photoetching, laser direct-writing
With electron beam exposure etc., the barrier layer 6 of 16 lower end of gate electrode etched will be needed to be exposed in etching solution 10, rest part makes
Use exposure mask 5 as protection, the exposure mask 5 of etching can choose but be not limited to photoresist, silica and silicon nitride etc..
Secondly, the etching electrode 7 of sample is connect with ammeter 8, ammeter 8 is connect with the anode of etching power supply 11, is carved
The cathode of erosion power supply 11 is connect with cathode plate 12, and etching solution 10 is added in etching container 13, by cathode plate 12 and etching sample
Product are contacted with etching solution 10, in this way, between etching solution 10, cathode plate 12, etching power supply 11, ammeter 8 and etching sample
Series connection forms an etching circuit.The flowing through channel of electric current is to need to carve under 11 anode of power supply, ammeter 8, two-dimensional electron gas 3, grid
The Al of erosionxGa(1-x)The cathode of N barrier layer 6, etching solution 10 and power supply 11.Etching solution 10 can choose but be not limited to sulfuric acid,
The etch liquids such as potassium hydroxide and oxalic acid.
Preferably, present invention series electrical flow table 8 in etching circuit, for monitoring in AlxGa(1-x)N barrier layer 6 is etched
In journey electric current with etch period change curve, it is therefore intended that etching effect is estimated by the change curve of electric current, to etch into
Row monitoring in real time, improves the repeatability of etching, certainly, can also not use ammeter in the present invention.
During electrochemical etching, it is contemplated that some etching solutions 10 could only etch potential barrier in the case where illumination
Layer 4, so adjusting the wavelength of light source 18 by setting external light source 9 in etching process, etching the energy of light source 18
(the material such as Al of barrier layer 6xGa(1-x)N), but it is unable to etched volume layer 21 (material such as aluminium nitride AlN), realizes in space layer
The self-stopping technology on surface.
In order to realize the self-stopping technology of etching, need to filter the light source of the part wavelength of broad spectrum light source 18 by filter 19
It removes, only remaining etching light source 20, filter 19 can be, but not limited to realize by filter plate.In general HEMT device extension
In structure, the forbidden bandwidth Eg22 of cap 22, the forbidden bandwidth Eg4 of barrier layer 4, space layer 21 forbidden bandwidth Eg21 this three
There are a kind of relationships for the forbidden bandwidth of kind material are as follows: Eg22 < Eg4 < Eg21, it is possible to select certain wave by filter 19
The energy of long light source 20, light source 20 is E20, and meets Eg22 < Eg4 < E20 < Eg21 requirement, can thus set conjunction
Suitable etching voltage, so that electrochemistry can only etch barrier layer 4 and cap 22 in etching process, without enough energy
Etched volume layer 21 realizes the purpose of self-stopping technology.Entire etching process can use constant current etch mode or constant pressure etch mode,
For the thickness that grid lower barrierlayer 6 needs to etch about in 10~30nm, specific thickness depends on the component of aluminium in the barrier layer 4 of sample
With 4 thickness of barrier layer.
When it is implemented, space layer 21 is generally aluminium nitride (AlN), barrier layer 4 is generally Al0.25Ga0.75The ternary of N half
Conductor material, cap 22 generally choose GaN material, and under room temperature environment, the forbidden bandwidth of AlN is about 6.2eV, corresponding spectrum
Wavelength be 200nm, Al0.25Ga0.75The forbidden bandwidth of N barrier layer 4 is 4.1eV according to the calculation formula of linear component, corresponding
Wavelength is 302nm, and the forbidden bandwidth of GaN is 3.4eV, and corresponding optical wavelength is 365nm, it is possible to will by filter 19
Wavelength in broad spectrum light source 18 is less than 200nm or the light source near 200nm filters out, only remaining to etch barrier layer
4Al0.25Ga0.75N realizes automatic stop when etching reaches AlN space layer without the light source of enough energy etched volume layers 21
Only state.
It is after etching that sample clean is clean, source electrode 14 and drain electrode 15 are made on the surface of sample, first in sample
Then spin coating photoresist in product surface forms the figure in source, drain electrode by the mask plate of design and photoetching technique in sample surfaces
Change, then redeposited metal, be typically chosen deposition titanium, aluminium, nickel, gold (Ti, Al, Ni, Au, thickness be respectively 20nm, 130nm,
50nm, 150nm) etc. multiple layer metals, it is the metal-stripping outside source, drain electrode is clean after metal deposit, then carry out short annealing,
Condition is 890 DEG C and anneals 30 seconds that source electrode 14 and drain electrode 15 are connected with two-dimensional electron gas 3 after annealing.
Then one layer of dielectric layer 17 is grown in sample surfaces, growth pattern can be, but not limited to Plasma Enhanced Chemical Vapor
Deposit (PECVD), atomic layer deposition (ALD), low-pressure chemical vapor deposition (LPCVD) and inductively coupled plasma chemical gaseous phase
The common semiconductor deposition techniques such as deposition.The medium of deposition is optional but is not limited to aluminium oxide, aluminium nitride, silica and silicon nitride
Common dielectric film in equal semiconductors.
The figure that forms grid metal after the completion of deposition by the method for photoetching again, in the barrier layer etch areas 23 of sample
Disposed thereon grid metal and stripping technology form gate electrode 16, finally etch the dielectric layer on source, drain electrode clean.Grid gold
Category is typically chosen Ni, Au, and thickness is respectively 50nm, 150nm,
Therefore, referring to shown in Fig. 3, the enhanced HEMT device for finally making realization includes source, leakage, gate electrode, gate medium
17, grid lower 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 semiconductor group is at source, drain electrode are located at 2 surface of gallium nitride and by Ohmic contacts and two dimension
Electron gas 3 is connected, and gate electrode 16 is set between source, drain electrode, in gate electrode metal and AlxGa(1-x)There are grid between the surface N
Medium 17 forms enhanced MISHEMT structure, and forms Xiao Jite with semiconductor surface and contact, the gesture of the lower end of gate electrode 16
Barrier layer AlxGa(1-x)N is all etched by the method for electrochemistry.
The working principle for the enhanced HEMT that the present invention realizes are as follows: it is illustrated with reference to Fig. 3, in enhanced HEMT device, threshold
Threshold voltage Vth is positive value, in gate electrode 16 plus zero-bias or not biasing, gate voltage Vg < Vth, due to grid lower barrierlayer 6
It 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 to not having under grid
Conducting channel, so source electrode 14 and drain electrode 15 are in and disconnect, so device is in an off state.It is positive electric when adding in grid
When pressure, gate voltage Vg > Vth, at this moment region can accumulate electronics under grid, and accumulation electronically forms new communication channel, makes source electrode
14 and drain electrode 15 be connected, device is in the open state.HEMT device is transformed into enhancement device from original depletion device.
Technology contents and technical characteristic of the invention have revealed that as above, however those skilled in the art still may base
Make various replacements and modification without departing substantially from spirit of that invention, therefore, the scope of the present invention in teachings of the present invention and announcement
It should be not limited to the revealed content of embodiment, and should include various without departing substantially from replacement and modification of the invention, and be this patent Shen
Please claim covered.
Claims (7)
1. a kind of system that etching self-stopping technology realizes the enhanced HEMT device of recessed grid, characterized by comprising:
To provide the etching power supply of etching electric current and to the etching solution as electrolyte and etching liquid, in the system work
When making, etching sample and cathode plate be impregnated in the etching solution, it is described etching power supply anode and cathode respectively with quarter
The electrode of erosion sample is connected with cathode plate, to connect between the etching solution, cathode plate, etching power supply and etching sample
Form an etching circuit, wherein the etching sample includes epitaxial layer structure, is formed with Two-dimensional electron in the epitaxial layer structure
The electrode of gas, the etching sample is connected with the two-dimensional electron gas；The etching solution is described using can effectively etch
The etching liquid of the barrier layer of sample is etched, the etching liquid is at least selected from sulfuric acid, potassium hydroxide and oxalic acid；
Light source is etched, to provide in system work there is the etching light of setting wavelength to irradiate the etching sample,
So that realizing the self-stopping technology of etching when being etched to form required recessed grid structure on the etching sample；The etching light source
It include: broad spectrum light source,
The energy of the etching light is enough that the etching solution is assisted to etch the barrier layer but cannot etch the etching sample
The space layer of product, the material of the barrier layer include AlxGa(1-x)N, 0 < x≤1, the material of the space layer include aluminium nitride, institute
The barrier layer etching depth for stating the recessed grid structure region of HEMT device is 10nm-20nm；
And filter is set to filter out some light in the light emitted line of the broad spectrum light source to obtain and have
The long etching light of standing wave.
2. the system that etching self-stopping technology according to claim 1 realizes the enhanced HEMT device of recessed grid, it is characterised in that also
Including the ammeter being connected between the anode of the etching power supply and the electrode of etching sample.
3. a kind of method that etching self-stopping technology realizes the enhanced HEMT device of recessed grid, it is characterised in that the following steps are included:
S1, etching sample is provided, the etching sample includes epitaxial layer structure, is formed with Two-dimensional electron in the epitaxial layer structure
Gas；
S2, the electrode being connected with the two-dimensional electron gas is made on etching sample；
S3, processing is patterned to the surface of the etching sample, to expose etching surface；
S4, sample and cathode plate immersion etching solution will be etched, and will be directly exposed to the etching surface in etching solution, and will
The anode and cathode for etching power supply is connect with the electrode of etching sample and cathode plate respectively, thus in the etching solution, cathode
Series connection forms an etching circuit between plate, etching power supply and etching sample, and simultaneously also to have the etching light of setting wavelength
The etching sample is irradiated, to etch required recessed grid structure on etching sample, and is forming the same of the recessed grid structure
The self-stopping technology of Shi Shixian etching；Wherein, the etching solution is using the quarter that can effectively etch the barrier layer for etching sample
Liquid is lost, the etching liquid is at least selected from sulfuric acid, potassium hydroxide and oxalic acid；The energy of the etching light is enough to assist the etching
Barrier layer described in solution etches but the space layer that cannot etch the etching sample, the material of the barrier layer includes AlxGa(1-x)
N, 0 < x≤1, the material of the space layer include aluminium nitride, and the barrier layer in the recessed grid structure region of the HEMT device etches deep
Degree is 10nm-20nm.
4. the method that etching self-stopping technology according to claim 3 realizes the enhanced HEMT device of recessed grid, which is characterized in that step
Rapid S2 includes: to be formed or by depositing indium metal on the surface of the etching sample by deposition titanium, aluminium, nickel, golden multilayer gold
It is annealed after category and makes to form the electrode.
5. the method that etching self-stopping technology according to claim 4 realizes the enhanced HEMT device of recessed grid, which is characterized in that institute
State the edge part that the etching sample is arranged in electrode.
6. the method that etching self-stopping technology according to claim 3 realizes the enhanced HEMT device of recessed grid, it is characterised in that: step
Graphic processing method described in rapid S3 includes photoetching, laser direct-writing or electron beam exposure.
7. the method that etching self-stopping technology according to claim 3 realizes the enhanced HEMT device of recessed grid, it is characterised in that packet
It includes: barrier layer some or all of in the epitaxial structure for etching sample being etched and forms the recessed grid structure.
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