CN105185841A - Field effect diode and manufacturing method therefor - Google Patents
Field effect diode and manufacturing method therefor Download PDFInfo
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- CN105185841A CN105185841A CN201510158880.XA CN201510158880A CN105185841A CN 105185841 A CN105185841 A CN 105185841A CN 201510158880 A CN201510158880 A CN 201510158880A CN 105185841 A CN105185841 A CN 105185841A
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- 230000005669 field effect Effects 0.000 title claims abstract description 65
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 230000004888 barrier function Effects 0.000 claims abstract description 163
- 238000005530 etching Methods 0.000 claims abstract description 38
- 239000000758 substrate Substances 0.000 claims abstract description 17
- 238000000034 method Methods 0.000 claims description 46
- 229910002601 GaN Inorganic materials 0.000 claims description 40
- 239000000463 material Substances 0.000 claims description 36
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 claims description 24
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 22
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 18
- RNQKDQAVIXDKAG-UHFFFAOYSA-N aluminum gallium Chemical group [Al].[Ga] RNQKDQAVIXDKAG-UHFFFAOYSA-N 0.000 claims description 15
- 229910052782 aluminium Inorganic materials 0.000 claims description 13
- 239000004411 aluminium Substances 0.000 claims description 13
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 13
- 229910052759 nickel Inorganic materials 0.000 claims description 11
- 230000003647 oxidation Effects 0.000 claims description 11
- 238000007254 oxidation reaction Methods 0.000 claims description 11
- 229910052751 metal Inorganic materials 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 8
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 7
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 7
- 239000010931 gold Substances 0.000 claims description 7
- 229910052737 gold Inorganic materials 0.000 claims description 7
- 229910052719 titanium Inorganic materials 0.000 claims description 7
- 239000010936 titanium Substances 0.000 claims description 7
- 230000007797 corrosion Effects 0.000 claims description 5
- 238000005260 corrosion Methods 0.000 claims description 5
- 229910052697 platinum Inorganic materials 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- 238000001259 photo etching Methods 0.000 claims description 3
- 230000015556 catabolic process Effects 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 4
- 230000000903 blocking effect Effects 0.000 abstract 2
- 230000005533 two-dimensional electron gas Effects 0.000 description 26
- 239000011248 coating agent Substances 0.000 description 10
- 238000000576 coating method Methods 0.000 description 10
- 230000010287 polarization Effects 0.000 description 8
- 238000009825 accumulation Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 4
- 229910002704 AlGaN Inorganic materials 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 3
- 238000001312 dry etching Methods 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000002269 spontaneous effect Effects 0.000 description 3
- 238000001039 wet etching Methods 0.000 description 3
- 229910017083 AlN Inorganic materials 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 2
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- -1 gallium-nitride metal oxide Chemical class 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a 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
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
- H01L29/872—Schottky diodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a 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
- H01L29/66083—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
- H01L29/66196—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices with an active layer made of a group 13/15 material
- H01L29/66204—Diodes
- H01L29/66212—Schottky diodes
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Ceramic Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
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Abstract
The invention discloses a field effect diode and a manufacturing method therefor. The field effect diode comprises a substrate, a channel layer located on the substrate, a first barrier layer located on the channel layer, an etching blocking layer located on the first barrier layer, a second barrier layer located on the etching blocking layer, a mask layer located on the second barrier layer, a groove located between the second barrier layer and the mask layer, a negative electrode located on the second barrier layer, and a positive electrode composed of Schottky electrodes located inside and outside the groove and a positive electrode ohmic contact electrode located on the second barrier layer in short circuit connection. The field effect diode has advantages of low forward cut-in voltage, low reverse leakage current and high breakdown voltage, the groove etching depth is easy to control, and the manufacturing technology is simple.
Description
Technical field
The present invention relates to technical field of semiconductors, particularly relate to a kind of field-effect diode and preparation method thereof.
Background technology
The third generation semiconductor material with wide forbidden band being representative with GaN (gallium nitride) has that forbidden band is loose, breakdown field strength is high, saturated electron drift velocity is high, thermal conductivity is high, the material property feature of the high excellence of heterogeneous interface two-dimensional electron gas, compared to Si material, GaN is more suitable for making high-power, high current density, high switching speed power electronic device.Compared with conventional Si devices, GaN device can carry higher power density, has higher energy conversion efficiency, can reduce the volume and weight of whole system, thus reduces system cost.
Schottky barrier diode based on GaN can tolerate very high reverse breakdown voltage, but its forward conduction voltage will reach about 1V usually.For expanding the range of application of GaN base Schottky diode, the high and diode of forward conduction voltage very low (close to 0V) of puncture voltage need be obtained.
In order to regulate the forward conduction voltage of GaN diode, usually adopt the method for the injection of barrier layer fluorine ion or barrier layer etching groove.The people such as Chen Jing (publication number CN101562182A) propose to inject fluorine ion in a part of barrier layer under diode anode, introduce permanent negative electrical charge, effectively can exhaust the two-dimensional electron gas under Schottky gate, thus pinch off conduction path, be shorted together by Schottky gate and diode anode, the threshold voltage that the forward conduction voltage achieving diode controls raceway groove by Schottky determines, not by the impact of Schottky junction barrier.But fluorine ion injection technology is complicated, and can cause the problem of device stability.Therefore, Many researchers all realizes being studied close to the diode of the forward conduction voltage of 0V to barrier layer etching groove.Usually, the degree of depth of the etching groove of barrier layer is difficult to control, and technique is comparatively complicated, and etching apparatus is expensive.
ZheXu (ZheXu, JinyanWang, YangLiu, JinbaoCai, JingqianLiu, MaojunWang, MinYu, BingXie, WenggangWu, XiaohuaMa, andJinchengZhang.FabricationofNormallyOffAlGaN/GaNMOSFET UsingaSelf-TerminatingGateRecessEtchingTechnique, IEEEElectronDeviceLetters, VOL.34, No.7, etc. July2013) people proposes a kind of method of thermal oxidation and wet etching to obtain the gallium-nitride metal oxide semiconductor field effect transistor (MOSFET) of enhancement mode.The implementation procedure of the method first carries out thermal oxidation to AlGaN layer, then etches in KOH solution.The method has easy to control, the feature that repeatability is high, and this lithographic method has high Selection radio to AlGaN/GaN, can automatically stop at AlGaN/GaN interface.But because barrier layer is removed completely, the two-dimensional electron gas under groove all exhausts, the threshold voltage of the MOSFET of therefore the method acquisition is too large, and therefore this structure is not suitable for diode.And the impact that channel bottom channel layer surface place is corroded, can roughness be increased, cause the increase of reverse leakage.
Summary of the invention
The object of the invention is to propose a kind of field-effect diode and preparation method thereof, this field-effect diode can solve that cut-in voltage in prior art is high, reverse leakage is large, and the degree of depth of etching groove is difficult to control, the problem of complex manufacturing technology.
For reaching this object, the present invention by the following technical solutions:
First aspect, the invention discloses a kind of field-effect diode, comprising:
Substrate;
Channel layer, described channel layer is positioned at described substrate;
First barrier layer, described first barrier layer is positioned on described channel layer;
Etching barrier layer, described etching barrier layer is positioned on described first barrier layer;
Second barrier layer, described second barrier layer is positioned on described etching barrier layer;
Mask layer, described mask layer is positioned on described second barrier layer;
Groove, described groove is positioned within described second barrier layer and described mask layer, and the degree of depth of described groove equals the thickness of described second barrier layer and the thickness sum of described mask layer;
Negative electrode, described negative electrode is positioned on described second barrier layer;
Anode, described anode is made up of the Schottky electrode be positioned at outside described groove and described groove and the anode ohmic contact electrode phase short circuit be positioned on described second barrier layer.
Further, the material of described negative electrode and described anode ohmic contact electrode is the combination of any one or at least two kinds in titanium, aluminium, nickel or gold, described Schottky electrode is single or multiple lift metal, and described metal is the combination of any one or at least two kinds in nickel, platinum or aluminium.
Further, the material of described second barrier layer is aluminum gallium nitride, and the mass percent of the al composition of described second barrier layer reduces from top to bottom gradually.
Further, the shape of described groove is inverted trapezoidal.
Further, also comprise:
Back of the body barrier layer, described back of the body barrier layer is between described substrate and described channel layer, and the material of described back of the body barrier layer is P type gallium nitride or P type aluminum gallium nitride.
Second aspect, the invention discloses a kind of manufacture method of field-effect diode, comprising:
Substrate is provided;
Channel layer, the first barrier layer, etching barrier layer, the second barrier layer and mask layer is prepared successively in described substrate;
Negative electrode and anode ohmic contact electrode is prepared successively on described second barrier layer;
Prepare groove within the second barrier layer between described negative electrode and described anode ohmic contact electrode and mask layer, and the degree of depth of described groove equals the thickness of described second barrier layer and the thickness sum of described mask layer;
Schottky electrode is prepared, described Schottky electrode and described anode ohmic contact electrode phase short circuit on described groove.
Further, within the second barrier layer between described negative electrode and described anode ohmic contact electrode, prepare groove, and the degree of depth of described groove equals the thickness of described second barrier layer, comprising:
Photoetching technique is utilized to determine the region needing to form groove;
Remove the described mask layer needing the region forming groove;
Thermal oxidation is carried out to described second barrier layer;
Utilize wet etch techniques to be eroded by described second barrier layer in the region forming groove that needs, form groove.
Further, the temperature of described thermal oxidation is 500-700 degree Celsius, and the liquid that described wet etch techniques is used is potassium hydroxide, and the time of corrosion is 30-60 minute.
Field-effect diode of the present invention has the advantage of low forward cut-in voltage, low reverse current leakage and high-breakdown-voltage, and by introducing etching barrier layer between the first barrier layer and the second barrier layer, when preparing groove, the degree of depth of groove equals the thickness of the second barrier layer, the degree of depth of etching groove is easily controlled, can obtain the diode that cut-in voltage is close to 0V, and manufacture craft is simple.
Accompanying drawing explanation
In order to the technical scheme of exemplary embodiment of the present is clearly described, one is done to the accompanying drawing used required for describing in embodiment below and simply introduce.Obviously, the accompanying drawing introduced is the accompanying drawing of a part of embodiment that the present invention will describe, instead of whole accompanying drawings, for those of ordinary skill in the art, under the prerequisite not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the structure chart of the field-effect diode that the embodiment of the present invention one provides.
Fig. 2 be the field-effect diode that provides of the embodiment of the present invention one when anode applies less forward voltage (being less than 1V), at groove place along A-A
/the band structure figure of distribution.
Wherein, B district is etching barrier layer; C district is the first barrier layer; D district is channel layer; E
cat the bottom of conduction band; E
vfor top of valence band; E
ffor Fermi level.
Fig. 3 be the field-effect diode that provides of the embodiment of the present invention one when reverse-biased, at groove place along A-A
/the band structure figure of distribution.
Fig. 4 is the flow chart of the manufacture method of the field-effect diode that the embodiment of the present invention one provides.
Fig. 5 prepares groove within second barrier layer of step between negative electrode and anode ohmic contact electrode and mask layer in the manufacture method of the field-effect diode that the embodiment of the present invention one provides, and the degree of depth of groove equals the flow chart of the thickness of the second barrier layer and the thickness sum of mask layer.
Fig. 6 is the structure chart of the field-effect diode that the embodiment of the present invention two provides.
Fig. 7 is the flow chart of the manufacture method of the field-effect diode that the embodiment of the present invention two provides.
Fig. 8 is the structure chart of the field-effect diode that the embodiment of the present invention three provides.
Fig. 9 is the structure chart of the field-effect diode that the embodiment of the present invention four provides.
Figure 10 is the flow chart of the manufacture method of the field-effect diode that the embodiment of the present invention four provides.
Embodiment
For making the object, technical solutions and advantages of the present invention clearly, below with reference to the accompanying drawing in the embodiment of the present invention, by embodiment, technical scheme of the present invention is intactly described.Obviously; described embodiment is a part of embodiment of the present invention, instead of whole embodiments, based on embodiments of the invention; the every other embodiment that those of ordinary skill in the art obtain under the prerequisite not making creative work, all falls within protection scope of the present invention.
Embodiment one:
Fig. 1 is the structure chart of the field-effect diode that the embodiment of the present invention one provides.As shown in Figure 1, this field-effect diode comprises:
Substrate 1.
In the present embodiment, backing material can be gallium nitride, silicon, sapphire or carborundum.
Nucleating layer 2, is positioned on substrate 1.
In the present embodiment, nucleating layer material can be aluminium nitride, gallium nitride or aluminum gallium nitride,
Resilient coating 3, is positioned on nucleating layer 2.
In the present embodiment, cushioning layer material can be aluminum gallium nitride or other III-V, and thickness can be 1-3.5 micron.
Channel layer 4, is positioned on resilient coating 3.
In the present embodiment, channel layer materials can be gallium nitride, and thickness can be 15-35 nanometer.
First barrier layer 5, is positioned on channel layer 4.
In the present embodiment, the first barrier layer and channel layer form heterojunction structure, and the interface place of the first barrier layer and channel layer is formed with two-dimensional electron gas 6.First abarrier layer material can be aluminum gallium nitride, and the mass percent of aluminium can be 10%-20%, and thickness can be 2-5 nanometer.
Etching barrier layer 7, is positioned on the first barrier layer 5.
In the present embodiment, etching barrier layer materials can be gallium nitride, and thickness can be 1-5 nanometer.
Second barrier layer 8, is positioned on etching barrier layer 7.
In the present embodiment, the material of the second barrier layer can be aluminum gallium nitride, and the mass percent of aluminium can be 20%-45%, and thickness can be 15-50 nanometer.
Negative electrode 9, is positioned on the second barrier layer 8.
In the present embodiment, negative electrode and the second barrier layer form ohmic contact.The material of negative electrode can be the combination of any one or at least two kinds in titanium, aluminium, nickel or gold.The forming process of negative electrode can comprise dry etching second barrier layer, and this kind of forming process can promote the performance of the ohmic contact of negative electrode and the formation of the second barrier layer.
Anode ohmic contact electrode 10, is positioned on the second barrier layer 8.
In the present embodiment, anode ohmic contact electrode and the second barrier layer form ohmic contact.The material of anode ohmic contact electrode can be the combination of any one or at least two kinds in titanium, aluminium, nickel or gold.The forming process of anode ohmic contact electrode can comprise dry etching second barrier layer, and this kind of forming process can promote the performance of the ohmic contact of anode ohmic contact electrode and the formation of the second barrier layer.
Mask layer 11, is positioned on the second barrier layer 8, and the region that non-negative electrode 9 and anode ohmic contact electrode 10 cover.
In the present embodiment, mask material can be gallium nitride or silicon dioxide.
Groove, within the second barrier layer 8 between negative electrode 9 and anode ohmic contact electrode 10 and mask layer 11, and the degree of depth of groove equals the thickness of the second barrier layer 8 and the thickness sum of mask layer 11.
In the present embodiment, the concentration of beneath trenches two-dimensional electron gas is lower than the concentration of groove both sides two-dimensional electron gas.
Schottky electrode 12, is positioned on groove, and with anode ohmic contact electrode 10 phase short circuit.
In the present embodiment, Schottky electrode and anode ohmic contact electrode form anode.Schottky electrode can be single or multiple lift metal, and metal can be the combination of any one or at least two kinds in nickel, platinum or aluminium.
In the present embodiment, due to the second barrier layer, between the first barrier layer and channel layer, there is piezoelectric effect and spontaneous polarization effect, form the two-dimensional electron gas that polarization charge induces at the interface place of the first barrier layer and channel layer.Because second abarrier layer material at groove place is removed, and the first barrier layer thickness corresponding to channel bottom is less, and piezoelectric polarization effect and the spontaneous polarization effect of the first barrier layer and channel layer are not enough to the two-dimensional electron gas inducing high concentration.Therefore, the two-dimensional electron gas between the first barrier layer and channel layer has exhausting to a certain degree in beneath trenches, and namely the two-dimensional electron gas of beneath trenches is lower than the concentration of the two-dimensional electron gas of both sides.Increase the thickness of the first barrier layer, obtain the two-dimensional electron gas that concentration under groove is higher, reduce the thickness of the first barrier layer, obtain the two-dimensional electron gas that concentration under groove is lower.Regulate the thickness of the first barrier layer can obtain piezoelectric polarization in various degree and spontaneous polarization, thus the field-effect diode of cut-in voltage close to 0V can be obtained.
When the anode of this field-effect diode applies positive bias-voltage, under the effect of Schottky electrode in the trench, conduction band in the heterojunction of the channel layer under trench bottom regions and the first barrier layer is bent downwardly, closer to Fermi level, the accumulation area of electronics is formed in the interface of channel layer and the first barrier layer, this electronics accumulation area is connected with Two-dimensional electron gas channel, forms the conductive channel of diode.Electronics flows into from negative electrode, the Two-dimensional electron gas channel of the first barrier layer and channel layer under electronics accumulation area under negative electrode under the Two-dimensional electron gas channel at the first barrier layer and channel layer interface place, trench bottom regions, anode ohmic contact electrode, finally flow out from anode, that is this field-effect diode possesses forward conduction characteristic.
By the concentration regulating the thickness of the first barrier layer can control the two-dimensional electron gas formed, thus control the cut-in voltage of this field-effect diode.First barrier layer thickness is less, and the degree that the two-dimensional electron gas of beneath trenches exhausts is larger, and namely concentration is less, needs larger anode voltage could realize the forward conduction of this field-effect diode.The thickness increasing by the first barrier layer can reduce the cut-in voltage of this field-effect diode.Therefore, the field-effect diode cut-in voltage that the first suitable barrier layer thickness can realize close to 0V is selected.
This field-effect diode is when positively biased, only need apply less bias voltage at anode, the interface place of channel layer under groove and the first barrier layer will there is electronics accumulation horizon, be communicated with high concentration, high mobility two-dimensional electron gas as conductive channel, therefore the forward voltage drop of this field-effect diode and conducting resistance less.
Fig. 2 be the field-effect diode that provides of the embodiment of the present invention one when anode applies less forward voltage (being less than 1V), at groove place along A-A
/the band structure figure of distribution.As shown in Figure 2, when the anode of this field-effect diode applies less forward voltage (being less than 1V), the conduction band at the first barrier layer and channel layer interface place is bent downwardly, and is positioned under Fermi level, therefore occurs electronics accumulation horizon at channel layer surface.This electronics accumulation horizon connects channel layer two-dimensional electron gas, and form diode conduction passage, therefore the cut-in voltage of diode is low, and conducting resistance is also less.
Fig. 3 be the field-effect diode that provides of the embodiment of the present invention one when reverse-biased, at groove place along A-A
/the band structure figure of distribution.As shown in Figure 3, when the anode applying reversed bias voltage of this field-effect diode (anode opposing cathode applies negative bias voltage), conduction band in the heterojunction of the channel layer under the Schottky electrode of trench region and the first barrier layer is bent upwards, gradually away from Fermi level, in groove, Schottky electrode strengthens the depletion action of two-dimensional electron gas, two-dimensional electron gas depleted region is by further broadening, form cut-off raceway groove, thus under reversed bias voltage, electric current can not conducting between a cathode and an anode, makes reverse leakage current lower.
Fig. 4 is the flow chart of the manufacture method of the field-effect diode that the embodiment of the present invention one provides.As shown in Figure 4, the method comprises:
Step 401, provide substrate.
In this step, backing material can be gallium nitride.
Step 402, be prepared into stratum nucleare and resilient coating successively in substrate.
In this step, the method being prepared into stratum nucleare or resilient coating can be MOCVD method or molecular beam epitaxial method.
Wherein, nucleating layer material can be aluminium nitride, gallium nitride or aluminum gallium nitride, and cushioning layer material can be aluminum gallium nitride or other III-V.
Step 403, on resilient coating, prepare channel layer, the first barrier layer, etching barrier layer, the second barrier layer and mask layer successively.
In this step, the method preparing channel layer, the first barrier layer, etching barrier layer or the second barrier layer can be MOCVD method or molecular beam epitaxial method.
Wherein, channel layer materials can be gallium nitride, and the first abarrier layer material can be aluminum gallium nitride, and etching barrier layer materials can be gallium nitride, and the material of the second barrier layer can be aluminum gallium nitride.
Preferably, the preparation process of etching barrier layer is carried out after completing the first barrier layer in same cavity, and the growth course of etching barrier layer does not contact ambient atmosphere.
Step 404, on the second barrier layer, prepare negative electrode and anode ohmic contact electrode successively.
In this step, the structure obtained is isolated, etching mask layer after step 403, on the second barrier layer, prepare negative electrode and anode ohmic contact electrode.
Wherein, the material of negative electrode can be the combination of any one or at least two kinds in titanium, aluminium, nickel or gold, and the material of anode ohmic contact electrode can be the combination of any one or at least two kinds in titanium, aluminium, nickel or gold.
Prepare groove within step 405, the second barrier layer between negative electrode and anode ohmic contact electrode and mask layer, and the degree of depth of groove equals the thickness of the second barrier layer and the thickness sum of mask layer.
Preferably, as shown in Figure 5, step 405 comprises the following steps:
Step 415, photoetching technique is utilized to determine to need to be formed the region of groove.
Step 425, removal need the mask layer in the region forming groove.
Step 435, thermal oxidation is carried out to the second barrier layer.
In this step, the temperature of thermal oxidation is 500-700 degree Celsius.
Step 445, utilizing wet etch techniques to erode needing second barrier layer in region forming groove, forming groove.
In this step, the liquid that wet etching is used is potassium hydroxide, and the time of corrosion is 30-60 minute.Aluminum gallium nitride as the second abarrier layer material can be dissolved in the alkaline solutions such as potassium hydroxide easily after thermal oxidation, and is insoluble to the alkaline solutions such as potassium hydroxide as the gallium nitride of etching barrier layer materials.Therefore, gallium nitride can as the etching barrier layer of effective etching groove.
In this step, utilize wet etching method to prepare groove, solve in prior art the damage and the defect that adopt dry etching method to prepare the material that groove causes, technique is simple, and reliability is high.
Step 406, on groove, prepare Schottky electrode, Schottky electrode and anode ohmic contact electrode phase short circuit.
In this step, prepare Schottky electrode by Schottky metal on groove.
Wherein, Schottky electrode can be single or multiple lift metal, and the material of metal is the combination of any one or at least two kinds in nickel, platinum or aluminium.
The field effect transistor diode that the embodiment of the present invention one provides has the advantage of low forward cut-in voltage, low reverse current leakage and high-breakdown-voltage.And on channel layer, introduce the first barrier layer and etching barrier layer, the etching of the second barrier layer groove is made to end on etching barrier layer, compared with not increasing the structure of etching barrier layer, reduce the etching injury of channel layer interface, thus reduce the reverse leakage current at raceway groove place.This structure also can select the first suitable barrier layer thickness, and obtaining cut-in voltage is the field-effect diode of about 0V.
Embodiment two:
Fig. 6 is the structure chart of the field-effect diode that the embodiment of the present invention two provides.As shown in Figure 6, with the embodiment of the present invention one unlike, the field-effect diode that the embodiment of the present invention two provides also comprises: the back of the body barrier layer 13 between resilient coating 3 and channel layer 4.
In the present embodiment, the material of back of the body barrier layer can be P type gallium nitride or P type aluminum gallium nitride.In the structure shown here, the negative electrical charge that P type doping in back of the body barrier layer is introduced and the negative electrical charge that piezoelectric polarization produces further suppress the two-dimensional electron gas in channel layer, can regulate and control the cut-in voltage of diode further, thus to obtain numerical value be just and close to the cut-in voltage of 0V.
Fig. 7 is the flow chart of the manufacture method of the field-effect diode that the embodiment of the present invention two provides.As shown in Figure 7, compared with the embodiment of the present invention one, the manufacture method of the field-effect diode that the embodiment of the present invention two provides in step 402, after substrate is prepared into stratum nucleare and resilient coating successively, step 403, on resilient coating, prepare channel layer, the first barrier layer, etching barrier layer, the second barrier layer and mask layer successively before also comprise:
Step 423, on resilient coating preparation the back of the body barrier layer.
In this step, the material of back of the body barrier layer can be P type gallium nitride or P type aluminum gallium nitride.
Correspondingly, step 403 prepares channel layer, the first barrier layer, etching barrier layer, the second barrier layer and mask layer successively on back of the body barrier layer.
Compared with the field-effect diode provided with the embodiment of the present invention one, the field-effect diode that the embodiment of the present invention two provides by introducing back of the body barrier layer between resilient coating and channel layer, the negative electrical charge that P type doping in back of the body barrier layer is introduced and the negative electrical charge that piezoelectric polarization produces further suppress the two-dimensional electron gas in channel layer, can regulate and control the cut-in voltage of diode further, thus to obtain numerical value be just and close to the cut-in voltage of 0V.
Embodiment three:
Fig. 8 is the structure chart of the field-effect diode that the embodiment of the present invention three provides.As shown in Figure 8, with the embodiment of the present invention one unlike, the mass percent of the al composition of the second barrier layer 8 of the field-effect diode that the embodiment of the present invention three provides reduces from top to bottom gradually, and the shape of groove is inverted trapezoidal.
In the present embodiment, the mass percent of the al composition of the second barrier layer increases from bottom to top gradually, changes in gradient.In the thermal oxidation process of the second barrier layer, along with the difference of the mass percent of al composition, degree of oxidation is different, and the mass percent of al composition is more high more oxidized.Therefore formed in corrosion in the process of groove, the part that al composition mass percent is high is easily corroded, and forms the groove of inverted trapezoidal structure wide at the top and narrow at the bottom.The sidewall of this inverted trapezoidal groove can form field plate structure, expands the depleted region of beneath trenches two-dimensional electron gas, promotes the puncture voltage of diode.
Compared with the field-effect diode provided with the embodiment of the present invention one, second barrier layer of the field-effect diode that the embodiment of the present invention three provides by utilizing the mass percent of al composition to reduce gradually from top to bottom, when corrosion second barrier layer forms groove, the groove of inverted trapezoidal structure can be formed, the sidewall of inverted trapezoidal groove forms field plate structure, the depleted region of beneath trenches two-dimensional electron gas can be expanded, promote the puncture voltage of diode.
Embodiment four:
Fig. 9 is the structure chart of the field-effect diode that the embodiment of the present invention four provides.As shown in Figure 9, with the embodiment of the present invention one unlike, the field-effect diode that the embodiment of the present invention four provides also comprises:
Dielectric layer 14, on the mask layer 11 between Schottky electrode 12 and negative electrode 9, and extends on Schottky electrode 12, cover part Schottky electrode 12.
Field plate 15, originates on the unlapped anode of dielectric layer 14, and extends on dielectric layer 14.
In the present embodiment, the material of field plate can be the combination of any one or at least two kinds in titanium, aluminium, nickel or gold.
Figure 10 is the manufacture method flow chart of the field-effect diode that the embodiment of the present invention four provides.As shown in Figure 10, compared with the embodiment of the present invention two, the manufacture method of the field-effect diode that the embodiment of the present invention three provides in step 406, prepare Schottky electrode on groove, comprises after Schottky electrode and anode ohmic contact electrode phase short circuit:
Prepare dielectric layer on step 407, mask layer between Schottky electrode and negative electrode, and extend on Schottky electrode, cover part Schottky electrode.
Step 408, on the unlapped Schottky electrode of dielectric layer, prepare field plate, and extend on dielectric layer.
Compared with the embodiment of the present invention one, the field-effect diode that the embodiment of the present invention three provides, by introducing dielectric layer and field plate, improves the reverse breakdown voltage of this field-effect diode.
The know-why that above are only preferred embodiment of the present invention and use.The invention is not restricted to specific embodiment described here, the various significant changes can carried out for a person skilled in the art, readjust and substitute all can not depart from protection scope of the present invention.Therefore, although be described in further detail invention has been by above embodiment, the present invention is not limited only to above embodiment, when not departing from the present invention's design, can also comprise other Equivalent embodiments more, and scope of the present invention is determined by the scope of claim.
Claims (9)
1. a field-effect diode, is characterized in that, comprising:
Substrate;
Channel layer, described channel layer is positioned at described substrate;
First barrier layer, described first barrier layer is positioned on described channel layer;
Etching barrier layer, described etching barrier layer is positioned on described first barrier layer;
Second barrier layer, described second barrier layer is positioned on described etching barrier layer;
Mask layer, described mask layer is positioned on described second barrier layer;
Groove, described groove is positioned within described second barrier layer and described mask layer, and the degree of depth of described groove equals the thickness of described second barrier layer and the thickness sum of described mask layer;
Negative electrode, described negative electrode is positioned on described second barrier layer;
Anode, described anode is made up of the Schottky electrode be positioned at outside described groove and described groove and the anode ohmic contact electrode phase short circuit be positioned on described second barrier layer.
2. field-effect diode according to claim 1, it is characterized in that, the material of described negative electrode and described anode ohmic contact electrode is the combination of any one or at least two kinds in titanium, aluminium, nickel or gold, described Schottky electrode is single or multiple lift metal, and described metal is the combination of any one or at least two kinds in nickel, platinum or aluminium.
3. field-effect diode according to claim 1, is characterized in that, the material of described second barrier layer is aluminum gallium nitride, and the mass percent of the al composition of described second barrier layer reduces from top to bottom gradually.
4. field-effect diode according to claim 1, is characterized in that, the shape of described groove is inverted trapezoidal.
5. field-effect diode according to claim 1, is characterized in that, also comprises:
Back of the body barrier layer, described back of the body barrier layer is between described substrate and described channel layer, and the material of described back of the body barrier layer is P type gallium nitride or P type aluminum gallium nitride.
6. a manufacture method for field-effect diode, is characterized in that, comprising:
Substrate is provided;
Channel layer, the first barrier layer, etching barrier layer, the second barrier layer and mask layer is prepared successively in described substrate;
Negative electrode and anode ohmic contact electrode is prepared successively on described second barrier layer;
Prepare groove within the second barrier layer between described negative electrode and described anode ohmic contact electrode and mask layer, and the degree of depth of described groove equals the thickness of described second barrier layer and the thickness sum of described mask layer;
Schottky electrode is prepared, described Schottky electrode and described anode ohmic contact electrode phase short circuit on described groove.
7. the manufacture method of field-effect diode according to claim 6, it is characterized in that, prepare groove within the second barrier layer between described negative electrode and described anode ohmic contact electrode, and the degree of depth of described groove equals the thickness of described second barrier layer, comprising:
Photoetching technique is utilized to determine the region needing to form groove;
Remove the described mask layer needing the region forming groove;
Thermal oxidation is carried out to described second barrier layer;
Utilize wet etch techniques to be eroded by described second barrier layer in the region forming groove that needs, form groove.
8. the manufacture method of field-effect diode according to claim 7, is characterized in that, the temperature of described thermal oxidation is 500-700 degree Celsius.
9. the manufacture method of field-effect diode according to claim 7, is characterized in that, the liquid that described wet etch techniques is used is potassium hydroxide, and the time of corrosion is 30-60 minute.
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