A kind of enhanced AlGaN based on slot grid structure/GaN MISHEMT device architecture and
Its preparation method
Technical field
The present invention relates to microelectronics technology, especially relate to a kind of enhanced AlGaN/GaN based on slot grid structure
MISHEMT device architecture and preparation method thereof.
Background technology
The 3rd bandwidth bandgap semiconductor with SiC and GaN as representative is big with its energy gap in recent years, breakdown electric field
The characteristic such as high, thermal conductivity high, saturated electrons speed big and heterojunction boundary two-dimensional electron gas is high so that it is extensively closed
Note.In theory, the high electron mobility transistor (HEMT), LED, laser diode that these materials make is utilized
The devices such as LD have obvious advantageous characteristic than existing device, therefore domestic and international in the last few years researcher it has been carried out extensively and
In-depth study, and achieve the achievement in research attracting people's attention.
AlGaN/GaN hetero-junctions high electron mobility transistor (HEMT) in terms of high-temperature device and HIGH-POWERED MICROWAVES device
Showing advantageous advantage, pursuit device high-frequency, high pressure, high power have attracted numerous research.In recent years, make
Higher frequency high pressure AlGaN/GaN HEMT becomes the another study hotspot of concern.Owing to the growth of AlGaN/GaN hetero-junctions completes
After, heterojunction boundary exists for a large amount of two-dimensional electron gas 2DEG, and its mobility is very high, and therefore we are obtained in that higher
Device frequency characteristic.In terms of improving AlGaN/GaN hetero-junctions electron mobility transistor breakdown voltage, people have been carried out in a large number
Research, discovery AlGaN/GaN HEMT device puncture occur mainly in grid lean on drain terminal, the therefore breakdown potential of device to be improved
Pressure, it is necessary to make the electric field redistribution in grid leak region, especially reduce the electric field by drain terminal for the grid, to this end, there has been proposed employing
The method of field plate structure:
Use field plate structure.See Yuji Ando, the Novel of Akio Wakejima, Yasuhiro Okamoto etc.
AlGaN/GaN dual-field-plate FET with high gain,increased linearity and
stability,IEDM 2005,pp.576-579,2005.Use field plate structure in AlGaN/GaN HEMT device, by device
Breakdown potential be pressed with one and be greatly improved, and reduce gate leakage capacitance, improve the linearity and the stability of device.
Content of the invention
The present invention, in order to overcome above-mentioned deficiency, provides a kind of enhanced AlGaN/GaN based on slot grid structure
MISHEMT device architecture and preparation method thereof, uses field plate structure and dipole layer to carry out grid near the electric field of drain terminal simultaneously
Modulation.
Technical scheme is as follows:
A kind of enhanced AlGaN based on slot grid structure/GaN MISHEMT device architecture, includes lining from the bottom up successively
The end, GaN cushion, AlN separation layer, GaN channel layer, AlGaN intrinsic layer and AlGaN doped layer, described AlGaN doped layer sets
Have source electrode, passivation layer the 1st, ITO gate electrode the 1st, organic insulator PTFE, passivation layer the 2nd, LiF and drain electrode, described source electrode and described ITO
Being provided with passivation layer 1 between gate electrode 1, described organic insulator PTFE is provided with ITO gate electrode 2, described organic insulator PTFE
Being provided with passivation layer 2 near drain electrode side, being deposited with LiF film layer between described drain electrode and passivation layer 2, described drain electrode is thin with LiF
It is deposited with Al metal level on film layer.
Described backing material is sapphire, carborundum, GaN or MgO.
In described AlGaN doped layer, the constituent content of Al is between 0~1, the constituent content of Ga and the constituent content of Al it
With for 1.
The thickness of described organic insulator PTFE layer is 200nm~300nm.
Described passivation layer 1 and 2 includes Si3N4、Al2O3、HfO2With one or more in HfSiO.
Above-mentioned a kind of enhanced AlGaN based on slot grid structure/GaN MISHEMT device architecture is made by the following method
Make:
(1) organic washing is carried out to epitaxially grown AlGaN/GaN material, after cleaning by the deionized water of flowing, put into
HCl:H2The solution of O=1:1 carries out corroding 30-60s, finally cleans by the deionized water of flowing and dry up with high pure nitrogen;
(2) photoetching and dry etching are carried out to the AlGaN/GaN material cleaning up, be formed with region meas;
(3) carry out photoetching to the AlGaN/GaN material preparing table top, form source-drain area, put in electron beam evaporation platform
Deposit metal ohmic contact Ti/Al/Ni/Au=20/120/45/50nm, and peel off, finally carry out in nitrogen environment
The rapid thermal annealing of 850 DEG C of 35s, forms Ohmic contact;
(4) device preparing Ohmic contact is carried out photoetching, form organic dielectric PTFE depositing region, then put
Enter in oxygen plasma treatment room and mild oxidation treatments is carried out to AlGaN surface, be then placed in electron beam evaporation platform: reative cell is true
Sky is evacuated to 4.0 × 10-3Handkerchief, it is 0.1nm/s that slow making alive makes control PTFE evaporation rate, the thick PTFE of deposit 200-300nm
Film;
(5) device having deposited PTFE film is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping;
(6) photoetching is carried out to the device completing PTFE stripping, form grid and grid field plate region, put in electron beam evaporation platform
The thick ITO gate electrode of deposit 200nm;
(7) device having deposited gate electrode is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping, form grid
Field plate structure;
(8) carry out photoetching by completing device prepared by grid field plate, form the depositing region of dielectric LiF, be then placed in
Electron-beam reaction room vacuum is evacuated to 4.0 × 10-3Handkerchief, it is 0.5nm/s that slow making alive makes control LiF evaporation rate, deposits 100-
The thick LiF film of 200nm;
(9) device having deposited LiF film is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping;
(10) carry out photoetching to completing device prepared by LiF, form field plate region, source, put in electron beam evaporation platform and deposit
The thick Al metal of 200nm;
(11) device having deposited Al metal is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping, formed
Leakage field plate structure;
(12) device completing is put into PECVD reative cell deposit SiN passivating film;
(13) device is carried out again, photoetching development, form the etched area of SiN film, and put into ICP dry etching
In reative cell, the SiN film that source electrode, drain electrodes cover is etched away;
(14) device is carried out, photoetching development, and put into electron beam evaporation platform deposit Ti/Au=20/200nm
Thicken electrode, complete the preparation of integral device.
Process conditions in described step (12) are: SiH4Flow be 40sccm, NH3Flow be 10sccm, reative cell
Pressure is 1~2Pa, and radio-frequency power is 40W, the thick SiN passivating film of deposit 200nm~300nm
Process conditions in described step (13) are: upper electrode power is 200W, and lower electrode power is 20W, react chamber pressure
Power is 1.5Pa, CF4Flow be 20sccm, the flow of Ar gas is 10sccm, and etch period is 10min.
The invention has the beneficial effects as follows:
(1) present invention uses dipole layer produced by PTFE and ITO to achieve the part depletion effect to 2DEG concentration,
Achieve the modulation near drain terminal electric field for the grid;
(2) present invention make use of ITO as grid field version simultaneously, again realizes the modulation near drain terminal electric field for the grid, improves
Breakdown voltage when AlGaN/GaN HEMT device is reverse-biased;
(3) part that the present invention utilizes dipole layer produced by LiF and Al to achieve 2DEG concentration increases, and reduces device
The conducting resistance of part, and utilize metal Al formed leakage field plate, further increase AlGaN/GaN HEMT device reverse-biased when hit
Wear voltage.
Brief description
Examples of the present invention will be described by way of reference to the accompanying drawings, wherein:
Fig. 1 is the schematic diagram of the present invention;
Fig. 2-4 is the Making programme figure of the present invention.
Detailed description of the invention
In conjunction with the accompanying drawings, the present invention is further detailed explanation.These accompanying drawings are the schematic diagram of simplification, only with
The basic structure of the illustration explanation present invention, therefore it only shows the composition relevant with the present invention.
As it is shown in figure 1, present embodiments provide a kind of enhanced AlGaN based on slot grid structure/GaN MISHEMT device
Structure, includes that substrate, GaN cushion, AlN separation layer, GaN channel layer, AlGaN intrinsic layer and AlGaN mix from the bottom up successively
Diamicton, described AlGaN doped layer is provided with source electrode, passivation layer the 1st, ITO gate electrode the 1st, organic insulator PTFE, passivation layer the 2nd, LiF
And drain electrode, it is provided with passivation layer 1 between described source electrode and described ITO gate electrode 1, described organic insulator PTFE is provided with ITO grid
Electrode 2, described organic insulator PTFE is provided with passivation layer 2 near drain electrode side, is deposited with between described drain electrode and passivation layer 2
LiF film layer, described drain electrode and LiF film layer are deposited with Al metal level, and wherein, described backing material is sapphire, carbonization
Silicon, GaN or MgO, in described AlGaN doped layer, the constituent content of Al is between 0~1, and the constituent content of Ga contains with the component of Al
Amount sum is 1, and the thickness of described organic insulator PTFE layer is 200nm~300nm.Described passivation layer 1 and 2 includes Si3N4、
Al2O3、HfO2With one or more in HfSiO.
Depend on deposit organic insulator PTFE near drain edge at grid, in PTFE structure, then deposit ITO gate electrode, now
Dipole layer can be produced on PTFE surface: can produce positive polarisation charge at PTFE with ITO side, PTFE and AlGaN can produce side
Raw negative polarization electric charge, thus depletion action is created to the 2DEG concentration of lower section, result in the reduction of 2DEG concentration, add grid
The depletion length in electrode reverse-biased lower channel region, meanwhile, utilizes Al to contact produced reverse electrical double layer with LiF
Field effect so that the concentration of the 2DEG below LiF corresponding region rises, thus further improves hitting of depletion device
Wear voltage.
As in Figure 2-4, the making step of the present invention is as follows:
(1) organic washing is carried out to epitaxially grown AlGaN/GaN material, after cleaning by the deionized water of flowing, put into
HCl:H2The solution of O=1:1 carries out corroding 30-60s, finally cleans by the deionized water of flowing and dry up with high pure nitrogen;
(2) photoetching and dry etching are carried out to the AlGaN/GaN material cleaning up, be formed with region meas;
(3) carry out photoetching to the AlGaN/GaN material preparing table top, form source-drain area, put in electron beam evaporation platform
Deposit metal ohmic contact Ti/Al/Ni/Au=20/120/45/50nm, and peel off, finally carry out in nitrogen environment
The rapid thermal annealing of 850 DEG C of 35s, forms Ohmic contact;
(4) device preparing Ohmic contact is carried out photoetching, form organic dielectric PTFE depositing region, then put
Enter in oxygen plasma treatment room and mild oxidation treatments is carried out to AlGaN surface, be then placed in electron beam evaporation platform: reative cell is true
Sky is evacuated to 4.0 × 10-3Handkerchief, it is 0.1nm/s that slow making alive makes control PTFE evaporation rate, the thick PTFE of deposit 200-300nm
Film;
(5) device having deposited PTFE film is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping;
(6) photoetching is carried out to the device completing PTFE stripping, form grid and grid field plate region, put in electron beam evaporation platform
The thick ITO gate electrode of deposit 200nm;
(7) device having deposited gate electrode is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping, form grid
Field plate structure;
(8) carry out photoetching by completing device prepared by grid field plate, form the depositing region of dielectric LiF, be then placed in
Electron-beam reaction room vacuum is evacuated to 4.0 × 10-3Handkerchief, it is 0.5nm/s that slow making alive makes control LiF evaporation rate, deposits 100-
The thick LiF film of 200nm;
(9) device having deposited LiF film is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping;
(10) carry out photoetching to completing device prepared by LiF, form field plate region, source, put in electron beam evaporation platform and deposit
The thick Al metal of 200nm;
(11) device having deposited Al metal is put into immersion 30-60min in acetone soln, carry out ultrasonic stripping, formed
Leakage field plate structure;
(12) device completing is put into PECVD reative cell deposit SiN passivating film;Process conditions are: SiH4Flow be
40sccm, NH3Flow be 10sccm, chamber pressure is 1~2Pa, and radio-frequency power is 40W, and 200nm~300nm is thick in deposit
SiN passivating film;
(13) device is carried out again, photoetching development, form the etched area of SiN film, and put into ICP dry etching
In reative cell, process conditions are: upper electrode power is 200W, and lower electrode power is 20W, and chamber pressure is 1.5Pa, CF4's
Flow is 20sccm, and the flow of Ar gas is 10sccm, and etch period is 10min, the SiN film covering source electrode, drain electrodes
Etch away;
(14) device is carried out, photoetching development, and put into electron beam evaporation platform deposit Ti/Au=20/200nm
Thicken electrode, complete the preparation of integral device.
The above is only the preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For Yuan, under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should
It is considered as protection scope of the present invention.