CN107275386A - Gallium nitride semiconductor device and preparation method thereof - Google Patents

Gallium nitride semiconductor device and preparation method thereof Download PDF

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Publication number
CN107275386A
CN107275386A CN201710488981.2A CN201710488981A CN107275386A CN 107275386 A CN107275386 A CN 107275386A CN 201710488981 A CN201710488981 A CN 201710488981A CN 107275386 A CN107275386 A CN 107275386A
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gallium nitride
layer
compound medium
contact hole
semiconductor device
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刘美华
林信南
刘岩军
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Shenzhen Crystal Phase Technology Co Ltd
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Shenzhen Crystal Phase Technology Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor 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
    • H01L29/02Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0611Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor 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
    • H01L29/02Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0638Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for preventing surface leakage due to surface inversion layer, e.g. with channel stopper
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00Semiconductor 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
    • H01L29/40Electrodes ; Multistep manufacturing processes therefor
    • H01L29/402Field plates
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    • H01L29/00Semiconductor 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
    • H01L29/40Electrodes ; Multistep manufacturing processes therefor
    • H01L29/43Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/47Schottky barrier electrodes
    • H01L29/475Schottky barrier electrodes on AIII-BV compounds
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    • H01L29/66Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007Multistep manufacturing processes
    • H01L29/66075Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
    • H01L29/66227Multistep 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
    • H01L29/66409Unipolar field-effect transistors
    • H01L29/66446Unipolar 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]
    • H01L29/66462Unipolar 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
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
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    • H01L29/00Semiconductor 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
    • H01L29/66Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76Unipolar devices, e.g. field effect transistors
    • H01L29/772Field effect transistors
    • H01L29/778Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface
    • H01L29/7782Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with confinement of carriers by at least two heterojunctions, e.g. DHHEMT, quantum well HEMT, DHMODFET
    • H01L29/7783Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with confinement of carriers by at least two heterojunctions, e.g. DHHEMT, quantum well HEMT, DHMODFET using III-V semiconductor material

Abstract

Include the present invention relates to technical field of semiconductor there is provided a kind of gallium nitride semiconductor device:Epitaxial layer of gallium nitride;And, it is arranged at the compound medium layer on the epitaxial layer of gallium nitride;Source electrode, drain and gate on the compound medium layer are arranged at, the source electrode, drain and gate extend through the compound medium layer and be connected with the epitaxial layer of gallium nitride;The insulating barrier on the source electrode, drain and gate and the compound medium layer is arranged at, the material of the insulating barrier is silica.The gallium nitride semiconductor device of the present invention is less prone to the phenomenon for puncturing aluminum gallium nitride; and then the problem of avoid the electric leakage for gallium nitride semiconductor device occur and puncture; gallium nitride semiconductor device is effectively protected, the reliability of gallium nitride semiconductor device is enhanced.

Description

Gallium nitride semiconductor device and preparation method thereof
Technical field
The present invention relates to field of semiconductor technology, more particularly to a kind of gallium nitride semiconductor device and preparation method thereof.
Background technology
Gallium nitride have big energy gap, high electron saturation velocities, high breakdown electric field, higher heat-conductivity, it is corrosion-resistant and The advantages of radiation resistance, so as to make semi-conducting material using gallium nitride, and obtain gallium nitride semiconductor device.
In the prior art, the preparation method of gallium nitride semiconductor device is:Nitrogen is formed on the surface of epitaxial layer of gallium nitride SiClx layer, etches on silicon nitride layer and is deposited in source contact openings and drain contact hole, source contact openings and drain contact hole Metal, so as to form source electrode and drain electrode;The aluminum gallium nitride in etch nitride silicon layer and epitaxial layer of gallium nitride, forms one again Groove, in a groove deposited metal layer, so as to form grid;Then deposited silicon dioxide layer and field plate metal layer so that shape Into gallium nitride semiconductor device.
But in the prior art, because electric field density is larger, thus can cause gallium nitride semiconductor device electric leakage and The problem of puncturing, and then gallium nitride semiconductor device can be damaged, reduce the reliability of gallium nitride semiconductor device.Further, Gallium nitride power device is after Hi-pot test repeatedly, and the breakdown voltage of device can drift about, this nonsteady behavior and electric charge Trap is relevant, and the reliability to device can cause harm, it should be suppressed.
The content of the invention
To solve the above problems, the present invention provides a kind of gallium nitride semiconductor device, including:Epitaxial layer of gallium nitride;And,
The compound medium layer on the epitaxial layer of gallium nitride is arranged at, the material of the compound medium layer is silicon nitride and waited Gas ions strengthen tetraethoxysilance;
Source electrode, drain and gate on the compound medium layer are arranged at, the source electrode, drain and gate extend through institute Compound medium layer is stated to be connected with the epitaxial layer of gallium nitride;Wherein, the grid in the gate contact hole is in inverted trapezoidal;
It is arranged at the insulating barrier on the source electrode, drain and gate and the compound medium layer, the material of the insulating barrier Matter is silica;
Also include the field plate metal layer being arranged on the insulating barrier, the field plate metal layer runs through the insulating barrier and institute State source electrode connection.
Also include several floating field plates being arranged on the compound medium layer, the floating field plate is through described compound Dielectric layer is connected with the epitaxial layer of gallium nitride.
There is provided a nitridation for the preparation method of the invention for also providing this gallium nitride semiconductor device with inverted trapezoidal grid Gallium epitaxial layer, wherein, the epitaxial layer of gallium nitride includes layer-of-substrate silicon, gallium nitride layer and the aluminium nitride from bottom to top set gradually Gallium layer;
In the epitaxy of gallium nitride layer surface deposited silicon nitride and plasma enhancing tetraethoxysilance, complex media is formed Layer;
The acquisition of drain contact hole:The compound medium layer is etched to form drain contact hole, the drain contact hole is passed through Wear the compound medium layer and reach the aluminum gallium nitride;In the source contact openings and the compound medium layer table On face, the first metal is deposited, to be drained;
Source contact openings, the acquisition in floating field plate hole:The compound medium layer is etched to form source contact openings, floating Plate hole, the source contact openings, floating field plate hole reach the aluminum gallium nitride through the compound medium layer;In the source electrode In contact hole, floating field plate hole and on the surface of the compound medium layer, the first metal is deposited, to obtain source electrode, floating Plate;
Photoetching and etching are carried out to first metal, Ohm contact electrode window is formed;Now obtain first assembly;
The high temperature anneal is carried out to the first assembly, connect with to be contained in the source contact openings and the drain electrode First metal in contact hole forms alloy and reacted with the aluminum gallium nitride;
The acquisition in gate contact hole:By the Ohm contact electrode window, to the compound medium layer and the nitridation Gallium aluminium layer carries out dry etching, forms the gate contact hole of inverted trapezoidal, wherein, the bottom in the gate contact hole and the nitridation There is pre-determined distance between the bottom of gallium aluminium layer;
The second metalwork is deposited in the outward flange in the gate contact hole and the gate contact hole, to obtain grid, this When obtain the second component;
A layer insulating is deposited on the surface of second component;
Dry etching is carried out on the insulating barrier, to form perforate, the perforate is corresponding with the source contact openings;
Field plate metal layer is deposited in the perforate and the insulating barrier, the projection of the field plate metal layer is at least
Cover the perforate and from the source contact openings to the region between the gate contact hole.
Beneficial effect:
The present invention applies a variety of novel materials by the compound medium layer on the surface of epitaxial layer of gallium nitride, also by heavy The first metal of product is carrying out the high temperature anneal, to be carried out by the first metal after the etching contacted with each other and aluminum gallium nitride Alloy is formed after reaction, to reduce the contact resistance of the first metal and aluminum gallium nitride after etching;
The invention enables electric leakage, also, aluminium gallium nitride alloy are difficult on the contact surface in the middle of compound medium layer and aluminum gallium nitride The field strength peak value of layer is higher, is less prone to the phenomenon for puncturing aluminum gallium nitride, and then avoids and gallium nitride semiconductor device occur Electric leakage and the problem of puncture, be effectively protected gallium nitride semiconductor device, enhance gallium nitride semiconductor device can By property.
The present embodiment combination floating field plate, extends the depletion region of power device, reduces the electric-field strength of main schottky junction Degree, so that it is pressure-resistant to improve device.So as to be effectively protected gallium nitride semiconductor device, gallium nitride semiconductor device is enhanced Reliability.
Brief description of the drawings
Fig. 1 a are the structural representation of the gallium nitride semiconductor device of the embodiment of the present invention.
Fig. 1 b are the first metal structure schematic diagram of the gallium nitride semiconductor device of the embodiment of the present invention.
Fig. 1 c are the grid structure schematic diagram of the gallium nitride semiconductor device of the embodiment of the present invention.
Fig. 1 d are another structural representation of grid of the gallium nitride semiconductor device of the embodiment of the present invention.
Fig. 1 e are the another structural representation of grid of the gallium nitride semiconductor device of the embodiment of the present invention.
Fig. 1 f are the preparation flow schematic diagram of the gallium nitride semiconductor device of the embodiment of the present invention.
Fig. 2 a are the structural representation of the gallium nitride semiconductor device of another embodiment of the present invention.
Fig. 2 b are the preparation flow schematic diagram of the gallium nitride semiconductor device of another embodiment of the present invention.
Fig. 3 a are the structural representation of the gallium nitride semiconductor device of further embodiment of this invention.
Fig. 3 b are the grid structure schematic diagram of the gallium nitride semiconductor device of further embodiment of this invention.
Fig. 3 c are the grid structure schematic diagram of the gallium nitride semiconductor device of further embodiment of this invention.
Fig. 3 d are the grid structure schematic diagram of the gallium nitride semiconductor device of further embodiment of this invention.
Fig. 3 e are the preparation flow schematic diagram of the gallium nitride semiconductor device of further embodiment of this invention.
Embodiment
To make the purpose, technical scheme and advantage of the embodiment of the present invention clearer, below in conjunction with the embodiment of the present invention In accompanying drawing, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is A part of embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art The every other embodiment obtained under the premise of creative work is not made, belongs to the scope of protection of the invention.
As shown in Figure 1a, the embodiment of the present invention provides a kind of gallium nitride semiconductor device, and it includes from bottom to up:Gallium nitride Epitaxial layer 110, compound medium layer 120, source electrode 131 and drain electrode 132, grid 133, insulating barrier 140, field plate metal layer 150.
Wherein, epitaxial layer of gallium nitride 110 is by silicon (Si) substrate 112, gallium nitride (GaN) layer 113 and aluminium gallium nitride alloy (AlGaN) Layer 114 is constituted, wherein, silicon substrate 112, gallium nitride layer 113 and aluminum gallium nitride 114 are from bottom to top set gradually.
Compound medium layer 120 is arranged on the epitaxial layer of gallium nitride 110;The compound medium layer 120 of the present embodiment Material may be, for example, silicon nitride and plasma enhancing tetraethoxysilance (PETEOS).The silicon nitride and the positive silicon of plasma enhancing Sour second fat belongs to a kind of high-k (high-k) medium.
Source electrode 131, drain electrode 132 and grid 133 are arranged on the compound medium layer 120.Specifically, source electrode 131, drain electrode 132 and the outer image " nail " of grid 133 as a part be inserted into the compound medium layer 120, the source electrode 131, drain electrode 132 and grid 133 extend through the compound medium layer 120 and be connected with the epitaxial layer of gallium nitride 110;And a part is protruded from The top of compound medium layer 120.The source electrode 131 and/or drain electrode 132 are made up of the first metal;First metal (referring to Fig. 1 b) include successively from bottom to up:First titanium coating 134, aluminum metal layer 135, the second titanium coating 136 and titanium nitride layer 137.Wherein, the thickness of first titanium coating 134 is 200 angstroms, and the thickness of the aluminum metal layer 135 is 1200 angstroms, described The thickness of second titanium coating 136 is 200 angstroms, and the thickness of the titanium nitride layer 137 is 200 angstroms.Using the first metal material shape Into source electrode 131, drain electrode 132, can in higher device temperature annealing process with the aluminum gallium nitride in the epitaxial layer of gallium nitride 110 Layer 114 reacts, and generates alloy, so that source electrode 131,132 contacts with the contact surface of aluminum gallium nitride of drain electrode are well, Source electrode 131, drain electrode 132 and the contact resistance of aluminum gallium nitride can be effectively reduced;Avoid the occurrence of gallium nitride semiconductor device Electric leakage and soft breakdown the problem of.
Preferably, the grid 133 is down extended into the aluminum gallium nitride 114, the bottom of grid 133 to institute State the bottom of aluminum gallium nitride 114 is preferably the half of the whole aluminum gallium nitride 114 apart from H.Grid 133 is by the second metal Composition, second metal is Ni, Au alloy.
Preferably, the grid 133 has special configuration.With reference to shown in Fig. 1 c, Fig. 1 d and Fig. 1 e, the grid of the present embodiment Pole 133 can also have various deformation.Seen according to the observation sequence of gallium nitride semiconductor device from bottom to up, the transverse direction of grid 133 Width gradually increases, and one " upside-down trapezoid " is presented.Further, the part of " upside-down trapezoid " of grid 133 can be from grid Just the shape (as illustrated in figure 1 c) uniformly broadened from bottom to up is presented in contact hole 123, has being higher by compound medium layer 120 Then increase width causes gate contact hole 123 is completely covered protuberance 133a suddenly;Or can be in aluminum gallium nitride 114 The part of grid 133 still keeps rectangular configuration, aluminum gallium nitride 114 with the part at the top of up to gate contact hole 114 then under It is supreme uniformly to broaden (as shown in Figure 1 d);It can also be that composition can just be presented uniform from bottom to up from gate contact hole 123 The shape (as shown in fig. le) broadened, being higher by the protuberance 133a of compound medium layer 120, then width keeps constant, only increases thick Degree.
Insulating barrier 140 is arranged at drain electrode 132, grid 133 and the top of a part of source electrode 131, and exposes the whole come On compound medium layer 120, the material of the insulating barrier 140 is silica.Wherein, insulating barrier 140 is on the surface of whole device Uniform deposition is carried out, the thickness precipitated everywhere is identical.Due to source electrode 131, drain electrode 132, the presence of grid 133, so that in source electrode Insulating barrier 140 between 131 and grid 133, the insulating barrier 140 between grid 133 and drain electrode 132 be to lower recess, can It is allowed to smooth using technique is polished.
It can also for example include field plate metal layer 150, it is arranged on the insulating barrier 140.The field plate metal layer 150 It is connected through the insulating barrier 140 with the source electrode 131.Preferably, the material of the field plate metal layer 150 is aluminium copper silicon gold Belong to layer.
The section of grid 133 in above-mentioned gallium nitride semiconductor device is different from " T-shaped " structure of existing grid, but is in Existing " trapezoidal " construction of inversion wide at the top and narrow at the bottom, the high electric field at suppressor grid edge is effectively guaranteed gallium nitride high tension apparatus steady Fixed blocking characteristics, make device after high pressure repeatedly, still can keep good reliability.
The present invention also provides the preparation method of above-mentioned gallium nitride semiconductor device.As shown in Figure 1 f, specific steps include:
Step 101:Gallium nitride layer 113 and aluminum gallium nitride 114 are sequentially depositing on silicon substrate 112, is formed outside gallium nitride Prolong layer 110.Gallium nitride is third generation semiconductor material with wide forbidden band, with big energy gap, high electron saturation velocities, high breakdown potential Characteristics such as field, higher heat-conductivity, corrosion-resistant and radiation resistance and in high pressure, high frequency, high temperature, high-power and Flouride-resistani acid phesphatase ring There is stronger advantage, so as to be the optimal material for studying shortwave opto-electronic device and high voltagehigh frequency rate high power device under the conditions of border Material;Wherein, big energy gap is 3.4 electron-volts, and high electron saturation velocities are 2e7 centimeters per seconds, and high breakdown electric field is 1e10 ~-3e10 volts per cm.
Then chemical gaseous phase electrodeposition method can be strengthened with using plasma, is sunk on the surface of epitaxial layer of gallium nitride 110 One layer of silicon nitride of product and plasma enhancing tetraethoxysilance (PETEOS), form compound medium layer 120.Wherein, silicon nitride and The thickness of plasma enhancing tetraethoxysilance for example can be 2000 angstroms.
Step 102, dry etching is carried out to the compound medium layer 120, forms the He of source contact openings 21 being oppositely arranged Drain contact hole 122.
In order that the source contact openings 121, the few impurity of the cleaning of drain contact hole 122 are obtained, in addition to removal step.Specifically , after dry etching is carried out to compound medium layer 120, it can first use " DHF (dilute hydrofluoric acid)+chemical SC- 1+ chemicals SC-2 " method, for example, can then be used first using the hydrofluoric acid solution processing apparatus after dilution At the alkaline mixed solution processing apparatus of hydrogen oxide and aqua ammonia, then acidic mixed solution using hydrogen peroxide and hydrogen chloride Device is managed, and then the impurity thing on the surface of whole device can be removed.
Step 103, in the present embodiment, in source contact openings 121 and drain contact hole 122 and compound medium layer The first metal 121 is deposited on 120 surface.
Specifically, magnetron sputtering membrane process can be used, in source contact openings and drain contact hole and compound is situated between On the surface of matter layer, the first titanium coating, aluminum metal layer, the second titanium coating and titanium nitride layer are sequentially depositing, to form first Metal;Wherein, the thickness of the first titanium coating may be, for example, 200 angstroms, and the thickness of aluminum metal layer may be, for example, 1200 angstroms, the second titanium The thickness of metal level may be, for example, 200 angstroms, and the thickness of titanium nitride layer may be, for example, 200 angstroms.
Photoetching and etching are carried out to the first metal, Ohm contact electrode window 119 is formed.
Carry out photoetching and etching to the first metal, the program of wherein photoetching includes gluing, exposed and developed, so as to Form an Ohm contact electrode window 119;Through Ohm contact electrode window 119, it can be seen that the portion of compound medium layer 120 Divide surface.In this way, the first metal on source contact openings 121 constitutes on the source electrode 131 of device, drain contact hole 122 One metal constitutes the drain electrode 132 of device.Now, in order to be able to clear expression process of the present invention, the device that name is now obtained is First assembly.
Step 104, the high temperature anneal is carried out to whole first assembly, to pass through the first gold medal after the etching contacted with each other Category forms alloy after being reacted with aluminum gallium nitride 114.
In the present embodiment, specifically, being passed through nitrogen gas in reacting furnace, to whole in the environment of 840~850 DEG C First assembly carries out the high temperature anneal of 30 seconds, so that the first metal after etching can turn into alloy, and contact with each other The first metal after etching can also also form alloy after being reacted with aluminum gallium nitride 114 on its contact surface, so that The contact resistance between the first metal and aluminum gallium nitride 114 can be reduced.That is, reduction source electrode 131, drain electrode 132 and aluminium nitride Contact resistance between gallium layer 14.
Step 105, by Ohm contact electrode window 119, compound medium layer 120 and aluminum gallium nitride 114 are done Method is etched, and forms gate contact hole 123, wherein, the bottom in gate contact hole 123 has pre- with the bottom of aluminum gallium nitride 114 If distance.
In the present embodiment, using the method for dry etching, by Ohm contact electrode window 119, to compound medium layer 120 and partial aluminum gallium nitride 114, dry etching is carried out, and then form on the first device a gate contact hole 123.Wherein, gate contact hole 123 is complete breaks through compound medium layer 120, and through the aluminum gallium nitride 114 of part, makes The bottom of bottom and the aluminum gallium nitride 114 in gate contact hole 123 be preferably apart from H aluminum gallium nitride 114 half.Enter One step, cause gate contact hole 123 is presented one wide at the top and narrow at the bottom, inverted trapezoidal during etching.In the present embodiment, formed After one gate contact hole 123, there can be the impurity things such as impurity, particle and ion in gate contact hole 123, so as to So that using hydrochloric acid solution cleaning gate contact hole 120, the impurity thing in gate contact hole 120 to be got rid of.
The present embodiment is by after dry etching is carried out to compound medium layer 120, using DHF+SC1+SC2 method Impurity thing in removal devices;And formed after gate contact hole 123, will be miscellaneous in gate contact hole 123 using hydrochloric acid solution Matter thing is got rid of.So as to the cleaning being effectively guaranteed in the surface and gate contact hole 123 of compound medium layer, and then It ensure that the performance of gallium nitride semiconductor device.
Step 106, in the present embodiment, specifically, using magnetron sputtering membrane process, in gate contact hole 123 and grid The outward flange deposition Ni/Au of pole contact hole 123 is as the second metal, and metal thickness is 0.01~0.04 μm/0.08~0.4 μm; So as to constitute grid 133.Now, in order to become apparent from expressing present invention, it is the second component to name the device now obtained.
Step 107, a layer insulating 140 is deposited on the surface of whole second component.
In the present embodiment, specifically, in the surface deposition layer of silicon dioxide (SiO of whole second component2), thickness can For example, 5000 angstroms, form silicon dioxide layer and be used as a layer insulating 140.Wherein, silica enters on the surface of whole device Row uniform deposition, thickness is identical everywhere, due to source electrode 131, drain electrode 132 and the presence of grid 133, so that in source electrode 131 and grid Insulating barrier 140 between pole 133, the insulating barrier 140 between grid 133 and drain electrode 132 are to lower recess, using polishing Technique is allowed to smooth.
Step 108, after to the progress dry etching of insulating barrier 140 of the top of source contact openings 131, perforate 141 is formed.Institute Stating grid 33 has the protuberance 133a protruded from outside the gate contact hole 123, and the width of the perforate 141 is less than described convex Go out portion 133a width.
Step 109, the insulation of the top of gate contact hole 123 is extended in perforate 141 and from source contact openings 131 Field plate metal 150 is deposited on layer 140, field plate metal layer 150 is formed.
In the present embodiment, specifically, magnetron sputtering membrane process can be used, connect in perforate 141 and from source electrode Compound medium layer of outer peripheral first metal of contact hole 121 above outer peripheral first metal in gate contact hole 123 Field plate metal is deposited on 120, thickness may be, for example, 10000 angstroms, so as to form field plate metal layer 150.The thickness of field plate metal layer 150 Degree be it is uniform, field plate metal layer 150 at the position of perforate 141 and source contact openings 121 and gate contact hole 123 it Between position at be, to lower recess, to pass through polishing technique and can be allowed to smooth in subsequent step.
The present embodiment replaces existing silicon oxide layer by depositing compound medium layer on the surface of epitaxy of gallium nitride substrate It is used as compound medium layer;The high temperature anneal technique is recycled, makes the aluminum gallium nitride in source electrode, drain electrode and epitaxial layer of gallium nitride Alloy is formed after being reacted, so that source electrode, drain electrode contact with the contact surface of aluminum gallium nitride are well, can be effective Reduction source electrode, the contact resistance of drain electrode and aluminum gallium nitride;Avoid the occurrence of the electric leakage of gallium nitride semiconductor device and soft hit The problem of wearing.Further, the field plate metal layer of formation, makes to be difficult on the contact surface in the middle of compound medium layer and aluminum gallium nitride Electric leakage, also, the field strength peak value of aluminum gallium nitride is higher, is less prone to the phenomenon for puncturing aluminum gallium nitride, and then avoid out The problem of showing the electric leakage of gallium nitride semiconductor device and puncture, gallium nitride semiconductor device is effectively protected, nitrogen is enhanced Change the reliability of gallium semiconductor devices.The gallium nitride semiconductor device that the present embodiment is obtained can be applied to power electronic element, filter In the technical fields such as ripple device, radio communication element, have a good application prospect.
As shown in Figure 2 a, the embodiment of the present invention provides a kind of gallium nitride semiconductor device, and it includes from bottom to up:Gallium nitride Epitaxial layer 610, compound medium layer 620, source electrode 631 and drain electrode 632, grid 633, insulating barrier 640, field plate metal layer 650.
Wherein, epitaxial layer of gallium nitride 610 is by silicon (Si) substrate 612, gallium nitride (GaN) layer 613 and aluminium gallium nitride alloy (AlGaN) Layer 614 is constituted, wherein, silicon substrate 612, gallium nitride layer 613 and aluminum gallium nitride 614 are from bottom to top set gradually.
Compound medium layer 620 is arranged on the epitaxial layer of gallium nitride 610;The compound medium layer 620 of the present embodiment Material may be, for example, silicon nitride and plasma enhancing tetraethoxysilance (PETEOS).The silicon nitride and the positive silicon of plasma enhancing Sour second fat belongs to a kind of high-k (high-k) medium.
Source electrode 631, drain electrode 632 and grid 633 are arranged on the compound medium layer 620.Specifically, source electrode 631, drain electrode 632 and the outer image " nail " of grid 633 as a part be inserted into the compound medium layer 620, the source electrode 631, drain electrode 632 The compound medium layer 620 is extended through with grid 633 to be connected with the epitaxial layer of gallium nitride 610;And a part protrudes from institute State the top of compound medium layer 620.The source electrode 631 and/or drain electrode 632 by the first metal constitute and above-described embodiment shown in.Adopt With the first metal material formation source electrode 631, drain electrode 632, can in higher device temperature annealing process with the epitaxy of gallium nitride Aluminum gallium nitride layer 614 in layer 610 reacts, and generates alloy, so that source electrode 631, drain electrode 632 and aluminum gallium nitride Contact surface contact it is good, source electrode 631, drain electrode 632 and the contact resistance of aluminum gallium nitride can be effectively reduced;Avoid out The problem of electric leakage and soft breakdown of existing gallium nitride semiconductor device.
Preferably, the grid 633 is down extended into the aluminum gallium nitride 614 and gone directly to the aluminium gallium nitride alloy 614 bottom of layer, obtain one " penetrating type grid ".Grid 633 is made up of the second metal, and second metal is Ni, Au alloy.
Insulating barrier 640 is arranged at drain electrode 632, grid 633 and the top of a part of source electrode 631, and exposes the whole come On compound medium layer 620, the material of the insulating barrier 640 is silica.Wherein, insulating barrier 640 is on the surface of whole device Uniform deposition is carried out, the thickness precipitated everywhere is identical.Due to source electrode 631, drain electrode 632, the presence of grid 633, so that in source electrode Insulating barrier 640 between 631 and grid 633, the insulating barrier 640 between grid 633 and drain electrode 632 be to lower recess, can It is allowed to smooth using technique is polished.
It can also for example include field plate metal layer 650, it is arranged on the insulating barrier 640.The field plate metal layer 650 It is connected through the insulating barrier 640 with the source electrode 631.Preferably, the material of the field plate metal layer 650 is aluminium copper silicon metal Layer.
Grid 633 in above-mentioned gallium nitride semiconductor device penetrates whole aluminum gallium nitride and reaches gallium nitride layer, can suppress The high electric field of gate edge, is effectively guaranteed the stable blocking characteristics of gallium nitride high tension apparatus, makes device by repeatedly high After pressure, still good reliability can be kept.
The present invention also provides the preparation method of above-mentioned gallium nitride semiconductor device.As shown in Figure 2 b, specific steps include:
Step 601:Gallium nitride layer 613 and aluminum gallium nitride 614 are sequentially depositing on silicon substrate 612, is formed outside gallium nitride Prolong layer 610.Gallium nitride is third generation semiconductor material with wide forbidden band, with big energy gap, high electron saturation velocities, high breakdown potential Characteristics such as field, higher heat-conductivity, corrosion-resistant and radiation resistance and in high pressure, high frequency, high temperature, high-power and Flouride-resistani acid phesphatase ring There is stronger advantage, so as to be the optimal material for studying shortwave opto-electronic device and high voltagehigh frequency rate high power device under the conditions of border Material;Wherein, big energy gap is 3.4 electron-volts, and high electron saturation velocities are 2e7 centimeters per seconds, and high breakdown electric field is 1e10 ~-3e10 volts per cm.
Then chemical gaseous phase electrodeposition method can be strengthened with using plasma, is sunk on the surface of epitaxial layer of gallium nitride 610 One layer of silicon nitride of product and plasma enhancing tetraethoxysilance (PETEOS), form compound medium layer 620.Wherein, silicon nitride and The thickness of plasma enhancing tetraethoxysilance for example can be 2000 angstroms.
Step 602, dry etching is carried out to the compound medium layer 620, forms the He of source contact openings 21 being oppositely arranged Drain contact hole 622.
In order that the source contact openings 621, the few impurity of the cleaning of drain contact hole 622 are obtained, in addition to removal step.Specifically , after dry etching is carried out to compound medium layer 620, it can first use " DHF (dilute hydrofluoric acid)+chemical SC- 1+ chemicals SC-2 " method, for example, can then be used first using the hydrofluoric acid solution processing apparatus after dilution At the alkaline mixed solution processing apparatus of hydrogen oxide and aqua ammonia, then acidic mixed solution using hydrogen peroxide and hydrogen chloride Device is managed, and then the impurity thing on the surface of whole device can be removed.
Step 603, in the present embodiment, in source contact openings 621 and drain contact hole 622 and compound medium layer The first metal 621 is deposited on 620 surface.
Specifically, magnetron sputtering membrane process can be used, in source contact openings and drain contact hole and compound is situated between On the surface of matter layer, the first titanium coating, aluminum metal layer, the second titanium coating and titanium nitride layer are sequentially depositing, to form first Metal;Wherein, the thickness of the first titanium coating may be, for example, 200 angstroms, and the thickness of aluminum metal layer may be, for example, 6200 angstroms, the second titanium The thickness of metal level may be, for example, 200 angstroms, and the thickness of titanium nitride layer may be, for example, 200 angstroms.
Photoetching and etching are carried out to the first metal, Ohm contact electrode window 619 is formed.
Carry out photoetching and etching to the first metal, the program of wherein photoetching includes gluing, exposed and developed, so as to Form an Ohm contact electrode window 619;Through Ohm contact electrode window 619, it can be seen that the portion of compound medium layer 620 Divide surface.In this way, the first metal on source contact openings 621 constitutes on the source electrode 631 of device, drain contact hole 622 One metal constitutes the drain electrode 632 of device.Now, in order to be able to clear expression process of the present invention, the device that name is now obtained is First assembly.
Step 604, the high temperature anneal is carried out to whole first assembly, to pass through the first gold medal after the etching contacted with each other Category forms alloy after being reacted with aluminum gallium nitride 614.
In the present embodiment, specifically, being passed through nitrogen gas in reacting furnace, to whole in the environment of 840~850 DEG C First assembly carries out the high temperature anneal of 30 seconds, so that the first metal after etching can turn into alloy, and contact with each other The first metal after etching can also also form alloy after being reacted with aluminum gallium nitride 614 on its contact surface, so that The contact resistance between the first metal and aluminum gallium nitride 614 can be reduced.That is, reduction source electrode 631, drain electrode 632 and aluminium nitride Contact resistance between gallium layer 14.
Step 605, by Ohm contact electrode window 619, compound medium layer 620 and aluminum gallium nitride 614 are done Method is etched, and forms gate contact hole 623, wherein, the bottom in gate contact hole 623 has pre- with the bottom of aluminum gallium nitride 614 If distance.
In the present embodiment, using the method for dry etching, by Ohm contact electrode window 619, to compound medium layer 620 and partial aluminum gallium nitride 614, dry etching is carried out, and then form on the first device a gate contact hole 623.Wherein, gate contact hole 623 is complete breaks through compound medium layer 620, and through the aluminum gallium nitride 614 of part, makes The bottom of bottom and the aluminum gallium nitride 614 in gate contact hole 623 be preferably apart from H aluminum gallium nitride 614 half.
In the present embodiment, formed after a gate contact hole 623, can there is impurity, particle in gate contact hole 623 And the impurity thing such as ion, will be miscellaneous in gate contact hole 620 so as to using hydrochloric acid solution cleaning gate contact hole 620 Matter thing is got rid of.
The present embodiment is by after dry etching is carried out to compound medium layer 620, using DHF+SC1+SC2 method Impurity thing in removal devices;And formed after gate contact hole 623, will be miscellaneous in gate contact hole 623 using hydrochloric acid solution Matter thing is got rid of.So as to the cleaning being effectively guaranteed in the surface and gate contact hole 623 of compound medium layer, and then It ensure that the performance of gallium nitride semiconductor device.
Step 606, in the present embodiment, specifically, using magnetron sputtering membrane process, in gate contact hole 623 and grid The outward flange deposition Ni/Au of pole contact hole 623 is as the second metal, and metal thickness is 0.01~0.04 μm/0.08~0.4 μm; So as to constitute grid 633.Now, in order to become apparent from expressing present invention, it is the second component to name the device now obtained.
Step 607, a layer insulating 640 is deposited on the surface of whole second component.
In the present embodiment, specifically, in the surface deposition layer of silicon dioxide (SiO2) of whole second component, thickness can For example, 5000 angstroms, form silicon dioxide layer and be used as a layer insulating 640.Wherein, silica enters on the surface of whole device Row uniform deposition, thickness is identical everywhere, due to source electrode 631, drain electrode 632 and the presence of grid 633, so that in source electrode 631 and grid Insulating barrier 640 between pole 633, the insulating barrier 640 between grid 633 and drain electrode 632 are to lower recess, using polishing Technique is allowed to smooth.
Step 608, after to the progress dry etching of insulating barrier 640 of the top of source contact openings 631, perforate 641 is formed.Institute Stating grid 33 has the protuberance 633a protruded from outside the gate contact hole 623, and the width of the perforate 641 is less than described convex Go out portion 633a width.
Step 609, the insulation of the top of gate contact hole 623 is extended in perforate 641 and from source contact openings 631 Field plate metal 650 is deposited on layer 640, field plate metal layer 650 is formed.
In the present embodiment, specifically, magnetron sputtering membrane process can be used, connect in perforate 641 and from source electrode Compound medium layer of outer peripheral first metal of contact hole 621 above outer peripheral first metal in gate contact hole 623 Field plate metal is deposited on 620, thickness may be, for example, 10000 angstroms, so as to form field plate metal layer 650.The thickness of field plate metal layer 650 Degree be it is uniform, field plate metal layer 650 at the position of perforate 641 and source contact openings 621 and gate contact hole 623 it Between position at be, to lower recess, to pass through polishing technique and can be allowed to smooth in subsequent step.
The present embodiment replaces existing silicon oxide layer by depositing compound medium layer on the surface of epitaxy of gallium nitride substrate It is used as compound medium layer;The high temperature anneal technique is recycled, makes the aluminum gallium nitride in source electrode, drain electrode and epitaxial layer of gallium nitride Alloy is formed after being reacted, so that source electrode, drain electrode contact with the contact surface of aluminum gallium nitride are well, can be effective Reduction source electrode, the contact resistance of drain electrode and aluminum gallium nitride;Avoid the occurrence of the electric leakage of gallium nitride semiconductor device and soft hit The problem of wearing.Further, the structure of optimization grid causes grid to penetrate whole aluminum gallium nitride, compatible with CMOS technology line, Electric Field Distribution is adjusted, improves the pressure-resistant of device with this.The gallium nitride semiconductor device that the present embodiment is obtained can be applied to electric power In the technical fields such as electronic component, wave filter, radio communication element, have a good application prospect.
As shown in Figure 3 a, the embodiment of the present invention provides a kind of gallium nitride semiconductor device, and it includes from bottom to up:Gallium nitride Epitaxial layer 710, compound medium layer 720, source electrode 731 and drain electrode 732, grid 733, floating plate 729, insulating barrier 740, field plate gold Belong to layer 750.
Wherein, epitaxial layer of gallium nitride 710 is by silicon (Si) substrate 712, gallium nitride (GaN) layer 713 and aluminium gallium nitride alloy (AlGaN) Layer 714 is constituted, wherein, silicon substrate 712, gallium nitride layer 713 and aluminum gallium nitride 714 are from bottom to top set gradually.
Compound medium layer 720 is arranged on the epitaxial layer of gallium nitride 710;The compound medium layer 720 of the present embodiment Material may be, for example, silicon nitride and plasma enhancing tetraethoxysilance (PETEOS).The silicon nitride and the positive silicon of plasma enhancing Sour second fat belongs to a kind of high-k (high-k) medium.
Source electrode 731, drain electrode 732 and grid 733 are arranged on the compound medium layer 720.Specifically, source electrode 731, drain electrode 732 and the outer image " nail " of grid 733 as a part be inserted into the compound medium layer 720, the source electrode 731, drain electrode 732 and grid 733 extend through the compound medium layer 720 and be connected with the epitaxial layer of gallium nitride 710;And a part is protruded from The top of compound medium layer 720.The source electrode 731 and/or drain electrode 732 by the first metal constitute and above-described embodiment shown in. Using the first metal material formation source electrode 731, drain electrode 732, can in higher device temperature annealing process with outside the gallium nitride The aluminum gallium nitride layer 714 prolonged in layer 710 reacts, and generates alloy, so that source electrode 731, drain electrode 732 and aluminium gallium nitride alloy The contact of the contact surface of layer is good, can effectively reduce source electrode 731, drain electrode 732 and the contact resistance of aluminum gallium nitride;Avoid The problem of there is the electric leakage and soft breakdown of gallium nitride semiconductor device.
Preferably, the grid 733 is down extended into the aluminum gallium nitride 714, the bottom of grid 733 to institute State the bottom of aluminum gallium nitride 714 is preferably the half of the whole aluminum gallium nitride 714 apart from H.Grid 733 is by the second metal Composition, second metal is Ni, Au alloy.
Preferably, the grid 733 has special configuration.With reference to shown in Fig. 3, Fig. 3 c and Fig. 3 d, the grid of the present embodiment Pole 733 can also have various deformation.Seen according to the observation sequence of gallium nitride semiconductor device from bottom to up, the transverse direction of grid 733 Width gradually increases, and one " upside-down trapezoid " is presented.Further, the part of " upside-down trapezoid " of grid 733 can be from grid Just the shape (as shown in Figure 3 b) uniformly broadened from bottom to up is presented in contact hole 723, has being higher by compound medium layer 720 Then increase width causes gate contact hole 723 is completely covered protuberance 733a suddenly;Or can be in aluminum gallium nitride 714 The part of grid 733 still keeps rectangular configuration, aluminum gallium nitride 714 with the part at the top of up to gate contact hole 714 then under It is supreme uniformly to broaden (as shown in Figure 3 c);It can also be that composition can just be presented uniform from bottom to up from gate contact hole 723 The shape (as shown in Figure 3 d) broadened, being higher by the protuberance 733a of compound medium layer 720, then width keeps constant, only increases thick Degree.
Further, including several floating field plates 729 for being arranged on the compound medium layer 720, the floating Plate 729 is connected through the compound medium layer 720 with the epitaxial layer of gallium nitride 710, and the floating field plate 729 is independently arranged Between the source electrode 731, drain electrode 732 and it is presented ring-type.
The height of each floating field plate 729 is preferably 0.25~6 micron.
Insulating barrier 740 is arranged at drain electrode 732, grid 733 and the top of a part of source electrode 731, and exposes the whole come On compound medium layer 720, the material of the insulating barrier 740 is silica.Wherein, insulating barrier 740 is on the surface of whole device Uniform deposition is carried out, the thickness precipitated everywhere is identical.Due to source electrode 731, drain electrode 732, the presence of grid 733, so that in source electrode Insulating barrier 740 between 731 and grid 733, the insulating barrier 740 between grid 733 and drain electrode 732 be to lower recess, can It is allowed to smooth using technique is polished.
It can also for example include field plate metal layer 750, it is arranged on the insulating barrier 740.The field plate metal layer 750 It is connected through the insulating barrier 740 with the source electrode 731.Preferably, the material of the field plate metal layer 750 is aluminium copper silicon gold Belong to layer.
The section of grid 733 in above-mentioned gallium nitride semiconductor device is different from " T-shaped " structure of existing grid, but is in Existing " trapezoidal " construction of inversion wide at the top and narrow at the bottom, the high electric field at suppressor grid edge is effectively guaranteed gallium nitride high tension apparatus steady Fixed blocking characteristics, make device after high pressure repeatedly, still can keep good reliability.
The present invention also provides the preparation method of above-mentioned gallium nitride semiconductor device.As shown in Figure 3 e, specific steps include:
Step 701:Gallium nitride layer 713 and aluminum gallium nitride 714 are sequentially depositing on silicon substrate 712, is formed outside gallium nitride Prolong layer 710.Gallium nitride is third generation semiconductor material with wide forbidden band, with big energy gap, high electron saturation velocities, high breakdown potential Characteristics such as field, higher heat-conductivity, corrosion-resistant and radiation resistance and in high pressure, high frequency, high temperature, high-power and Flouride-resistani acid phesphatase ring There is stronger advantage, so as to be the optimal material for studying shortwave opto-electronic device and high voltagehigh frequency rate high power device under the conditions of border Material;Wherein, big energy gap is 3.4 electron-volts, and high electron saturation velocities are 2e7 centimeters per seconds, and high breakdown electric field is 1e10 ~-3e10 volts per cm.
Then chemical gaseous phase electrodeposition method can be strengthened with using plasma, is sunk on the surface of epitaxial layer of gallium nitride 710 One layer of silicon nitride of product and plasma enhancing tetraethoxysilance (PETEOS), form compound medium layer 720.Wherein, silicon nitride and The thickness of plasma enhancing tetraethoxysilance for example can be 2000 angstroms.
Step 702, dry etching is carried out to the compound medium layer 720, forms the He of source contact openings 721 being oppositely arranged Drain contact hole 722 and multiple floating field plate contact holes 725;Again the pole contact hole 721 and drain contact hole 722, And the first metal of deposition forms corresponding electrode in multiple floating field plate contact holes 725.
First, drain contact hole 722 is first opened up on compound medium layer 720;Then magnetron sputtering plating work can be used Skill, in drain contact hole and on the surface of compound medium layer, is sequentially depositing the first titanium coating, aluminum metal layer, the second titanium Metal level and titanium nitride layer, to form the first metal;Wherein, the thickness of the first titanium coating may be, for example, 200 angstroms, aluminum metal layer Thickness may be, for example, 1200 angstroms, the thickness of the second titanium coating may be, for example, 200 angstroms, and the thickness of titanium nitride layer may be, for example, 200 angstroms.Form drain electrode.
Step 7031, then in source contact openings 721 and the table of the compound medium layer 720 of multiple floating field plate contact holes 725 The first metal is deposited on face.
Similarly, magnetron sputtering membrane process can be used, in source contact openings and multiple floating field plate contact holes 725th, on the surface of part compound medium layer, the first titanium coating, aluminum metal layer, the second titanium coating and titanium nitride are sequentially depositing Layer, to form the first metal;Wherein, the thickness of the first titanium coating may be, for example, 200 angstroms, and the thickness of aluminum metal layer can be such as For 1200 angstroms, the thickness of the second titanium coating may be, for example, 200 angstroms, and the thickness of titanium nitride layer may be, for example, 200 angstroms.Thus, obtain Obtain source electrode 731 and floating field plate 735.
Wherein, the length of each floating field plate 735 may be, for example, 0.25~6 micron.
In order that obtaining the source contact openings 721, drain contact hole 722, the cleaning of multiple floating field plate contact holes 725 less Impurity, in addition to removal step.Specifically, after dry etching is carried out to compound medium layer 720, can first use " DHF (dilute hydrofluoric acid)+chemical SC-1+ chemicals SC-2 " method, for example, can be first using the hydrogen fluorine after dilution Acid solution processing apparatus, then using hydrogen peroxide and the alkaline mixed solution processing apparatus of aqua ammonia, then using peroxidating The acidic mixed solution processed device of hydrogen and hydrogen chloride, and then the impurity thing on the surface of whole device can be removed.
Photoetching and etching are carried out to the first metal, Ohm contact electrode window 719 is formed.
Carry out photoetching and etching to the first metal, the program of wherein photoetching includes gluing, exposed and developed, so as to Form an Ohm contact electrode window 719;Through Ohm contact electrode window 719, it can be seen that the portion of compound medium layer 720 Divide surface.In this way, the first metal on source contact openings 721 constitutes on the source electrode 731 of device, drain contact hole 722 One metal constitutes the drain electrode 732 of device.Now, in order to be able to clear expression process of the present invention, the device that name is now obtained is First assembly.
Step 704, the high temperature anneal is carried out to whole first assembly, to pass through the first gold medal after the etching contacted with each other Category forms alloy after being reacted with aluminum gallium nitride 714.
In the present embodiment, specifically, being passed through nitrogen gas in reacting furnace, to whole in the environment of 840~850 DEG C First assembly carries out the high temperature anneal of 30 seconds, so that the first metal after etching can turn into alloy, and contact with each other The first metal after etching can also also form alloy after being reacted with aluminum gallium nitride 714 on its contact surface, so that The contact resistance between the first metal and aluminum gallium nitride 714 can be reduced.That is, reduction source electrode 731, drain electrode 732 and aluminium nitride Contact resistance between gallium layer 14.
Step 705, by Ohm contact electrode window 719, compound medium layer 720 and aluminum gallium nitride 714 are done Method is etched, and forms gate contact hole 723, wherein, the bottom in gate contact hole 723 has pre- with the bottom of aluminum gallium nitride 714 If distance.
In the present embodiment, using the method for dry etching, by Ohm contact electrode window 719, to compound medium layer 720 and partial aluminum gallium nitride 714, dry etching is carried out, and then form on the first device a gate contact hole 723.Wherein, gate contact hole 723 is complete breaks through compound medium layer 720, and through the aluminum gallium nitride 714 of part, makes The bottom of bottom and the aluminum gallium nitride 714 in gate contact hole 723 be preferably apart from H aluminum gallium nitride 714 half.Enter One step, cause gate contact hole 723 is presented one wide at the top and narrow at the bottom, inverted trapezoidal during etching.In the present embodiment, formed After one gate contact hole 723, there can be the impurity things such as impurity, particle and ion in gate contact hole 723, so as to So that using hydrochloric acid solution cleaning gate contact hole 720, the impurity thing in gate contact hole 720 to be got rid of.
The present embodiment is by after dry etching is carried out to compound medium layer 720, using DHF+SC1+SC2 method Impurity thing in removal devices;And formed after gate contact hole 723, will be miscellaneous in gate contact hole 723 using hydrochloric acid solution Matter thing is got rid of.So as to the cleaning being effectively guaranteed in the surface and gate contact hole 723 of compound medium layer, and then It ensure that the performance of gallium nitride semiconductor device.
Step 706, in the present embodiment, specifically, using magnetron sputtering membrane process, in gate contact hole 723 and grid The outward flange deposition Ni/Au of pole contact hole 723 is as the second metal, and metal thickness is 0.01~0.04 μm/0.08~0.4 μm; So as to constitute grid 733.Now, in order to become apparent from expressing present invention, it is the second component to name the device now obtained.
Step 707, a layer insulating 740 is deposited on the surface of whole second component.
In the present embodiment, specifically, in the surface deposition layer of silicon dioxide (SiO of whole second component2), thickness can For example, 5000 angstroms, form silicon dioxide layer and be used as a layer insulating 740.Wherein, silica enters on the surface of whole device Row uniform deposition, thickness is identical everywhere, due to source electrode 731, drain electrode 732 and the presence of grid 733, so that in source electrode 731 and grid Insulating barrier 740 between pole 733, the insulating barrier 740 between grid 733 and drain electrode 732 are to lower recess, using polishing Technique is allowed to smooth.
Step 708, after to the progress dry etching of insulating barrier 740 of the top of source contact openings 731, perforate 741 is formed.Institute Stating grid 33 has the protuberance 733a protruded from outside the gate contact hole 723, and the width of the perforate 741 is less than described convex Go out portion 733a width.
Step 709, the insulation of the top of gate contact hole 723 is extended in perforate 741 and from source contact openings 731 Field plate metal 750 is deposited on layer 740, field plate metal layer 750 is formed.
In the present embodiment, specifically, magnetron sputtering membrane process can be used, connect in perforate 741 and from source electrode Compound medium layer of outer peripheral first metal of contact hole 721 above outer peripheral first metal in gate contact hole 723 Field plate metal is deposited on 720, thickness may be, for example, 10000 angstroms, so as to form field plate metal layer 750.The thickness of field plate metal layer 750 Degree be it is uniform, field plate metal layer 750 at the position of perforate 741 and source contact openings 721 and gate contact hole 723 it Between position at be, to lower recess, to pass through polishing technique and can be allowed to smooth in subsequent step.
The present embodiment replaces existing silicon oxide layer by depositing compound medium layer on the surface of epitaxy of gallium nitride substrate It is used as compound medium layer;The high temperature anneal technique is recycled, makes the aluminum gallium nitride in source electrode, drain electrode and epitaxial layer of gallium nitride Alloy is formed after being reacted, so that source electrode, drain electrode contact with the contact surface of aluminum gallium nitride are well, can be effective Reduction source electrode, the contact resistance of drain electrode and aluminum gallium nitride;Avoid the occurrence of the electric leakage of gallium nitride semiconductor device and soft hit The problem of wearing.Further, with reference to the becket of floating, by the becket of this floating, exhausting for power device is extended Area, reduces the electric-field intensity of main schottky junction, so that it is pressure-resistant to improve device.The gallium nitride semiconductor device that the present embodiment is obtained It can be applied in the technical fields such as power electronic element, wave filter, radio communication element, have a good application prospect.
Finally it should be noted that:The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations;Although The present invention is described in detail with reference to the foregoing embodiments, it will be understood by those within the art that:It still may be used To be modified to the technical scheme described in foregoing embodiments, or equivalent substitution is carried out to which part technical characteristic; And these modification or replace, do not make appropriate technical solution essence depart from various embodiments of the present invention technical scheme spirit and Scope.

Claims (11)

1. a kind of gallium nitride semiconductor device, it is characterised in that including:Epitaxial layer of gallium nitride;And,
The compound medium layer on the epitaxial layer of gallium nitride is arranged at, the compound medium layer material is silicon nitride and plasma Strengthen tetraethoxysilance;
It is arranged at source electrode, drain and gate on the compound medium layer, the source electrode, drain electrode, grid extend through described multiple Dielectric layer is closed to be connected with the epitaxial layer of gallium nitride;Wherein, the grid is in inverted trapezoidal;
The insulating barrier on the source electrode, drain and gate and the compound medium layer is arranged at, the material of the insulating barrier is Silica;
Also include the field plate metal layer being arranged on the insulating barrier, the field plate metal layer is through the insulating barrier and the source Pole is connected;
Also include several floating field plates being arranged on the compound medium layer, the floating field plate runs through the complex media Layer is connected with the epitaxial layer of gallium nitride.
2. gallium nitride semiconductor device according to claim 1, it is characterised in that the epitaxial layer of gallium nitride includes silicon lining Bottom, and be arranged at the gallium nitride layer of the surface of silicon, be arranged at the aluminum gallium nitride on the gallium nitride layer surface.
3. gallium nitride semiconductor device according to claim 2, it is characterised in that the grid stretches to the aluminium gallium nitride alloy In layer.
4. gallium nitride semiconductor device according to claim 2, it is characterised in that the gate bottom to the aluminium gallium nitride alloy The distance of layer bottom is the half of the aluminum gallium nitride.
5. according to the gallium nitride semiconductor device of claim 1 or 2 or 3 or described, it is characterised in that the thickness of the compound medium layer Spend for 2000 angstroms.
6. according to the gallium nitride semiconductor device of claim 1 or 2 or 3 or described, it is characterised in that the height of each floating field plate For 0.25~6 micron.
7. a kind of preparation method of gallium nitride semiconductor device, it is characterised in that comprise the following steps:
One epitaxial layer of gallium nitride is provided, wherein, the epitaxial layer of gallium nitride includes layer-of-substrate silicon, the nitrogen from bottom to top set gradually Change gallium layer and aluminum gallium nitride;
In the epitaxy of gallium nitride layer surface deposited silicon nitride and plasma enhancing tetraethoxysilance, compound medium layer is formed;
The acquisition of drain contact hole:The compound medium layer is etched to form drain contact hole, the drain contact hole runs through institute State compound medium layer and reach the aluminum gallium nitride;In the source contact openings and on the surface of the compound medium layer, The first metal is deposited, to be drained;
Source contact openings, the acquisition in floating field plate hole:The compound medium layer is etched to form source contact openings, floating field plate Hole, the source contact openings, floating field plate hole reach the aluminum gallium nitride through the compound medium layer;Connect in the source electrode In contact hole, floating field plate hole and on the surface of the compound medium layer, the first metal is deposited, to obtain source electrode, floating Plate;
Photoetching and etching are carried out to first metal, Ohm contact electrode window is formed;Now obtain first assembly;
The high temperature anneal is carried out to the first assembly, to be contained in the source contact openings and the drain contact hole Interior first metal forms alloy and reacted with the aluminum gallium nitride;
The acquisition in gate contact hole:By the Ohm contact electrode window, to the compound medium layer and the aluminium gallium nitride alloy Layer carries out dry etching, forms the gate contact hole of inverted trapezoidal, the gate contact hole is through the compound medium layer and stretches into In the aluminum gallium nitride;
The second metalwork is deposited in the outward flange in the gate contact hole and the gate contact hole, to obtain grid, is now obtained Obtain the second component;
A layer insulating is deposited on the surface of second component;
Dry etching is carried out on the insulating barrier, to form perforate, the perforate is corresponding with the source contact openings;
Field plate metal layer is deposited in the perforate and the insulating barrier, the projection of the field plate metal layer at least covers described Perforate and from the source contact openings to the region between the gate contact hole.
8. the preparation method of gallium nitride semiconductor device according to claim 7, it is characterised in that the width of the perforate is small The protuberance width above the gate contact hole is protruded from the grid.
9. the preparation method of gallium nitride semiconductor device according to claim 7, it is characterised in that the high temperature anneal Step is:Under protection atmosphere, kept for 30~60 seconds at a temperature of 840~850 DEG C.
10. the preparation method of gallium nitride semiconductor device according to claim 7, it is characterised in that the gate bottom is arrived The distance of the aluminum gallium nitride bottom is the half of the aluminum gallium nitride.
11. the preparation method of gallium nitride semiconductor device according to claim 7, it is characterised in that each floating The height of plate is 0.25~6 micron.
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Application publication date: 20171020