CN104167438A - GaN-based HEMT device - Google Patents

GaN-based HEMT device Download PDF

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Publication number
CN104167438A
CN104167438A CN201310185820.8A CN201310185820A CN104167438A CN 104167438 A CN104167438 A CN 104167438A CN 201310185820 A CN201310185820 A CN 201310185820A CN 104167438 A CN104167438 A CN 104167438A
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CN
China
Prior art keywords
layer
described
insulating medium
grid
medium layer
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CN201310185820.8A
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Chinese (zh)
Inventor
文正
孟迪
林书勋
郝一龙
吴文刚
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北京天元广建科技研发有限责任公司
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Priority to CN201310185820.8A priority Critical patent/CN104167438A/en
Publication of CN104167438A publication Critical patent/CN104167438A/en

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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • 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
    • H01L29/41Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
    • H01L29/423Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions not carrying the current to be rectified, amplified or switched
    • H01L29/42312Gate electrodes for field effect devices
    • H01L29/42316Gate electrodes for field effect devices for field-effect transistors
    • H01L29/4232Gate electrodes for field effect devices for field-effect transistors with insulated gate
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • 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

Abstract

The invention relates to a GaN-based HEMT device which relates to the technical field of a semiconductor device. The GaN-based HEMT device comprises a substrate, a channel layer formed on the substrate, a barrier layer formed on the channel layer, a source electrode, a drain electrode, at least one layer of insulating medium layer and a grid electrode, wherein the source electrode, the drain electrode and the at least one layer of insulating medium layer are formed on the barrier layer, and the grid electrode is formed on the at least one layer of insulating medium layer. Therefore, grid leakage current of the device can be reduced, and microwave characteristic of the device is not influenced.

Description

A kind of GaN HEMT

Technical field

The present invention relates to technical field of semiconductor device, relate in particular to a kind of GaN HEMT.

Background technology

GaN (gallium nitride) based hemts (High Electron Mobility Transistors, High Electron Mobility Transistor) be known a kind of HFET in art technology, due to it, to have energy gap large, high breakdown electric field, high electron saturation velocities, thermal conductivity is high, stable chemical nature, the advantages such as radioresistance, be widely used in microwave power amplifier, in high voltage switch circuit, and at civilian communication base station, Aero-Space, automotive electronics, hyperthermia radiation environment and military radar, electronic countermeasures, in the fields such as military satellite communication, be with a wide range of applications.

Fig. 1 is the structural representation of typical a kind of GaN HEMT in prior art, in this HEMT device, specifically comprise: substrate 1 ', channel layer 2 ' (also can be called GaN layer), barrier layer 3 ' (also can be called AlGaN layer), source electrode 5 ', grid 4 ', drain electrode 6 ', wherein source electrode 5 ' and drain electrode 6 ' lay respectively at grid 4 ' both sides, source electrode 5 ' and grid 4 ' between and drain electrode 6 ' and grid 4 ' between all arrange passivation layer 10 ', source electrode 5 ' and grid 4 ' top arrange respectively source field plate 7 ' and grid field plate 8 ', passivation layer 10 ' on also arrange field plate dielectric layer 9 '.

But because grid directly contacts (these contact structures form Schottky contacts structure) with semiconductor layer (barrier layer), therefore leak into the grid leakage current of grid from raceway groove relatively large, simultaneously, the introducing of field plate structure and passivation layer, can increase parasitic capacitance (the grid source capacitor C between electrode gs, gate leakage capacitance C gd), and then the cut-off frequency of reduction device, limit its range of application in microwave power amplifier.

Summary of the invention

Embodiments of the invention provide a kind of GaN HEMT, can reduce the grid leakage current of device, and do not affect its microwave property.

For achieving the above object, embodiments of the invention adopt following technical scheme:

The embodiment of the present invention provides a kind of GaN HEMT, comprising:

Substrate;

Channel layer, is formed at the top of described substrate;

Barrier layer, is formed at the top of described channel layer;

Source electrode, drain electrode, one deck insulating medium layer at least, be formed at the top of described barrier layer, the both sides of one deck insulating medium layer at least described in described source electrode and described drain electrode lay respectively at;

Grid, the top of one deck insulating medium layer at least described in being formed at.

Preferably, described insulating medium layer is less than or equal to the length of described grid along channel direction along the length of channel direction.

Alternatively, the dielectric constant of described insulating medium layer is greater than 9.

Preferably, the dielectric constant of described insulating medium layer is greater than 30.

Preferably, the material of described insulating medium layer is TiO 2.

Alternatively, described device comprises two-layer the above insulating medium layer.

The GaN HEMT that the embodiment of the present invention provides, comprise: substrate, be formed at the channel layer of described substrate top, be formed at the barrier layer of described channel layer top, be formed at the source electrode, drain electrode of described barrier layer top, one deck insulating medium layer at least, and the grid of one deck insulating medium layer top at least described in being formed at, be not difficult to find out, insulating medium layer is positioned between grid and semiconductor device surface (barrier layer), can reduce like this grid leakage current that leaks into grid from raceway groove; And compare the GaN HEMT of same size (comprise grid length, grid width, grid spacing from, grid leak distance), the present invention does not arrange grid field plate, source field plate and passivation layer, therefore can avoid increasing the parasitic capacitance between electrode, and then can avoid reducing cut-off frequency, ensure that transistorized microwave property is unaffected.

Brief description of the drawings

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.

The structural representation of a kind of GaN HEMT that Fig. 1 provides for prior art;

The structural representation of the first GaN HEMT that Fig. 2 provides for the embodiment of the present invention;

The structural representation of the second GaN HEMT that Fig. 3 provides for the embodiment of the present invention;

The structural representation of the third GaN HEMT that Fig. 4 provides for the embodiment of the present invention.

Reference numeral:

1 ', 1-substrate, 2 ', 2-channel layer, 3 ', 3-barrier layer, 4 ', 4-grid, 5 ', 5-source electrode, 6 ', 6-grid, 7 '-source field plate, 7-insulating medium layer (gate dielectric layer), 8 '-grid field plate, the dielectric layer between 9 '-field plate, 10 '-passivation layer

Embodiment

As described in the part of background technology, GaN HEMT of the prior art exists grid leakage current larger, and because the field plate of introducing reduces the high frequency characteristics of HEMT, and then affect its microwave property, in view of this defect, the invention provides a kind of Novel MOS (Metal-Oxide-Semiconductor, metal-oxide semiconductor (MOS)) the GaN HEMT of structure, comprise: substrate, be formed at the channel layer of described substrate top, be formed at the barrier layer of described channel layer top, be formed at the source electrode of described barrier layer top, drain electrode, at least one deck insulating medium layer (also can be referred to as gate dielectric layer), and the grid of one deck insulating medium layer top at least described in being formed at, be not difficult to find out, insulating medium layer is positioned between grid and semiconductor device surface (barrier layer), can reduce like this grid leakage current that leaks into grid from raceway groove, and comparing the GaN HEMT of same size (comprise grid length, grid width, grid spacing from, grid leak distance), the present invention, without grid field plate, source field plate and passivation layer, therefore can avoid increasing electric capacity (the grid source capacitor C between electrode gs, gate leakage capacitance C gd), and then can avoid reducing cut-off frequency, ensure that transistorized microwave property is unaffected.

For those skilled in the art understand the present invention better, below in conjunction with accompanying drawing 2, Fig. 3 and Fig. 4 in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described.

Obviously, embodiment described below is only the present invention's part embodiment, instead of whole embodiment.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under the prerequisite of not making creative work, belongs to the scope of protection of the invention.

And in the accompanying drawing providing in the embodiment of the present invention, the profile of shown device architecture can be made local amplifying method not according to general ratio, and described schematic diagram is only also exemplary illustration, and it should not limit the scope of protection of the invention at this.In addition, in actual fabrication, should comprise the three-dimensional space of length, width and the degree of depth.

A kind of GaN HEMT that Fig. 2 provides for the embodiment of the present invention, with reference to Fig. 2, this HEMT device architecture specifically comprises substrate 1, be formed at the GaN channel layer 2 of described substrate 1 top, be formed at the AlGaN barrier layer 3 of described channel layer 2 tops, be formed at the source electrode 5 of described barrier layer 3 tops, drain electrode 6, at least one deck insulating medium layer 7, and the grid 4 of one deck insulating medium layer 7 tops at least described in being formed at, the both sides of one deck insulating medium layer at least described in described source electrode and described drain electrode lay respectively at, wherein GaN channel layer 2, AlGaN barrier layer 3 forms the heterojunction structure on substrate 1, source electrode 5, drain electrode 6 forms ohmic contact with barrier layer 3 respectively, grid 4, insulating medium layer 7 and barrier layer 3 form MOS structure.

Wherein, substrate 1 can be selected sapphire (Al 2o 3), the higher crystalline material of other thermal conductivity such as Si or SiC, source electrode 5, drain electrode 6 can select Ti/Al/Pt/Au, Ti/Al/Ni/Au, Ti/Al/Cr/Au or other any one can form the metal of ohmic contact, grid 4 can be selected the metals such as Ni/Au, Pt/Au, Pt/Ti/Au, Ni/Pt/Au.

Above-mentioned insulating medium layer 7 adopts the material of high-k, and its advantage is: (can react the comparatively direct index of grid-control ability is mutual conductance g to keep grid-control ability at device m) in constant situation, due to mutual conductance g mwith the gate capacitance C of unit ox(C ox=ε/t, ε represents the dielectric constant of gate dielectric layer, t represents the thickness of gate dielectric layer) relevant, therefore the dielectric constant of gate insulation dielectric layer 7 is higher, and its thickness also can increase in proportion, so further minimizing grid leakage current, the conduction current of raising raceway groove.

But, in the GaN HEMT providing in the embodiment of the present invention, the introducing of gate insulation dielectric layer can make the mutual conductance g of device conventionally mreduce, and mention grid source capacitor C above gs, gate leakage capacitance C gdalso reduce, according to the formula f of higher cutoff frequency simultaneously t=g m/ 2 π (C gs+ C gd), g min reducing, C gs, C gdalso can reduce with same ratio, the higher cutoff frequency of HEMT device just can remain unchanged like this, although therefore the present invention has added insulating medium layer 7 between grid 4 and device surface (barrier layer 3), but but can not make the original higher cutoff frequency of device-change, ensure that the high frequency characteristics of device is unaffected.

In order to make to there is less parasitic capacitance between electrode, with reference to Fig. 4, can make described insulating medium layer be less than distance L between source electrode 5, drain electrode 6 along the length of channel direction (being the left and right directions that is parallel to paper under shown position) ds, and the invention provides the more preferred scheme of one, as shown in Figure 2, can also make described insulating medium layer 7 be less than the length L of grid 4 along channel direction along the length of channel direction g, or as shown in Figure 3, described insulating medium layer 7 equals the length L of grid 4 along channel direction along the length of channel direction g, can ensure better that so the original higher cutoff frequency of device does not change.

In addition, for GaN HEMT, the peak value electric field of device inside appears at grid 4 belows and the edge near drain electrode 6, the size of this peak value electric field has directly determined the maximum breakdown voltage that device can reach, in the time that the distance between grid 4 and drain electrode 6 is constant, the highfield that the insulating medium layer 7 of high-k can produce grid 4 places, edge redistributes, weaken the peak value electric field of Liao Gai edge, and then can increase the grid leak puncture voltage of device, and in the time that this insulating medium layer 7 is thicker, grid leak puncture voltage can also further increase, the reliability of enhance device under high-power signal mode of operation.

The embodiment of the present invention can arrange one deck insulating medium layer 7 and achieve the above object, and in the time that the Thickness Ratio of dielectric is thicker, also can realize above-mentioned purpose by two-layer above insulating medium layer 7 is set.

Be understandable that, comparatively speaking, the relative dielectric constant that in the embodiment of the present invention, dielectric is selected is greater than 9 to the high-k of insulating medium layer 7, for example Al 2o 3, HfO 2, and in order to make device can strengthen the middle beneficial effect of mentioning above, relative dielectric constant can also be greater than 30, for example TiO 2, its relative dielectric constant is greater than 80 conventionally, under certain conditions, even can reach 130.It should be noted that, all select TiO with dielectric in embodiments of the present invention 2for preferred version describes.

Certainly, the dielectric constant of above-mentioned insulating medium layer 7 and thickness are not unlimited increase, are conventionally as the criterion and determine rational dielectric constant and thickness with practical situations.

Here also it should be noted that, in the embodiment of the present invention raising of GaN HEMT performance be all device to there is same size (comprise grid length, grid width, grid spacing from, grid leak distance) with it Comparatively speaking, the for example explanation as an example of structure shown in Fig. 2 example, the long L of grid g=0.4 μ m, insulating medium layer TiO 2thickness is greater than the GaN HEMT of 30nm, the cut-off frequency f of its acquisition t(40GHz) identical with the Schottky gate GaN based hemts with same size, guarantee high frequency characteristics is degenerated hardly; Its grid leak puncture voltage has been brought up to about 120V (Schottky gate GaN based hemts is about 70V), and grid leakage current has been reduced to and has been about 10 -9(Schottky gate GaN based hemts is about 10 to A/mm -7a/mm).

The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited to this, any be familiar with those skilled in the art the present invention disclose technical scope in; can expect easily changing or replacing, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of described claim.

Claims (6)

1. a GaN HEMT, is characterized in that, comprising:
Substrate;
Channel layer, is formed at the top of described substrate;
Barrier layer, is formed at the top of described channel layer;
Source electrode, drain electrode, one deck insulating medium layer at least, be formed at the top of described barrier layer, the both sides of one deck insulating medium layer at least described in described source electrode and described drain electrode lay respectively at;
Grid, the top of one deck insulating medium layer at least described in being formed at.
2. GaN HEMT according to claim 1, is characterized in that, described insulating medium layer is less than or equal to the length of described grid along channel direction along the length of channel direction.
3. GaN HEMT according to claim 1, is characterized in that, the dielectric constant of described insulating medium layer is greater than 9.
4. GaN HEMT according to claim 1, is characterized in that, the dielectric constant of described insulating medium layer is greater than 30.
5. GaN HEMT according to claim 1, is characterized in that, the material of described insulating medium layer is TiO 2.
6. according to the GaN HEMT described in claim 1-5 any one, it is characterized in that, described device comprises two-layer the above insulating medium layer.
CN201310185820.8A 2013-05-20 2013-05-20 GaN-based HEMT device CN104167438A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002324813A (en) * 2001-02-21 2002-11-08 Nippon Telegr & Teleph Corp <Ntt> Heterostructure field-effect transistor
US20110140121A1 (en) * 2009-12-14 2011-06-16 Kyungpook National University Industry Academic Cooperation Foundation Enhancement normally off nitride semiconductor device and method of manufacturing the same
CN102592999A (en) * 2012-03-19 2012-07-18 中国科学院上海技术物理研究所 Method for optimizing thickness of channel layer of quantum well high electron mobility transistor (HEMT) appliance
CN103000516A (en) * 2011-09-15 2013-03-27 台湾积体电路制造股份有限公司 Method of forming a semiconductor structure

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002324813A (en) * 2001-02-21 2002-11-08 Nippon Telegr & Teleph Corp <Ntt> Heterostructure field-effect transistor
US20110140121A1 (en) * 2009-12-14 2011-06-16 Kyungpook National University Industry Academic Cooperation Foundation Enhancement normally off nitride semiconductor device and method of manufacturing the same
CN103000516A (en) * 2011-09-15 2013-03-27 台湾积体电路制造股份有限公司 Method of forming a semiconductor structure
CN102592999A (en) * 2012-03-19 2012-07-18 中国科学院上海技术物理研究所 Method for optimizing thickness of channel layer of quantum well high electron mobility transistor (HEMT) appliance

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