阅读说明：本技术 基于再生长和离子注入的GaN凹槽阳极肖特基二极管制备方法 (GaN groove anode Schottky diode preparation method based on regrowth and ion implanting ) 是由 张进成 张燕妮 周弘 宁静 郝跃 于 2019-08-20 设计创作，主要内容包括：本发明公开了一种基于再生长和离子注入的GaN凹槽阳极肖特基二极管制备方法,主要解决现有方法制作的GaN肖特基二极管欧姆接触电阻较大的问题。其实现方案为：1)在清洗后的外延片上淀积SiN；2)在淀积有SiN的外延片上进行欧姆区离子注入,并将其清洗后进行热退火处理；3)在离子注入后的外延片上淀积SiO<Sub>2</Sub>；4)在淀积有SiO<Sub>2</Sub>的外延片上依次进行源漏区凹槽光刻和凹槽刻蚀,并进行清洗；5)在清洗后的外延片上生长n<Sup>+</Sup>-GaN,并去除生长有n<Sup>+</Sup>-GaN外延片上的剩余SiO<Sub>2</Sub>层,再进行阴极金属淀积,并热退火；6)在退火后的外延片上刻蚀出阳极凹槽并进行阳极制作。本发明的欧姆接触电阻低,刻蚀工艺简单,可用于制作电力电子器件。(The GaN groove anode Schottky diode preparation method based on regrowth and ion implanting that the invention discloses a kind of mainly solves the problems, such as that the GaN Schottky diode ohmic contact resistance of existing method production is larger.Its implementation are as follows: 1) deposit SiN on epitaxial wafer after cleaning；2) ohmic region ion implanting is carried out on the epitaxial wafer for be deposited with SiN, and carries out thermal anneal process after being cleaned；3) SiO is deposited on epitaxial wafer after ion implantation 2 ；4) it is being deposited with SiO 2 Epitaxial wafer on successively carry out the photoetching of source-drain area groove and recess etch, and cleaned；5) n is grown on epitaxial wafer after cleaning + - GaN, and remove growth and have n + The remaining SiO of GaN epitaxy on piece 2 Layer, then cathodic metal deposit is carried out, and thermal annealing；6) anode groove is etched on epitaxial wafer after annealing and carries out anode production.Ohmic contact resistance of the invention is low, and etching technics is simple, can be used for making power electronic devices.)

1. a kind of GaN groove anode Schottky diode preparation method based on regrowth and ion implanting, which is characterized in that packet Include following steps:

(1) epitaxial wafer is cleaned, the epitaxial wafer after cleaning is put into low-pressure chemical vapor phase deposition LPCVD reaction chamber, formed sediment The SiN passivation layer of product 10-30nm thickness；

(2) ion implanting photoetching in ohmic region is carried out on the epitaxial wafer for being deposited with SiN passivation layer, is placed into ion implant systems Si is injected to ohmic region, and is cleaned；Then by epitaxial wafer after cleaning 1000-1200 DEG C at a temperature of carry out 5-15min Thermal anneal process；

(3) regrowth n⁺-GaN

Epitaxial wafer after thermal annealing is put into plasma-enhanced chemical vapor deposition PECVD reaction chamber by (3a), in 250- At a temperature of 350 DEG C, the SiO of 200-300nm thickness is deposited₂；

(3b) is being deposited with SiO₂Epitaxial wafer on carry out the photoetching of ohmic area groove, and the epitaxial wafer that groove is crossed in photoetching is put into The SiN and SiO of ohmic area are etched away in plasma etching machine₂, then the AlGaN of 20-30nm thickness is etched, form insertion GaN layer Ohmic region groove；

The epitaxial wafer for etching ohmic region groove is first sequentially placed into acetone soln, ethanol solution and deionized water by (3c) Each ultrasonic cleaning 2-10min, then with being dried with nitrogen, be subsequently placed in metal organic chemical vapor deposition MOCVD reaction chamber, it is raw The n of long 25-35nm thickness⁺-GaN；

(4) cathode electrode is made

(4a) is by regrowth n⁺Piece after-GaN, which is put into HF acid solution, impregnates 3-5min, to remove remaining SiO₂Layer；

(4b) is eliminating SiO₂Cathode photoetching is carried out on the epitaxial wafer of layer, places into electron beam evaporation system or magnetron sputtering system The metal layer that deposit work function size is 4.2eV in system, forms negative electrode, and carry out 400-500 DEG C of thermal anneal process 30-60s；

(5) anode electrode is made:

Photoetching anode groove on the epitaxial wafer of (5a) after annealing, and etch away the SiO below anode₂Layer, SiN layer and AlGaN Layer；

(5b) carries out anode electrode photoetching on the epitaxial wafer for etching anode groove, and is put into electron beam evaporation system or magnetic control The metal that deposit work function size is 4.6eV in sputtering system, forms anode electrode, completes the production of entire device.

2. being by the extension of AlGaN/GaN structure according to the method described in claim 1, wherein (1) cleans epitaxial wafer Piece, which is first put into HF acid solution or HCl acid solution, impregnates 30s, then is sequentially placed into acetone soln, ethanol solution and deionization Respectively it is cleaned by ultrasonic 2-10min in water, then with being dried with nitrogen.

3. process conditions are as follows according to the method described in claim 1, wherein injecting Si to ohmic region in (3):

Implantation dosage: 1 × 10¹⁵-1×10¹⁶；

Implantation Energy: 30-100keV；

Implant angle: 0-10 °.

4. according to the method described in claim 1, wherein growing the n of 25-35nm thickness in (4c)⁺- GaN, process conditions are as follows:

Chamber pressure: 10-80Torr；

Reaction chamber temperature: 900-1100 DEG C；

Gallium source flux: 40-100 μm of ol/min；

Ammonia flow: 3000-6000sccm；

Hydrogen flowing quantity: 1000-2000sccm；

Silicon source flow: 10-60 μm of ol/min.

Technical field

The invention belongs to microelectronics technology, in particular to a kind of GaN groove anode Schottky diode preparation method, It can be used for rectifier and switching component.

Technical background

GaN material can generate very strong interface electricity in heterojunction boundary because of its stronger piezoelectricity and spontaneous polarization Lotus and electric field, accumulate two-dimensional electron gas.Electronics in two-dimensional electron gas in very thin two-dimensional layer, can get high by confinement Surface density and mobility.Another aspect GaN material makes that its breakdown electric field is big, high temperature resistant because of its biggish forbidden bandwidth.Cause This GaN base device is very suitable to high pressure, high-power and frequency applications.GaN base Schottky diode is because of its forward current density Big and switching speed is fast, becomes the ideal chose of low switching losses and high-frequency operation.Groove anode construction can be achieved at the same time pole Low cut-in voltage and big breakdown voltage.However device forms barrier layer frequently with the big material of forbidden bandwidth, with obtain compared with Big hetero-junctions conduction band is interrupted, realizes high-breakdown-voltage and big output electric current.But big barrier layer forbidden bandwidth makes device It is difficult to the Ohmic contact to have been formed, causes to export current capacity reduction.Therefore making high performance Ohmic contact is that realization is big defeated The key of current density and raising switching speed out.

To improve Ohmic contact, many researchers use different methods, such as make Two-dimensional electron by constituency etching Gas directly contacts with metal, reduces potential barrier etc. using with metal similar in GaN material work function, is detailed in Ohmic contacts To Gallium Nitride materials, Applied Surface Science, 383 (2016), 324-345.These Europe Nurse contacts optimization method cannot improve ohmic area current-carrying while increasing two-dimensional electron gas and ohmic metal contact area Sub- concentration, so that the reducing effect of Ohmic contact is not obvious.On the other hand since these methods will carry out high-temperature thermal annealing, It will lead to metal to go deep into inside GaN, generate ELECTROMIGRATION PHENOMENON, influence the stability of device.

Summary of the invention

It is an object of the invention to overcome the shortcomings of above-mentioned prior art, provide a kind of based on ion implanting and regrowth Low ohm contact GaN groove anode Schottky diode preparation method, in the contact area for increasing two-dimensional electron gas and cathode While, ohmic area carrier concentration is promoted, ohmic contact resistance is substantially reduced, improves electric current output density, and reduce and move back Fiery temperature improves device stability.

Realizing key problem in technology of the invention is: improving ohmic area carrier concentration using ion implanting.Using SiO₂It covers Mold layer etches groove in ohmic region.Using n⁺Groove is filled in-GaN regrowth, realizes n⁺- GaN is contacted with two-dimensional electron gas.In Metal and n are deposited at cathode⁺GaN layer Ohmic contact.Specific steps include the following:

(1) epitaxial wafer is cleaned, the epitaxial wafer after cleaning is put into low-pressure chemical vapor phase deposition LPCVD reaction chamber It is interior, deposit the SiN passivation layer of 10-30nm thickness；

(2) ion implanting photoetching in ohmic region is carried out on the epitaxial wafer for being deposited with SiN passivation layer, places into ion implanting system Si is injected to ohmic region in system, and is cleaned；Then by the epitaxial wafer after cleaning 1000-1200 DEG C at a temperature of carry out 5- The thermal anneal process of 15min；

(3) regrowth n⁺-GaN

Epitaxial wafer after thermal annealing is put into plasma-enhanced chemical vapor deposition PECVD reaction chamber by (3a), In At a temperature of 250-350 DEG C, the SiO of 200-300nm thickness is deposited₂；

(3b) is being deposited with SiO₂Epitaxial wafer on carry out the photoetching of ohmic area groove, and photoetching is crossed to the epitaxial wafer of groove It is put into the SiN and SiO that ohmic area is etched away in plasma etching machine₂, then the AlGaN of 20-30nm thickness is etched, form insertion The ohmic region groove of GaN layer；

The epitaxial wafer for etching ohmic region groove is first sequentially placed into acetone soln, ethanol solution and deionization by (3c) Respectively it is cleaned by ultrasonic 2-10min in water, then with being dried with nitrogen, is subsequently placed in metal organic chemical vapor deposition MOCVD reaction chamber In, grow the n of 25-35nm thickness⁺-GaN；

(4) cathode electrode is made

(4a) is by regrowth n⁺Piece after-GaN, which is put into HF acid solution, impregnates 3-5min, to remove remaining SiO₂Layer；

(4b) is eliminating SiO₂Cathode photoetching is carried out on the epitaxial wafer of layer, places into electron beam evaporation system or magnetic control splashes The metal layer that deposit work function size is 4.2eV in system is penetrated, forms negative electrode, and carry out 400-500 DEG C of thermal anneal process 30- 60s；

(5) anode electrode is made:

Photoetching anode groove on the epitaxial wafer of (5a) after annealing, and etch away the SiO below anode₂Layer, SiN layer and AlGaN layer；

(5b) on the epitaxial wafer for etching anode groove carry out anode electrode photoetching, and be put into electron beam evaporation system or The metal that deposit work function size is 4.6eV in magnetic control sputtering system, forms anode electrode, completes the production of entire device.

The present invention has the advantage that

1. the present invention increases ohmic area carrier concentration, effectively reduces ohm due to using ion implantation technique Contact resistance.

2. the present invention is due to using n in ohmic region⁺- GaN regrowth, so that the annealing temperature of ohmic metal is substantially reduced, To reduce the phenomenon that metal penetrates into material, device stability is improved.

Detailed description of the invention

Fig. 1 is implementation process schematic diagram of the invention.

Specific embodiment

Below in conjunction with attached drawing, embodiments of the present invention is further illustrated.

Implementation of the invention is carried out on existing AlGaN/GaN epitaxial wafer, which is SiC lining from bottom to top Bottom, AlN nucleating layer, GaN buffer layer and AlGaN potential barrier, wherein SiC substrate with a thickness of 300-800 μm, AlN nucleating layer With a thickness of 20-100nm, GaN buffer layer with a thickness of 0.5-2 μm, AlGaN potential barrier with a thickness of 20-30nm.

Referring to Fig.1, the present invention provides following three kinds of embodiments: