CN117976695A - Gallium oxide Schottky barrier diode and preparation method thereof - Google Patents
Gallium oxide Schottky barrier diode and preparation method thereof Download PDFInfo
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- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 title claims abstract description 40
- 229910001195 gallium oxide Inorganic materials 0.000 title claims abstract description 39
- 230000004888 barrier function Effects 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title abstract description 13
- 239000000758 substrate Substances 0.000 claims abstract description 67
- 150000002500 ions Chemical class 0.000 claims abstract description 40
- 239000010931 gold Substances 0.000 claims description 42
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 27
- 239000010936 titanium Substances 0.000 claims description 24
- 229910052737 gold Inorganic materials 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 17
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 16
- 238000000137 annealing Methods 0.000 claims description 14
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 14
- 229910052759 nickel Inorganic materials 0.000 claims description 14
- 229910052719 titanium Inorganic materials 0.000 claims description 14
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 11
- 238000000151 deposition Methods 0.000 claims description 9
- 229910052721 tungsten Inorganic materials 0.000 claims description 9
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 8
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
- 229910017052 cobalt Inorganic materials 0.000 claims description 8
- 239000010941 cobalt Substances 0.000 claims description 8
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 8
- 229910052741 iridium Inorganic materials 0.000 claims description 8
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims description 8
- 239000011733 molybdenum Substances 0.000 claims description 8
- 229910052758 niobium Inorganic materials 0.000 claims description 8
- 239000010955 niobium Substances 0.000 claims description 8
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 8
- 229910052697 platinum Inorganic materials 0.000 claims description 8
- 229910052715 tantalum Inorganic materials 0.000 claims description 8
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 8
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 8
- 239000010937 tungsten Substances 0.000 claims description 8
- 229910052726 zirconium Inorganic materials 0.000 claims description 8
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 5
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- 239000010405 anode material Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 230000005684 electric field Effects 0.000 abstract description 18
- 230000000779 depleting effect Effects 0.000 abstract description 2
- QZQVBEXLDFYHSR-UHFFFAOYSA-N gallium(III) oxide Inorganic materials O=[Ga]O[Ga]=O QZQVBEXLDFYHSR-UHFFFAOYSA-N 0.000 description 18
- 238000005566 electron beam evaporation Methods 0.000 description 10
- 230000008569 process Effects 0.000 description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 6
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- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
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Abstract
The invention discloses a gallium oxide Schottky barrier diode and a preparation method thereof, wherein the gallium oxide Schottky barrier diode comprises a cathode, a Ga 2O3 substrate, a Ga 2O3 drift layer and an anode which are sequentially stacked, and acceptor ions are injected into a concentric annular region, close to one side surface of the anode, of the Ga 2O3 drift layer. According to the invention, the concentric annular high-resistance region formed by implanting acceptor ions into the concentric ring region on the surface of the Ga 2O3 drift layer can transversely expand a depletion layer and share a surface electric field, so that the electric field crowding at the edge of an anode is weakened, the electric field concentration is inhibited, the voltage resistance of the gallium oxide Schottky barrier diode is improved, the junction terminal region is prevented from being broken down, and meanwhile, the acceptor ion is used for implanting and depleting a nearby region, so that the reverse leakage current of a device can be reduced.
Description
Technical Field
The invention relates to the technical field of diodes, in particular to a gallium oxide Schottky barrier diode and a preparation method thereof.
Background
Ultra-wide band gap semiconductor gallium oxide (Ga 2O3) is a novel high-power semiconductor material which is rising in recent years. Ga 2O3 has five different structures, alpha-Ga 2O3、β-Ga2O3、γ-Ga2O3、δ-Ga2O3 and epsilon-Ga 2O3, respectively. The beta-Ga 2O3 with the monoclinic structure is the most stable, the energy band width can reach 4.9eV, the expected breakdown field intensity is up to 8MV/cm, the intrinsic electron mobility limit is 250cm 2/V.s, and the application of high voltage and high current can be realized. The critical electric field achieved by Ga 2O3 is up to 5.2MV/cm, exceeds the theoretical limit of SiC and GaN, and achieves electron mobility of 100-150cm 2/V.s in both Ga 2O3 substrate and epitaxial layer. In addition, another great advantage of Ga 2O3 over SiC and GaN is that it can be obtained by melt growth, while Ga 2O3 substrate obtained by melt growth has the advantages of large area low dislocation density (-10 2cm-2) and the like. The epitaxial layer with high quality, high mobility and controllable n-type doping obtained through the Ga 2O3 substrate lays a foundation for the development of power devices. In the last decade, although power devices based on Ga 2O3 have advanced, including Schottky Barrier Diodes (SBD) and Metal Oxide Semiconductor (MOS) field effect transistors, for example, by implementing advanced electric field management techniques to optimize device structures such as field plates, trenches, and implanted edge terminals, conventional gallium oxide vertical schottky barrier diodes (whose structure is schematically shown in fig. 1) have poor voltage withstand performance due to field concentration effects at junction termination regions where the anode metal contacts the gallium oxide drift layer, where they are broken down at lower voltages. Therefore, researchers adopt heterojunction structures to improve the pressure resistance, specifically, electrons on a PN heterojunction depleted gallium oxide drift layer are utilized to transfer the pressure resistance of the device from a junction terminal area to a depletion area, but the currently obtained P-type NiO film is amorphous, so that a large number of defects exist in the film, and the pressure resistance of the device is difficult to be greatly improved. How to obtain high performance devices with a relatively simple manufacturing process remains a considerable problem.
Accordingly, the prior art is still in need of improvement and development.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a gallium oxide schottky barrier diode and a preparation method thereof, which aims to solve the problem that the voltage-withstanding performance of the existing gallium oxide schottky barrier diode needs to be further improved.
The technical scheme of the invention is as follows:
According to a first aspect of the invention, a gallium oxide Schottky barrier diode is provided, wherein the gallium oxide Schottky barrier diode comprises a cathode, a Ga 2O3 substrate, a Ga 2O3 drift layer and an anode which are sequentially stacked, and acceptor ions are injected into a concentric annular region, close to one side surface of the anode, of the Ga 2O3 drift layer.
Optionally, the acceptor ions include at least one of N ions and Mg ions.
Optionally, the acceptor ions are implanted at a concentration of 1 x 10 18～5×1018/cm 3.
Optionally, the thickness of the concentric annular region is 1% -5% of the thickness of the Ga 2O3 drift layer.
Optionally, the width of each ring in the concentric ring shaped region is 2 to 20 μm and the spacing between the rings is 2 to 20 μm.
Optionally, the material of the cathode comprises at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium, and tungsten; the anode material comprises at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium and tungsten.
In a second aspect of the present invention, there is provided a method for preparing the gallium oxide schottky barrier diode according to the present invention, including the steps of:
providing a Ga 2O3 substrate;
Forming a Ga 2O3 drift layer on the Ga 2O3 substrate, injecting acceptor ions into the concentric annular region on the surface of the Ga 2O3 drift layer, and then performing first annealing;
Forming a cathode on the surface of the Ga 2O3 substrate on the side facing away from the Ga 2O3 drift layer;
an anode is formed on the surface of the concentric annular region of the Ga 2O3 drift layer.
Optionally, the temperature of the first annealing is 800-1100 ℃, and the time of the first annealing is 10-40 min.
Optionally, a Ga 2O3 drift layer is formed on the Ga 2O3 substrate by epitaxy.
Optionally, depositing a first metal on the surface of the Ga 2O3 substrate on the side facing away from the Ga 2O3 drift layer, and forming a cathode after performing a second annealing; and depositing a second metal on the surface of the concentric annular region of the Ga 2O3 drift layer to form an anode.
The beneficial effects are that: according to the invention, the concentric annular high-resistance region formed by implanting acceptor ions into the concentric annular region on the surface of the Ga 2O3 drift layer can transversely expand a depletion layer and share a surface electric field, so that the electric field crowding at the edge of an anode is weakened, the electric field concentration is inhibited, the voltage resistance of the gallium oxide Schottky barrier diode is improved, the junction terminal region is prevented from being broken down, and meanwhile, the acceptor ion is used for implanting and depleting a nearby region, so that the reverse leakage current of a device can be reduced.
Drawings
Fig. 1 is a schematic diagram of a gallium oxide schottky barrier diode in the prior art.
Fig. 2 is a schematic diagram of another gallium oxide schottky barrier diode according to the prior art.
Fig. 3 is a schematic diagram of a gallium oxide schottky barrier diode according to an embodiment of the invention.
Fig. 4 is a schematic diagram of a process flow of preparing a gallium oxide schottky barrier diode according to an embodiment of the invention, wherein (a) is a schematic diagram of forming a Ga 2O3 drift layer on a Ga 2O3 substrate; (b) Is a schematic diagram for injecting acceptor ions into a concentric annular region on the surface of the Ga 2O3 drift layer; (c) A schematic view for forming a cathode on a surface of the Ga 2O3 substrate on a side facing away from the Ga 2O3 drift layer; (d) Is a schematic illustration of forming an anode on the surface of the concentric annular region of the Ga 2O3 drift layer.
Detailed Description
The invention provides a gallium oxide Schottky barrier diode and a preparation method thereof, which are used for making the purposes, technical schemes and effects of the invention clearer and more definite, and are further described in detail below. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The terms such as "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
If there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated.
The embodiment of the invention provides a gallium oxide schottky barrier diode, which comprises a cathode 1, a Ga 2O3 substrate 2, a Ga 2O3 drift layer 3 and an anode 4 which are sequentially stacked, wherein acceptor ions are injected into a concentric annular region 31, which is close to one side surface of the anode 4, of the Ga 2O3 drift layer 2, as shown in fig. 3.
In this embodiment, the multiple guard ring structure is formed by using acceptor ion implantation, and the concentric annular high-resistance region formed by the acceptor ion implantation concentric annular region can laterally expand the depletion layer and share the surface electric field, weaken the electric field crowding at the edge of the anode, inhibit the electric field concentration, improve the withstand voltage performance of the gallium oxide schottky barrier diode, avoid the breakdown of the junction termination region, and simultaneously utilize the acceptor ion implantation to deplete the nearby region, so that the reverse leakage current of the device can be reduced.
In some embodiments, the acceptor ion includes at least one of N ion, mg ion, but is not limited thereto.
According to the embodiment of the invention, the leakage current and the saturation current of the device can be regulated and controlled by adjusting the implantation depth and concentration of acceptor ions and setting the width and the interval of each ring of the concentric ring region.
Thus, in some embodiments, the acceptor ions are implanted at a concentration of 1 x 10 18～5×1018 per cm 3 to form a high-resistance region.
In some embodiments, as shown in fig. 3, the thickness h1 of the concentric annular region (i.e., the implantation depth of acceptor ions) is 1% to 5% of the thickness h2 of the Ga 2O3 drift layer. The thickness of the concentric annular region is used to regulate the surface electric field and leakage current, but the thickness is too large to be process and cost prohibitive.
In some embodiments, the concentric annular region may be a concentric annular region, or may be a concentric square annular region.
In some embodiments, each ring in the concentric ring shaped region has a width of 2 to 20 μm (for example, if the rings are circular rings, the width of the rings is the outer circle radius minus the inner circle radius), and the spacing between the rings is 2 to 20 μm. The width and spacing may be biased according to device size and process requirements.
In some embodiments, the projected area of the concentric annular region on the Ga 2O3 substrate is 20% -80% of the projected area of the Ga 2O3 drift layer on the Ga 2O3 substrate. Thus, the device can be ensured to have smaller leakage current and larger saturation current.
In some specific embodiments, the concentric annular region, in an inside-out direction, has an outer contour projected by the outermost annular shape on the Ga 2O3 substrate coincident with an outer contour projected by the Ga 2O3 drift layer on the Ga 2O3 substrate.
In some embodiments, the material of the Ga 2O3 substrate comprises at least one of α-Ga2O3、β-Ga2O3、γ-Ga2O3、ε-Ga2O3、δ-Ga2O3.
In some specific embodiments, the material of the Ga 2O3 substrate is selected from at least one of n-type α -Ga 2O3, n-type β -Ga 2O3, n-type γ -Ga 2O3, n-type epsilon-Ga 2O3, n-type delta-Ga 2O3.
In further embodiments, the material of the Ga 2O3 substrate is n + -type Ga 2O3 (i.e., the electron concentration of n-type heavily doped Ga 2O3),n+ -type Ga 2O3 is 1X 10 18～2×1019cm-3; the material of the Ga 2O3 substrate is selected from at least one of n + -type alpha-Ga 2O3、n+ -type beta-Ga 2O3、n+ -type gamma-Ga 2O3、n+ -type epsilon-Ga 2O3、n+ -type delta-Ga 2O3, wherein the doping element includes, but is not limited to, at least one of Si, sn, ge, V, nb, ta, mo, W, sb.
In some embodiments, the thick bottom of the Ga 2O3 substrate is 100-1000 μm. For example, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, or the like can be used.
In some embodiments, the material of the Ga 2O3 drift layer includes at least one of α-Ga2O3、β-Ga2O3、γ-Ga2O3、ε-Ga2O3、δ-Ga2O3. In particular doped or unintentionally doped α-Ga2O3、β-Ga2O3、γ-Ga2O3、ε-Ga2O3、δ-Ga2O3.
In some specific embodiments, the material of the Ga 2O3 drift layer is selected from at least one of n-type α -Ga 2O3, n-type β -Ga 2O3, n-type γ -Ga 2O3, n-type epsilon-Ga 2O3, n-type delta-Ga 2O3.
In further embodiments, the material of the Ga 2O3 drift layer is n-type Ga 2O3 (i.e., an n-type lightly doped Ga 2O3 substrate), the electron concentration of n-type Ga 2O3 being 5 x 10 15～1×1017cm-3; the material of the Ga 2O3 drift layer is at least one selected from n-type alpha-Ga 2O3, n-type beta-Ga 2O3, n-type gamma-Ga 2O3, n-type epsilon-Ga 2O3 and n-type delta-Ga 2O3, wherein the doping element comprises at least one of Si, sn, ge, V, nb, ta.
In some embodiments, the thickness of the Ga 2O3 drift layer is 5-20 μm, for example, 5nm, 8nm, 10nm, 15nm, 18nm, 20nm, or the like.
In some embodiments, the material of the cathode includes at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium, tungsten, but is not limited thereto. In some embodiments, the cathode has a thickness of 50 to 200nm, which may be, for example, 50nm, 80nm, 100nm, 150nm, 200nm, or the like.
By way of example, when the material of the cathode is selected from titanium and gold, the cathode is composed of a laminated titanium layer and gold layer (which may be referred to as Ti/Au), wherein the thickness of the titanium layer may be 50nm, the thickness of the gold layer may be 150nm (the thickness of the Ti/Au layer may be referred to as 50/150 nm), and the titanium layer is disposed to be bonded to the Ga 2O3 substrate.
In some embodiments, the material of the anode includes at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium, tungsten, but is not limited thereto. In some embodiments, the anode has a thickness of 50 to 200nm, which may be, for example, 50nm, 80nm, 100nm, 150nm, 200nm, or the like. By way of example, when the material of the anode is selected from nickel and gold, the anode is composed of a laminated nickel layer and gold layer (which may be referred to as Ni/Au), wherein the thickness of the nickel layer may be 50nm, the thickness of the gold layer may be 150nm (the thickness of the Ni/Au layer may be referred to as 50/150 nm), and the nickel layer is disposed in conformity with the concentric annular region of the Ga 2O3 drift layer.
The embodiment of the invention also provides a preparation method of the gallium oxide Schottky barrier diode, which is disclosed by the embodiment of the invention, and comprises the following steps:
S1, providing a Ga 2O3 substrate;
S2, as shown in (a) and (b) in fig. 4, forming a Ga 2O3 drift layer 3 on the Ga 2O3 substrate 2, implanting acceptor ions (including but not limited to N ions, mg ions, etc.) into the concentric annular region 31 on the surface of the Ga 2O3 drift layer 3, and then performing a first annealing;
S3, as shown in fig. 4 (c), forming a cathode 1 on a surface of the Ga 2O3 substrate 2 on a side facing away from the Ga 2O3 drift layer 3;
S4, as shown in fig. 4 (d), an anode 4 is formed on the surface of the concentric annular region 31 of the Ga 2O3 drift layer.
The preparation process provided by the embodiment of the invention is simple, can be compatible with other processes (such as adding a field plate structure), does not need to carry out Inductively Coupled Plasma (ICP) etching, avoids etching damage, and ensures higher channel electron mobility. According to the embodiment of the invention, acceptor ions (such as N ions and Mg ions) are injected into the concentric annular region on the Ga 2O3 drift layer to form a high-resistance region, so that a depletion layer can be transversely expanded, a surface electric field is shared, electric field crowding at the edge of an anode is weakened, electric field concentration is inhibited, the withstand voltage performance of the gallium oxide Schottky barrier diode is improved, a junction terminal region is prevented from being broken down, and meanwhile, the acceptor ions are injected into a nearby region to be depleted, so that reverse leakage current of a device is reduced.
In step S1, the material, thickness, doping element, electron concentration, etc. of the Ga 2O3 substrate are as described above, and will not be described in detail herein.
In step S2, before forming the Ga 2O3 drift layer on the Ga 2O3 substrate, the method further includes a step of cleaning the Ga 2O3 substrate.
In some embodiments, a Ga 2O3 drift layer is formed on the Ga 2O3 substrate by epitaxy; the material, thickness and doping elements, electron concentration, etc. of the Ga 2O3 drift layer are as described above and will not be described in detail herein.
In some embodiments, a high quality low roughness Ga 2O3 drift layer is formed on a Ga 2O3 substrate by an epitaxial process including, but not limited to, metal Organic Chemical Vapor Deposition (MOCVD), molecular Beam Epitaxy (MBE), hydride Vapor Phase Epitaxy (HVPE), and the like.
In some embodiments, the temperature of the first anneal is 800 to 1100 ℃ and the time of the first anneal is 10 to 40 minutes. In this way, acceptor ions can be efficiently activated.
In step S3, in some embodiments, a first metal is deposited on the surface of the Ga 2O3 substrate facing away from the Ga 2O3 drift layer, and after a second anneal (to form an ohmic contact between the cathode and the Ga 2O3 substrate), a cathode is formed. In particular, a first metal material may be deposited on a surface of the Ga 2O3 substrate on a side facing away from the Ga 2O3 drift layer using methods including, but not limited to, electron beam evaporation or sputtering.
In some embodiments, the first metal includes at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium, tungsten, but is not limited thereto.
In some specific embodiments, ti and Au are sequentially deposited on the surface of the Ga 2O3 substrate on the side away from the Ga 2O3 drift layer by using an electron beam evaporation method, so as to form a Ti/Au layer (the thickness is 50/150 nm), the Ti layer is attached to the Ga 2O3 substrate, and metal stripping is performed by using a Lift-Off (Lift-Off) process, so as to form a cathode.
In step S4, in some embodiments, a second metal is deposited on the surface of the concentric annular region of the Ga 2O3 drift layer, forming an anode. In particular, a second metal material may be deposited on the surface of the concentric annular region of the Ga 2O3 drift layer using a process including, but not limited to, electron beam evaporation or sputtering.
In some embodiments, the second metal includes at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium, tungsten, but is not limited thereto.
In some specific embodiments, ni and Au are sequentially deposited on the surface of the concentric annular region of the Ga 2O3 drift layer by adopting an electron beam evaporation method to form a Ni/Au (the thickness is 50/150 nm) layer, the Ni layer is attached to the surface of the concentric annular region of the Ga 2O3 drift layer, and metal stripping is carried out by utilizing a Lift-Off (Lift-Off) process to form the anode.
The following is a detailed description of specific examples.
Example 1
The embodiment provides a preparation method of a gallium oxide Schottky barrier diode, which comprises the following steps:
(1) Providing an n + type beta-Ga 2O3 substrate with the thickness of 650 mu m, which is doped with Sn and has the electron concentration of 1 multiplied by 10 19cm-3, sequentially ultrasonically cleaning the substrate for 5min by acetone and isopropanol, flushing the substrate by a large amount of deionized water, and drying the substrate by nitrogen;
(2) Using TMGa and O 2 as gallium source and oxygen source, siH 4 as doping source, adopting MOCVD method to make epitaxial growth on the n + type beta-Ga 2O3 substrate to obtain n-type beta-Ga 2O3 drift layer with thickness of 10 μm, which is doped with Si and electron concentration of 2×10 16cm-3;
(3) N ions (the implantation concentration of the N ions is 2×10 18/cm 3) are implanted by an ion implanter in a concentric annular region with the surface thickness of the N-type β -Ga 2O3 drift layer of 200nm (the projection area of the concentric annular region on the N + type β -Ga 2O3 substrate occupies 77% of the projection area of the N-type β -Ga 2O3 drift layer on the N + type β -Ga 2O3 substrate, the concentric annular region has 4 annular shapes in total, the widths of the annular shapes are 5 μm, 5 μm and 20 μm respectively from the center to the outside, and the intervals between the annular shapes are 5 μm), and then the N ions are activated by annealing at 900 ℃ for 20 min;
(4) Depositing Ti and Au on the surface of the n + -type beta-Ga 2O3 substrate on the side away from the n-type beta-Ga 2O3 drift layer by utilizing an electron beam evaporation method to obtain a Ti/Au layer with the thickness of 50/150nm, then placing the Ti/Au layer into stripping liquid for stripping, and annealing for 1min at the temperature of 475 ℃ to form a cathode;
(5) And depositing Ni and Au on the surface of the concentric annular region of the n-type beta-Ga 2O3 drift layer by using an electron beam evaporation method to obtain a Ni/Au layer with the thickness of 50/150nm, and then putting the Ni/Au layer into stripping liquid for stripping to form an anode so as to obtain the gallium oxide Schottky barrier diode.
Example 2
The embodiment provides a preparation method of a gallium oxide Schottky barrier diode, which comprises the following steps:
(1) Providing an n + type beta-Ga 2O3 substrate with the thickness of 100 mu m, which is V-doped and has the electron concentration of 5 multiplied by 10 18cm-3, sequentially ultrasonically cleaning the substrate for 5min by acetone and isopropanol, flushing the substrate by a large amount of deionized water, and drying the substrate by nitrogen;
(2) Respectively taking TMGa and O 2 as a gallium source and an oxygen source, taking (C 2H5)4 Sn as a doping source, and adopting an MOCVD method to carry out epitaxial growth on the n + type beta-Ga 2O3 substrate to obtain an n-type beta-Ga 2O3 drift layer with the thickness of 5 mu m, wherein the Sn doping is carried out, and the electron concentration is 1 multiplied by 10 17cm-3;
(3) N ions (the implantation concentration of the N ions is 1×10 18/cm 3) are implanted by an ion implanter in a concentric annular region with the surface thickness of the N-type β -Ga 2O3 drift layer of 100nm (the projection area of the concentric annular region on the N + type β -Ga 2O3 substrate occupies 70% of the projection area of the N-type β -Ga 2O3 drift layer on the N + type β -Ga 2O3 substrate, the concentric annular region has 5 annular shapes in total, the widths of the annular shapes are 3 μm, 3 μm and 10 μm respectively, and the interval between the annular shapes is 5 μm) from the center to the outside, and then the N ions are activated by annealing at 800 ℃ for 10min;
(4) Depositing Ti and Au on the surface of the n + -type beta-Ga 2O3 substrate on the side away from the n-type beta-Ga 2O3 drift layer by utilizing an electron beam evaporation method to obtain a Ti/Au layer with the thickness of 50/150nm, then placing the Ti/Au layer into stripping liquid for stripping, and annealing for 1min at the temperature of 475 ℃ to form a cathode;
(5) And depositing Ni and Au on the surface of the concentric circular area of the n-type beta-Ga 2O3 drift layer by using an electron beam evaporation method to obtain a Ni/Au layer with the thickness of 50/150nm, and then putting the Ni/Au layer into stripping liquid to strip the Ni/Au layer to form an anode so as to obtain the gallium oxide Schottky barrier diode.
Example 3
The embodiment provides a preparation method of a gallium oxide Schottky barrier diode, which comprises the following steps:
(1) Providing an n + type beta-Ga 2O3 substrate with the thickness of 1000 mu m, which is doped with Si and has the electron concentration of 1 multiplied by 10 19cm-3, sequentially ultrasonically cleaning the substrate for 5min by acetone and isopropanol, flushing the substrate by a large amount of deionized water, and drying the substrate by nitrogen;
(2) Respectively using TMGa and O 2 as a gallium source and an oxygen source, and carrying out epitaxial growth on the n + type beta-Ga 2O3 substrate by adopting an MOCVD method to obtain an n type beta-Ga 2O3 drift layer with the thickness of 20 mu m, wherein the n type beta-Ga 2O3 drift layer is undoped, and the electron concentration is 5 multiplied by 10 15cm-3;
(3) N ions (the implantation concentration of the N ions is 5×10 18/cm 3) were implanted by an ion implanter in a concentric annular region (the projection area of which on an N + type β -Ga 2O3 substrate accounts for 55% of the projection area of the N type β -Ga 2O3 drift layer on an N + type β -Ga 2O3 substrate) with a surface thickness of 400nm in the above N type β -Ga 2O3 drift layer, the concentric annular region having a total of 4 annular rings, the width of each annular ring being 10 μm, 20 μm, and the spacing between the annular rings being 15 μm from the center, and then annealed at 1100 ℃ for 30min to activate the N ions;
(4) Depositing Ti and Au on the surface of the n + type beta-Ga 2O3 substrate on the side away from the n type beta-Ga 2O3 drift layer by utilizing an electron beam evaporation method to obtain a Ti/Au layer with the thickness of 50/150nm, then placing the Ti/Au layer into stripping liquid for stripping, and annealing for 1min at the temperature of 475 ℃ to form a cathode;
(5) And depositing Ni and Au on the surface of the concentric circular area of the n-type beta-Ga 2O3 drift layer by using an electron beam evaporation method to obtain a Ni/Au layer with the thickness of 50/150nm, and then putting the Ni/Au layer into stripping liquid to strip the Ni/Au layer to form an anode so as to obtain the gallium oxide Schottky barrier diode.
In summary, the gallium oxide schottky barrier diode and the preparation method thereof form a multiple guard ring structure by using acceptor ion implantation, and the concentric annular high-resistance region formed by the acceptor ion implantation concentric annular region can laterally expand a depletion layer, share a surface electric field, weaken electric field crowding at the edge of an anode, inhibit electric field concentration, improve the voltage resistance of the gallium oxide schottky barrier diode, avoid breakdown of a junction terminal region, and simultaneously use the acceptor ion implantation depletion nearby region to reduce reverse leakage current of a device. The preparation process provided by the invention is simple, and can be compatible with other processes, such as adding a field plate structure, and the prepared device has excellent performance.
It is to be understood that the invention is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.
Claims (10)
1. The gallium oxide Schottky barrier diode is characterized by comprising a cathode, a Ga 2O3 substrate, a Ga 2O3 drift layer and an anode which are sequentially stacked, wherein acceptor ions are injected into a concentric annular area, which is close to one side surface of the anode, of the Ga 2O3 drift layer.
2. The gallium oxide schottky barrier diode of claim 1, wherein the acceptor ions comprise at least one of N ions, mg ions.
3. The gallium oxide schottky barrier diode of claim 1, wherein the acceptor ions are implanted at a concentration of 1 x 10 18～5×1018/cm 3.
4. The gallium oxide schottky barrier diode of claim 1, wherein the concentric annular region has a thickness of 1-5% of the thickness of the Ga 2O3 drift layer.
5. The gallium oxide schottky barrier diode of claim 1, wherein each ring in the concentric ring-shaped region has a width of 2-20 μm and a spacing between rings of 2-20 μm.
6. The gallium oxide schottky barrier diode of claim 1, wherein the material of the cathode comprises at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium, tungsten; the anode material comprises at least one of titanium, gold, aluminum, nickel, platinum, iridium, molybdenum, tantalum, niobium, cobalt, zirconium and tungsten.
7. A method of making a gallium oxide schottky barrier diode as defined in any one of claims 1-6, comprising the steps of:
providing a Ga 2O3 substrate;
Forming a Ga 2O3 drift layer on the Ga 2O3 substrate, injecting acceptor ions into the concentric annular region on the surface of the Ga 2O3 drift layer, and then performing first annealing;
Forming a cathode on the surface of the Ga 2O3 substrate on the side facing away from the Ga 2O3 drift layer;
an anode is formed on the surface of the concentric annular region of the Ga 2O3 drift layer.
8. The method according to claim 7, wherein the temperature of the first annealing is 800 to 1100 ℃, and the time of the first annealing is 10 to 40 minutes.
9. The method of claim 7, wherein a Ga 2O3 drift layer is formed on the Ga 2O3 substrate by epitaxy.
10. The method according to claim 7, wherein a first metal is deposited on a surface of the Ga 2O3 substrate on a side facing away from the Ga 2O3 drift layer, and a cathode is formed after a second annealing; and depositing a second metal on the surface of the concentric annular region of the Ga 2O3 drift layer to form an anode.
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