阅读说明：本技术 新型GaN结势垒肖特基二极管及其制备方法 (Novel GaN junction barrier Schottky diode and preparation method thereof ) 是由 黎大兵 刘新科 孙晓娟 贾玉萍 石芝铭 于 2019-10-31 设计创作，主要内容包括：新型GaN结势垒肖特基二极管及其制备方法利用新颖的设计及相对简单易达成的工艺为提高肖特基二极管的性能提供了新途径。新型GaN结势垒肖特基二极管,二极管由下到上依次包括：阴极、衬底、n<Sup>+</Sup>型GaN外延层、n型GaN外延层、在n型GaN外延层的外沿上环形注入等离子体形成的高阻区、梳状的p型GaN外延层、梳状的p<Sup>+</Sup>型GaN外延层和阳极。本专利无需在n型GaN层内再生长p型GaN以及后续的激活工艺,大大降低了工艺难度和复杂程度。通过4层外延GaN结构,能形成良好的欧姆接触以及更好的PN结,降低了正向导通电阻及增加了反向击穿电压,有效提高了器件的性能。另外,N<Sub>2</Sub> Plasma形成的高阻区能有效抑制器件在高压下位于电极边缘的击穿,增强了击穿性能。(The novel GaN junction barrier Schottky diode and the preparation method thereof provide a new way for improving the performance of the Schottky diode by utilizing novel design and relatively simple and easy-to-achieve process. Novel GaN junction barrier Schottky diode, the diode includes by lower to last in proper order: cathode, substrate, n + A type GaN epitaxial layer, an n-type GaN epitaxial layer, a high resistance region formed by annularly injecting plasma on the outer edge of the n-type GaN epitaxial layer, a comb-shaped p + A type GaN epitaxial layer and an anode. According to the method, p-type GaN does not need to be regrown in the n-type GaN layer and a subsequent activation process, so that the process difficulty and complexity are greatly reduced. Through the 4-layer epitaxial GaN structure, good ohmic contact and better PN junction can be formed, the forward on-resistance is reduced, the reverse breakdown voltage is increased, and the performance of the device is effectively improved. In addition, N 2 The high-resistance region formed by the Plasma can effectively inhibit the breakdown of the device at the edge of the electrode under high voltage, and the breakdown performance is enhanced.)

1. Novel GaN junction barrier Schottky diode, its characterized in that, the diode includes by lower to last in proper order: cathode, substrate, n⁺A type GaN epitaxial layer, an n-type GaN epitaxial layer, a high resistance region formed by annularly injecting plasma on the outer edge of the n-type GaN epitaxial layer, a comb-shaped p⁺A type GaN epitaxial layer and an anode.

2. The novel GaN junction barrier schottky diode of claim 1 wherein the substrate is made of: gallium nitride, silicon, and silicon carbide substrates.

3. The novel GaN junction barrier schottky diode of claim 1Wherein n is⁺Type GaN epitaxial layer, n-type GaN epitaxial layer, comb-shaped p-type GaN epitaxial layer and comb-shaped p⁺The growth method of the GaN epitaxial layer is organic chemical vapor deposition or hydride vapor phase epitaxy.

4. The novel GaN junction barrier schottky diode of claim 1 wherein the n is⁺The thickness of the GaN epitaxial layer is 2 μm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a The thickness of the n-type GaN epitaxial layer is 23 μm, and the carrier concentration is about 8x10¹⁵cm^-3(ii) a The thickness of the comb-shaped p-type GaN epitaxial layer is 500nm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a Comb-shaped p⁺The thickness of the GaN epitaxial layer is 30nm, and the carrier concentration is about 1.5x10²⁰cm^-3。

5. The GaN junction barrier schottky diode of claim 1 wherein the plasma is N₂Or Ar.

6. The GaN junction barrier schottky diode as claimed in claim 1, wherein the cathode is formed by evaporating a metal film by thermal evaporation, magnetron sputtering or electron beam evaporation, and forming an electrode by lift-off process at 650 ℃, N₂And annealing under the environment.

7. The method for fabricating a novel GaN junction barrier schottky diode as claimed in claims 1 to 7, wherein the method comprises the steps of:

the method comprises the following steps: sequentially growing n on a substrate by organic chemical vapor deposition or hydride vapor phase epitaxy⁺Type GaN epitaxial layer, n-type GaN epitaxial layer, p-type GaN epitaxial layer, and p⁺A GaN epitaxial layer;

step two: at said p⁺Growing a layer of SiN on the upper surface of the GaN epitaxial layer through plasma enhanced chemical vapor deposition or atomic layer deposition;

step three: preparing a cathode of an ohmic contact electrode on the back of the substrate through thermal evaporation, magnetron sputtering or electron beam evaporation;

step four: etching the p-type GaN epitaxial layer and the p-type GaN epitaxial layer on the SiN surface by a dry method⁺Preparing a comb-mounted structure by using the GaN epitaxial layer, and then removing the SiN layer;

step five: preparing a circular high-resistance region on the upper surface of the n-type GaN epitaxial layer through photoetching and plasma injection;

step six: in the high resistance region and comb-mounting p⁺And evaporating the anode of the ohmic contact electrode on the GaN epitaxial layer to complete the manufacture method of the novel GaN junction barrier Schottky diode.

8. The method of claim 7, wherein n in the first step⁺The thickness of the GaN epitaxial layer is 2 μm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a The thickness of the n-type GaN epitaxial layer is 23 μm, and the carrier concentration is about 8x10¹⁵cm^-3(ii) a The thickness of the comb-shaped p-type GaN epitaxial layer is 500nm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a Comb-shaped p⁺The thickness of the GaN epitaxial layer is 30nm, and the carrier concentration is about 1.5x10²⁰cm^-3。

9. The method according to claim 7, wherein silane hydride is used as n in the first step⁺GaN-type doped Si source material, and cyclopentadienyl magnesium can be used as p⁺Type GaN doped Mg feedstock.

10. The method according to claim 7, wherein in the third step, the cathode is formed by evaporating a metal film by thermal evaporation, magnetron sputtering, electron beam evaporation, or the like, and the electrode is formed by a lift-off process at 650 ℃ and N₂And annealing under the environment.

Technical Field

The invention belongs to the technical field of semiconductors, and particularly relates to a novel GaN junction barrier Schottky diode and a preparation method thereof.

Background

In recent years, high importance and wide application are brought to the improvement of the efficiency of a circuit system due to the low conduction voltage drop and the extremely short reverse recovery time of a Schottky Barrier Diode (SBD). The conventional schottky diode has the following defects: (1) the forward voltage drop V of the Schottky rectifier is close to 200V due to the reverse blocking capability_FWill approach the forward voltage drop of the PIN rectifier and therefore the reverse blocking voltage of conventional schottky barrier diodes is typically below 200V, making them less efficient in application. (2) The reverse leakage current of the conventional schottky diode is large and sensitive to temperature, and the junction temperature of the conventional schottky diode is between 125 ℃ and 175 ℃.

Based on the above defects, a Junction Barrier Schottky (JBS) becomes a hot point of research as an enhancement Schottky, and a Junction Barrier Schottky structure is typically characterized in that a plurality of PN junctions integrated on an epitaxial layer of a conventional Schottky diode are comb-shaped. The Schottky contact part of the junction barrier Schottky diode is conducted when the junction barrier Schottky diode is in zero bias and forward bias, and the PN junction part is not conducted; when the junction barrier Schottky diode is reversely biased, a PN junction depletion region is widened to pinch off a current channel, so that the Schottky barrier lowering effect is effectively inhibited, and the reverse leakage current is effectively controlled. The junction barrier schottky diode has the outstanding advantage of possessing the on-state and fast switching characteristics of the schottky barrier diode, as well as the off-state and low leakage current characteristics of the PIN diode.

The conventional JBS device needs to etch an n-type epitaxial layer and then regrow a p-type epitaxial layer in the n-type epitaxial layer, and needs to anneal for many times at the temperature of 1100 ℃ to complete the activation of the p-type epitaxial layer, so that the process difficulty and complexity of the device are greatly increased, and the development of a gallium nitride-based JBS structure device is limited. In addition, similar to a Schottky Barrier Diode (SBD), the electric field intensity at the positive electrode edge of the JBS is high, easily causing reverse breakdown of the device.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a novel GaN junction barrier Schottky diode and a preparation method thereof, and provides a new way for improving the performance of the Schottky diode by utilizing a novel design and a relatively simple and easily achieved process.

The technical scheme adopted by the invention for solving the technical problem is as follows:

novel GaN junction barrier Schottky diode, the diode includes by lower to last in proper order: cathode, substrate, n⁺A type GaN epitaxial layer, an n-type GaN epitaxial layer, a high resistance region formed by annularly injecting plasma on the outer edge of the n-type GaN epitaxial layer, a comb-shaped p⁺A type GaN epitaxial layer and an anode.

Preferably, the substrate is made of: gallium nitride, silicon, and silicon carbide substrates.

Preferably, said n⁺Type GaN epitaxial layer, n-type GaN epitaxial layer, comb-shaped p-type GaN epitaxial layer and comb-shaped p⁺The growth method of the GaN epitaxial layer is organic chemical vapor deposition or hydride vapor phase epitaxy.

Preferably, said n⁺The thickness of the GaN epitaxial layer is 2 μm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a The thickness of the n-type GaN epitaxial layer is 23 μm, and the carrier concentration is about 8x10¹⁵cm^-3(ii) a The thickness of the comb-shaped p-type GaN epitaxial layer is 500nm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a Comb-shaped p⁺The thickness of the GaN epitaxial layer is 30nm, and the carrier concentration is about 1.5x10²⁰cm^-3。

Preferably, the plasma is N₂Or Ar.

Preferably, the cathode is formed by evaporating a metal film by thermal evaporation, magnetron sputtering, electron beam evaporation, or the like, forming an electrode by a lift-off process, and then performing N deposition at 650 DEG C₂And annealing under the environment.

The manufacturing method of the novel GaN junction barrier Schottky diode comprises the following steps:

the method comprises the following steps: sequentially growing n on a substrate by organic chemical vapor deposition or hydride vapor phase epitaxy⁺Type GaN epitaxial layer, n-type GaN epitaxial layer, p-type GaN epitaxial layer, and p⁺A GaN epitaxial layer;

step two: at said p⁺Growing a layer of SiN on the upper surface of the GaN epitaxial layer through plasma enhanced chemical vapor deposition or atomic layer deposition;

step three: preparing a cathode of an ohmic contact electrode on the back of the substrate through thermal evaporation, magnetron sputtering or electron beam evaporation;

step four: etching the p-type GaN epitaxial layer and the p-type GaN epitaxial layer on the SiN surface by a dry method⁺Preparing a comb-mounted structure by using the GaN epitaxial layer, and then removing the SiN layer;

step five: preparing a circular high-resistance region on the upper surface of the n-type GaN epitaxial layer through photoetching and plasma injection;

step six: in the high resistance region and comb-mounting p⁺And evaporating the anode of the ohmic contact electrode on the GaN epitaxial layer to complete the manufacture method of the novel GaN junction barrier Schottky diode.

Preferably, n in said step one⁺The thickness of the GaN epitaxial layer is 2 μm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a The thickness of the n-type GaN epitaxial layer is 23 μm, and the carrier concentration is about 8x10¹⁵cm^-3(ii) a The thickness of the comb-shaped p-type GaN epitaxial layer is 500nm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a Comb-shaped p⁺The thickness of the GaN epitaxial layer is 30nm, and the carrier concentration is about 1.5x10²⁰cm^-3。

Preferably, in step one, hydrosilane is used as n⁺GaN-type doped Si source material, and cyclopentadienyl magnesium can be used as p⁺Type GaN doped Mg feedstock.

Preferably, in the third step, the cathode is evaporated with a metal film by thermal evaporation, magnetron sputtering or electron beam evaporation, and the like, and the electrode is formed by a stripping process at 650 ℃ and N₂And annealing under the environment.

The invention has the beneficial effects that: the novel GaN JBS device provided by the patent is in operationIn the aspect of process flow, p-type GaN does not need to be grown in the n-type GaN layer and a subsequent activation process is not needed, and the process difficulty and complexity are greatly reduced. In the aspect of device structure, a good ohmic contact and a better PN junction can be formed through a 4-layer epitaxial GaN structure, the forward on-resistance is reduced, the reverse breakdown voltage is increased, and the performance of the device is effectively improved. In addition, N₂The high-resistance region formed by the Plasma can effectively inhibit the breakdown of the device at the edge of the electrode under high voltage, and the breakdown performance is enhanced. The method provided by the patent is an effective new way for improving the performance of the GaN-based Schottky barrier diode. The invention has the advantages of simple process, obvious effect, wide application prospect and the like.

Drawings

FIG. 1 is a schematic diagram of a novel GaN junction barrier Schottky diode structure according to the present invention.

Fig. 2 is a schematic diagram of a first step and a second step of the manufacturing method of the novel GaN junction barrier schottky diode of the present invention.

Fig. 3 is a schematic diagram of a third step of the manufacturing method of the novel GaN junction barrier schottky diode of the present invention.

Fig. 4 is a schematic diagram showing a fourth step of the manufacturing method of the novel GaN junction barrier schottky diode of the present invention.

Fig. 5 is a schematic diagram showing a fifth step of the manufacturing method of the novel GaN junction barrier schottky diode of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

As shown in fig. 1, the novel GaN junction barrier schottky diode sequentially includes, from bottom to top: cathode, substrate, n⁺A type GaN epitaxial layer, an n-type GaN epitaxial layer, a high resistance region formed by annularly injecting plasma on the outer edge of the n-type GaN epitaxial layer, a comb-shaped p⁺A type GaN epitaxial layer and an anode. Wherein the substrate may be of a material: gallium nitride, silicon, and silicon carbide substrates. N is⁺Type GaN epitaxial layer, n-type GaN epitaxial layer, comb-shaped p-type GaN epitaxial layer and comb-shaped p⁺The growth method of the GaN epitaxial layer is organic chemical vapor deposition or hydride vapor phase epitaxy. In thatIn this embodiment, n is⁺The thickness of the GaN epitaxial layer is 2 μm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a The thickness of the n-type GaN epitaxial layer is 23 μm, and the carrier concentration is about 8x10¹⁵cm^-3(ii) a The thickness of the comb-shaped p-type GaN epitaxial layer is 500nm, and the carrier concentration is about 1.5x10¹⁸cm^-3(ii) a Comb-shaped p⁺The thickness of the GaN epitaxial layer is 30nm, and the carrier concentration is about 1.5x10²⁰cm^-3. Wherein the thickness of the epitaxial layer and the concentration of the carriers can be properly adjusted and changed.

In a high resistance region formed by annularly injecting plasma H into the outer edge of the n-type GaN epitaxial layer₂、N₂F or Ar.

In the electrode material of the novel GaN junction barrier Schottky diode, the cathode is evaporated with a metal film by methods such as thermal evaporation, magnetron sputtering or electron beam evaporation, and the like, and the electrode is formed by a stripping process at 650 ℃ and N₂And annealing under the environment. The electrode material type in the invention is Ni/Au, Pt and other electrode materials which can form Schottky type gold half contact with n-type GaN; the electrode material of the cathode of the device is Ti/Al, Ti/Al/Ni/Au and other materials capable of forming ohmic gold half-contact with the n-type GaN.

The manufacturing method of the barrier Schottky diode based on the novel GaN junction comprises the following steps:

the method comprises the following steps: as shown in FIG. 2, 2 μm n was sequentially grown on a double-side polished n-type highly doped self-supporting GaN substrate by organic chemical vapor deposition or hydride vapor phase epitaxy⁺Type GaN epitaxial layer, 23 μm n-type GaN epitaxial layer, 500 μm p-type GaN epitaxial layer, and 30 μm p⁺A type GaN epitaxial layer in which hydrido silane can be used as Si source for n-type dopants (donor) and cyclopentadienyl magnesium can be used as Mg source for p-type dopants (acceptor).

Step two: at said p⁺Growing a layer of 20 μm SiN on the upper surface of the GaN epitaxial layer by plasma enhanced chemical vapor deposition or atomic layer deposition to protect the surface of the structure, wherein the SiN may be SiO₂Or Al₂O₃Replacement;

step three: preparing a cathode of an ohmic contact electrode on the back of the substrate through thermal evaporation, magnetron sputtering or electron beam evaporation, and adopting a TI/Al/Ti/Au metal film;

step four: passing Cl on the surface of the SiN₂/SiCl₄Dry etching to separate p-type GaN epitaxial layer and p⁺Preparing a ring-shaped comb structure from the GaN epitaxial layer, and removing the SiN layer by dry etching;

step five: a barrier layer is manufactured on the upper surface of the n-type GaN epitaxial layer through a photoetching process, and H is passed through₂、N₂F or Ar plasma is injected into the upper surface of the n-type GaN epitaxial layer to prepare a circular high-resistance region so as to form a terminal structure;

step six: in the high resistance region and comb-mounting p⁺And evaporating anode Ni (10nm)/Au (125nm) of the ohmic contact electrode on the type GaN epitaxial layer to complete the manufacturing method of the novel GaN junction barrier Schottky diode.

In this embodiment, n in the first step⁺Type GaN has a carrier concentration of about 1.5x10¹⁸cm^-3(ii) a The carrier concentration of n-type GaN was about 8x10¹⁵cm^-3(ii) a The carrier concentration of comb-shaped p-type GaN was about 1.5x10¹⁸cm^-3(ii) a Comb-shaped p⁺Type GaN has a carrier concentration of about 1.5x10²⁰cm^-3。