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CN-115621327-B - JBS power diode based on self-assembled Ni nano island and preparation method thereof

CN115621327BCN 115621327 BCN115621327 BCN 115621327BCN-115621327-B

Abstract

The invention provides a JBS power diode based on self-assembled Ni nanometer islands and a preparation method thereof. The diode comprises a cathode, an N+ substrate, a JBS structure and an anode which are sequentially arranged from bottom to top, wherein the JBS structure comprises an N-drift layer, a PN heterojunction and a Ni nanometer island, a groove structure is arranged on the N-drift layer, the PN heterojunction is formed by P-type metal oxides positioned on the inner side surface and the bottom of the groove and the N-drift layer, the Ni nanometer island is positioned on the top of the groove and forms Schottky contact with the N-drift layer, and the PN heterojunction is connected in parallel with the Schottky contact. The invention uses the self-assembled nanometer island formed by the Ni film under the rapid thermal annealing as a mask instead of photoresist, thereby omitting the step of photoetching, greatly simplifying the preparation process, shortening the preparation period and saving the cost.

Inventors

  • YE JIANDONG
  • HU TIANCHENG
  • GONG HEHE
  • YU XINXIN
  • XU YANG
  • ZHANG YIJUN
  • REN FANGFANG
  • GU SHULIN
  • ZHANG RONG

Assignees

  • 南京大学

Dates

Publication Date
20260512
Application Date
20210714

Claims (6)

  1. 1. The preparation method of the JBS power diode based on the self-assembled Ni nano island is characterized by comprising the steps of evaporating a layer of Ni film on the surface of a substrate, performing rapid thermal annealing, etching an N-drift layer by using the self-assembled Ni nano island formed by the Ni film under the rapid thermal annealing as a metal mask to form a groove structure, growing P-type metal oxide in the groove structure, forming a lateral PN heterojunction between the metal oxide positioned on the inner side surface and the bottom of the groove and the N-drift layer, and connecting the lateral PN heterojunction with Schottky contact formed by the Ni nano island at the top of the groove in parallel, thereby forming the JBS structure.
  2. 2. The preparation method according to claim 1, wherein the specific steps of the method are as follows: (1) Evaporating a layer of Ni film on the surface of the substrate by utilizing an electron beam evaporation technology; (2) Carrying out rapid thermal annealing on the sample evaporated in the step (1) to enable the Ni film to form a self-assembled Ni nano island; (3) Etching the N-drift layer by using the Ni nano island as a mask and using an ICP (inductively coupled plasma) process to form a groove structure; (4) Evaporating Ti and Au on the back of the substrate by utilizing electron beam evaporation; (5) Carrying out rapid thermal annealing on the sample evaporated in the step (4) to enable the sample to form back titanium Jin Oum for contact; (6) Covering the surface of the sample with a hard mask, and growing hundred-nanometer-level P-type metal oxide on the groove structure by utilizing magnetron sputtering; (7) And evaporating Ni and Au on the surface of the sample by utilizing electron beam evaporation to prepare the front nickel-gold electrode.
  3. 3. The method according to claim 2, wherein in the step (1), the thickness of the Ni thin film is 5 to 15 nm a.
  4. 4. The method according to claim 2, wherein in the step (2), the rapid thermal annealing is performed for a time of 1 to 5min and the annealing temperature is 850 ℃.
  5. 5. The method according to claim 2, wherein in the step (2), the Ni nano islands have a diameter of 100 to 500 nm and a pitch of hundred nanometers.
  6. 6. The method according to claim 2, wherein in the step (6), the thickness of the P-type metal oxide is 100 to 300 nm a.

Description

JBS power diode based on self-assembled Ni nano island and preparation method thereof Technical Field The invention relates to the field of ultra-wide band-gap semiconductor power devices, in particular to a novel self-assembled Ni nano island-based JBS power diode and a preparation method thereof. Background The ultra-wide band gap semiconductor represented by diamond, ga 2O3, alN and other materials shows a band gap width far greater than that of the traditional wide band gap semiconductor (GaN, siC and the like), and has wide application prospect in the fields of power devices, radio frequency devices and the like. Ga 2O3 is used as an ultra-wide band-gap semiconductor, has a larger band gap (4.5-4.9 eV) and high breakdown field strength (8 MV/cm), has a Baliga figure of merit higher than 3000 and is about 5 to 10 times that of GaN and SiC, and is easy to carry out n-type controllable doping in the concentration range of 10 16cm-3 to 10 19cm-3. Ga 2O3 has five phases of alpha, beta, gamma, epsilon, kappa, among which beta-Ga 2O3 has the best thermal stability and a high quality single crystal is easily produced by a melt growth method. So most of the research related to Ga 2O3 power devices is based on beta-Ga 2O3. However, ga 2O3 still faces a number of technical challenges in research. At present, stable P-type doping of Ga 2O3 is difficult to realize, so that related researches are mainly focused on unipolar devices such as Schottky diodes (SBDs). Although SBD has advantages of high switching speed and low forward voltage drop compared to PN junction, reverse breakdown voltage is relatively low and reverse leakage current is serious. In contrast, the Junction barrier schottky diode (JBS) structure integrates the advantages of low SBD forward conduction loss and high PN Junction reverse breakdown voltage, low off-state loss, and the like. The conventional JBS structure is realized by photoetching a pattern on the surface of a substrate, etching the substrate by taking photoresist as a mask to form a groove, growing P-type material in the groove, removing the photoresist, evaporating metal and forming Schottky contact with the substrate. The P-type material forms a lateral PN junction with the N-type substrate when in reverse bias, and the current in the middle part is pinched off, so that the Schottky junction with a lower potential barrier is shielded, and better reverse characteristic than that of the traditional SBD is obtained. In the preparation process, the substrate etching is not needed, the photoresist is taken as a mask to directly grow the P-type material, and the metal is evaporated after the photoresist is stripped. JBS structures have been implemented in Ga 2O3 (e.g., Q.Yan, H.Gong, J.Zhang et al, appl. Phys. Lett.118,122102 (2021), but substrate etching, material growth, however, necessitates masking of a portion of the area to form the JBS structure, while hard masking does not enable patterns of a few microns in size, and thus requires photolithographic techniques with photoresist as a mask, which results in a relatively complex manufacturing process, requires design of photolithographic patterns, and performs photolithography of a few microns in size. The technology of taking the self-assembled nano-islands as a mask is mainly used for etching GaN or Ga 2O3 nano-pillars at present, but no research has been made on the application of the technology of self-assembled nano-islands in JBS preparation. Disclosure of Invention Aiming at the defects existing in the existing JBS structure preparation method, the invention utilizes the characteristic that the Ni film can form nano Ni particles under the rapid thermal annealing, uses self-assembled Ni nano islands to replace photoresist as a mask to prepare the JBS power diode structure, and can omit the photolithography step. The technical scheme adopted by the invention is as follows: The JBS power diode based on the self-assembled Ni nanometer island comprises a cathode, an N+ substrate, a JBS structure and an anode which are sequentially arranged from bottom to top, wherein the JBS structure comprises an N-drift layer, a PN heterojunction and the Ni nanometer island, a groove structure is arranged on the N-drift layer, P-type metal oxides positioned on the inner side surface and the bottom of the groove form the PN heterojunction with the N-drift layer, the Ni nanometer island is positioned on the top of the groove and forms Schottky contact with the N-drift layer, and the PN heterojunction is connected with the Schottky contact in parallel. Further, the N+ substrate and the N-drift layer both adopt beta-Ga 2O3 crystals. Further, the diameter of the Ni nanometer island is 100-500nm, and the distance between the Ni nanometer islands is hundred nanometers. Further, the thickness of the P-type metal oxide is 100-300nm, and the depth of the groove structure on the N-drift layer is 100-300nm. The invention provides a preparation method of a JBS