Gallium oxide SBD terminal structure and preparation method

Abstract

The disclosure is applicable for the technical field of semiconductor devices manufacturing, and provides a gallium oxide SBD terminal structure. The gallium oxide SBD terminal structure comprises a cathode metal layer, an N.sup.+ high-concentration substrate layer, an N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer and an anode metal layer from bottom to top, wherein the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer is within a range of certain thickness close to the anode metal layer; and a doping concentration below the anode metal layer is greater than a doping concentration on two sides of the anode metal layer. Namely, only a doping concentration of the part outside the corresponding area of the anode metal layer is changed, so that the breakdown voltage of the gallium oxide SBD terminal structure is improved under the condition of guaranteeing low on resistance.

Claims

1. A preparation method of fabricating a gallium oxide SBD terminal structure, the preparation method comprising: providing an N+high-concentration substrate layer; growing an N−low-concentration Ga.sub.2O.sub.3 epitaxial layer on the N+high-concentration substrate layer; depositing a mask layer on the N− low-concentration Ga.sub.2O.sub.3 epitaxial layer; removing side portions of the mask layer, wherein: removing the side portions of the mask layer leaves a central portion of the mask layer; removing the side portions of the mask layer exposes the N−low-concentration Ga.sub.2O.sub.3 epitaxial layer; and removing the side portions of the mask layer forms a remaining mask layer; performing a high-temperature annealing treatment containing at least two temperatures after removing the side portions of the mask layer; removing the remaining mask layer after performing the high-temperature annealing treatment; forming a cathode metal layer on a bottom surface of the N+high-concentration substrate layer after removing the remaining mask layer; and forming an anode metal layer on a top surface of the N−low-concentration Ga.sub.2O.sub.3 epitaxial layer after removing the remaining mask layer.

2. The preparation method of claim 1, wherein a material of the mask layer is SiO.sub.2, SiN or Al.sub.2O.sub.3 which is formed by PECVD or sputtering.

3. The preparation method of claim 2, wherein one of the at least two temperatures of the high-temperature annealing treatment is any value from 200° C. to 900° C., and an annealing time of the high-temperature annealing treatment is from 10 seconds to 100 minutes.

4. The preparation method of claim 3, wherein the high-temperature annealing treatment has two annealing temperatures, and the two annealing temperatures are 400° C. and 450° C. respectively, and the annealing time at each temperature is 10 minutes.

5. The preparation method of claim 1, wherein the high-temperature annealing treatment is performed in an oxygen atmosphere.

6. The preparation method of claim 5, wherein one of the at least two temperatures of the high-temperature annealing treatment is any value from 200° C. to 900° C., and an annealing time of the high-temperature annealing treatment is from 10 seconds to 100 minutes.

7. The preparation method of claim 6, wherein the high-temperature annealing treatment has two annealing temperatures, and the two annealing temperatures are 400° C. and 450° C. respectively, and the annealing time at each temperature is 10 minutes.

8. The preparation method of claim 1, wherein a temperature variation manner of the high-temperature annealing treatment is a linear or stepped variation.

9. The preparation method of claim 8, wherein one of the at least two temperatures of the high-temperature annealing treatment is any value from 200° C. to 900° C., and an annealing time of the high-temperature annealing treatment is from 10 seconds to 100 minutes.

10. The preparation method of claim 9, wherein the high-temperature annealing treatment has two annealing temperatures, and the two annealing temperatures are 400° C. and 450° C. respectively, and the annealing time at each temperature is 10 minutes.

11. The preparation method of claim 1, wherein an annealing temperature of the high-temperature annealing treatment is any value from 200° C. to 900° C., and an annealing time of the high-temperature annealing treatment is from 10 seconds to 100 minutes.

12. The preparation method of claim 11, wherein the high-temperature annealing treatment has two annealing temperatures, and the two annealing temperatures are 400° C. and 450° C. respectively, and the annealing time at each temperature is 10 minutes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to explain the technical solutions in the embodiments of the present application more clearly, the following will briefly introduce the drawings that need to be used in the embodiments or in the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the application, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor.

(2) FIG. 1 is a schematic view of a gallium oxide SBD terminal structure provided in an embodiment of the disclosure;

(3) FIG. 2 is a flowchart of the preparation method of the gallium oxide SBD terminal structure provided in an embodiment of the disclosure;

(4) FIG. 3 is a schematic view of the gallium oxide SBD terminal structure depositing a mask layer provided in an embodiment of the disclosure; and

(5) FIG. 4 is a schematic view showing the structure of the gallium oxide SBD terminal sample after annealing treatment provided in an embodiment of the disclosure.

(6) In the figures: 1. a cathode metal layer; 2. an N.sup.+ high-concentration substrate layer; 3. an N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer; 31. a second N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer; 3′. a mask layer; 4. an anode metal layer.

(7) Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(8) The making and using of the embodiments of this disclosure are discussed in detail below. It should be appreciated, however, that the concepts disclosed herein can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative, and do not limit the scope of the claims.

(9) In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

(10) In order to illustrate the technical solution in the present application, specific examples are set forth below.

(11) As shown in FIG. 1, the gallium oxide Schottky barrier diode (SBD) terminal structure comprises a cathode metal layer 1, an N.sup.+ high-concentration substrate layer 2, an N-low-concentration Ga.sub.2O.sub.3 epitaxial layer 3 and an anode metal layer 4, wherein the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer 3 is within a range of a certain thickness close to the anode metal layer 4; and a doping concentration below the anode metal layer is greater than a doping concentration on two sides of the anode metal layer.

(12) In particular, a second N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer 31 belongs to the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer 3, and is the part outside the corresponding area of the anode metal layer in a certain thickness range close to the anode metal layer. A doping concentration of the second N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer 31 is lower than a doping concentration of the corresponding area of the anode metal layer.

(13) On the basis of the above embodiments, other embodiments are as follows.

(14) In one embodiment, an electron concentration of the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer is from 1.0×10.sup.15 cm.sup.−3 to 1.0×10.sup.20 cm.sup.−3.

(15) Specifically, the doping concentration of the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer 3 may be a fixed value or a gradient value.

(16) In one embodiment, the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer 3 has a thickness of from 100 nm to 50 μm.

(17) In one embodiment, the material of the N.sup.+ high-concentration substrate layer 2 is Ga.sub.2O.sub.3 or SiC.

(18) In one embodiment, the anode metal layer is an Ni/Au layer, and the cathode metal layer is a Ti/Au layer.

(19) As shown in FIG. 2, the application discloses a preparation method of the gallium oxide SBD terminal structure, and the preparation method comprising the following steps.

(20) At Step S101, grow an N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer on the N.sup.+ high-concentration substrate layer.

(21) At Step S102, as shown in FIG. 3, deposit a mask layer 3′ on the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer.

(22) In one embodiment, the material of the mask layer is SiO.sub.2, SiN or Al.sub.2O.sub.3 which is formed by PECVD or sputtering.

(23) Specifically, the thickness of the mask layer is from 50 nm to 3000 nm.

(24) At Step S103, remove the part, outside the corresponding area of the anode metal layer, of the mask layer to obtain a gallium oxide SBD terminal sample.

(25) Specifically, a photoresist layer can be coated on the corresponding area of the anode metal layer, and then the mask layer of the part outside the corresponding area of the anode metal layer is removed by adopting a dry etching method or a wet etching method.

(26) At Step S104, as shown in FIG. 4, carry out a high-temperature annealing treatment containing at least two temperatures on the gallium oxide SBD terminal sample.

(27) Specifically, since the mask layer 3′ is deposited on the upper surface of the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer corresponding to the anode metal layer, the doping concentration of the part outside the corresponding area of the anode metal layer can be gradually reduced from bottom to top within a certain thickness range close to the anode metal layer through an annealing treatment. But the doping concentration of the corresponding area of the anode metal layer is not changed by the annealing treatment, namely, the area below the anode metal layer is not subjected to the annealing treatment, so that the transverse concentration change is introduced into the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer within a certain thickness range close to the anode metal layer, and the on resistance of the whole gallium oxide SBD terminal structure is lower.

(28) The doping concentration of the surface area of the N.sup.− low-concentration Ga.sub.2O.sub.3 epitaxial layer is reduced by the annealing treatment at two different temperatures, so that the doping concentration is gradually reduced from bottom to top and from inside to surface.

(29) At Step S105, remove the mask layer on the gallium oxide SBD terminal sample subjected to the high-temperature annealing treatment, and respectively form an anode metal layer and a cathode metal layer on two sides of the gallium oxide SBD terminal sample.

(30) In one embodiment, the high-temperature annealing treatment is performed in an oxygen atmosphere.

(31) In one embodiment, the temperature variation manner of the high-temperature annealing treatment is a linear or stepped variation.

(32) The temperature change can be firstly a high temperature and then a low temperature, or can be firstly a low temperature and then a high temperature.

(33) In one embodiment, the annealing temperature of the high-temperature annealing treatment is any value from 200° C. to 900° C., and the annealing time of the high-temperature annealing treatment is from 10 seconds to 100 minutes.

(34) In one embodiment, the high-temperature annealing treatment has two annealing temperatures, and the two annealing temperatures are 400° C. and 450° C. respectively, and the annealing time at each temperature is 10 minutes.

(35) The above-described embodiments are merely illustrative of the technical solutions of the present application and are not intended to be limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that: the technical solutions of the above-mentioned embodiments can still be modified, or some of the technical features thereof can be equivalently replaced; such modifications and substitutions do not depart the essence of the corresponding technical solutions from the spirit and scope of the embodiments of the present application, and are intended to be included within the scope of this application.

(36) Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

(37) Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments described here. As one of ordinary skill in the art will readily appreciate from the disclosure of the present disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.