JP2015005602A - Method for manufacturing schottky barrier diode and schottky barrier diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a Schottky barrier diode and a Schottky barrier diode, capable of increasing the effect of improvement in withstand voltage by a guard ring.SOLUTION: A method for manufacturing a Schottky barrier diode includes a step of preparing a drift layer 22 made from gallium nitride and a laminated film 50 provided on the drift layer 22. The laminated film 50 includes an intermediate layer 51 provided on the drift layer 22 and made from InAlGaN(0<x1+y1) and a guard ring layer 52 provided on the intermediate layer 51 and made from InAlGaN. The method also includes a step of etching the laminated layer 50 using a mask layer 60. The step of etching the laminated layer 50 further includes the steps of: exposing the drift layer 22 by etching the intermediate layer 51; detecting exposure of the drift layer 22; and stopping etching after the step of detecting the exposure of the drift layer 22.

Description

  The present invention relates to a Schottky barrier diode manufacturing method and a Schottky barrier diode, and more particularly to a Schottky barrier diode manufacturing method and a Schottky barrier diode having a drift layer made of gallium nitride and provided with a guard ring. .

  According to Japanese Patent Laying-Open No. 2008-177369 (Patent Document 1), a Schottky barrier diode using a gallium nitride based semiconductor is disclosed. This diode has a p-type guard ring to increase the breakdown voltage.

  In a gallium nitride material, unlike a silicon material or a silicon carbide material, a technique for forming a p-type region by ion implantation has not been established. For this reason, a guard ring cannot be easily formed by ion implantation. Therefore, in the manufacturing method shown as an example in the above publication, after the p-type layer is grown on the n-type layer by vapor deposition, the p-type layer is patterned by plasma etching using a mask. , A p-type guard ring is formed.

JP 2008-177369 A

  In the above technique, if the etching for patterning the p-type layer is insufficient, the p-type layer remains inside the guard ring, so that the n-type layer is not sufficiently exposed inside the guard ring. In this case, the contact between the n-type layer and the Schottky electrode inside the guard ring becomes insufficient. Therefore, in order to obtain an industrially sufficient yield, it is necessary to sufficiently perform overetching. As a result, the surface of the n-type layer is greatly over-etched, and as a result, a protrusion corresponding to the shape of the guard ring is formed on the n-type layer. The electric field concentration caused by the protrusions cancels out the breakdown voltage improvement effect by the guard ring.

  An object of the present invention is to provide a Schottky barrier diode manufacturing method and a Schottky barrier diode capable of solving the above-mentioned problems and enhancing the breakdown voltage improvement effect by a guard ring.

The manufacturing method of the Schottky barrier diode of this invention has the following processes.
A drift layer made of n-type semiconductor gallium nitride and a laminated film provided on the drift layer are prepared. The stacked film is provided on the drift layer, and is formed of an intermediate layer made of In _x1 Al _{y1 Gaz1} N (x1 + y1 + Z1 = 1, 0 <x1 + y1 ≦ 1) of either a p-type semiconductor or a true semiconductor, and on the intermediate layer And a guard ring layer made of p-type semiconductor In _x2 Al _{y2 Gaz2} N (x2 + y2 + Z2 = 1, 0 ≦ x2 + y2 <x1 + y1). A mask layer having an opening is formed on the stacked film. The laminated film is etched using the mask layer. The process of etching the laminated film is stopped after the step of exposing the drift layer by etching the intermediate layer, the step of detecting that the drift layer is exposed, and the step of detecting that the drift layer is exposed. Including the step of. After the stacked film is etched, a Schottky electrode in contact with the drift layer is formed.

The Schottky barrier diode of the present invention has a drift layer, a laminated film, and a Schottky electrode. The drift layer is made of n-type semiconductor gallium nitride. The laminated film is provided on the drift layer and has an opening. The laminated film has an intermediate layer and a guard ring layer. The intermediate layer is provided on the drift layer, and is made of In _x1 Al _{y1 Gaz1} N (x1 + y1 + Z1 = 1, 0 <x1 + y1 ≦ 1) which is either a p-type semiconductor or a true semiconductor. The guard ring layer is provided on the intermediate layer, and is made of p-type semiconductor In _x2 Al _{y2 Gaz2} N (x2 + y2 + Z2 = 1, 0 ≦ x2 + y2 <x1 + y1). The Schottky electrode is in contact with the drift layer at the opening.

  According to the present invention, the effect of improving the breakdown voltage by the guard ring can be enhanced.

It is a figure which shows schematically the structure of the Schottky barrier diode in Embodiment 1 of this invention, and is sectional drawing which follows the line II of FIG. FIG. 2 is a top view of FIG. 1. It is sectional drawing which shows schematically the 1st process of the manufacturing method of the Schottky barrier diode in Embodiment 1 of this invention. It is sectional drawing which shows schematically the 2nd process of the manufacturing method of the Schottky barrier diode in Embodiment 1 of this invention. It is sectional drawing which shows schematically the 3rd process of the manufacturing method of the Schottky barrier diode in Embodiment 1 of this invention. It is sectional drawing which shows schematically the 4th process of the manufacturing method of the Schottky barrier diode in Embodiment 1 of this invention. It is sectional drawing which shows schematically the 5th process of the manufacturing method of the Schottky barrier diode in Embodiment 1 of this invention. It is sectional drawing which shows 1 process of the manufacturing method of the Schottky barrier diode of a comparative example. It is sectional drawing of the Schottky barrier diode of a comparative example. It is a schematic diagram which shows the 1st example of the manufacturing apparatus of the Schottky barrier diode in Embodiment 1 of this invention. It is a schematic diagram which shows the 2nd example of the manufacturing apparatus of the Schottky barrier diode in Embodiment 1 of this invention. It is sectional drawing which shows the modification of FIG. It is a figure which shows schematically the structure of the Schottky barrier diode in Embodiment 2 of this invention, and is sectional drawing which follows the line II of FIG. It is sectional drawing which shows schematically the 1st process of the manufacturing method of the Schottky barrier diode in Embodiment 2 of this invention. It is sectional drawing which shows schematically the 2nd process of the manufacturing method of the Schottky barrier diode in Embodiment 2 of this invention. It is sectional drawing which shows schematically the 3rd process of the manufacturing method of the Schottky barrier diode in Embodiment 2 of this invention. It is sectional drawing which shows schematically the 4th process of the manufacturing method of the Schottky barrier diode in Embodiment 2 of this invention. It is sectional drawing which shows schematically the 5th process of the manufacturing method of the Schottky barrier diode in Embodiment 2 of this invention. It is sectional drawing which shows schematically the 6th process of the manufacturing method of the Schottky barrier diode in Embodiment 2 of this invention. It is sectional drawing which shows roughly the 1st process of the manufacturing method of the Schottky barrier diode in the modification of Embodiment 2 of this invention. It is sectional drawing which shows schematically the 2nd process of the manufacturing method of the Schottky barrier diode in the modification of Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

First, the outline will be described in the following (i) to (viii).
(i) The manufacturing method of the Schottky barrier diodes 101 and 102 includes the following steps.

A drift layer 22 made of n-type semiconductor gallium nitride and a laminated film 50 provided on the drift layer 22 are prepared. The laminated film 50 is provided on the drift layer 22 and includes an intermediate layer 51 made of In _x1 Al _{y1 Gaz1} N (x1 + y1 + Z1 = 1, 0 <x1 + y1 ≦ 1), which is either a p-type semiconductor or a true semiconductor. A guard ring layer 52 formed on the layer 51 and made of p-type semiconductor In _x2 Al _y2 Ga _z2 N (x2 + y2 + Z2 = 1, 0 ≦ x2 + y2 <x1 + y1). A mask layer 60 having an opening OP is formed on the stacked film 50. The laminated film 50 is etched using the mask layer 60. The step of etching the laminated film 50 includes a step of exposing the drift layer 22 by etching the intermediate layer 51, a step of detecting that the drift layer 22 is exposed, and a step of detecting that the drift layer 22 is exposed. And the step of stopping the etching. After the stacked film 50 is etched, the Schottky electrode 40 in contact with the drift layer 22 is formed.

  According to this manufacturing method, the intermediate layer 51 made of a material different from the material of the drift layer 22 is provided. Therefore, when the laminated film 50 is patterned to form the guard ring structure, the etching is accurately performed by detecting that the material to be etched moves from the material of the intermediate layer 51 to the material of the drift layer 22. Can be stopped. As a result, overetching of the drift layer 22 can be minimized. Therefore, it becomes difficult for the protrusion corresponding to the shape of the guard ring to be formed on the drift layer 22. Thereby, the offset of the pressure | voltage resistant improvement effect by a guard ring resulting from the electric field concentration which arises by this protrusion is suppressed. In other words, the effect of improving the breakdown voltage by the guard ring can be enhanced.

  (ii) In the above (i), the guard ring layer 52 is preferably made of gallium nitride. Thereby, the material of the guard ring layer 52 can be the same as the material of the drift layer 22. Therefore, lattice matching between the guard ring layer 52 and the drift layer 22 is enhanced.

  (iii) In the above (i) or (ii), the intermediate layer 51 is preferably made of a p-type semiconductor. Thereby, the depletion layer can be further developed at the interface between the intermediate layer 51 and the drift layer 22 as compared with the case where the intermediate layer 51 is made of a genuine semiconductor. Therefore, the withstand voltage is further increased.

  (iv) In the steps (i) to (iii), mass spectrometry may be performed on the etched substance in the detecting step. Thereby, the end point of etching can be detected using mass spectrometry.

  (v) In (i) to (iii) above, in the detecting step, spectroscopic analysis may be performed on the light generated by the etching. Thereby, the end point of etching can be detected using spectroscopic analysis.

(vi) The Schottky barrier diodes 101 and 102 include the drift layer 22, the laminated film 50, and the Schottky electrode 40. The drift layer 22 is made of n-type semiconductor gallium nitride. The laminated film 50 is provided on the drift layer 22 and has an opening OP. The laminated film 50 has an intermediate layer 51 and a guard ring layer 52. The intermediate layer 51 is provided on the drift layer 22 and is made of In _x1 Al _y1 Ga _z1 N (x1 + y1 + Z1 = 1, 0 <x1 + y1 ≦ 1) which is either a p-type semiconductor or a true semiconductor. The guard ring layer 52 is provided on the intermediate layer 51 and is made of p-type semiconductor In _x2 Al _{y2 Gaz2} N (x2 + y2 + Z2 = 1, 0 ≦ x2 + y2 <x1 + y1). Schottky electrode 40 is in contact with drift layer 22 at opening OP.

  According to the Schottky barrier diodes 101 and 102, the materials of the drift layer 22 and the intermediate layer 51 are different. Therefore, when the laminated film 50 is patterned to form the guard ring structure, the etching is accurately performed by detecting that the material to be etched moves from the material of the intermediate layer 51 to the material of the drift layer 22. Can be stopped. As a result, overetching of the drift layer 22 can be minimized. Therefore, it becomes difficult for the protrusion corresponding to the shape of the guard ring to be formed on the drift layer 22. Thereby, the offset of the pressure | voltage resistant improvement effect by a guard ring resulting from the electric field concentration which arises by this protrusion is suppressed. In other words, the effect of improving the breakdown voltage by the guard ring can be enhanced.

  (vii) Preferably in the above (vi), the guard ring layer 52 is made of gallium nitride. Thereby, the material of the guard ring layer 52 can be the same as the material of the drift layer 22. Therefore, lattice matching between the guard ring layer 52 and the drift layer 22 is enhanced.

  (viii) In the above (vi) or (vii), the intermediate layer 51 is preferably made of a p-type semiconductor. Thereby, the depletion layer can be further developed at the interface between the intermediate layer 51 and the drift layer 22 as compared with the case where the intermediate layer 51 is made of a genuine semiconductor. Therefore, the withstand voltage is further increased.

Next, more detailed contents will be described in the following first and second embodiments.
(Embodiment 1)
As shown in FIGS. 1 and 2, the Schottky barrier diode 101 includes a single crystal substrate 20, a drift layer 22, a stacked film 50, a Schottky electrode 40, and an ohmic electrode 72.

Single crystal substrate 20 is preferably a free-standing substrate, and has a thickness of, for example, about 400 μm. The single crystal substrate 20 is preferably a GaN substrate. Single crystal substrate 20 has n-type. Single crystal substrate 20 preferably has a carrier concentration higher than that of drift layer 22, for example, a carrier concentration of 5 × 10 ¹⁸ cm ⁻³ .

The drift layer 22 is made of gallium nitride (GaN). Drift layer 22 is made of an n-type semiconductor and has a carrier concentration of 5 × 10 ¹⁵ cm ⁻³ , for example. The thickness of the drift layer 22 is, for example, about 10 μm.

  The stacked film 50 is provided on the drift layer 22. The laminated film 50 has an opening OP, and may have, for example, an annular shape as shown in FIG. The laminated film 50 has an intermediate layer 51 and a guard ring layer 52. The intermediate layer 51 is provided on the drift layer 22. The guard ring layer 52 is provided on the intermediate layer 51. In other words, the guard ring layer 52 is provided on the drift layer 22 via the intermediate layer 51.

The intermediate layer 51 is made of either a p-type semiconductor or a true semiconductor, and is preferably made of a p-type semiconductor. The intermediate layer 51 is made of In _x1 Al _{y1 Gaz1} N (x1 + y1 + Z1 = 1). Regarding the composition, 0 <x1 + y1 ≦ 1 is satisfied, and preferably 0.01 ≦ x1 + y1 ≦ 0.1 is satisfied. The thickness of the intermediate layer 51 is preferably 1 nm or more and 50 nm or less, for example, about 10 nm.

The guard ring layer 52 is made of a p-type semiconductor. Mg can be used as a dopant for obtaining the p-type. The dopant concentration is, for example, 4 × 10 ¹⁷ cm ⁻³ . The guard ring layer 52 is made of In _x2 Al _{y2 Gaz2} N (x2 + y2 + Z2 = 1). Regarding the composition, 0 ≦ x2 + y2 <x1 + y1 is satisfied, and preferably z2 = 1 is satisfied. When z2 = 1, the guard ring layer 52 is made of GaN. The thickness of the guard ring layer 52 is, for example, about 50 nm.

  The Schottky electrode 40 is in contact with the drift layer 22 in the opening OP of the stacked film 50. The Schottky electrode 40 is separated from the laminated film 50. The Schottky electrode 40 has a Schottky layer in contact with the drift layer 22, and an additional layer may be provided thereon. The Schottky layer is, for example, a Ni layer or a Ti layer. The thickness of the Schottky layer is, for example, about 50 nm. The additional layer is, for example, an Au layer having a thickness of about 300 nm.

  The ohmic electrode 72 is provided on the surface opposite to the surface on which the Schottky electrode 40 is provided (the back surface in the drawing) of the pair of main surfaces of the drift layer 22 via the single crystal substrate 20. The ohmic electrode 72 has, for example, a structure in which Ti (20 nm) / Al (100 nm) / Ti (20 nm) / Au (300 nm) are stacked in the order closer to the drift layer 22 (the dimension in parentheses is the thickness of each layer). .

Next, a method for manufacturing the Schottky barrier diode 101 will be described below.
As shown in FIG. 3, single crystal substrate 20, drift layer 22 provided on single crystal substrate 20, and laminated film 50 (that is, intermediate layer 51 and guard ring layer 52) provided on drift layer 22, Is prepared. Specifically, drift layer 22, intermediate layer 51, and guard ring layer 52 are formed in this order by epitaxial growth on single crystal substrate 20. Epitaxial growth is performed, for example, by metal organic vapor phase epitaxy.

  As shown in FIG. 4, a mask layer 60 having an opening OP is formed on the stacked film 50. The material of the mask layer 60 is, for example, silicon nitride (SiN) having a thickness of 300 nm. The mask layer 60 can be formed by, for example, film formation by chemical vapor deposition and patterning by photolithography and etching. Etching can be performed, for example, by wet etching using buffered hydrofluoric acid (BHF).

  As shown in FIGS. 5 and 6, the laminated film 50 is etched using the mask layer 60. As a result, the opening OP of the mask layer 60 is transferred to the laminated film 50. This etching is performed by dry etching, for example, by an ICP (Inductively coupled plasma) etching method using chlorine gas.

  The step of etching the laminated film 50 detects the step of exposing the drift layer 22 by etching the intermediate layer 51 (step from FIG. 5 to FIG. 6) and the exposure of the drift layer 22 (FIG. 6). And a step of stopping etching after the step of detecting that the drift layer 22 is exposed. In other words, the etching is accurately stopped by using the end point detection performed by detecting the exposure of the drift layer 22. As a method for detecting the end point, a method of performing mass analysis on an etched material or a method of performing spectroscopic analysis on light generated by etching can be used. Details of the end point detection method will be described later. Next, the mask layer 60 is removed.

  As shown in FIG. 7, next, the Schottky electrode 40 in contact with the drift layer 22 in the opening OP is formed. Referring to FIG. 1 again, ohmic electrode 72 is formed. Thereby, the Schottky barrier diode 101 is obtained.

  Next, a manufacturing method of a comparative example will be described. In this comparative example, as shown in FIG. 8, the intermediate layer 51 (FIG. 6) is not provided. In this case, it is difficult to detect that the drift layer 22 is exposed by etching the guard ring layer 52. This is because the material of the guard ring layer 52 and the material of the drift layer 22 are the same or very similar. Therefore, it is difficult to detect the etching end point by detecting the exposure of the drift layer 22.

  In order to reliably expose the drift layer 22 without detecting the end point, it is necessary to sufficiently perform overetching. In this case, since the surface of the drift layer 22 is greatly over-etched, protrusions (range OE in FIGS. 8 and 9) corresponding to the pattern of the mask layer 60 are formed in the drift layer 22. Due to the electric field concentration caused by the protrusions, in the Schottky barrier diode 109 of the comparative example, the effect of improving the breakdown voltage by the guard ring layer 52 is offset.

  On the other hand, according to the present embodiment, the intermediate layer 51 made of a material different from the material of the drift layer 22 is provided. Therefore, when the laminated film 50 is patterned to form the guard ring structure (FIGS. 4 to 6), it is detected that the material to be etched moves from the material of the intermediate layer 51 to the material of the drift layer 22. Thus, the etching can be stopped with high accuracy. As a result, overetching of the drift layer 22 can be minimized. Therefore, it becomes difficult for the protrusion corresponding to the shape of the guard ring to be formed on the drift layer 22. Thereby, the offset of the pressure | voltage resistant improvement effect by a guard ring resulting from the electric field concentration which arises by this protrusion is suppressed. In other words, the effect of improving the breakdown voltage by the guard ring can be enhanced.

In order to detect that the material to be etched moves from the material of the intermediate layer 51 to the material of the drift layer 22, the material composition must be different enough to be detected. In other words, the material of the intermediate layer 51 (In _x1 Al _y1 Ga _z1 N) must be sufficiently different from the material of the drift layer 22 (GaN). From this point of view, the ratio of Ga substituted by In or Al in In _x1 Al _y1 Ga _z1 N, that is, x1 + y1, is preferably 0.01 or more. Further, this ratio is preferably 0.1 or less in order to sufficiently ensure the epitaxial property.

  In order to detect that the material to be etched moves from the material of the intermediate layer 51 to the material of the drift layer 22, it is first necessary to detect that the material of the intermediate layer 51 is etched. By making the thickness of the intermediate layer 51 about 1 nm or more, it can be detected more reliably that the material of the intermediate layer 51 is etched. Further, the thickness of the intermediate layer 51 is preferably about 50 nm or less in order to maintain the quality of the guard ring layer 52 grown thereon.

  Preferably, the guard ring layer 52 is made of GaN. Thereby, the material of the guard ring layer 52 can be the same as the material of the drift layer 22. Therefore, lattice matching between the guard ring layer 52 and the drift layer 22 is enhanced.

  Preferably, the intermediate layer 51 is made of a p-type semiconductor. Thereby, the depletion layer can be further developed at the interface between the intermediate layer 51 and the drift layer 22 as compared with the case where the intermediate layer 51 is made of a genuine semiconductor. Therefore, the withstand voltage is further increased.

  In the detecting step, mass analysis may be performed on the etched material. Thereby, the end point of etching can be detected using mass spectrometry.

  In the detecting step, spectroscopic analysis may be performed on the light generated by the etching. Thereby, the end point of etching can be detected using spectroscopic analysis.

  Next, a method for detecting the end point of etching will be described. Typically, endpoint detection methods include mass spectrometry (FIG. 10) and spectroscopic analysis (FIG. 11).

  As shown in FIG. 10, the dry etching apparatus 80 having an end point detection system by mass spectrometry includes, for example, a processing chamber 81, a turbo molecular pump 82, a dry pump 83, and a quadrupole mass spectrometer 84. The process gas (arrow GI) introduced into the processing chamber 81 is exhausted by the exhaust system (arrow GO). Since the exhausted gas contains an etched substance, the type of material being etched at that time can be specified by the quadrupole mass spectrometer 84 provided in the exhaust system. Therefore, a change in the material being etched can be detected.

  As shown in FIG. 11, a dry etching apparatus 90 having an end point detection system by spectroscopic analysis includes, for example, a main body 91 for performing plasma etching and an end point detection system 92. The main body 91 includes a processing chamber 91a provided with a view port 91b that transmits light. The end point detection system 92 includes an optical sensor 92a, an optical fiber 92b, and an incident portion 92c. The wavelength of light generated by plasma etching depends on the material to be etched. Therefore, the light is guided to the optical sensor 92a through the incident portion 92c and the optical fiber 92b and subjected to spectroscopic analysis, so that the type of material etched at that time can be specified. Therefore, a change in the material being etched can be detected.

  Next, a Schottky barrier diode 101V of a modification (FIG. 12) will be described. The Schottky barrier diode 101V has a Schottky electrode 40V. Unlike the Schottky electrode 40 (FIG. 1), the Schottky electrode 40V is in contact with the laminated film 50. According to this modification, the potential of the laminated film 50, particularly the guard ring layer 52, can be stabilized by contact with the Schottky electrode 40V.

(Embodiment 2)
As shown in FIG. 13, the Schottky barrier diode 102 has a contact layer 21 instead of the single crystal substrate 20 (FIG. 1). Contact layer 21 has n-type. Contact layer 21 has a carrier concentration higher than that of drift layer 22. The contact layer 21 is made of group III nitride.

  Since the configuration other than the above is substantially the same as the configuration of the first embodiment described above, the same or corresponding elements are denoted by the same reference numerals, and description thereof is not repeated.

Next, a method for manufacturing the Schottky barrier diode 102 will be described below.
As shown in FIG. 14, the bonding film 12 a is formed on the freestanding substrate 11. The material of the self-supporting substrate 11 preferably has a difference from the thermal expansion coefficient of the drift layer 22 of 2 × 10 ⁻⁶ K ⁻¹ or less, for example, a molybdenum substrate, mullite (Al ₂ O ₃ —SiO), or yttria. Stabilized zirconia-mullite is preferred. The bonding film 12a can be made of silicon oxide or silicon nitride.

  Referring to FIG. 15, a group III nitride substrate 13D made of high quality group III nitride is prepared. Bonding film 12b is formed on group III nitride substrate 13D. The bonding film 12b can be made of the same material as the bonding film 12a. Implanted region 13i is formed by ion implantation (arrow I in the figure) at a predetermined depth from main surface 13n of group III nitride substrate 13D.

  As shown in FIG. 16, the bonding film 12a is formed by bonding the bonding film 12a (FIG. 14) and the bonding film 12b (FIG. 15). As a bonding method, for example, a direct bonding method, a surface activated bonding method, a high-pressure bonding method, or an ultra-high vacuum bonding method can be used.

  As shown in FIG. 17, the group III nitride substrate 13D is divided at the implantation region 13i. Thereby, a part of the group III nitride substrate 13D becomes the group III nitride film 13 located on the bonding film 12, and the other part 13E is removed. The other portion 13E can be reused as the group III nitride substrate 13D (FIG. 15).

  As shown in FIG. 18, the contact layer 21, the drift layer 22, and the stacked film 50 are formed in order on the group III nitride film 13. Thereafter, the same steps as those in FIGS. 4 to 7 of the first embodiment are performed.

  As shown in FIG. 19, the self-standing substrate 11, the bonding film 12, and the group III nitride film 13 are removed. For the removal of the free-standing substrate 11, nitric acid etching is suitable for molybdenum, and hydrofluoric acid etching is suitable for mullite or yttria-stabilized zirconia-mullite. The bonding film 12 can be removed by hydrofluoric acid etching. ICP-RIE (Reactive Ion Etching) using chlorine gas is suitable for removing the group III nitride film 13.

  Referring to FIG. 13 again, ohmic electrode 72 is formed. Thereby, the Schottky barrier diode 102 is obtained.

Next, the manufacturing method of a modification is demonstrated below.
As shown in FIG. 20, a structure in which a self-supporting substrate 11 and a group III nitride substrate 13D are bonded by a bonding film 12 is prepared. In order to obtain this structure, the same steps as in FIGS. 14 to 16 may be performed while the ion implantation (arrow I in FIG. 15) is omitted.

  As shown in FIG. 21, group III nitride substrate 13D is sliced at a predetermined depth from bonding film 12 (broken line SL in the figure). Thereby, a part of the group III nitride substrate 13D becomes the group III nitride film 13 located on the bonding film 12, and the other part 13E is removed. The other portion 13E can be reused as the group III nitride substrate 13D (FIG. 15). As a result, a configuration substantially similar to that shown in FIG. 17 is obtained. The subsequent steps are the same as those described above.

  Also in the present embodiment, the same operational effects as in the first embodiment can be obtained. Further, since the Schottky barrier diode 102 does not have a substrate, the thickness can be reduced accordingly. Further, since the group III nitride substrate 13D can be used a plurality of times, the cost required for the substrate can be reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the claims of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

11 Free-standing substrate 12, 12a, 12b Bonding film 13 Group III nitride film 13D Group III nitride substrate 13E Other part 13i Injection region 13n Main surface 20 Single crystal substrate 21 Contact layer 22 Drift layer 40, 40V Schottky electrode 50 Multilayer film 51 Intermediate layer 52 Guard ring layer 60 Mask layer 72 Ohmic electrodes 80, 90 Dry etching apparatus 81, 91a Processing chamber 82 Turbo molecular pump 83 Dry pump 84 Mass spectrometer 91 Main body 91b Viewport 92 End point detection system 92a Optical sensor 92b Light Fiber 92c Incident portion 101, 101V, 102 Schottky barrier diode OP opening

Claims (8)

a step of preparing a drift layer made of n-type semiconductor gallium nitride and a laminated film provided on the drift layer, wherein the laminated film is provided on the drift layer; And an intermediate layer made of In _x1 Al _y1 Ga _z1 N (x1 + y1 + Z1 = 1, 0 <x1 + y1 ≦ 1) and a p-type semiconductor In _x2 Al _y2 Ga _z2 N (x2 + y2 + Z2) provided on the intermediate layer = 1, 0 ≦ x2 + y2 <x1 + y1), and a step of forming a mask layer having an opening on the laminated film,
Etching the laminated film using the mask layer, and the etching the laminated film includes exposing the drift layer by etching the intermediate layer and exposing the drift layer And a step of stopping etching after the step of detecting that the drift layer is exposed, and after the step of etching the laminated film, a Schottky electrode in contact with the drift layer is formed. A method for manufacturing a Schottky barrier diode, comprising a step.   The method for manufacturing a Schottky barrier diode according to claim 1, wherein the guard ring layer is made of gallium nitride.   The method for manufacturing a Schottky barrier diode according to claim 1, wherein the intermediate layer is made of a p-type semiconductor.   The method of manufacturing a Schottky barrier diode according to any one of claims 1 to 3, wherein the detecting step includes a step of performing mass spectrometry on the etched substance.   The method of manufacturing a Schottky barrier diode according to any one of claims 1 to 3, wherein the detecting step includes a step of performing a spectral analysis on light generated by etching. a drift layer made of n-type semiconductor gallium nitride;
A laminated film having an opening provided on the drift layer, and the laminated film is provided on the drift layer and is one of a p-type semiconductor and a true semiconductor, In _x1 Al _y1 Ga _z1 N (x1 + y1 + Z1 = 1, 0 <x1 + y1 ≦ 1) and a p-type semiconductor In _x2 Al _{y2 Gaz2} N (x2 + y2 + Z2 = 1, 0 ≦ x2 + y2 <x1 + y1) provided on the intermediate layer A Schottky barrier diode comprising a guard ring layer, and further comprising a Schottky electrode in contact with the drift layer in the opening.   The Schottky barrier diode according to claim 6, wherein the guard ring layer is made of gallium nitride.   The Schottky barrier diode according to claim 6 or 7, wherein the intermediate layer is made of a p-type semiconductor.

Images