METHOD OF MANUFACTURING SILICON CARBIDE SEMICONDUCTOR DEVICE

• US 20160315169A1
• Filed: 03/10/2016
• Published: 10/27/2016
• Est. Priority Date: 04/24/2015
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: SEKI, Yasukazu, YOSHIKAWA, Koh, NAKAZAWA, Haruo, IGUCHI, Kenichi
• Granted Patent: US 9,825,145 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/0455 Making n or p doped regions or layers, e.g. using diffusion
• CPC Class Codes: H01L 21/0495 Schottky electrodes
• CPC Class Codes: H01L 21/268 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/0638 for preventing surface leakage due to surface inversion layer, e.g. with channel stopper channel stoppers in combination with isolation region for integrated circuits H01L21/762
• CPC Class Codes: H01L 29/0692 Surface layout
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/167 further characterised by the doping material H01L29/1604 takes precedence
• CPC Class Codes: H01L 29/47 Schottky barrier electrodes H01L29/435 takes precedence
• CPC Class Codes: H01L 29/6603 Diodes
• CPC Class Codes: H01L 29/6606 the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

When p-type impurities are implanted into a SiC substrate using a laser, controlling the concentration is difficult. A p-type impurity region is formed by a laser in a region where the control of the concentration in the SiC substrate is not necessary almost at all. A SiC semiconductor device having withstanding high voltage is manufactured at a lower temperature process compared to ion implantation process. A method of manufacturing a silicon carbide semiconductor device includes forming, on one main surface of a first conductivity-type silicon carbide substrate, a first conductivity-type drift layer having a lower concentration than that of the silicon carbide substrate; forming, on a front surface side of the drift layer, a second conductivity-type electric field control region by a laser doping technology; forming a Schottky electrode in contact with the drift layer; and forming, on the other main surface of the silicon carbide substrate, a cathode electrode.

Claims

1. A method of manufacturing a silicon carbide semiconductor device, comprising:

forming, on one main surface of a first conductivity-type silicon carbide substrate, a first conductivity-type drift layer having a lower concentration than that of the silicon carbide substrate;

forming, on a front surface side of the drift layer, a second conductivity-type electric field control region by a laser doping technology;

forming a Schottky electrode in contact with the drift layer; and

forming, on the other main surface of the silicon carbide substrate, a cathode electrode.

2. The method according to claim 1, wherein the second conductivity-type electric field control region includes a ring-shaped electric field relaxation region formed at an outer circumferential portion in a region where the drift layer and the Schottky electrode contact with each other.

3. The method according to claim 2, wherein the second conductivity-type electric field control region includes a plurality of junction barrier regions selectively formed on the inner circumferential side of the electric field relaxation region.

4. The method according to claim 2, wherein the second conductivity-type electric field control region includes one or more field limiting rings provided on the outer circumferential side of the ring-shaped electric field relaxation region.

5. The method according to claim 4, further comprising forming one or more trenches after the formation of the first conductivity-type drift layer and before the formation of the electric field control region, wherein the one or more field limiting rings are formed below the one or more trenches.

6. The method according to claim 4, wherein the second conductivity-type electric field control region includes a ring-shaped channel stopper region provided on the outer circumferential side of the one or more field limiting rings, the method further comprising:

forming an insulating film in contact with the drift layer;

forming a channel stopper electrode in contact with the channel stopper region and the insulating film after the formation of the insulating film; and

forming an anode electrode in contact with the Schottky electrode after the formation of the Schottky electrode,

wherein a region between the channel stopper electrode and the anode electrode is covered by the insulating film.

7. The method according to claim 6, further comprising forming a field plate electrode connected to the one or more field limiting rings.

8. The method according to claim 3, further comprising:

forming an ohmic electrode which has an ohmic connection to the plurality of selectively formed junction barrier regions; and

forming an anode electrode in contact with the Schottky electrode and the ohmic electrode after the formation of the ohmic electrode.

9. The method according to claim 8, wherein the Schottky electrode and the ohmic electrode are the same material.

10. The method according to claim 8, wherein the ohmic electrode and the anode electrode are the same material.

11. The method according to claim 1, wherein the formation of the second conductivity-type electric field control region by the laser doping technology comprises:

forming a mask layer having a plurality of openings on the drift layer; and

implanting aluminum into the drift layer through the plurality of openings by irradiating the drift layer with a laser in a state where the drift layer is exposed to a gas containing aluminum.

12. The method according to claim 1, wherein the formation of the second conductivity-type electric field control region by the laser doping technology comprises:

depositing an aluminum layer onto the drift layer;

forming a plurality of patterns by patterning the aluminum layer; and

implanting aluminum into the drift layer through the plurality of patterns by irradiating the plurality of patterns with the laser.

13. The method according to claim 12, wherein the formation of the second conductivity-type electric field control region by the laser doping technology further comprises removing the plurality of patterns.

14. The method according to claim 1, wherein a laser light source in the laser doping technology in the formation of the electric field control region is any of KrF, ArF, XeF, XeCl, and YAG3ω

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