Silicon carbide junction barrier Schottky diodes with suppressed minority carrier injection

• US 8,901,699 B2
• Filed: 05/11/2005
• Issued: 12/02/2014
• Est. Priority Date: 05/11/2005
• Status: Active Grant

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Ryu, Sei-Hyung, Agarwal, Anant K.
• Primary Examiner(s): HSIEH, HSIN YI
• Application Number:
  US11/126,816
• Publication Number:
  US 20060255423A1
• Time in Patent Office: 3,492 Days
• Field of Search: 257/475, 257/E29.338
• US Class Current: 257/475
• CPC Class Codes: H01L 29/0615 by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] LDD or drain offset regions H01L29/7833
• 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 29/1608 Silicon carbide
• 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

Integral structures that block the current conduction of the built-in PiN diode in a junction barrier Schottky (JBS) structure are provided. A Schottky diode may be incorporated in series with the PiN diode, where the Schottky diode is of opposite direction to that of the PiN diode. A series resistance or and insulating layer may be provided between the PiN diode and a Schottky contact. Silicon carbide Schottky diodes and methods of fabricating silicon carbide Schottky diodes that include a silicon carbide junction barrier region disposed within a drift region of the diode are also provided. The junction barrier region includes a first region of silicon carbide having a first doping concentration in the drift region of the diode and a second region of silicon carbide in the drift region and disposed between the first region of silicon carbide and a Schottky contact of the Schottky diode. The second region is in contact with the first region of silicon carbide and the Schottky contact. The second region of silicon carbide has a second doping concentration that is less than the first doping concentration.

Claims

1. A diode comprising:

a silicon carbide drift region;

a Schottky contact on the silicon carbide drift region and forming a Schottky junction with the silicon carbide drift region; and

a silicon carbide junction barrier region disposed within the silicon carbide drift region of the diode, the silicon carbide junction barrier region comprising;

a plurality of first regions of silicon carbide having respective first doping concentrations in the silicon carbide drift region of the diode; and

a plurality of second regions of silicon carbide in the silicon carbide drift region and disposed between the plurality of first regions of silicon carbide and the Schottky contact of the diode and in electrical contact with the plurality of first regions of silicon carbide and the Schottky contact so that the plurality of first regions of silicon carbide are spaced apart from the Schottky contact by the plurality of second regions of silicon carbide, the plurality of second regions of silicon carbide having respective second doping concentrations that are less than the first doping concentrations and forming resistive ohmic contacts with the Schottky contact, wherein the second regions of silicon carbide have a surface doping concentration at the resistive ohmic contacts of from 10¹⁷ cm<sup>−

3</sup> to about 5×

10¹⁸ cm<sup>−

3</sup>; and

the silicon carbide drift region has a first conductivity type opposite a second conductivity type of the first regions and the second regions;

wherein the plurality of first and second regions define a junction barrier grid that is configured to shield the Schottky junction when a reverse bias is applied to the diode.

2. The diode of claim 1, wherein the silicon carbide drift region comprises n-type silicon carbide and the first and second regions comprise p-type silicon carbide.

3. The diode of claim 2, wherein the second regions of silicon carbide extend into the silicon carbide drift region from about 0.01 to about 0.5 μ

m from a surface of the silicon carbide drift region and the first regions of silicon carbide extend into the silicon carbide drill region from about 0.1 to about 1 μ

m from the surface of the silicon carbide drift region.

4. The diode of claim 2, wherein the silicon carbide drift region comprises a first n-type silicon carbide epitaxial layer.

5. The diode of claim 4, further comprising an n-type silicon carbide substrate having a doping concentration greater than a doping concentration of the first n-type silicon carbide epitaxial layer, the first n-type silicon carbide epitaxial layer being disposed on the n-type silicon carbide substrate.

6. The diode of claim 5, farther comprising a second n-type silicon carbide epitaxial layer disposed between the first silicon carbide epitaxial layer and the n-type silicon carbide substrate, the second n-type silicon carbide epitaxial layer having a higher carrier concentration than the first n-type silicon carbide epitaxial.

7. The diode of claim 5, further comprising an ohmic contact on the silicon carbide substrate opposite the first n-type silicon carbide epitaxial layer.

8. The diode of claim 1, further comprising a plurality of floating field rings surrounding the silicon carbide junction barrier region.

9. The diode of claim 1, wherein the plurality of first regions comprise p+ regions.

10. The diode of claim 1, wherein the plurality of first regions have a doping concentration of from about ×

10¹⁹ cm<sup>−

3</sup> to about 1×

10²¹ cm<sup>−

3</sup>.