High voltage semiconductor power device

• US 6,054,748 A
• Filed: 03/13/1998
• Issued: 04/25/2000
• Est. Priority Date: 03/18/1997
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Tsukuda, Masanori, Shinohe, Takashi, Yamaguchi, Masakazu
• Primary Examiner(s): Guay, John
• Application Number:
  US09/041,799
• Time in Patent Office: 774 Days
• Field of Search: 257/496, 257/487, 257/492, 257/493, 257/618, 257/619
• US Class Current: 257/496
• 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 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/66136 PN junction diodes
• CPC Class Codes: H01L 29/66333 Vertical insulated gate bipolar transistors
• CPC Class Codes: H01L 29/7396 with a non planar surface, e.g. with a non planar gate or with a trench or recess or pillar in the surface of the emitter, base or collector region for improving current density or short circuiting the emitter and base regions H01L29/7398 takes precedence
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/861 Diodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A semiconductor power device includes a high-resistance semiconductor substrate of the first conductivity type having first and second major surfaces and a recess in either one of the first and second major surfaces, and a semiconductor power element with a field relaxation structure, at least part of which is formed in a region of the semiconductor substrate where the recess is formed.

Claims

1. A semiconductor power device comprising:

a high-resistance semiconductor substrate of a first conductivity type having a first and a second major surface and a recess having at least one step in either one of the first and the second major surface; and

a semiconductor power element with a field relaxation structure, at least part of which is formed in a region of said semiconductor substrate where the recess is formed,

wherein said semiconductor power element is a diode, and a second-conductivity-type anode layer of said diode has a plurality of steps at an interface between said anode layer and said semiconductor substrate of the first conductivity type.

2. A device according to claim 1, wherein said semiconductor power element comprises a main element with an active region and the field relaxation structure of a second conductivity type, and a thickness of at least one high-resistance portion of said semiconductor substrate at which said main element of said semiconductor element is formed is smaller than a thickness of a high-resistance portion of said semiconductor substrate below the field relaxation structure.

3. A device according to claim 1, wherein the field relaxation structure is formed in a region extending from a part of a bottom surface and a side wall surface of the recess formed in the first major surface to the first major surface surrounding the recess, and has a plurality of steps at an interface between the field relaxation structure and said semiconductor substrate of the first conductivity type.

4. A device according to claim 1, wherein the field relaxation structure comprises either one of a resurf layer and a guard ring.

5. A device according to claim 1, wherein the field of relaxation structure includes a resurf layer formed on the first major surface of said semiconductor substrate, surrounding the recess to contact the second-conductivity-type anode layer of said diode.