Semiconductor device and process for the same

• US 6,515,349 B2
• Filed: 03/07/2001
• Issued: 02/04/2003
• Est. Priority Date: 09/18/2000
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Terashima, Tomohide
• Primary Examiner(s): Meier, Stephen D.
• Application Number:
  US09/799,577
• Publication Number:
  US 20020053719A1
• Time in Patent Office: 699 Days
• Field of Search: 257/630
• US Class Current: 257/630
• CPC Class Codes: H01L 23/60 Protection against electrostatic charges or discharges, e.g. Faraday shields
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/41741 for vertical or pseudo-vertical devices
• CPC Class Codes: H01L 29/66712 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• 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

The main purpose is to provide a semiconductor device which has a field plate wherein the electric field concentration at a step part can be eliminated and a higher withstanding voltage can be gained.

A field plate is provided on a substrate. The field plate has a step part which bends toward the downward direction from the surface of the substrate.

Claims

1. A semiconductor device including:

a substrate having an upper surface and an indented portion;

an oxide film formed in the indented portion of the substrate and having an edge part sloping downwardly toward the indented portion;

a field plate provided over the substrate, wherein said field plate has a step part over the edge part of the oxide film that slopes downwardly from the upper surface of said substrate toward the indented portion.

2. A semiconductor device including:

a substrate; and

a field plate provided on the above substrate,

wherein said field plate has a step part which bends downward from the surface of said substrate to the downward direction, wherein;

an indent part of which the side walls are sloped is provided in the surface of said substrate;

an oxide film of which the parts of the edge parts are slopes facing downward in the indented part of said substrate;

said step part of said field plate is provided so as to cover said slopes of said oxide film; and

said field plate bends toward downward direction with the bending angle φ

which satisfies the following inequity at said step part;

3. The semiconductor device according to claim 2 wherein said substrate is an Si substrate and said oxide film is SiO₂.

4. A semiconductor device including:

a substrate of which a part of the surface is indented;

an oxide film provided in said indented part of the surface of said substrate;

a first field plate provided on said substrate; and

a second field plate which is provided on said oxide film and which has a part which extends in the horizontal direction,

wherein the following inequity is achieved when the distance in the horizontal direction between said first field plate and the part which extends in said horizontal direction of said second field plate is assumed to be 1,

the depth of the bottom of said oxide film from the surface of said substrate is assumed to be x, and

the depth of the part which extends in the horizontal direction of said second field plate is denoted as y;

5. The semiconductor device according to claim 4, wherein said substrate is formed of Si and said oxide film is formed of SiO₂.

6. The semiconductor device according to claim 4, wherein other parts of said second field plate is overlapped on said first plate field by interposing an interlayer insulating film.

7. The semiconductor device according to claim 4, wherein said first field plate and said second field plate are integrated.

8. The process for a semiconductor device including:

the first step of forming a field oxide film on a surface of a substrate through a LOCOS method;

the second step of shaving off part of the edge parts of said field oxide film so that part of the surface of said substrate is exposed;

the third step of oxidizing again the part of the surface of said substrate which has been exposed in said second step; and

the fourth step of forming a field plate on said substrate so as to cover the part again oxidized of said field oxide film.

9. The process for a semiconductor device according to claim 8 wherein said process is applied in a process for a double diffused MOS transistor.