MOS semiconductor device

• US 9,123,767 B2
• Filed: 03/19/2014
• Issued: 09/01/2015
• Est. Priority Date: 03/21/2013
• 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: Inoue, Masanori
• Primary Examiner(s): Shamsuzzaman, Mohammed
• Application Number:
  US14/219,709
• Publication Number:
  US 20140284656A1
• Time in Patent Office: 531 Days
• Field of Search: 257/139, 257/330, 257/333, 257/335, 257/329, 257/140, 257/328, 257/629, 257/341, 438/138
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/1037 and non-planar channel resulting from the gate electrode disposition, e.g. within a trench, H01L29/42356
• 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 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/7393 Insulated gate bipolar mode transistors, i.e. IGBT; IGT; COMFET
• CPC Class Codes: H01L 29/7395 Vertical transistors, e.g. vertical IGBT
• 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 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/13055 : Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]

Abstract

An MOS semiconductor device including an MOS gate structure is disclosed. The MOS semiconductor device includes a p-type well region selectively disposed on the surface layer of an n-type drift layer formed on a semiconductor substrate forming an n-type drain region; an n-type source region selectively disposed on the surface layer of the p-type well region; and a gate electrode placed, via an insulating film, on the surface of a channel formation region on the surface layer of the p-type well region sandwiched between the n-type source region and the surface layer of the n-type drain region, wherein a surface in the channel formation region has a level difference formed in the direction of the peripheral length, and all over the length, of the channel formation region.

Claims

1. A MOS semiconductor device including a MOS gate structure, the MOS semiconductor device comprising:

a first conductivity type drain region;

a drift region of the first conductivity type that is formed on the drain region;

a second conductivity type well region selectively disposed on a surface of the first conductivity type drift region;

a source region of the first conductivity type selectively disposed on a surface of the second conductivity type well region;

an insulating film extending along partially on an upper surface of the source region, a portion of the surface of the well region and a principal surface of the drift region;

a conformal gate electrode disposed on an upper surface of the insulating film;

a channel formation region sandwiched between the source region and the portion of the surface of the well region; and

wherein a surface of the channel formation region has a level difference formed in a direction of a peripheral length, and across a length, of the channel formation region, the level difference including a low portion that is parallel to the principal surface of the first conductivity type drift region and is low in a direction orthogonal to the principal surface of the first conductivity type drift region, a high portion that is parallel to the principal surface of the first conductivity type drift region and is higher than the low portion in the direction orthogonal to the principal surface of the first conductivity type drift region, and an intermediate portion connecting the low portion and the high portion,

wherein a height of the level difference is set between 0.1 μ

m and 10 μ

m.

2. The MOS semiconductor device according to claim 1, wherein the first conductivity type source region is located adjacent to the low portion of the level difference of the channel formation region.

3. The MOS semiconductor device according to claim 1, wherein the MOS semiconductor device is a MOSFET.