Semiconductor device with deep diffusion region

• US 10,665,705 B2
• Filed: 02/28/2019
• Issued: 05/26/2020
• Est. Priority Date: 10/27/2015
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Wuebben, Thomas, Irsigler, Peter, Schulze, Hans-Joachim
• Primary Examiner(s): Hossain, Moazzam
• Assistant Examiner(s): Isaac, Stanetta D
• Application Number:
  US16/289,166
• Publication Number:
  US 20190198650A1
• Time in Patent Office: 453 Days
• Field of Search: None
• CPC Class Codes: H01L 21/2236 from or into a plasma phase
• CPC Class Codes: H01L 21/2252 using predeposition of impurities into the semiconductor surface, e.g. from a gaseous phase
• CPC Class Codes: H01L 21/2253 by ion implantation
• CPC Class Codes: H01L 21/265 producing ion implantation
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 21/266 using masks H01L21/26586 takes precedence
• 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 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/36 characterised by the concentration or distribution of impurities in the bulk material within semiconductor regions H01L29/06
• CPC Class Codes: H01L 29/66348 with a recessed gate
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• 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 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A method of processing a semiconductor device, comprising: providing a semiconductor body having dopants of a first conductivity type; forming at least one trench that extends into the semiconductor body along a vertical direction, the trench being laterally confined by two trench sidewalls and vertically confined by a trench bottom; applying a substance onto at least a section of a trench surface formed by one of the trench sidewalls and/or the trench bottom of the at least one trench, such that applying the substance includes preventing that the substance is applied to the other of the trench sidewalls; and diffusing of the applied substance from the section into the semiconductor body, thereby creating, in the semiconductor body, a semiconductor region having dopants of a second conductivity type and being arranged adjacent to the section.

Claims

1. A power semiconductor transistor comprising:

a semiconductor body; and

at least one transistor cell, the at least one transistor cell comprising;

a semiconductor drift region included in the semiconductor body and having dopants of a first conductivity type;

a semiconductor body region included in the semiconductor body and having dopants of a second conductivity type;

a source region, wherein the semiconductor body region isolates the source region from the semiconductor drift region;

a trench extending into the semiconductor body along a vertical direction and comprising a control electrode electrically insulated from each of the semiconductor drift region, the semiconductor body region and the source region; and

a semiconductor region having dopants of the second conductivity type and being arranged adjacent to the trench and separated from the semiconductor body region, wherein a transition between the trench and the semiconductor region extends along a trench sidewall of the trench,

wherein a dopant concentration of the semiconductor region adjacent to the trench sidewall amounts to a value that is within a range of 50% to 150% of a fixed dopant concentration value at any point along at least 60% of a total extension of the semiconductor region in the vertical direction.

2. A power semiconductor transistor comprising:

a semiconductor body; and

at least one transistor cell, the at least one transistor cell comprising;

a semiconductor drift region included in the semiconductor body and having dopants of a first conductivity type;

a semiconductor body region included in the semiconductor body and having dopants of a second conductivity type;

a source region, wherein the semiconductor body region isolates the source region from the semiconductor drift region;

a trench extending into the semiconductor body along a vertical direction and comprising a control electrode electrically insulated from each of the semiconductor drift region, the semiconductor body region and the source region; and

a semiconductor region having dopants of the second conductivity type and being arranged adjacent to the trench and separated from the semiconductor body region, wherein a transition between the trench and the semiconductor region extends along a trench sidewall of the trench,

wherein a dopant concentration of the semiconductor region adjacent to the trench sidewall changes, in a portion amounting to at least 80% of a total extension of the semiconductor region in the vertical direction, by at least 30% from a dopant concentration value being present in the portion of the total extension.

3. The transistor of claim 2, wherein the change of the dopant concentration in the portion of the total extension is constituted by an increase along the vertical direction.

4. The transistor of claim 2, wherein the change of the dopant concentration in the portion of the total extension is constituted by a decrease along the vertical direction.

5. The transistor of claim 2, wherein the portion of the total extension is divided into a first part and a second part,

wherein, in the first part, the dopant concentration decreases along the vertical direction, and, in the second part, the dopant concentration increases along the vertical direction.