Schottky device having conductive trenches and a multi-concentration doping profile therebetween

Patent metadata

Field	Value
Publication number	US-9716151-B2
Application number	US-201414160273-A
Country	US
Kind code	B2
Filing date	Jan 21, 2014
Priority date	Sep 24, 2013
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

A Schottky device includes a plurality of mesa structures where one or more of the mesa structures includes a doped region having a multi-concentration dopant profile. In accordance with an embodiment, the Schottky device is formed from a semiconductor material of a first conductivity type. Trenches having sidewalk and floors are formed in the semiconductor material to form a plurality of mesa structures. A doped region having a multi-concentration impurity profile is formed in at least one trench, where the impurity materials of the doped region having the multi-concentration impurity profile are of a second conductivity type. A Schottky contact is formed to at least one of the mesa structures having the dope region with the multi-concentration impurity profile.

First claim

What is claimed is:

1. A Schottky device, comprising:
a semiconductor material of a first conductivity type having first and second major surfaces and a first concentration;
a first trench having sidewalls and a floor, the first trench extending from the first major surface of the semiconductor material into a first portion of the semiconductor material;
a second trench having sidewalls and a floor, the second trench extending from the first major surface of the semiconductor material into a second portion of the semiconductor material, wherein a third portion of the semiconductor material is between the first and second trenches and a seventh portion of the semiconductor material is adjacent the second trench, and wherein the third portion of the semiconductor material has a multi-concentration impurity profile comprising a first doped region of a second conductivity type and a second concentration extending from the first major surface of the semiconductor material into the third portion of the semiconductor material and a second doped region of the second conductivity type and a third concentration extending from the first doped region into the third portion of the semiconductor material, wherein a bottom of the second doped region is closer to the floor of the first trench than to the first major surface of the semiconductor material, and wherein the second concentration and the third concentration are selected so that a first portion of a first contact formed in contact with the third portion of the semiconductor material forms a first multi-concentration contact portion of the first contact and has electrical properties between a conventional Schottky contact and a conventional Ohmic contact, without being a conventional Schottky contact or a conventional Ohmic contact;
the first contact formed in contact with the first major surface of the semiconductor material, the first portion of the first contact in contact with the third portion of the semiconductor material and a second portion of the first contact in contact with the seventh portion of the semiconductor material, wherein the first concentration is selected so that the second portion of the first contact forms a first Schottky contact portion of the first contact; and
a second contact formed in contact with the second major surface of the semiconductor material.

2. The Schottky device of claim 1 , wherein the first doped region comprises a first impurity material of the second conductivity type that extends into the semiconductor material a first distance and the second doped region comprises a second impurity material of the second conductivity type that extends into the semiconductor material a second distance, the first distance less than the second distance and the concentration of the first impurity material greater than the concentration of the second impurity material.

3. The Schottky device of claim 1 , further including:
a first layer of dielectric material on the sidewalls and the floor of the first trench; and
a first electrically conductive material on the first layer of dielectric material, wherein a third portion of the first contact is in contact with the first electrically conductive material in the first trench forming a first Ohmic contact portion of the first contact.

4. The Schottky device of claim 3 , wherein the first electrically conductive material is a first semiconductor material of the first conductivity type.

5. The Schottky device of claim 3 , further including:
a third trench having sidewalls and a floor, the third trench extending from the first major surface of the semiconductor material into a fourth portion of the semiconductor material, the seventh portion of the semiconductor material between the second trench and the third trench;
a second layer of dielectric material on the sidewalls and the floor of the second trench;
a second electrically conductive material on the second layer of dielectric material; and wherein
the first contact includes a fourth portion in contact with the second electrically conductive material to form a second Ohmic contact portion of the first contact.

6. The Schottky device of claim 5 , further including
a fourth trench having sidewalls and a floor, the fourth trench extending from the first major surface of the semiconductor material into a fifth portion of the semiconductor material, wherein a sixth portion of the semiconductor material is between the third and fourth trenches, and wherein the sixth portion of the semiconductor material has a multi-concentration impurity profile comprising a third doped region of the second conductivity type and the second concentration extending from the first major surface of the semiconductor material into the sixth portion of the semiconductor material and a fourth doped region of the second conductivity type and the third concentration extending from the third doped region into the sixth portion of the semiconductor material, wherein the second concentration and the third concentration are selected so that a fifth portion of a first contact formed in contact with the sixth portion of the semiconductor material forms a second multi-concentration contact portion of the first contact and has electrical properties between a conventional Schottky contact and a conventional Ohmic contact, without being a conventional Schottky contact or a conventional Ohmic contact.

7. A Schottky device, comprising:
a semiconductor material of a first conductivity type having first and second major surfaces;
a plurality of trenches extending from the first major surface into the semiconductor material, wherein the plurality of trenches comprises at least first, second, and third trenches, the first trench having first and second sidewalls and a floor and the second trench having first and second sidewalls and a floor, wherein a first portion of the semiconductor material is between the first and second trenches, a second portion of the semiconductor material is between the second and third trenches, and a third portion of the semiconductor material is adjacent a side of the third trench;
a first layer of dielectric material on the first and second sidewalls and the floor of the first trench;
a first electrically conductive material on the first layer of dielectric material;
a second layer of dielectric material on the first and second sidewalls and the floor of the second trench;
a second electrically conductive material on the second layer of dielectric material;
a conductivity modulation means that modulates conductivity in the first portion of the semiconductor material and the third portion of the semiconductor material, wherein the conductivity modulation means includes a first multi-concentration impurity profile comprising a first doped region of a second conductivity type and a first concentration extending a first distance from the first major surface of the semiconductor material into the first portion of the semiconductor material and in direct contact with the second sidewall of the first trench and the first sidewall of the second trench, and a second doped region of the second conductivity type and a second concentration extending from the first doped region into the first portion of the semiconductor material, wherein a bottom of the second doped region is closer to the floor of the first trench than to the first major surface of the semiconductor material, and wherein the first concentration is selected so that a first portion of a first contact formed in contact with the first portion of the semiconductor material has electrical properties between a conventional Schottky contact and a conventional Ohmic contact, without being a conventional Schottky contact or a conventional Ohmic contact; and
a second portio

Assignees

• Semiconductor Components Ind Llc

Inventors

• Quddus Mohammed Tanvir
• Mudholkar Mihir
• Liu Mingjiao
• Thomason Michael

Classifications

• H10P30/212

  Through-implantation · CPC title

• H10P30/204

  into Group IV semiconductors · CPC title

• H10P30/22

  using masks · CPC title

• H01L21/2652

  Electricity · mapped topic

• H01L29/36 Primary

  Electricity · mapped topic