US 2007/0176244 A1 · SEMICONDUCTOR DEVICE AND METHOD OF FORMING THE SAME

Abstract

A semiconductor device and a method of forming thereof have a semiconductor substrate, an active region, and an inclined trench formed around the outer periphery of the active region. The semiconductor substrate at least includes an n-type high impurity concentration layer inhibiting a depletion layer from spreading, an n-type low impurity concentration drift layer, and a p-type high impurity concentration layer forming a p-n main junction between the drift layer, which are arranged in this order. In the active region, an effective current flows in the direction of the thickness of the substrate. The inclined trench cuts the p-n main junction at a positive bevel angle from the semiconductor substrate surface on the side of the n-type high impurity concentration layer to penetrate through the substrate for separating it into chips. In the semiconductor device, along the sidewall of the inclined trench in the n-type drift layer, an n-type surface region is formed with an impurity concentration lower than that in the n-type drift layer. Thus provided semiconductor device can prevent the electric field strength therein from reaching the critical electric field strength that causes a breakdown in a surface breakdown voltage blocking structure prior to in the active region, as well as reducing the area ratio of the surface breakdown voltage blocking structure to the entire chip area.

Claims17

Dependent claims

A semiconductor device comprising:

a semiconductor substrate comprising:
a first high impurity concentration layer of a first conductivity type;
a low impurity concentration drift layer of the first conductivity type;
and
a second high impurity concentration layer of a second conductivity type, the second high impurity concentration layer and the drift layer forming a p-n main junction therebetween,
wherein the drift layer is formed between the first high impurity concentration layer and the second high impurity concentration layer;
an active region where current flows in the direction of the thickness of the semiconductor substrate;
and
a junction termination structure surrounding an outer periphery of the active region, the junction termination structure comprising:
a sidewall extending between the first high impurity concentration layer and the second high impurity concentration layer, and forming a positive bevel angle with respect to a principal surface of the first high impurity concentration layer;
and
a surface region of the first conductivity type extending along the sidewall and extending between the first high impurity concentration layer and the second high impurity concentration layer,
wherein the surface region has an impurity concentration lower than an impurity concentration of the first high impurity concentration layer and an impurity concentration of the second high impurity concentration layer, but higher than an impurity concentration of the drift layer.

10 more elements

A method of forming a semiconductor device, the method comprising the steps of:

forming a semiconductor substrate comprising:
a first high impurity concentration layer of a first conductivity type;
a low impurity concentration drift layer of the first conductivity type;
and
a second high impurity concentration layer of a second conductivity type, the second high impurity concentration layer and the drift layer forming a p-n main junction therebetween,
wherein the drift layer is formed between the first high impurity
concentration layer and the second high impurity concentration layer;
forming an active region where current flows in the direction of the thickness of the semiconductor substrate;
and
forming a junction termination structure surrounding an outer periphery of the active region, the junction termination structure comprising:
a sidewall extending between the first high impurity concentration layer and the second high impurity concentration layer, and forming a positive bevel angle with respect to a principal surface of the first high impurity concentration layer;
and
a surface region of the first conductivity type extending along the sidewall and extending between the first high impurity concentration layer and the second high impurity concentration layer,
wherein the surface region has an impurity concentration lower than an impurity concentration of the first high impurity concentration layer and an impurity concentration of the second high impurity concentration layer, but higher than an impurity concentration of the drift layer.

11 more elements

Dependencies are inferred from the claim text.

Semiconductor device and method of forming the same

Life of this patent

Semiconductor device and method of forming the same

Life of this patent

Abstract

Claims17