Super-junction corner and termination structure with improved breakdown and robustness

Patent metadata

Field	Value
Publication number	US-10580868-B2
Application number	US-201815937674-A
Country	US
Kind code	B2
Filing date	Mar 27, 2018
Priority date	Mar 27, 2018
Publication date	Mar 3, 2020
Grant date	Mar 3, 2020

Abstract

A superjunction power semiconductor device includes a termination region with superjunction structures having higher breakdown voltage than the breakdown voltage of the active cell region. In one embodiment, the termination region includes superjunction structures having lower column charge as compared to the superjunction structures formed in the active cell region. In other embodiments, a superjunction power semiconductor device incorporating superjunction structures with slanted sidewalls where the grading of the superjunction columns in the termination region is reduced as compared to the column grading in the active cell region. The power semiconductor device is made more robust by ensuring any breakdown occurs in the core region as opposed to the termination region. Furthermore, the manufacturing process window for the power semiconductor device is enhanced to improve the manufacturing yield of the power semiconductor device.

First claim

What is claimed is:

1. A superjunction power semiconductor device, comprising:
a semiconductor substrate of a first conductivity type;
a semiconductor body of the first conductivity type formed on the semiconductor substrate and including an active cell region encircled by a termination region;
the active cell region including a first superjunction structure including a first plurality of alternating N-type and P-type thin semiconductor regions formed substantially perpendicular with a major surface of the semiconductor body; and
the termination region including a second superjunction structure including a second plurality of alternating N-type and P-type thin semiconductor regions formed substantially perpendicular with the major surface of the semiconductor body,
wherein the first superjunction structure comprises alternating first columns of the first conductivity type and second columns of a second conductivity type as the first plurality of alternating N-type and P-type thin semiconductor regions, the first columns and second columns having respective first column charge and second column charge to realize charge balance; and the second superjunction structure comprises alternating third columns of the first conductivity type and fourth columns of the second conductivity type as the second plurality of alternating N-type and P-type thin semiconductor regions, the third columns and fourth columns having respective third column charge and fourth column charge to realize charge balance, the third column charge and the fourth column charge being lower than respective first column charge and second column charge for at least a portion of the third and fourth columns; and
wherein the first columns and the second columns in the first superjunction structure have the same doping profile along the direction of substantially perpendicular with the major surface of the semiconductor body, and the third columns and the fourth columns in the first superjunction structure have the same doping profile along the direction of substantially perpendicular with the major surface of the semiconductor body; and
wherein a breakdown voltage of the termination region is greater than a breakdown voltage of the active cell region over a manufacturing process window of the active cell region.

2. The superjunction power semiconductor device of claim 1 , wherein the manufacturing process window of the active cell region comprises fabrication process conditions for fabricating the active cell region having a breakdown voltage greater than a minimum allowable breakdown voltage.

3. The superjunction power semiconductor device of claim 1 , wherein the termination region comprises a plurality of edge termination regions and a plurality of corner regions, both of the edge termination regions and the corner regions having breakdown voltage values greater than the breakdown voltage of the active cell region over the manufacturing process window of the active cell region.

4. The superjunction power semiconductor device of claim 1 , wherein each of the third column charge and the fourth column charge is at least 10% less than the respective first column charge and the second column charge for at least 10% of the third and fourth columns.

5. The superjunction power semiconductor device of claim 1 , wherein the first superjunction structure comprises the second columns being formed as doped columns of the second conductivity type in the semiconductor body and the first columns being formed in the semiconductor body between a pair of adjacent doped columns, the second columns having a first column width and a first column pitch; and the second superjunction structure comprises the fourth columns being formed as doped columns of the second conductivity type in the semiconductor body and the third columns being formed in the semiconductor body between a pair of adjacent doped columns, the fourth columns having a second column width and a second column pitch.

6. The superjunction power semiconductor device of claim 5 , wherein the second column width is less than the first column width.

7. The superjunction power semiconductor device of claim 5 , wherein the second column pitch is less than the first column pitch.

8. The superjunction power semiconductor device of claim 5 , wherein the fourth columns have a doping level lower than a doping level of the second columns.

9. The superjunction power semiconductor device of claim 5 , further comprising a transition region between the active cell region and the termination region, the transition region comprising a third superjunction structure having fifth columns of the first conductivity and sixth columns of the second conductivity types, the sixth columns having a column width that decreases from the first column width to the second column width from the active cell region to the termination region, and the sixth columns having a column pitch that decreases from the first column pitch to the second column pitch from the active cell region to the termination region.

10. The superjunction power semiconductor device of claim 1 , wherein the superjunction power semiconductor device comprises a superjunction MOSFET device, the superjunction structure formed in the active cell region forming a drain drift region of the MOSFET device.

11. The superjunction power semiconductor device of claim 1 , wherein the semiconductor substrate comprises a heavily doped semiconductor substrate of the first conductivity type and the semiconductor body comprises an epitaxial layer of the first conductivity type.

12. The superjunction power semiconductor device of claim 1 , wherein the first conductivity type comprises N-type conductivity and the second conductivity type comprises P-type conductivity.

Assignees

• Alpha & Omega Semiconductor Cayman Ltd

Inventors

• Bobde Madhur
• Padmanabhan Karthik
• Guan Lingpeng

Classifications

• H01L29/0878

  Electricity · mapped topic

• H01L29/0886

  Electricity · mapped topic

• H01L29/158

  Electricity · mapped topic

• H01L29/0619

  Electricity · mapped topic

• H01L29/0696

  Electricity · mapped topic