Fast recovery rectifier

• US 20070262304A1
• Filed: 05/08/2007
• Published: 11/15/2007
• Est. Priority Date: 05/10/2006
• Status: Active Grant

• Current Assignee: Ho-Yuan Yu
• Original Assignee: Ho-Yuan Yu
• Inventors: Yu, Ho-Yuan
• Granted Patent: US 7,880,166 B2
• Time in Patent Office: Days
• US Class Current: 257/44
• CPC Class Codes: H01L 29/32 the imperfections being within the semiconductor body
• 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 29/861 Diodes
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

A fast recovery rectifier structure with the combination of Schottky structure to relief the minority carriers during the forward bias condition for the further reduction of the reverse recovery time during switching in addition to the lifetime killer such as Pt, Au, and/or irradiation. This fast recovery rectifier uses unpolished substrates and thick impurity diffusion for low cost production. A reduced p-n junction structure with a heavily doped film is provided to terminate and shorten the p-n junction space charge region. This reduced p-n junction with less total charge in the p-n junction to further improve the reverse recovery time. This reduced p-n junction can be used alone, with the traditional lifetime killer method, with the Schottky structure and/or with the epitaxial substrate.

Claims

1. A rectifier device, comprising:

a doped substrate;

a p-n junction formed on top of said doped substrate, diffusion to said doped substrate using opposite polarity species at said p-n junction;

at least one etched structure etched on said doped substrate and said p-n junction;

a top metal layer having a first side and a second side formed on top over said p-n junction and each of said at least one etched structure;

wherein said top metal layer having ohmic contact with said p-n junction and having schottky contact with each of said at least one etched structure for the purpose of absorbing minority carrier;

a passivation layer formed on both sides of said top metal layer and covering portion of said doped substrate and said top metal layer;

a backside layer formed immediately below said doped substrate, diffusion to said doped substrate using same polarity species at said backside layer; and

a bottom layer formed below said backside layer.