Modified-anode gate turn-off thyristor

• US 6,501,099 B2
• Filed: 03/05/2001
• Issued: 12/31/2002
• Est. Priority Date: 03/05/2001
• Status: Expired due to Term

• Current Assignee: Army The United Stastes of America As Represented By The Secretary of The
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Shah, Pankaj B.
• Primary Examiner(s): Loke, Steven
• Application Number:
  US09/798,585
• Publication Number:
  US 20020134992A1
• Time in Patent Office: 666 Days
• Field of Search: 257/115, 257/132, 257/138, 257/139, 257/147, 257/77, 257/157, 257/120, 257/110
• US Class Current: 257/77
• CPC Class Codes: H01L 29/0834 Anode regions of thyristors or gated bipolar-mode devices, e.g. supplementary regions surrounding anode regions
• CPC Class Codes: H01L 29/744 Gate-turn-off devices

Abstract

A gate turn-off thyristor includes a substrate formed of n-type silicon carbide; a growth buffer formed of n-type silicon carbide and positioned to overlie said substrate; a field buffer region formed of p-type silicon carbide and positioned to overlie said growth buffer; a drift region formed of p-type silicon carbide and positioned to overlie said field buffer region; a gated base region formed of n-type silicon carbide and positioned to overlie said drift region; a modified anode region formed of first, second and third layers of silicon carbide and positioned to overlie said gated base region, said first layer comprising p-type silicon carbide and disposed adjacent said gated base region, said second layer comprising n-type silicon carbide and disposed adjacent said first layer, said third layer comprising p-type silicon carbide and disposed adjacent said second layer; an anode contact disposed on said third layer of said modified anode region; a cathode contact disposed on said substrate; and a gate contact disposed on said gated base region.

Claims

1. A gate turn-off thyristor, comprising:

a substrate formed of n-type silicon carbide;

a growth buffer formed of n-type silicon carbide and positioned to overlie said substrate;

a field buffer region formed of p-type silicon carbide and positioned to overlie said growth buffer;

a drift region formed of p-type silicon carbide and positioned to overlie said field buffer region;

a gated base region formed of n-type silicon carbide and positioned to overlie said drift region;

a modified anode region formed of first, second and third layers of silicon carbide and arranged in a stacked array positioned to overlie said gated base region, said first layer comprising p-type silicon carbide and overlying said gated base region, said second layer comprising n-type silicon carbide and overlying said first layer, and said third layer comprising p-type silicon carbide and overlying said second layer;

an anode contact disposed on said third layer of said modified anode region;

a cathode contact disposed on said substrate; and

a gate contact disposed on said gated base region.

2. The gate turn-off thyristor of claim 1 further comprising passivation material disposed on external surfaces of said gate turn-off thyristor not otherwise covered by one of said anode contact, said cathode contact and said gate contact.

3. The gate turn-off thyristor of claim 2 wherein said passivation material comprises silicon dioxide.

4. The gate turn-off thyristor of claim 1 wherein said cathode contact and said gate contact comprise nickel.

5. The gate turn-off thyristor of claim 1 wherein said anode contact comprises one of aluminum and titanium.

6. the gate turn-off thyristor of claim 1 wherein each of the thicknesses of said first layer and said second layer of said modified anode region is less than a thickness of said third layer of said modified anode region.

7. The gate turn-off thyristor of claim 1 wherein a thickness of said first layer of said modified anode region is less than one-fifth a diffusion length of free carriers in the silicon carbide comprising said first layer and a thickness of said second layer of said modified anode region is less than one-fifth a diffusion length of free carriers in the silicon carbide comprising said second layer.