Non-volatile random access memory cell constructed of silicon carbide

US5510630A · kind A · utility

Assignee

• Westinghouse Electric Company LLC · US

Inventors

• Anant Agarwal · San Jose, US
• Richard R. Siergiej · Irwin, US
• Charles D. Brandt · Mount Lebanon, US
• Marvin H. White · Laurel, US

Key dates

• Filing date: Oct 18, 1993
• Grant date: Apr 23, 1996
• Expiry date: Oct 18, 2013

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D30/637

Abstract

A non-volatile random access memory (NVRAM) cell that utilizes a simple, single-transistor DRAM cell configuration. The present NVRAM employs an enhancement mode nMOS transistor made as an accumulation mode transistor. The transistor has an n-type silicon carbide channel layer on a p-type silicon carbide buffer layer, with the channel and buffer layers being on a highly resistive silicon carbide substrate. The transistor also has n+ source and drain contact regions on the channel layer. A polysilicon/oxide/metal capacitor is preferably used which has a very low leakage current. Furthermore, this type of capacitor can be stacked on top of the transistor to save area and achieve high cell density. It is preferred to use a non-reentrant (edgeless) gate transistor structure to further reduce edge effects.