Inventors:
Rashid Bashir - Santa Clara CA
Wipawan Yindeepol - San Jose CA
Assignee:
National Semiconductor Corporation - Santa Clara CA
International Classification:
H01L 21302
Abstract:
A semiconductor device, polysilicon-contacted trench isolation structure that provides improved electrical isolation stability, a method of operating a polysilicon-contacted trench isolated semiconductor device, and a process for manufacturing a polysilicon-contacted trench isolation structure. The trench isolation structure includes an isolation trench formed in a semiconductor substrate. The isolation trench has a layer of trench lining oxide, a layer of trench lining silicon nitride and a trench fill polysilicon (poly 1) layer. Exposed lateral surfaces of the poly 1, which extend above the trench lining silicon nitride, are contacted to another layer of polysilicon (poly 2). The method of operation includes applying a bias voltage to the trench fill poly 1 layer via poly 2. The process for manufacture includes etching an isolation trench that extends through a layer of field oxide and into a semiconductor substrate. After forming layers of trench lining oxide, trench lining silicon nitride and trench fill poly 1 in the isolation trench, the trench lining silicon nitride is etched back to expose lateral surfaces of the trench fill poly 1.