Patent ID: 9425019
Filing Date: 2016-08-23
CPC Classification: H01J,H01L

Claim Text:
1. A method of semiconductor manufacturing, comprising: depositing a top silicon oxide film on a silicon substrate; depositing a polysilicon etch-stop film over the top silicon oxide film; etching an annular isolation trench through the polysilicon etch-stop film and the top silicon oxide film; depositing a silicon nitride layer that overlies the top silicon oxide film and fills the annular isolation trench; etching an annular recess through the silicon nitride layer such that the etched annular recess is concentric with and surrounded by the silicon-nitride-filled annular trench in the top silicon oxide film; deepening the annular recess by anisotropically etching the polysilicon etch-stop film through the annular recess etched in the silicon nitride layer; lining the annular recess with a conformally deposited polysilicon sidewall film; etching the top silicon oxide film through the polysilicon-lined annular recess using an isotropic etching process such that an annular cavity having a rounded cross section forms in the top silicon oxide film and partially undercuts the silicon nitride layer; and filling the annular cavity in the top silicon oxide film with metal.