Method of high selectivity SAC etching
AssigneeTokyo Electron Limited
InventorKazuo Tsuchiya
Life of this patent
Estimating the term…
Abstract
A method for SAC etching is provided involving a) etching a Si wafer having a nitride present thereon with a first etching gas containing a first perfluorocarbon and carbon monoxide, and b) etching the resultant Si wafer having an initially etched nitride photoresist thereon with a second etching gas containing a second perfluorocarbon in the substantial absence of carbon monoxide, wherein the etching steps a) and b) are performed at high RF power and low pressure compared to conventional processes to provide higher selectivity etching and a larger process window for SAC etching, as well as the ability to perform SAC etching and island contact etching under the same conditions with high verticality of the island contact and SAC walls.
Claims30
A method for SAC etching comprising:
- a) etching a silicon oxide layer above a silicon nitride layer present thereon with a first etching gas comprising a first perfluorocarbon and carbon monoxide to etch through the silicon oxide layer, and
- b) etching the silicon nitride layer with a second etching gas comprising a second perfluorocarbon in the absence of carbon monoxide,
- wherein the silicon nitride layer under the etched silicon oxide layer is not etched through.
Dependencies are inferred from the claim text.