Process for forming slots having near vertical sidewalls at their upper extremities
First Claim
1. A process for fabricating slots in a wafer of semiconductor material wherein the slots have nearly vertical sidewalls near the mouth of the slot, comprising the steps of:
- applying an etch-resistant mask material to the surface of said wafer of semiconductor material;
patterning said mask material to expose regions in said substrate in which slots are to be formed;
etching said exposed regions in said substrate to form said slots; and
forming an etch resistant coating on the walls of said slots while they are being formed whereby said etch resistant coating protects said sidewalls near the mouth of the slot from unwanted etching so they retain a nearly vertical shape.
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Accused Products
Abstract
A slot formation process is provided in which the regions near the mouth of the slot are coated, while the slot is being formed, with a material which is resistant to the etchant being used to form the slot. The coating may be applied continuously or may be applied at specific points in the slot formation process. During the formation of the middle and bottom regions of the slot the coated upper regions retain a nearly vertical contour shape since they are protected from undesired etching by ions whose trajectories have been impacted by charge accumulations at the mouth of the slot. The coating material may be a thin oxide layer of the semiconductor material or may be a layer of an appropriate etch resistant material.
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Citations
13 Claims
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1. A process for fabricating slots in a wafer of semiconductor material wherein the slots have nearly vertical sidewalls near the mouth of the slot, comprising the steps of:
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applying an etch-resistant mask material to the surface of said wafer of semiconductor material; patterning said mask material to expose regions in said substrate in which slots are to be formed; etching said exposed regions in said substrate to form said slots; and forming an etch resistant coating on the walls of said slots while they are being formed whereby said etch resistant coating protects said sidewalls near the mouth of the slot from unwanted etching so they retain a nearly vertical shape. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification