Postponed ROM programming
AssigneeNational Semiconductor Corporation
InventorsHaluk M. Aytac, John F. MacDonald
Life of this patent
Estimating the term…
Abstract
A process to program ROM's after the insulation, gates, and interconnect circuitry have been formed by using a contact mask to define openings at the depletion cells, which openings extend beside the gates to the sources and drain so as to allow phosphorus dopant to be diffused sideways under the gates to short out the cell.
Claims4
In the fabrication of a silicon semiconductor field effect memory device wherein spaced apart source and drain areas are formed on a substrate with a channel extending therebetween and a control gate is formed above the channel with an oxide insulating layer covering the gate and device, an improvement to the process that allows the device to be converted into a normally conducting device late in the fabrication process comprising:
- masking and etching the device so as to create openings to the source and drain areas on the substrate beside the control gate;
- and
- doping said source and drain areas through said openings so as to expand said areas toward each other, under said gate, until they form a continuous conduction path.
Dependencies are inferred from the claim text.