| 摘要 |
<p>A process is provided for fabricating contacts (46s, 40g, 46d) in a completely self-aligned, planarized configuration for EPROM elements (66). The process of the invention permits higher packing densities, and allows feature distances to approach 0.5 mu m and lower. The EPROM element comprises source (18) and drain (20) regions separated by a gate region (22) and is characterized by the gate region comprising two separate gates, a floating gate (40g) and a control gate (58), capacitively coupled together. The floating gate is formed on a gate oxide (38) over the substrate (16) and the gates are separated from each other and from the source and drain contacts by a dielectric (56). The EPROM element has two threshold voltages, one related to the operation of a "normal" MOS transistor and the other related to a "programmed" threshold, following programming of the transistor. Sensing the threshold voltage of the device permits a determination to be made whether the device is programmed. UV radiation erases the programming and restores the threshold voltage of the device to its pre-programmed level.</p> |
