Flash memory with i - shaped potential unsaturated collar a gate and method for its production

摘要

A novel flash memory has (a) a first conductivity type substrate (31) with spaced-apart second conductivity type source and drain regions (35, 36) at its surface; (b) T-shaped source and drain electrodes (35a, 36a) respectively formed on and in contact with the source and drain regions (35, 36); (c) an I-shaped floating gate (39) formed on the substrate between and in contact with the source and drain electrodes; and (d) a control gate (41) formed on the floating gate. Also claimed is a flash memory production process involving (i) forming first and second insulating layers (32) on a first conductivity type substrate (31); (ii) structuring the layers to produce two spaced-apart openings, through which second conductivity type impurities are implanted to form source and drain regions (35, 36); (iii) producing a second conductivity type semiconductor layer on the insulating layers and in the openings for contact with the source and drain regions; (iv) structuring the semiconductor layer to form T-shaped source and drain electrodes (35a, 36a) and then removing the second insulating layer; (v) applying a third insulating layer (38) over the entire surface, including the source and drain electrodes; (vi) applying and structuring a second conductivity type semiconductor layer to form an I-shaped floating gate (39) between and overlapping the source and drain electrodes (35a, 36a); (vii) producing a fourth insulating layer (40) on the entire surface, including the floating gate (39); and (viii) forming and structuring a semiconductor layer to produce a control gate (41) above the floating gate (39).