Semiconductor device e.g. DRAM production

摘要

A semiconductor device production process involves: (a) selectively forming a first conductive layer (4) on a semiconductor substrate (1) surface; (b) successively forming first, second, third and fourth insulating layers (5, 6, 7, 8); (c) selectively and individually etching the fourth, third and second insulating layers in this sequence to expose part of the substrate surface at a location in which the first conductive layer (4) is not present; and (d) forming a second conductive layer (9) for electrically contacting the substrate at the exposed location. The novelty is that the etching rate of the third insulating layer is lower than that of the fourth insulating layer. Also claimed is a similar process in which the fourth insulating layer is omitted; the etching rate of the second insulating layer is lower than that of the third insulating layer; and the second insulating layer (6) is present in a first region, at the side walls of the first conductive layer (4) and the first insulating layer (5), and in a second region at the substrate surface except for the portion where the first conductive layer (4) is formed, the second insulating layer having a width in the first region which is greater than its thickness in the second region. Further claimed is a semiconductor device having the above described structure with four insulating layers, the first, second and fourth insulating layers (5, 6, 8) being oxide layers and the third insulating layer (7) being a nitride layer.