Prodn. of ion-sensitive FET with contact at back

摘要

Prodn. of an ISFET with back face contacts involves (a) structuring a source region (6,22), a drain region (8,24) and an ion-sensitive gate region, in an active region (14) between the source and drain regions, at the front face (VS) of a substrate (2); (b) depositing a silicon oxide-silicon nitride double layer (16,18) as gate insulator and then a first silicon carbide layer (30) on the front face (VS); (c) structuring a back face (RS) insulation layer (12) to define contact hole regions opposite the source and drain regions; (d) depositing and structuring a second silicon carbide layer on the back face (RS); (e) etching trenches (36) extending from the contact hole regions towards the front face (VS); (f) introducing material of the same conductivity type as the source and drain regions, into substrate regions (38) adjacent to the trenches; (g) depositing conductor lines (40) on the substrate back face (RS) and in the trenches; and (h) removing the silicon carbide layer from t he front face (VS) at least in the ion-sensitive gate region.