Ion-sensitive FET prodn., useful for mfg. integrated liq. sensor circuit

摘要

ISFET prodn. involves (a) structuring source, drain and ion-sensitive gate regions; (b) depositing a silicon oxide-silicon nitride double layer (12a, 12b) as gate insulator (12); (c) forming contact openings in the double layer above the source and drain regions; (d) depositing and structuring conductor lines (24, 28) which directly contact the source and drain regions; (e) depositing an insulating surface planarising layer (26, 26', 30); (f) etching a trench extending down to the double layer above the source and drain regions respectively adjacent the ion-sensitive region; (g) depositing a silicon carbide layer (38); and (h) etching a cavity (40) which is enclosed by the trench and which extends down to the double layer (12a, 12b) above the ion-sensitive region.