Production of a storage cell used in DRAMs comprises using a multiple step process in which a word line contact is eventually formed to electrically connect the gate to the word line

摘要

A storage cell used in DRAMs is produced by a multiple step process in which a word line contact is eventually formed to electrically connect the gate to the word line. Production of a storage cell comprises: (a) forming a trench (30) in a substrate (5); (b) depositing a capacitor dielectric (35) in the trench; (c) depositing a conductive filling (40) in the trench; (d) depositing a first insulating layer (45) on the filling; (e) epitaxially growing the insulating layer with an epitaxially grown layer (55); (f) forming a second trench (60) in the epitaxially grown layer; (g) etching the first insulating layer; (h) depositing and sinking in a contact layer so that the contact layer remains below the epitaxially grown layer; (i) depositing and sinking in a second insulating layer (75) in the second trench; (j) forming a gate oxide (80) followed by a gate (85); inserting a dopant; (k) forming a bit line (15) and a word line (10); and (l) forming a word line contact (110) to electrically connect the gate to the word line. Preferred Features: The second trench is displaced by more than a third of the width of the first trench. The epitaxially grown layer is under-etched. The contact layer is made of doped silicon.