Process for forming a buried cavity in a semiconductor material wafer

摘要

The process comprises the steps of forming, on top of a semiconductor material wafer (10), a holed mask (16) having a lattice structure and comprising a plurality of openings (18) each having a substantially square shape and a side with an inclination of 45 DEG with respect to the flat (110) of the wafer; carrying out an anisotropic etch in TMAH of the wafer (10), using said holed mask (16), thus forming a cavity (20), the cross section of which has the shape of an upside-down isosceles trapezium; and carrying out a chemical vapour deposition (CVD) using TEOS, thus forming a TEOS layer (24) which completely closes the openings of the holed mask (16) and defines a diaphragm (26) overlying the cavity (20) and on which a suspended integrated structure can subsequently be manufactured.