Abstract: Disclosed is a process of growing a conformal and etch-resistant silicon dioxide on a surface by forming a conformal layer of polysilicon and subjecting the polysilicon to thermal oxidation to completely convert the polysilicon into (poly) silicon oxide.Disclosed also is a method of forming an isolation trench in a semiconductor substrate having a high integrity oxide sidewall. After forming the trench in the substrate surface using a suitable etch mask and RIE, a single (thermal) oxide or dual (thermal) oxide and (CVD) nitride liner is formed on all trench surfaces. A conformal layer of undoped polysilicon is then formed (by. e.g. LPCVD) on the liner. By subjecting to thermal oxidation, the polysilicon is completely converted into a conformal (poly) silicon oxide layer having a thickness about 2.5 times that of the polysilicon layer. The resulting (poly) silicon oxide has the conformality of CVD oxide and the high etch resistance of thermally grown oxide.

Abstract: This device comprises a v-shaped cavity in a planar semiconductor substrate having a substantially thin-walled v-shaped cantilever beam inset therein. The beam is movable in directions normal to and laterally of the plane of the substrate, whereby acceleration is sensed in both of these directions. A planar substrate of n-type silicon is arranged with the major face oriented in the (100) plane. A v-shaped groove is anisotropically etched in the substrate and capacitor electrode regions are diffused into the sloping walls. An epitaxial layer is grown over this substrate, and over that a layer of insulation is added. A layer of conductive material is laid down on the insulation to define an electrode. The substrate is again subjected to an anisotropic etchant for cutting the epitaxial layer from under the cantilever beam formed of the insulating layer and the conducting layer.