High density selective SiO2:Si3N4 etching using a stoichiometrically altered nitride etch stop layer

摘要

Selectivity of SiO2 to Si3N4 is increased with the addition of silicon rich nitride conformal layer which may be used in place of or in addition to standard nitride conformal layers in manufacture. As can be seen in the drawing, a structure having a silicon substrate (1), gate electrodes (2), nitride cap (3) and conformal nitride (4) layers is constructed. A stoichiometrically altered conformal nitride layer (6) is then added. However this structure can be constructed having the altered conformal nitride layer (6) replacing the first conformal nitride layer (4). This same type of altered nitride could additionally be included in the cap (3) of the gate electrode (2). This nitride layer consists of higher concentrations of some materials, such as silicon and hydrogen, which add substantial selectivity to the nitride film during the etch process, without substantially changing the dielectric properties of the material.