A method of forming shallow trench isolation structure in a semiconductor device

Abstract From the Canadian patent

A method (Figs. 3A-3I) for fabricating a shallow trench isolation structure (Fig. 4) is described, in which a bottom pad oxide layer (62) a middle , silicon nitride layer (64), a middle oxide layer (66) and a top silicon nitride layer (68) are sequentially formed on a silicon substrate (60). Photolithographic masking and anisotropic etching are then conducted to form a trench (70) in the substrate. An oxide material (80) is then deposited on top of the top silicon nitride layer, filling up the trenches at the same time (Fig. 3E). The top silicon nitride layer is then removed followed by an , isotropic etch of the oxide layer below. With the middle nitride layer acting as a natural …