Abstract: Embodiments of the present invention are directed to a method of forming a bottom oxide layer in the trench in semiconductor devices, such as Double-Diffused Metal-Oxide Semiconductor (DMOS) devices. In one embodiment, a method of forming a bottom oxide layer in a trench structure comprises providing a semiconductor substrate; forming a silicon nitride layer on the semiconductor substrate; forming a first oxide layer on the silicon nitride layer; forming a trench structure in the semiconductor substrate; forming a second oxide layer on a bottom and sidewalls of the trench and on a surface of the first oxide layer; removing the first oxide layer and the second oxide layer on the surface of the silicon nitride layer; and removing the second oxide layer on the sidewalls of the trench and a portion of the second oxide layer on the bottom of the trench.

Abstract: Embodiments of the present invention relate to a method for preventing gate oxide thinning in a recess LOCOS process. The plurality of trenches are separated by a patterned pad oxide and a patterned silicon nitride layer The patterned silicon nitride layer and the patterned pad oxide layer are removed to expose a surface of the substrate as an active area of the semiconductor device. An ion drive-in to the active area on the substrate is performed by directing a flow of oxygen and nitrogen toward the substrate at a predetermined temperature and with a sufficient amount of oxygen to at least substantially prevent silicon nitride from forming on the field oxide regions. The method further comprises forming a sacrificial oxide layer on the active area, removing the sacrificial oxide layer to expose the active area, and forming a gate oxide layer on the active area.

Abstract: Embodiments of the present invention are directed to a method of forming a bottom oxide layer in the trench in semiconductor devices, such as Double-Diffused Metal-Oxide Semiconductor (DMOS) devices. In one embodiment, a method of forming a bottom oxide layer in a trench structure comprises providing a semiconductor substrate; forming a silicon nitride layer on the semiconductor substrate; forming a first oxide layer on the silicon nitride layer; forming a trench structure in the semiconductor substrate; forming a second oxide layer on a bottom and sidewalls of the trench and on a surface of the first oxide layer; removing the first oxide layer and the second oxide layer on the surface of the silicon nitride layer; and removing the second oxide layer on the sidewalls of the trench and a portion of the second oxide layer on the bottom of the trench.

Abstract: Embodiments of the present invention relate to a method for preventing gate oxide thinning in a recess LOCOS process. A method of forming a gate oxide on a substrate comprises providing a substrate having thereon a plurality of trenches having gate oxides formed therein, wherein the plurality of trenches are separated by a patterned pad oxide and a patterned silicon nitride layer disposed thereon and used to form the plurality of trenches. The patterned silicon nitride layer and the patterned pad oxide layer are removed to expose a surface of the substrate as an active area of the semiconductor device. An ion drive-in to the active area on the substrate is performed by directing a flow of oxygen and nitrogen toward the substrate at a predetermined temperature and with a sufficient amount of oxygen to at least substantially prevent silicon nitride from forming on the field oxide regions.

Abstract: A method for improving gate oxide thinning issue at trench corners is disclosed. The method comprises steps as follows. Firstly, a silicon substrate having a trench therein is provided. HDPCVD technology to form a first oxide layer on the sidewall and the bottom of the trench is carried out. After performing an etchback to leave the first oxide layer on the bottom of the trench, a second oxide layer is formed on the first oxide layer and on sidewalls of the trench by LPCVD technology. Thereafter, an isotropic etching is performed so as to remove a substantially portion of the second oxide layer and leave a remnant portion of second oxide layer on the trench corners. As a consequently, the trench corners are smooth. Finally, a thermal oxidation to form a third oxide layer on the sidewall of the trench is carried achieved to accomplish the gate oxide formation.