Deep isolation trench structure and deep trench capacitor on a semiconductor-on-insulator substrate

摘要

Two trenches having different widths are formed in a semiconductor-on-insulator (SOI) substrate. An oxygen-impermeable layer and a fill material layer are formed in the trenches. The fill material layer and the oxygen-impermeable layer are removed from within a first trench. A thermal oxidation is performed to convert semiconductor materials underneath sidewalls of the first trench into an upper thermal oxide portion and a lower thermal oxide portion, while the remaining oxygen-impermeable layer on sidewalls of a second trench prevents oxidation of the semiconductor materials. After formation of a node dielectric on sidewalls of the second trench, a conductive material is deposited to fill the trenches, thereby forming a conductive trench fill portion and an inner electrode, respectively. The upper and lower thermal oxide portions function as components of dielectric material portions that electrically isolate two device regions.

主权项

1. A method of forming a semiconductor structure comprising:
forming a first trench and a second trench in a semiconductor-on-insulator (SOI) substrate including a stack, from bottom to top of, at least one semiconductor layer, a buried insulator layer, and a top semiconductor layer; providing a contiguous oxygen-impermeable layer on sidewalls of said first trench and second trench in said SOI substrate; depositing a fill material layer on said contiguous oxygen-impermeable layer, wherein a cavity is present within said first trench after said depositing said fill material layer in said first trench, and wherein after said depositing said fill material layer said second trench is completely filled with said fill material layer and said contiguous oxygen-impermeable layer; isotropically etching said fill material layer, wherein said fill material layer is completely removed within said first trench, and a remaining portion of said fill material layer is present within said second trench; removing said oxygen-impermeable layer from said sidewalls of said first trench, but not said second trench; oxidizing semiconductor materials on said sidewalls of said first trench, while said oxygen-impermeable layer covers said sidewalls of said second trench; and depositing a conductive material in said first trench and said second trench.