Methods of forming an isolation trench in a semiconductor, methods of forming an isolation trench in a surface of a silicon wafer, methods of forming an isolation trench-isolated transistor, trench-isolated transistor, trench isolation structures formed in a semiconductor, memory cells and drams

Abstract

A method of forming an isolation trench in a semiconductor includes forming a first isolation trench portion having a first depth and having a first sidewall intersecting a surface of the semiconductor at a first angle. The method also includes forming a second isolation trench portion within and extending below the first isolation trench portion. The second isolation trench portion has a second depth and includes a second sidewall. The second sidewall intersects the first sidewall at an angle with respect to the surface that is greater than the first angle. A dielectric material fills the first and second isolation trench portions.