Semiconductor Strips with Undercuts and Methods for Forming the Same

摘要

An integrated circuit device includes a semiconductor substrate, and a semiconductor strip extending into the semiconductor substrate. A first and a second dielectric region are on opposite sides of, and in contact with, the semiconductor strip. Each of the first dielectric region and the second dielectric region includes a first portion level with the semiconductor strip, and a second portion lower than the semiconductor strip. The second portion further includes a portion overlapped by the semiconductor strip.

主权项

1. A method comprising:
performing a first etching to etch a semiconductor substrate and to form top portions of a plurality of trenches, wherein portions of the semiconductor substrate are separated from each other by the plurality of trenches as semiconductor strips; performing a second etching to etch the semiconductor substrate and to form bottom portions of the plurality of trenches, wherein the bottom portions of the plurality of trenches are wider than the respective top portions of the plurality of trenches; filling a first dielectric material into the top portions and the bottom portions of the plurality of trenches, wherein portions of the first dielectric material in the top portions of the plurality of trenches form dielectric strips; etching end portions of the dielectric strips and the semiconductor strips to form a third trench and a fourth trench; and filling the third trench and the fourth trench with a second dielectric material to form additional dielectric regions.