Semiconductor strips with undercuts and methods for forming the same
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsTai-Chun Huang, Chih-Tang Peng, Chia-Wei Chang, Ming-Hua Yu, Hao-Ming Lien, Chao-Cheng Chen, Tze-Liang Lee
Life of this patent
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Abstract
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.
Claims20
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.
A method comprising:
- performing a first etching to etch a semiconductor substrate and to form a first trench and a second trench parallel to each other, with a remaining portion of the semiconductor substrate acting as a semiconductor strip separating the first trench from the second trench;
- performing a second etching to form an opening overlapped by the semiconductor strip, wherein during the second etching, a polymer generated during the first etching protects a top portion of the semiconductor strip from being etched;
- and
- filling a first dielectric material into the first trench and the second trench to form a first dielectric strip and a second dielectric strip, respectively.
A method comprising:
- forming a patterned mask layer over a semiconductor substrate;
- etching the semiconductor substrate using the patterned mask layer as an etching mask to form a top portion of a trench;
- etching the semiconductor substrate using the patterned mask layer as the etching mask to widen a bottom portion of the trench, wherein the top portion of the trench is protected from being widened when the bottom portion of the trench is widened, and a portion of the semiconductor substrate with a sidewall exposed to the trench forms a semiconductor strip;
- removing the patterned mask layer;
- filling the trench with a dielectric material;
- etching opposite end portions of the semiconductor strip to form a second trench and a third trench;
- and
- filling the second trench and the third trench with an additional dielectric material to form a first dielectric strip and a second dielectric strip, respectively.
Dependencies are inferred from the claim text.