Method and structure for forming vertical transistors with various gate lengths
AssigneeInternational Business Machines Corporation
InventorsKangguo Cheng, Shogo Mochizuki, Choonghyun Lee, Juntao Li
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Abstract
Various methods and structures for fabricating a plurality of vertical fin FETs on the same semiconductor substrate in which a first gate length of a first gate in a first vertical fin FET is less than a second gate length of a second gate in a second vertical fin FET. A difference in gate lengths between different vertical fin FETs can be precisely fabricated by using atomic layer silicon germanium epitaxy. Gate length offset is formed at a bottom source/drain junction region of each vertical fin FET transistor, which allows downstream processing for all vertical fin FET transistors to be the same.
Claims12
A method of fabricating a semiconductor structure, the method comprising:
- patterning a semiconductor stack to form on a semiconductor substrate a first vertical fin in a first vertical fin region and a second vertical fin in a second vertical fin region;
- epitaxially growing a sacrificial semiconductor material on the semiconductor substrate wherein the sacrificial semiconductor material covers a lower portion of the first vertical fin and the second vertical fin;
- removing the sacrificial semiconductor material in the second vertical fin region while leaving the sacrificial semiconductor material in the first vertical fin region;
- forming a sidewall spacer on the first vertical fin and on the second vertical fin;
- contemporaneously etching the sacrificial semiconductor material and a portion of the semiconductor substrate in the first vertical fin region, and a portion of the semiconductor substrate in the second vertical fin region;
- removing the sacrificial semiconductor material in the first vertical fin region;
- forming a first bottom source/drain layer on the sidewalls of the first vertical fin;
- and
- forming a second bottom source/drain layer on the sidewalls of the second vertical fin.
Dependencies are inferred from the claim text.