Double trench well formation in SRAM cells

摘要

A method is provided for forming SRAM cells with low energy implants. Embodiments include forming deep trenches in a silicon substrate; forming a deep n-well or deep p-well around a bottom of each deep trench; filling the deep trenches with oxide; forming a first or second shallow trench between each pair of adjacent deep trenches; forming a first p-well or first n-well, respectively, above each deep n-well or p-well; forming a second n-well at a bottom of each first shallow trench; forming a p+ region above each second n-well on each side of each first shallow trench; filling the first shallow trenches with oxide; forming a second p-well at a bottom of each second shallow trench; filling the second shallow trenches with oxide; forming a n+ region above each second p-well on each side of each second shallow trench.

主权项

1. A device comprising:
a silicon (Si) substrate; a deep n-well or deep p-well formed in the Si substrate; a first p-well or first n-well, respectively, formed above the deep n-well or deep p-well; a plurality of deep trenches having a first depth extending into the deep n-well or deep p-well; a plurality of first and second shallow trenches each first and second shallow trench having a second depth less than the first depth, a first or second shallow trench being formed between a pair of adjacent deep trenches; an oxide filling each deep trench and each of the first and second shallow trenches; a silicon fin on each side of each of the first and second shallow trenches; and a second n-well or a second p-well formed through and around a bottom portion of each first or second shallow trench, respectively.