TRANSISTOR STRUCTURE AND METHOD WITH AN EPITAXIAL LAYER OVER MULTIPLE HALO IMPLANTS

摘要

A transistor structure having an epitaxial layer deposited over an implanted substrate in order to reduce process variability. The epitaxial layer is able to be deposited doped, un-doped or lightly doped via up-diffusion from the implanted substrate, and used to form the channel for the transistor structure. As a result, this use of un-doped epitaxial layer provides the benefit of reducing process variability (e.g. random dopant fluctuation) and thus the transistor performance variability despite the small physical size of the transistors.

主权项

1. A transistor structure comprising:
a first control gate; a semiconductor substrate doped to a first conductivity type; a first shallow halo implant region of the first conductivity type at a first depth in a portion of the substrate that at least partially extends under the first control gate; a first deep halo implant region of the first conductivity type at a second depth in a portion of the substrate that at least partially extends under the first control gate, wherein the second depth is greater than the first depth; an epitaxial layer formed on top of the substrate and below the first control gate; and a first source region and a first drain region both of a second conductivity type and formed in the epitaxial layer over the first shallow halo implant and the first deep halo implant and to the sides of the first control gate.