Epitaxial channel with a counter-halo implant to improve analog gain

摘要

Some embodiments of the present disclosure relate to an implant that improves long-channel transistor performance with little to no impact on short-channel transistor performance. To mitigate DIBL, both long-channel and short-channel transistors on a substrate are subjected to a halo implant. While the halo implant improves short-channel transistor performance, it degrades long-channel transistor performance. Therefore, a counter-halo implant is performed on the long-channel transistors only to restore their performance. To achieve this, the counter-halo implant is performed at an angle that introduces dopant impurities near the source/drain regions of the long-channel transistors to counteract the effects of the halo implant, while the counter-halo implant is simultaneously shadowed from reaching the channel of the short-channel transistors.

主权项

1. A method, comprising:
forming a plurality of first gate structures over a substrate, wherein the plurality of first gate structures have a vertical dimension (h) and are separated by a first horizontal space (s1); forming a plurality of second gate structures on the substrate, wherein the plurality of second gate structures have the vertical dimension (h) and are separated by a second horizontal space (s2), which is greater than the first horizontal space (s1); performing a first implant at a first angle with a vertical line to form halo regions within the substrate, wherein the halo regions extend below the plurality of first gate structures and the plurality of second gate structures; and performing a second implant after the first implant and at a second angle with the vertical line to introduce dopant impurities into the substrate that reduce a doping concentration of the halo regions that extend below the plurality of second structures, wherein the second angle is greater than the first angle such that the second implant is blocked from reaching the substrate by the plurality of first gate structures.