Patent ID: 11862709
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  B | IPC H

Claim 0:
1. A method, comprising:
receiving a substrate;
forming a stack over the substrate, the forming of the stack including:
forming a first layer over the substrate, the first layer having a first semiconductor element;
forming a second layer over the first layer, the second layer having a second semiconductor element different from the first semiconductor element, wherein the second layer has the second semiconductor element at a first concentration in a first region of the second layer adjacent the first layer and at a second concentration in a second region of the second layer spaced apart from the first layer by the first region, the second concentration being smaller than the first concentration;
forming a third layer over the second semiconductor layer, the third layer having the first semiconductor element;

etching a source/drain trench in a region of the stack to expose a side surface of the stack;
removing a first portion of the second layer from the exposed side surface to form a gap between the first and the third layers;
forming a spacer in the gap; and
forming a source/drain feature in the source/drain trench and on a sidewall of the spacer.