Epitaxial Source/Drain Structure and Method of Forming Same

• Main Authors: Sung, Hsueh-Chang, Li, Kun-Mu
• Format: Patent
• Language: English
• Published: 20.07.2023
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

A semiconductor device and a method of forming the same are provided. The semiconductor device includes a gate stack over an active region and a source/drain region in the active region adjacent the gate stack. The source/drain region includes a first semiconductor layer having a first germanium concentration and a second semiconductor layer over the first semiconductor layer. The second semiconductor layer has a second germanium concentration greater than the first germanium concentration. The source/drain region further includes a third semiconductor layer over the second semiconductor layer and a fourth semiconductor layer over the third semiconductor layer. The third semiconductor layer has a third germanium concentration greater than the second germanium concentration. The fourth semiconductor layer has a fourth germanium concentration less than the third germanium concentration.