Lattice strain analysis of silicon fin field-effect transistor structures wrapped by Ge2Sb2Te5 liner stressor

Abstract

The local strain components in the source/drain (S/D) and channel regions of Si fin field-effect transistor (FinFET) structures wrapped around by a Ge2Sb2Te5 liner stressor were investigated for the first time using nano-beam diffraction. When the Ge2Sb2Te5 (GST) layer changes phase from amorphous to crystalline, it contracts and exerts a large stress on the Si fins. This results in large compressive strain in the S/D region of ⟨1¯10⟩-oriented Si FinFETs of up to −1.15% and −1.57% in the ⟨110⟩ (horizontal) and ⟨001⟩ (vertical) directions, respectively. In the channel region of the FinFETs under the metal gate, the GST contraction results in up to −1.47% and −0.61% compressive strain in the ⟨110⟩ and ⟨001⟩ directions, respectively. In the channel region, the ⟨110⟩ compressive strain is higher at the fin sidewalls and lower near the fin center, while the ⟨001⟩ compressive strain is lower at the sidewalls and higher near the center.