A Buried Thermal Rail (BTR) Technology to Improve Electrothermal Characteristics of Complementary Field-Effect Transistor (CFET)

Abstract

The complementary field-effect transistor (CFET) with N-type FET (NFET) stacked on P-type FET (PFET) is a promising device structure based on gate-all-around FET (GAAFET). Because of the high-density stacked structure, the self-heating effect (SHE) becomes more and more severe. Buried thermal rail (BTR) technology on top of the buried power rail (BPR) process is proposed to improve heat dissipation. Through a systematical 3D Technology Computer Aided Design (TCAD) simulation, compared to traditional CFET and CFET with BPR only, the thermal resistance (Rth) of CFET can be significantly reduced with BTR technology, while the drive capability is also improved. Furthermore, based on the proposed BTR technology, different power delivery structures of top-VDD–top-VSS (TDTS), bottom-VDD–bottom-VSS (BDBS), and bottom-VDD–top-VSS (BDTS) were investigated in terms of electrothermal and parasitic characteristics. The Rth of the BTR-BDTS structure is decreased by 5% for NFET and 9% for PFET, and the Ion is increased by 2% for NFET and 7% for PFET.

Keywords

• complementary field-effect transistor (CFET)
• technology computer-aided design (TCAD)
• self-heating effect (SHE)
• power delivery network (PDN)
• buried power rail (BPR)