Impact of Device-to-Device Thermal Interference Due to Self-Heating on the Performance of Stacked Nanosheet FETs

Abstract

The stacked nanosheet field effect transistor (SNSHFET) exhibits superior electrostatic performance with its increased effective channel width. However, as the technology node progressing towards angstrom dimensions, self-heating became one of the major challenges in SNSHFETs due to their confined geometry. The self-heating impacts not only the respective device, but also its contiguous device on the same substrate. In this paper, the thermal impact of heat stacked nanosheet FET (He-FET) on proximal cool stacked nanosheet FET (Co-FET) is studied at 7 nm technology node. Thermal impact on DC and analog/RF performance of Co-FET is deliberated by varying the inter-device spacing (IDS) and shallow trench isolation (STI) depth between the two stacked nanosheet FETs. It has been observed that, self-heating induced thermal energy of He-FET shows more impact on the bottom channels compared to the top channels in the Co-FET. The electron mobility is reduced by 4.25% in the channel near to the substrate compared to the channel near to contacts. The transit frequency (fT) and the maximum oscillation frequency (fmax) of 131.5 GHz and 435 GHz were obtained, respectively with the optimization of IDS of 30 nm and STI depth of 50 nm.

Keywords

• Inter-device spacing
• self-heating
• shallow trench isolation depth
• stacked nanosheet FET
• thermal intrude