Self-Heating Aware Threshold Voltage Modulation Conforming to Process and Ambient Temperature Variation for Reliable Nanosheet FET
Sunil Rathore, Rajeewa Kumar Jaisawal, P. N. Kondekar, Navneet Gandhi, Shashank Banchhor, Young Suh Song, Navjeet Bagga
Abstract
Internal and external process variations severely affect the device threshold voltage <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{V}_{\text{th}})$</tex> and, in turn, the device's reliability. For the first time, this paper presented a thorough analysis of the self-heating aware <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\text{th}}$</tex> variation of a Nanosheet FET and, thus, the device's aging. Using well-calibrated TCAD models, we evaluated the 'change in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{th}\ ^{\prime}$</tex> and performed an extensive design space exploration to analyze: (i) the impact of work function (WF) modulation owing to metal grain sizes and effective grains (for confined dimensions) on <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\text{th}}$</tex> variation; (ii) the impact of ambient temperature (TA) on <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\text{th}}$</tex> variation; (iii) the influence of trap charges on device characteristics; (iv) how the consideration of RDF impacted <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\text{th}};$</tex> (v) the device's aging, i.e., end of a lifetime (EOL). These investigations provided guidelines for designing a reliable Nanosheet FET (NSFET) to investigate and mitigate early aging.