High Performance and Reliable 4F2 IGZO Vertical Channel Transistor (VCT) with Extremely Low Contact Resistance and 10 year BTI lifetime for sub-10nm DRAM

For the first time, we present experimental demonstration of a high-performance and highly reliable IGZO vertical channel transistor (VCT). It exhibits excellent leakage current $(< 0.1 \text{aA}/\mu \mathrm{m})$ and switching characteristics $(98\ \text{mV}/\text{dec})$ with VT of -0.13V at $85^{\circ}\mathrm{C}$. Furthermore, it provides a symmetric ION of 49.5 $\mu \mathrm{A}/\mu \mathrm{m}$ at VDD = 1.5 V which is sufficient for DRAM $\text{read}/\text{write}$ operations of data “0” & “1”, primarily due to the enhanced mobility and extremely low storage contact (BC) resistivity $(\rho_{\mathrm{c}},\ 3.4\times 10^{-7}\Omega\cdot \text{cm}^{2})$. To best of our know ledge, this represents the best $\rho_{\mathrm{c}}$ reported for an IGZO transistor with physical dimension below 10 nm. In addition, comprehensive analysis of temperature dependence reveals differences in ION, compared to conventional BCAT. In addition, its wafer level reliability (WLR) assessment indicates that stable DRAM operation c an be guaranteed longer than 10 years, inc luding static NBTI, dynamic PBTI and TDDB. This is due to proper $Y$ controlled hydrogen $(H)$ & oxygen vacanc $\mathrm{y}(\mathrm{V}_{0})\mathrm{c}$ oncentration inside IGZO channel, interfaces, and interlayer dielectrics. Measured negligible floating body effects (FBE) and self-heating effect (SHE) suggests $4\mathrm{F}^{2}$ IGZO VCT can be an excellent candidate to sustain DRAM scaling trajectory.