A Novel Self-Aligned Offset-Gated Polysilicon TFT Using High- $kappa$ Dielectric Spacers

In this letter, a novel self-aligned offset-gated Poly-Si thin-film transistor (TFT) using high-/spl kappa/ dielectric Hafnium oxide (HfO/sub 2/) spacers is proposed and demonstrated. The HfO/sub 2/ film is deposited by magnetron sputter deposition, and the HfO/sub 2/ spacers are formed by reactive ion etching. The permittivity of the deposited HfO/sub 2/ is approximately 20. Experimental results show that with the high vertical field induced underneath the high-/spl kappa/ spacers, an inversion layer is formed, and it effectively increases the on-state current while still maintaining a low leakage current in the off-state, compared to the conventional lightly doped drain or oxide spacer TFTs. The on-state current in the offset-gated Poly-Si TFT using the HfO/sub 2/ spacers is approximately two times higher than that of the conventional oxide spacer TFT.