Reliability of HfAlO<inf>x</inf> in multi layered gate stack

Abstract

This work has demonstrated a high quality HfO 2 based gate stack by depositing HfAlO x along with HfO 2 in a layered structure. In order to get multifold enhancement of the gate stack quality both Al percentage and distribution were observed by varying the HfAlO x layer thickness and it was found that < 2% Al/(Al+Hf)% incorporation can result in up to 18% reduction in average EOT along with up to 41% reduction in gate leakage current as compared to the dielectric with no Al content. On the other hand, excess Al presence in the interfacial layer moderately increased the interface state density (D it ). When devices were stressed in the gate injection mode at a constant voltage stress, dielectrics with Al/(Hf+Al)% < 2% showed resistance to stress induced flat-band voltage shift (ΔV FB ), and stress induced leakage current (SILC). The time dependent dielectric breakdown (TDDB) characteristics showed a higher charge to breakdown and an increase in the extracted Weibull slope ( ) that further confirms an enhanced dielectric reliability for devices with < 2% Al/(Al+Hf)%. Keywords-Equivalent oxide thickness (EOT), HfAlO x , interface state density (D it ), stress induced flat-band voltage shift (ΔVFB), stress induced leakage current (SILC), time dependent dielectric breakdown (TDDB).

Frequency and Area Dependence of High-K/Ge MOS Capacitors

“…The dispersion is mainly attributed to the defects at the interface that leads to high leakage current. For the Ge/high-k devices the interface quality variation and the substrate resistance increase led to frequency dispersion as reported in previous studies (2,14,17,18).…”

“…Sample 1 has Chemox and then high-k/ALD and sample 4 has SPAO after the High-K/ALD. The identical DC seems to be due to identical interfacial layer thickness (2,8). The variations in Fig.…”

“…Low power requirements in semiconductor devices dictate the integration of advanced high-k dielectrics with metal gates in Complementary Metal Oxide Semiconductors (CMOS) technologies (1)(2). To enhance the device performance, high mobility channel materials like Ge has been extensively studied due to its bulk electron and hole mobility that are approximately two and four times higher than those of Si (3) respectively.…”