Abstract
The decreasing sizes in complementary metal oxide semiconductor (CMOS) transistor technology require the replacement of SiO2 with gate dielectrics that have a high dielectric constant (high-k). When the SiO2 gate thickness is reduced below 1.4 nm, electron tunneling effects and high leakage currents occur which present serious obstacles for device reliability. In recent years, various alternative gate dielectrics have been researched. Following the introduction of HfO2 into the 45 nm process by Intel in 2007, the screening and selection of high-k gate stacks, understanding their properties, and their integration into CMOS technology have been a very active research area. This paper reviews the progress and efforts made in the recent years for high-k dielectrics, which can be potentially integrated into 22 nm (and beyond) technology nodes. Our work includes deposition techniques, physical characterization methods at the atomic scale, and device reliability as the focus. For most of the materials discussed here, structural and physical properties, dielectric relaxation issues, and projections towards future applications are also discussed.
Highlights
With the advance of metal oxide semiconductor technology, Si-based semiconductors, with SiO2 as an outstanding dielectric, have been dominating microelectronic industry for decades
Deposited by liquid injection atomic layer deposition (LI-ALD) and postdeposition annealed (PDA) in nitrogen (N2) ambient Low hysteresis voltages and negligible flat band voltage shifts Dopant elements have been demonstrated to stabilize the cubic fluorite and tetragonal phases of HfO2 Improved C-V characteristics and reduced leakage current have been achieved from HfTiON gate dielectric MOS capacitor Exhibit excellent C-V characteristics with an equivalent oxide thickness (EOT) of 1.3 nm which are sufficient for implementing high mobility metal-oxide-semiconductor field-effect transistor (MOSFET) using compressively strained SiGe channels in future complementary metal oxide semiconductor (CMOS) technology
One of the possibilities to improve an Hf-based dielectric permittivity consists in adding another metal
Summary
With the advance of metal oxide semiconductor technology, Si-based semiconductors, with SiO2 as an outstanding dielectric, have been dominating microelectronic industry for decades. Deposited by liquid injection atomic layer deposition (LI-ALD) and PDA in nitrogen (N2) ambient Low hysteresis voltages and negligible flat band voltage shifts Dopant elements have been demonstrated to stabilize the cubic fluorite and tetragonal phases of HfO2 Improved C-V characteristics and reduced leakage current have been achieved from HfTiON gate dielectric MOS capacitor Exhibit excellent C-V characteristics with an EOT of 1.3 nm which are sufficient for implementing high mobility MOSFETs using compressively strained SiGe channels in future CMOS technology.
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