Title :
EOT, Workfunction, and Vfb Roll-Off in HfO2/Metal Gate Stacks
Author :
Goswami, Jaydeb ; McTeer, Allen
Author_Institution :
R&D Process Dev., Micron Technol., Inc., Boise, ID
Abstract :
At a given thickness of HfO2, atomic layer deposited (ALD) TaN metal-gates showed higher equivalent oxide thickness (EOT) and flat-band-voltage (Vfb) shift compared to physical vapor deposited (PVD) TaSiN after annealing at 750degC for 30 min in N2. TEM data revealed the growth of a thicker interfacial oxide of 1.7 nm for TaN compared to 0.9 nm for TaSiN. In addition, TaN showed higher effective workfunction of 4.7 eV compared to 4.4 eV for TaSiN. However, both TaN and TaSiN exhibited Vfb roll-off when the HfO2 thickness was decreased below 4 nm. XPS measurements showed the presence of 6 atom% oxygen in TaN, whereas no significant amount of oxygen was detected in TaSiN. Electrical results are discussed in terms of the oxygen content in metal-gates and oxygen vacancy in HfO2.
Keywords :
X-ray photoelectron spectra; annealing; dielectric materials; field effect transistors; hafnium compounds; high-k dielectric thin films; interface structure; silicon compounds; tantalum compounds; transmission electron microscopy; vacancies (crystal); work function; EOT; FET; HfO2-TaN; HfO2-TaSiN; TEM; XPS; annealing; atomic layer deposited metal-gates; equivalent oxide thickness; flat-band-voltage shift; interfacial oxide growth; metal gate stacks; metal-oxide field effect transistors; oxygen vacancy; physical vapor deposited metal-gate; temperature 750 degC; time 30 min; workfunction; Annealing; Atherosclerosis; Atomic layer deposition; Atomic measurements; Channel bank filters; FETs; Hafnium oxide; High-K gate dielectrics; Metal-insulator structures; Optical films;
Conference_Titel :
Microelectronics and Electron Devices, 2009. WMED 2009. IEEE Workshop on
Conference_Location :
Boise, ID
Print_ISBN :
978-1-4244-3551-7
Electronic_ISBN :
978-1-4244-3552-4
DOI :
10.1109/WMED.2009.4816138
