Title :
Effective Work-Function Modulation by Aluminum-Ion Implantation for Metal-Gate Technology (Poly-Si/TiN/SiO2)
Author :
Singanamalla, R. ; Yu, H.Y. ; van Daele, B. ; Kubicek, S. ; De Meyer, K.
Author_Institution :
Interuniv. Microelectron. Center (IMEC), Leuven
Abstract :
The impact of aluminum (Al) implantation into TiN/SiO2 on the effective work function (EWF) of poly-Si/ TiN/SiO2 is investigated. Al implanted at 5 keV with a dose of 5 times 1015 cm-2 reduces the flatband voltage (VFB) and the EWF of poly-Si/TiN/SiO2 stack by ~150 mV compared with the unimplanted poly-Si/TiN/SiO2 stack. This reduction of VFB is found to be dose-dependent, which is correlated to the Al concentration at the TiN-SiO2 interface as evidenced by secondary-ion-mass-spectrometry profiles. The interface dipole created due to the Al presence at the metal-dielectric interface is believed to contribute to the observed VFB (or EWF) reduction (or increase). This technique for EWF modulation is promising for further threshold-voltage (Vt) tuning without any process complexities and is quite significant for planar and multiple gate field-effect transistors on fully depleted silicon on insulator.
Keywords :
MOSFET; aluminium; ion implantation; silicon; silicon compounds; silicon-on-insulator; titanium compounds; work function; Si-TiN-SiO2:Al - System; aluminum concentration; aluminum ion implantation; flatband voltage; fully depleted silicon on insulator; metal dielectric interface; metal gate technology; multiple gate field effect transistors; secondary ion mass spectrometry profiles; work function modulation; Aluminum; CMOS technology; Dielectric substrates; Electrodes; FETs; Impurities; MOSFETs; Microelectronics; Silicon on insulator technology; Tin; $hbox{SiO}_{2}$; Atomic layer deposition (ALD); Fermi-level pinning and effective work function (EWF); TiN; metal gate (MG); poly-Si;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2007.909852
