ABSTRACT
CONTENTS 12.1 Introduction ...................................................................................................................... 359 12.2 Experimental Details ....................................................................................................... 361 12.3 Results and Discussion ................................................................................................... 363
12.3.1 Fast and Slow State Generation........................................................................ 363 12.3.2 H2=D2 Isotopic Effect.......................................................................................... 365 12.3.3 Impact of Nitrogen Incorporation .................................................................... 368
12.3.3.1 Experimental Results .......................................................................... 369 12.3.3.2 Model for Slow States Generation .................................................... 371 12.3.3.3 Vth Recovery......................................................................................... 374
12.3.4 Si-Substrate Orientation Effect .......................................................................... 375 12.4 Summary........................................................................................................................... 377 Acknowledgments ..................................................................................................................... 378 References.................................................................................................................................... 378
High-k gate dielectrics, in combination with metal gates, are currently under investigation for the replacement of the conventional SiON=polycrystalline-Si gate stack in future generations of metal-oxide-semiconductor field effect transistors (MOSFETs) [1,2]. One of the major reasons is that the leakage current flowing through SiON layers thinner than 1 nm exceeds 100 A=cm2 at operating voltage (around 1 V), leading to unacceptable power dissipation in the circuits. For a given technology, determined, e.g., by the transistor gate length and equivalent electrical thickness of the gate insulator, the use of high-k gate dielectrics would allow the use of physically thicker layers, aiming at reducing the leakage current flowing through the devices. In that respect, HfSiO(N) [3-5] and HfO2 [6-8] are considered as potential candidates, due to their high dielectric constants and good thermal stability in contact with Si, allowing them to sustain the high thermal budgets required for the fabrication of advanced metal-oxide semiconductor (MOS) devices. In addition, the Si=HfSiO(N) and Si=HfO2 conduction and valence band offsets are sufficiently high, about 1.5-2 eV [2], preventing thermoionic emission over these energetic barriers.
