We study in detail a newly discovered effect, phonon-energy-coupling enhancement (PECE) effect, produced by rapid thermal processing (RTP). It includes two aspects: (1) Strengthening Si-D bonds and Si-O bonds and (2) Change of energy band structure and effective mass due to thermal shock. It is shown that not only Si-D bonds but also Si-O bonds have been strengthened dramatically, leading to enhancement of robustness of the oxide structure and the oxide/Si interface. For thick oxides (>3 nm), the gate leakage current has been reduced by two orders of magnitude and the breakdown voltage has been improved by ~30% due to phonon-energy coupling. For ultrathin oxides (2.2 nm), the direct tunneling current has been reduced by five-orders of magnitude, equivalent to that of HfO2, probably due to the increased effective mass and barrier height.

In-line monitoring of the electrical properties of high-k dielectrics in logic or memory fab-lines has become increasingly important in the semiconductor industry. Non-contact corona-Kelvin based metrology can be used to affectively monitor in-line key dielectric properties. Furthermore, we present an important extension of this metrology to the micro-scale that allows measurement of dielectric properties on test sites as small as 40μm × 70μm. This is achieved through miniaturization of the corona charging apparatus and of the Kelvin probe without a sacrifice in precision or repeatability. Corona-Kelvin micro-metrology allows for the monitoring of the critical dielectric properties directly on product wafers that can then be returned to the fab-line for continued processing. Application examples are given for dielectric capacitance of advanced dielectrics and for the properties of an oxide-nitride-oxide (ONO) memory structure. In the latter case we demonstrate programming and erasing of the ONO structure realized by corona charging. We also use the measured flatband voltage and total charge to identify the location of the programmed charge at the first SiO2/Si3N4 interface in the ONO structure.

The electrical response and interfacial layer characterization of nitrogen doped HfO2 gate dielectric thin films are reported. The films were processed at relatively low temperature (~ 400 0C) by pulsed laser deposition and ultra-violet radiation assisted oxidation technique. Nitrogen incorporation in the hafnia films led to O-N and Hf-Si-O-N bonding in the bulk and at hafnia-Si interface respectively. The nitrogen doped hafnia films exhibited a leakage current density lower than 10E-5 A/sq cm at -1 V and a simulated equivalent oxide thickness of 9.4 Å.

The effect of strain and intrinsic defects on both electronic and structural characteristics of HfO2-x used for sub-100-nm semiconductor devices was analyzed by a quantum chemical molecular dynamics analysis. The magnitude of the band gap of HfO2 decreases by about 10% under the applied strain. The stable crystallographic structure of the monoclinic HfO2 changes to a cubic-like structure under the strain. The magnitude of the band gap of the HfO2-x decreases drastically from 5.7 eV to about 1.0 eV due to the formation of an electronic state within the band gap when an oxygen vacancy is introduced to the perfect HfO2. In the HfO2-x film, oxygen atoms near the oxygen vacancy can move drastically at temperatures higher than 800 K. Therefore, it is very important to control the chemical composition of the hafnium oxide film and to optimize the annealing condition to maintain both the high reliability and performance of the gate oxide film.

The electrical and material characterization of Ti(C)N deposited by metal organic chemical vapor deposition (MOCVD) technique, as metal gate electrode for advanced CMOS technology is investigated. The effects of the plasma treatment, post anneal treatment and the thickness variation of the Ti(C)N film on the flat band voltage (VFB) and effective work function (WF) of the Poly-Si/Ti(C)N/SiO2 Poly-Si/Ti(C)N/SiO2 gate stack s are reported. We found that both the in-situ plasma treatment and post anneal treatment help in reducing the carbon content (organic) in the film making it more metallic compared to the as-deposited films. However, the post anneal treatment was found to be a better option for getting rid of hydrocarbons as compared to plasma treatment from the gate dielectric integrity point of view. The thickness variation of post annealed Ti(C)N film ranged from 2.5 nm to 10 nm lead to WF shift of upto ~350 mV for both Poly-Si/Ti(C)N/SiO2 and Poly-Si/Ti(C)N/HfO2 gate stacks.

Rare earth scandate thin films (GdScO3 and DyScO3) were investigated with respect to future high-k applications. They were deposited on (100) silicon substrates using either pulsed laser deposition (PLD) or electron beam evaporation. The investigation of the films was done by means of Rutherford backscattering spectrometry, high-temperature X-ray-diffractometry, X-ray reflectometry, spectroscopic ellipsometry, transmission electron microscopy (TEM) and atomic force microscopy. For the electrical characterization capacitor stacks were prepared. Both materials show very promising characteristics independent from the deposition technique used. The films are stoichiometric and amorphous and exhibit a smooth surface (roughness RMS < 1 Å). The amorphous phase is stable up to 1000°C. The electrical characterization revealed featureless C-V-curves with a small hysteresis. From CET plots (CET = capacitance equivalent thickness) k-values between 20 and 23 could be extracted. The electron beam evaporation produces films with a better homogeneity and a thinner interfacial silicon dioxide and therefore a smaller CET value as confirmed by TEM. The leakage current density of the film with CET = 1.5 nm was as low as 7.7x10-4 A/cm2.

One of the major difficulties preventing the wide use of germanium (epi or bulk) as a gate material is the poor stability of its oxide, leading to reproducibility and reliability issues. In contrast to silicon, the nature and thickness of Ge “native” oxides are history dependent, and most phases of germanium oxide are water-soluble. As a result, the procedures for passivating Ge surfaces with hydrogen (HF last) are more complex and less forgiving.

We have used infrared absorption spectroscopy and x-ray photoelectron spectroscopy to investigate the nature of oxidized and H-terminated Ge surfaces. The GeO2, GeO and GeC phases have been identified and quantified as a function of processing conditions. The stability of the H-terminated surfaces has been examined in air and in controlled environments. The H-passivated Ge surfaces are found to be much less stable in air than H-terminated Si surfaces.

Roles of reactive species of germanium and silicon plasma nitridation were investigated by comparing nitrogen plasma chemistry and oxynitride layer physical properties. In high pressure remote plasma nitridation process, hydrogen containing neutral radicals (NH* and H*) were important to nitride germanium and silicon substrates. This process required high substrate temperature to nitride germanium substrate, whereas silicon substrates could be nitrided at low substrate temperature. In low pressure RLSA plasma nitridation process, N2+ ion species acted as dominant reactive species. Using this process, germanium could be nitrided at low substrate temperature without hydrogen and high nitrogen concentration (~22at.%) GeON was obtained.

Replacement of poly-Si and SiO2 with new gate electrode and high k gate oxide is an inevitable trend for next-generation CMOS integrated circuits. Therefore, work function (£Xm) of gate electrodes as well as the thermal stability and electrical behaviors of MOS capacitors should be understood. In this study, tungsten (W) is applied as the gate electrode and the gate dielectric materials are SiO2, SiON and HfO2. £Xm of W and electrical properties of the MOS structures are investigated. £Xm,measured of W is calculated from the flat-band voltage (VFB) of MOS capacitors with dielectrics of various thicknesse. For W/SiO2/Si structure, the £Xm,measured of W is 4.67 V; however, the £Xm,measured of W in W/SiON/Si and W/HfO2/Si structures is 4.60 V and 4.84 V, respectively. The result means that the £Xm,measured of W in W/HfO2/Si structures has extrinsic contributions to Fermi level pinning. The phase of as-deposited W is £]-W (or £]-W+£\-W) phase and transfers to £\-W+WO3 mix phase after annealing at 500°C in N2+H2 ambient for 30 min. The trapped charges and oxide charges of dielectric are reduced after annealing. However, the EOT of W/SiO2/Si increases significantly after annealing, indicating the thermal stability of this capacitor is poor.

We have investigated advanced MOS structures containing Ru gate electrode, HfxSi1-xOy dielectric film and Si substrate. The Ru gate electrode was grown by MOCVD at 300 °C. The MOS structures were annealed for 30 min in forming gas and nitrogen at temperatures up to 550 °C. Capacitance-voltage measurements showed important shift of the flat band voltage of the Ru/ HfxSi1-xOy/Si gate stack after treatment at 550 °C. X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), reflection electron energy loss spectroscopy (REELS) and secondary ion mass spectroscopy (SIMS) were used to analyze interface between ruthenium and high-k dielectric film. Based on the analysis we were able to build up energy-band alignement for the Ru/ HfxSi1-xOy interface. We observed that the energy-band structure of the Ru/HfxSi1-xOy interface remains stable upon annealing in forming gas up to 550 °C. Presence of hydrogen revealed by SIMS can account for compensation of negative charges in HfxSi1-xOy during thermal treatment.