We demonstrate that incorporating N in Hf-silicate films reduces B penetration through the dielectric film. By modeling the B depth profiles, we calculated the B diffusivities through Hf-silicate (HfSixOy) to be ∼2× higher than the corresponding diffusivities for Hf-silicon oxynitride (HfSixOyNz). B diffusion through grain boundaries after HfSixOy crystallization is believed to be responsible for the enhanced B diffusivity observed. Suppression of crystallization observed in HfSixOyNz films is attributed to the lower Hf content in the films and the incorporation of N. The decreased B penetration observed in HfSixOyNz is a combination of absence of grain boundaries and the fact that N blocks B diffusion by occluding diffusion pathways. The minimum temperatures for B penetration are estimated to be approximately 950 and 1050 °C for HfSixOy and HfSixOyNz, respectively.

We present detailed B penetration studies from B-doped polysilicon through alternate gate dielectric candidate HfSixOy films. No detectible B penetration is observed for annealing times as long as 20 s after 950 °C. Considerable B incorporation into the Si substrate is observed for annealing temperatures higher than 950 °C. By modeling the B depth profiles, we calculated the B diffusivities through HfSixOy to be higher than the corresponding diffusivities for SiO2. B diffusion through grain boundaries after HfSixOy crystallization is proposed to be responsible for the enhanced B diffusivity observed.

Effective work function (EWF) changes of TiN/HfO2 annealed at low temperatures in different ambient environments are correlated with the atomic concentration of oxygen in the TiN near the metal/dielectric interface. EWF increases of 550 meV are achieved with anneals that incorporate oxygen throughout the TiN with [O]=2.8×1021 cm−3 near the TiN/HfO2 interface. However, further increasing the oxygen concentration via more aggressive anneals results in a relative decrease of the EWF and increase in electrical thickness. First-principles calculations indicate the exchange of O and N atoms near the TiN/HfO2 interface cause the formation of dipoles that increase the EWF.

We present a study of the penetration of B, P, and As through Hf silicate (HfSixOy) and the effect of N incorporation in Hf silicate (HfSixOyNz) on dopant penetration from doped polycrystalline silicon capping layers. The extent of penetration through Hf silicate was found to be dependent upon the thermal annealing budget for each dopant investigated as follows: B(T⩾950°C∕60s), P(T⩾1000°C∕20s), and As (T⩾1050°C∕60s). We propose that the enhanced diffusion observed for these dopants in HfSixOy, compared with that of SiO2 films, is related to grain boundary formation resulting from HfSixOy film crystallization. We also find that, as in the case of SiO2, N incorporation inhibits dopant (B, P, and As) diffusion through the Hf silicate and thus penetration into the underlying Si substrate. Only B penetration is clearly observed through HfSiON films for anneals at 1050 °C for durations of 10 s or longer. The calculated B diffusivity through the HfSixOyNz layer is D0=5.2×10−15cm2∕s.

We have studied ferromagnetism of Mn-implanted epitaxial Ge films on silicon. The Ge films were grown by ultra high vacuum chemical vapor deposition using a mixture of germane (GeH 4 ) and methylgermane (CH 3 GeH 3 ) gases with a carbon concentration less than 1at%, and observed surface rms roughness of about 0.5 nm, as measured by atomic force microscopy.Manganese ions were implanted in epitaxial Ge films grown on Si (100) wafers to an effective concentration of about 16at%, 12at%, 6at% and 2at%. SQUID measurements showed that only the three highest Mn concentration samples are ferromagnetic, while the fourth sample, with [Mn]=2at%, is paramagnetic. X-ray absorption spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD) measurements indicate that localized Mn moments are ferromagnetically coupled below the Curie temperature. Isothermal annealing of Mnimplanted Ge films with [Mn]=16at% at 300 o C for up to 1200 seconds decreases the magnetization but does not change the Curie temperature, suggesting that the amount of the magnetic phase slowly decreases with time at this anneal temperature. Furthermore, transmission electron microscopy (TEM) and synchrotron grazing incidence x-ray diffraction (GI-XRD) experiments show that the Mn-implanted region is amorphous, and we believe that it is this phase that is responsible for the ferromagnetism. This is supported by our observation that high temperature annealing leads to recrystallization and transformation of the material into a paramagnetic phase. * samaresh@physics.utexas.edu † banerjee@ece.utexas.edu 2