The intrinsic and extrinsic contributions to Fermi level pinning of platinum (Pt) electrodes on hafnium dioxide (HfO2) gate dielectrics are investigated by examining the impact of oxygen and forming gas anneals on the effective work function of Pt-HfO2-silicon capacitors. The effective platinum work function is ∼4.6eV when annealed in forming gas. However, diffusion of oxygen to the Pt∕HfO2 interface increases the platinum work function to a value of ∼4.9eV. Subsequent annealing in forming gas returns the platinum work function to a value comparable to that measured prior to the oxygen anneal. The effective platinum work functions are compared to the prediction of the metal induced gap states (MIGS) model. The presence of interfacial oxygen vacancies or platinum–hafnium bonds is believed to be responsible for a degree of pinning that is stronger than predicted from the MIGS model alone.

The origin of the almost unique combination of optical transparency and the ability to bipolar dope tin monoxide is explained using a combination of soft and hard Xray photoemission spectroscopy, O K-edge X-ray emission and absorption spectroscopy, and density functional theory calculations incorporating van der Waals corrections. We reveal that the origin of the high hole mobility, bipolar ability, and transparency is a result of (i) significant Sn 5s character at the valence band maximum (due to O 2p−Sn 5s antibonding character associated with the lone pair distortion), (ii) the combination of a small indirect band gap of ∼0.7 eV (Γ−M) and a much larger direct band gap of 2.6−2.7 eV, and (iii) the location of both band edges with respect to the vacuum level. This work supports Sn 2+ -based oxides as a paradigm for nextgeneration transparent semiconducting oxides.

and PMOS (AQi is negligible. However, AVfb does not reach OV We report here for the first time that Fermi pinning at the because Si-Hf and Si-0-Hf bonds co-exist at the polySi interface. The polySilmetal oxide interface causes high threshold voltages in AVfb saturation value depends only on the bond number ratio. A MOSFET devices. Results indicate that pinning occurs due to the comparison of AVfb for HfOz (ALD or MOCVD) and HfSixOy interfacial Si-Hf and Si-0-AI bonds for HfO, and AIzO,, respectively. (MOCVD) films deposited with different precursors and dopant This fundamental characteristic also affects the observed polySi activation anneals produce, the universal curve in Fig. 11. The slight depletion. Device data and simulation results will be presented. variation in AVb for Hf02 can be attributed to differences in Keywords: Hf02, AI203, Fermi pinning, polYd, gate dielectric. processing conditions. Our data indicates that the shifts of Vfb(n+) INTRODUCTION and Vfb(pt) from the characteristic values for SiO, NMOS and Scaling MOSFETs to improve performance results in PMOS are a fundamental characteristic of the PolySilMeOx interface. higher gate leakage as the SiOz gate melectic becomes thinner. To These shifts are responsible for the observed high Vts. address this issue, there has been much interest in hafnium-based The impact of the sub-monolayer HfOz on the CETacc is dielectrics as a potential gate dielectric [1-3]. Two major issues shown in Figs. 12 and 13. Although the p+ gate CETacc increases evident in numerous publications [1-3] that must be addressed to with each subsequent cycle, the n+ gate has a CETacc minimum at IO fabricate useful devices for CMOS circuit applications are (1) the cycles, The n+ gate is in depletion and the minimum indicates Si-Hf high threshold voltages and (2) the large CETinv difference between bonds reduce the polySi depletion. To investigate this further, CMOS NMOS and PMOS. To date, a PolySiIMeOx CMOS process with devices were fabricated (Fig. 14). The polySi depletion for ntgate acceptable Vts for both NMOS and PMOS has not been reported. NMOS (p+ gate PMOS) is decreased (increased) when SiOz is capped Defects and charge within the gatestack (Fig. I ) can result with HfO,. This tradeoff in polySi depletion is attributed to Fermi in substantial Vt shifts. At the top interface, Fermi pinning is a pinning near (Fig. 8). Less band bending occurs for n+ polySi mechanism known to cause high Vts for metal gates [41. Considering because the polySi interface is pinned close to the bulk polySi Fermi the polySi/MeOx interface shown in Fig. 2, the question arises, 'Are level. For p+ gates, more band bending occurs because the interface is the metal atoms at the interface part of the dielectric or part of the pinned further away from the bulk. This effect occurs for low and gate electrode?' This raises the issue as to whether the interface bonds high temperame activation anneals (Fig. 15). This effect is the likely affect the Vt. In this work, we examine the role of the polySiIMeOx cause...

We have measured the low temperature internal friction ͑Q 21 ͒ of amorphous silicon ͑a-Si͒ films. e-beam evaporation or 28 Si 1 implantation leads to the temperature-independent Q 21

The spontaneous formation of organized nanocrystals in semiconductors has been observed during heteroepitaxial growth and chemical synthesis. The ability to fabricate size-controlled silicon nanocrystals encapsulated by insulating SiO2 would be of significant interest to the microelectronics industry. But reproducible manufacture of such crystals is hampered by the amorphous nature of SiO2 and the differing thermal expansion coefficients of the two materials. Previous attempts to fabricate Si nanocrystals failed to achieve control over their shape and crystallographic orientation, the latter property being important in systems such as Si quantum dots. Here we report the self-organization of Si nanocrystals larger than 80 A into brick-shaped crystallites oriented along the (111) crystallographic direction. The nanocrystals are formed by the solid-phase crystallization of nanometre-thick layers of amorphous Si confined between SiO2 layers. The shape and orientation of the crystallites results in relatively narrow photoluminescence, whereas isotropic particles produce qualitatively different, broad light emission. Our results should aid the development of maskless, reproducible Si nanofabrication techniques.