Uniaxial stressors have received much interest over the last few years as a method to enhance carrier mobility and, hence, drive current with minimal modification to the structure of the transistor. However, the shift in device design to complex structures with multiple crystallographic orientations like advanced bulk-FinFETs has significantly complicated the incorporation of mobility enhancing stressors. For the n-FinFET in particular, it turns out that the crystal quality and growth rate of Si:P and Si:C:P films can be strongly dependent upon the crystallographic orientation of the starting surface. Both for raised and recessed epi we find that formation of (111) facets and twin defects occurs already after a limited growth on the fin. Besides the growth on raised and recessed fins, we also discuss the resistivity increase in Si:C:P layers as a function of carbon content and demonstrate that laser annealed Si:P films with high phosphorus content (e.g. 4% or higher) can be considered as potential alternatives to Si:C:P with a lower resistivity for the same strain.
As contact resistance becomes a bottle-neck in scaled CMOS devices, there is a need for source/drain epitaxy with maximum dopant concentrations and optimized contacting schemes. In this paper we discuss the use of highly doped Si:P layers for the Source/Drain formation in Si bulk FinFETs. We report on the macroscopic and microscopic properties of the Si:P layers and discuss the details of the microstructure and the manifestation of Phosphorus-Vacancy complexes at high Phosphorus concentrations. We analyze how a post-epi thermal budget like spike or laser annealing modifies the microstructure and leads to an enhanced P activation and diffusion. We also zoom in on some of the integration aspects of the Si:P layers and discuss the benefit of the high-P concentration for the contact resistivity and the final device performance.
Hydrogen radicals play an important role in, e.g., the cleaning of extreme ultraviolet reflective mirrors. Therefore, there is a need to quantify the surface radical flux in the various (plasma) setups where these effects are studied. In this paper, a catalytic radical sensor is presented, based on the measurement of the recombination heat of radicals on a surface, using dual probe thermopile heat flux sensors (HFSs). The first HFS1 has a high recombination (probability) coefficient coating, e.g., Pt. The second HFS2 has a low recombination coefficient coating, e.g., Al2O3. Signal subtraction largely eliminates common mode heat losses/gains such as conduction/convection and IR radiation, the net result representing the radical recombination heat. The signal can be improved by switching the radical source on/off at regular intervals. Radical recombination rates were measured in a remote microwave plasma chamber (38 Pa H2) over the range 1018−1021 atH/(m2 s), with nearly linear response as a function of plasma power setting. The sensor full scale limit is ∼1023 atH/(m2 s) and is dictated by the maximum allowable sensor surface temperature (<250 °C).
The presence and influence of ions in several reactor configurations used for plasma-assisted atomic layer deposition (ALD) are discussed. It is shown that the ion energies are often moderate or even negligible in direct plasma and remote plasma ALD reactors under processing conditions typically employed. Plasma-induced damage by ion bombardment is therefore not a major issue during most processes. It has furthermore been demonstrated that ion energies can be enhanced using substrate biasing, which can be used to tailor the material properties as demonstrated for several metal-oxides.
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