In this paper, we present a modeling framework to simulate the electrical characteristics of SiC MOSFET. Our model also describes the mobility improvement with counter doping in channel. Our analyses show improved drive current and degraded/lower threshold voltage with a counter-doped channel. To this end, we investigate the impact of varying the doping concentrations of the counter-doped region and the underlying p-well for optimum device performance.

In this study, we control the oxidant dose to promote ferroelectricity in dopant-free ALD hafnium oxide films. By lowering the oxidant dose during growth, we show that we can achieve near total suppression of the monoclinic phase in sub-10 nm hafnium oxide films with no major impurity doping. Using metal-insulator-metal structures, we demonstrate that lowering the oxidant dose can give rise to a six-fold improvement in remanent polarization. Using this technique, we observe a remanent polarization of 13.5 μC/cm2 in a 6.9 nm-thick hafnium oxide film and show that some ferroelectricity can persist in pure hafnium oxide films as thick as 13.9 nm. Using a trap-assisted tunneling model, we show the relationship between the oxidant dose and oxygen vacancy concentration in the films, suggesting a possible mechanism for the suppression of the monoclinic phase.

Recent work has shown that ferroelectric (FE) behavior in doped HfO 2 thin films can be achieved by stabilizing the non-centrosymmetric orthorhombic phase (Pbc2 1 ) in films for thicknesses under 10 nm, 1 which has led to renewed interest in these films for non-volatile memory (NVM) applications. Following the initial work on doped HfO 2 , researchers were able to demonstrate that the polarization response in these films could be changed from paraelectric to ferroelectric (FE) and ultimately antiferroelectric (AFE) by increased blending of ZrO 2 in a solid solution. 2,3 Beyond composition, the FE response of the Hf x Zr 1-x O 2 solid solution is a complex function of a number of parameters including thickness, 4 the starting substrate, 5 annealing conditions (both temperature and ambient gas), 6,7,8 as well as the presence of a capping material during annealing. 3 While there are a number of reports on mapping the FE response of Hf x Zr 1-x O 2 with respect to these parameters individually, there is still no individual report detailing optimization of the FE response with respect to all of these variables across the Hf x Zr 1-x O 2 composition space. Here we report on the optimization of the FE response in Hf x Zr 1-x O­ 2 solid solutions relative to composition, physical thickness, top electrode processing and post metallization annealing conditions using TiN and Ir bottom electrodes (BEL). We utilize a combinatorial approach to rapidly identify an optimized workflow with respect to these variables and investigate the relationship between film microstructure and FE properties. Additionally, we demonstrate the compositionally driven transition from FE to AFE in Hf x Zr 1-x O 2 is sensitive to the choice of bottom electrode. Figure 1 shows the polarization response of 8.5 and 8 nm Hf .25 Zr .75 O 2 thin films grown on Ir and TiN BEL respectively. These films were subjected to identical annealing treatments (10 minutes at 500 °C in N 2 ), demonstrating the influence of the Ir and TiN BEL in determining the polarization characteristics. A triangular voltage waveform was utilized and both samples were subjected to a stress of ±3 MV/cm pulses at 1 KHz for 1 second before measurement. Devices using a TiN BEL exhibited AFE-like behavior similar to previous reports for this composition, 2 while devices using an Ir BEL showed strong FE characteristics and a remnant polarization (P r ) of 19 µC/cm 2 . Previously, such high remnant polarization (P r >16 μC/cm 2 ) has only been reported for more Hf rich Hf .5 Zr .5 O 2 films. 9 This suggests that the bottom electrode influences the composition at which the Hf x Zr 1-x O 2 transforms from a FE to an AFE film. These results show that the starting surface has a significant impact in determining the composition at which a strong FE response can be obtained in the Hf x Zr 1-x O 2 films, and that proper choice of workflow process conditions can lead to improvement in the exhibited FE properties. Further optimization of the FE response and detailed structural characterization of this material system will be discussed as a function of composition, thickness and annealing conditions. These findings are particularly important for NVM technology, where the remnant polarization and memory window play major roles in determining the usefulness of the film. References [1] T. S. Boscke et al, Appl. Phys. Lett., vol. 99, p. 102903, 2011. [2] J. Müller et al, Nano Letters, vol. 12, p. 4318, 2012. [3] M. H. Park et al, Adv. Energy Mat., vol 4, p.1811, 2014. [4] M.H. Park et al, Appl. Phys. Lett., vol. 104, p. 072901, 2014. [5] M. H. Park et al, Appl. Phys. Lett., vol. 105, p. 072902, 2014. [6] M. H. Park et al, Appl. Phys. Lett., vol. 102, p. 242905, 2013. [7] T. Shimizu et al, Appl. Phys. Lett., vol. 106, p. 112904, 2015. [8] M.H. Park et al, Appl. Phys. Lett., vol. 102, p. 112914, 2013. [9] H.J. Kim et al, Nanoscale, vol. 8, p. 1383, 2016. Figure 1

Progress in transistor scaling has increased the demands on the material properties of silicon nitride (SiNx) thin films used in device fabrication and at the same time placed stringent restrictions on the deposition conditions employed. Recently, low temperature plasma enhanced atomic layer deposition has emerged as a viable technique for depositing these films with a thermal budget compatible with semiconductor processing at sub-32 nm technology nodes. For these depositions, it is desirable to use precursors that are free from carbon and halogens that can incorporate into the film. Beyond this, it is necessary to develop processing schemes that minimize the wet etch rate of the film as it will be subjected to wet chemical processing in subsequent fabrication steps. In this work, the authors introduce low temperature deposition of SiNx using neopentasilane [NPS, (SiH3)4Si] in a plasma enhanced atomic layer deposition process with a direct N2 plasma. The growth with NPS is compared to a more common precursor, trisilylamine [TSA, (SiH3)3 N] at identical process conditions. The wet etch rates of the films deposited with NPS are characterized at different plasma conditions and the impact of ion energy is discussed.