@misc{FritscherUhlmannOstrovskyyetal., author = {Fritscher, Markus and Uhlmann, Max and Ostrovskyy, Philip and Reiser, Daniel and Chen, Junchao and Schubert, Andreas and Schulze, Carsten and Kahmen, Gerhard and Fey, Dietmar and Reichenbach, Marc and Krstic, Milos and Wenger, Christian}, title = {Area-efficient digital design using RRAM-CMOS standard cells}, series = {2024 IEEE Computer Society Annual Symposium on VLSI (ISVLSI)}, volume = {18}, journal = {2024 IEEE Computer Society Annual Symposium on VLSI (ISVLSI)}, publisher = {IEEE}, isbn = {979-8-3503-5411-9}, issn = {2159-3477}, doi = {10.1109/ISVLSI61997.2024.00026}, pages = {81 -- 87}, abstract = {Extending the scalability of digital integrated circuits through novel device concepts is an attractive option. Among these concepts, resistive random access memory (RRAM) devices allow fast and nonvolatile operation. However, building large memristive systems is still challenging since large analog circuits have to be designed and integrated. In this paper, we propose a novel solution - the implementation of digital standard cells by the means of RRAM devices. While this methodology is universal, with applications ranging from few-device-circuits to large macroblocks, we demonstrate it for a 2T2R-cell. The benefits of using RRAM devices are demonstrated by implementing a NAND standard cell merely consuming the area of two transistors. This cell is about 25 \% smaller than the equivalent CMOS NAND in the same technology. We use these cells to implement a half adder, beating the area of the equivalent CMOS implementation using more sophisticates gates by 15 \%. Lastly, we fully integrate this novel standard cell into a digital standard cell library and perform a synthesis and layout of a RISC-V CPU core.}, language = {en} } @misc{ReiterHanMaietal., author = {Reiter, Sebastian and Han, Weijia and Mai, Christian and Spirito, Davide and Jose, Josmy and Z{\"o}llner, Marvin Hartwig and Fursenko, Oksana and Schubert, Markus Andreas and Stemmler, Ivo and Wenger, Christian and Fischer, Inga Anita}, title = {Titanium Nitride Plasmonic Nanohole Arrays for CMOS-compatible integrated refractive index sensing: influence of layer thickness on optical properties}, series = {Plasmonics}, journal = {Plasmonics}, issn = {1557-1963}, doi = {10.1007/s11468-023-01810-3}, pages = {1 -- 13}, language = {en} } @misc{MoralesMahmoodinezhadTschammeretal., author = {Morales, Carlos and Mahmoodinezhad, Ali and Tschammer, Rudi and Kosto, Yuliia and Alvarado Chavarin, Carlos and Schubert, Markus Andreas and Wenger, Christian and Henkel, Karsten and Flege, Jan Ingo}, title = {Combination of Multiple Operando and In-Situ Characterization Techniques in a Single Cluster System for Atomic Layer Deposition: Unraveling the Early Stages of Growth of Ultrathin Al2O3 Films on Metallic Ti Substrates}, series = {Inorganics}, volume = {11}, journal = {Inorganics}, number = {12}, issn = {2304-6740}, doi = {10.3390/inorganics11120477}, abstract = {This work presents a new ultra-high vacuum cluster tool to perform systematic studies of the early growth stages of atomic layer deposited (ALD) ultrathin films following a surface science approach. By combining operando (spectroscopic ellipsometry and quadrupole mass spectrometry) and in situ (X-ray photoelectron spectroscopy) characterization techniques, the cluster allows us to follow the evolution of substrate, film, and reaction intermediates as a function of the total number of ALD cycles, as well as perform a constant diagnosis and evaluation of the ALD process, detecting possible malfunctions that could affect the growth, reproducibility, and conclusions derived from data analysis. The homemade ALD reactor allows the use of multiple precursors and oxidants and its operation under pump and flow-type modes. To illustrate our experimental approach, we revisit the well-known thermal ALD growth of Al2O3 using trimethylaluminum and water. We deeply discuss the role of the metallic Ti thin film substrate at room temperature and 200 °C, highlighting the differences between the heterodeposition (<10 cycles) and the homodeposition (>10 cycles) growth regimes at both conditions. This surface science approach will benefit our understanding of the ALD process, paving the way toward more efficient and controllable manufacturing processes.}, language = {en} } @misc{FranckDabrowskiSchubertetal., author = {Franck, Max and Dabrowski, Jarek and Schubert, Markus Andreas and Vignaud, Dominique and Achehboune, Mohamed and Colomer, Jean-Fran{\c{c}}ois and Henrard, Luc and Wenger, Christian and Lukosius, Mindaugas}, title = {Investigating Impacts of Local Pressure and Temperature on CVD Growth of Hexagonal Boron Nitride on Ge(001)/Si}, series = {Advanced Materials Interfaces}, volume = {12}, journal = {Advanced Materials Interfaces}, number = {1}, publisher = {Wiley}, issn = {2196-7350}, doi = {10.1002/admi.202400467}, pages = {9}, abstract = {AbstractThe chemical vapor deposition (CVD) growth of hexagonal boron nitride (hBN) on Ge substrates is a promising pathway to high-quality hBN thin films without metal contaminations for microelectronic applications, but the effect of CVD process parameters on the hBN properties is not well understood yet. The influence of local changes in pressure and temperature due to different reactor configurations on the structure and quality of hBN films grown on Ge(001)/Si is studied. Injection of the borazine precursor close to the sample surface results in an inhomogeneous film thickness, attributed to an inhomogeneous pressure distribution at the surface, as shown by computational fluid dynamics simulations. The additional formation of nanocrystalline islands is attributed to unfavorable gas phase reactions due to the radiative heating of the injector. Both issues are mitigated by increasing the injector-sample distance, leading to an 86\% reduction in pressure variability on the sample surface and a 200 °C reduction in precursor temperature. The resulting hBN films exhibit no nanocrystalline islands, improved thickness homogeneity, and high crystalline quality (Raman FWHM = 23 cm-1). This is competitive with hBN films grown on other non-metal substrates but achieved at lower temperature and with a low thickness of only a few nanometers.}, language = {en} } @misc{MoralesGertigKotetal., author = {Morales, Carlos and Gertig, Max and Kot, Małgorzata and Alvarado, Carlos and Schubert, Markus Andreas and Zoellner, Marvin Hartwig and Wenger, Christian and Henkel, Karsten and Flege, Jan Ingo}, title = {In situ X-ray photoelectron spectroscopy study of atomic layer deposited cerium oxide on SiO₂ : substrate influence on the reaction mechanism during the early stages of growth}, series = {Advanced materials interfaces}, volume = {12}, journal = {Advanced materials interfaces}, number = {5}, publisher = {Wiley}, address = {Weinheim}, issn = {2196-7350}, doi = {10.1002/admi.202400537}, pages = {1 -- 13}, abstract = {Thermal atomic layer deposition (ALD) of cerium oxide using commercial Ce(thd)4 precursor and O3 on SiO2 substrates is studied employing in-situ X-ray photoelectron spectroscopy (XPS). The system presents a complex growth behavior determined by the change in the reaction mechanism when the precursor interacts with the substrate or the cerium oxide surface. During the first growth stage, non-ALD side reactions promoted by the substrate affect the growth per cycle, the amount of carbon residue on the surface, and the oxidation degree of cerium oxide. On the contrary, the second growth stage is characterized by a constant growth per cycle in good agreement with the literature, low carbon residues, and almost fully oxidized cerium oxide films. This distinction between two growth regimes is not unique to the CeOx/SiO2 system but can be generalized to other metal oxide substrates. Furthermore, the film growth deviates from the ideal layer-by-layer mode, forming micrometric inhomogeneous and defective flakes that eventually coalesce for deposit thicknesses above 10 nm. The ALD-cerium oxide films present less order and a higher density of defects than films grown by physical vapor deposition techniques, likely affecting their reactivity in oxidizing and reducing conditions.}, language = {en} }