Composants Passifs Intégrés en Technologie CMOS pour la Miniaturisation des Circuits RF

Une démarche originale pour le développement de composants passifs dans une filière industrielle consiste à effectuer un report des contraintes en performances sur les caractéristiques électriques des matériaux utilisés en couches minces. Nous présentons dans cet article la démarche adoptée à travers trois phases clés du développement d’une technologie faibles coûts de composants passifs intégrés en filière CMOS. Le développement et la caractérisation de films minces d’oxyde de titane et de tantale. L’intégration de films résistifs d’oxynitrure de titane en filière industrielle et la modélisation électrique d’inductances spirales intégrées en CMOS

New synthesis methods for thin film high entropy alloys with tunable microstructure and enhanced mechanical properties

International audienceIn recent years, research on thin film high entropy alloys (TF-HEAs) has gained increasing interest due to the activation of mechanical size effects involving a combination of high ductility and yield strength (up to 30% and 10 GPa for NbMoTaW) [1]. One of the current challenges is to develop advanced techniques for synthesis of nanostructured TF-HEAs, while implementing nanoengineering design strategies such as multilayered systems, which are known to improve the mechanical properties by blocking the propagation of dislocations [2].CoCrCuFeNi is one of the first HEAs discovered, with an FCC structure and promising properties. It reports yield strength in compression of 450 MPa and 60% ductility [3], however very few studies focus on this alloy in thin film form. Here, we synthetized CoCrCuFeNi TF-HEAs and Al/CoCrCuFeNi multilayers by pulsed laser deposition (PLD), exploiting its large versatility providing different microstructures (i.e. compact and nanogranular) by simply varying the background gas pressure [2]. Our films show a transition from compact to nanogranular at ~1 Pa of He (Fig.1), as well as a loss of crystallographic texturing shown in SAED-TEM. Nanoindentation shows increased hardness in CoCrCuFeNi TF-HEAs from PLD (11 GPa) compared to magnetron sputtering (8 GPa), as a result of smaller domain size (10 nm) and compressive residual stresses. Nanogranular films report ~10% reduction of density and elastic constants due to the lower energy of the ablated species. Tensile tests on Kapton® show exceptional ductility of compact CoCrCuFeNi films, with an onset of crack formation of 3.4% decreasing for nanogranular films (vs ~2% from magnetron sputtering [4]). STEM-EDX of Al/CoCrCuFeNi multilayers (Fig.2) shows localchemical enrichments with ~2 nm Al layers separated by ~5 nm of the HEA with very little diffusion at the interfaces, showing good mechanical properties (H=9 GPa, E=157 GPa). Our results show that PLD is a powerful technique that enables a single step synthesis of advanced TF-HEAs with tunable microstructure and multilayering, leading to tunable mechanical properties with potential applications in microelectronics, MEMS or high performancecoatings

Novel thin film high entropy alloys with tunable microstructure and enhanced mechanical properties

In recent years, research on thin film high entropy alloys (TF-HEAs) has gained increasing interest due to the activation of mechanical size effects involving a combination of high ductility and yield strength (up to 30% and 10 GPa for NbMoTaW) [1]. One of the current challenges is to develop advanced techniques for synthesis of nanostructured TF-HEAs, while implementing nanoengineering design strategies such as multilayered systems, which are known to improve the mechanical properties by blocking the propagation of dislocations [2].CoCrCuFeNi is one of the first HEAs discovered, with an FCC structure and promising properties. It reports yieldstrength in compression of 450 MPa and 60% ductility [3], however very few studies focus on this alloy in thin film form. Here, we synthetized CoCrCuFeNi TF-HEAs and Al-CoCrCuFeNi multilayers by pulsed laser deposition (PLD), exploiting its large versatility providing different microstructures (i.e. compact and nanogranular) by simply varying the background gas pressure [2]. Our films show a transition from compact to nanogranular at ~1 Pa of He (Fig.1), as well as a loss of crystallographic texturing shown in SAED-TEM. Nanoindentation shows increased hardness in CoCrCuFeNi TF-HEAs from PLD (11 GPa) compared to magnetron sputtering (8 GPa), as a result of smaller domain size (7 nm) and compressive residual stresses. Nanogranular films report ~10% reduction of density and elastic constants due to the low energy of the ablated species. Tensile tests on Kapton® show exceptional ductility of compact and nanogranular CoCrCuFeNi films, with an onset of crack formation of 3.4% (vs ~2% from magnetron sputtering [4]). STEM-EDX of Al-CoCrCuFeNi multilayers (Fig.2) shows local chemical enrichments with ~2 nm Al layers separated by ~5 nm of the HEA with very little diffusion at the interfaces, showing good mechanical properties (H=9 GPa, E=157 GPa). Our results showthat PLD is a powerful technique that enables a single step synthesis of advanced TF-HEAs with tunable microstructure and multilayering, leading to tunable mechanical properties with potential applications in microelectronics, MEMS or high performance coatings