Comparative life cycle assessment of hybrid bonding and copper pillar die-to-wafer 3D integrations for sub-THz applications

International audienceAbstract. According to IPCC , global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate [1]. At the same time, global data traffic continues to rise significantly [2], spurring the development of next generation communication systems. Therefore, it is critical to measure, identify the main contributors, and decrease the environmental impacts of new technologies starting from R&D stage before industrialization. This study aims at comparing two die-to-wafer (DtW) 3D interconnections (hybrid bonding and copper pillar) required for 6G radiofrequency (RF) application using Cradle-to-Gate Life Cycle Assessment (LCA). This study is carried out on CEA-Leti R&D assembly process of silicon dies on 300 mm silicon wafer with CEA cleanroom consumptions and emissions data. Results show that hybrid bonding has 1,3 to 2,1 more impact than copper pillars on relevant selected impact categories in R&D scenario and almost similar impact in prospective industrial scenario. Future investigations are needed to consolidate results, taking into account the whole life cycle

Silicon Die Self-alignment on a Wafer: Stable and Unstable Modes

3D integration is the key to advanced microelectronic systems. Die-to-wafer assembly is a necessary step to reach full integration. Self-assembly methods are promising due to their parallel aspect which overcomes the main difficulties of the current techniques. The aim of this work is the understanding of the mechanisms of self-alignment with an evaporating droplet technique and the investigation the stable and unstable modes. Using the Surface Evolver software, we analyze the causes for misalignments of the system and their evolution

Self-alignment of Silicon Chips on Wafers: a Numerical Investigation of the Effect of Spreading and Wetting

3D integration is the key to advanced microelectronic systems. Die-to-wafer assembly is a necessary step to reach full integration. Self-assembly methods are promising due to their parallel aspect, which overcomes the main difficulties of the current techniques. Especially promising are the self-assembly methods based on capillary alignment. In such a method, capillary forces are used to align the chip and evaporation of the liquid droplet eventually leads to contact and direct bonding of the chip on the fixed pad. In a preceding work, the stable and unstable displacement modes have been investigated, assuming that the fluid completely wets the surfaces of the chip and the fixed pad, and that the liquid is anchored to the all the edges. However, it appears that these assumptions are the most favorable case, which is not always reached. Poor spreading and/or occasional overflow of the liquid are the causes of poor alignment. In this work we focus on the mechanisms of spreading and overflow, and analyze the motion of the chip during the spreading

Empreinte environnementale d'un composant de puissance à base de GaN

International audienceLes composants de puissance à base de semiconducteurs à large bande interdite (Wide Band Gap (WBG) sont intéressants pour augmenter l'efficacité énergétique des convertisseurs de puissance, par rapport aux composants conventionnels à base de silicium (Si). Alors que le potentiel gain en efficacité énergétique est connu, le coût énergétique et les impacts environnementaux à la fabrication restent peu documentés. En effet, à notre connaissance, il n'y a pas ou peu de données d'analyse de cycle de vie (ACV) disponibles pour les composants de puissance à base de nitrure de gallium (GaN ou GaN/Si) et carbure de silicium (SiC). Dans ce papier, nous présentons une analyse de cycle de vie du berceau à la porte pour un composant de puissance à base de GaN, permettant d'identifier les postes les plus impactants et de proposer des pistes d'éco-conception

Capillary self-alignment of polygonal chips: a generalization for the shift-restoring force

International audienceCapillary-driven self-alignment using droplets is currently extensively investigated for self-assembly and microassembly technology. In this technique, surface tension forces associated to capillary pinning create restoring forces and torques that tend to bring the moving part into the alignment. So far, most studies have addressed the problem of square chip alignment on a dedicated patch of a wafer, aiming to achieve 3D microelectronics. In this study, we investigate the shift-restoring forces for more complex moving parts such as regular—convex and non-convex—polygons and regular polygons with regular polygonal cavities. A closed-form approximate expression is derived for each of these polygonal geometries; this expression agrees with the numerical results obtained with the Surface Evolver software. For small shifts, it is found that the restoring force does not depend on the shift direction or on the polygonal shape. In order to tackle the problem of microsystem packaging, an extension of the theory is done for polygonal shapes pierced with connection vias (channels), and a closed form of the shift-restoring force is derived for these geometries and again checked against the numerical model. In this case, the restoring force depends on the shift direction. Finally, a non-dimensional number, the shift number, is proposed that indicates the isotropic or anisotropic behavior of the chip according to the shift direction

Study of Silicon Carbide high voltage ability: experimental results on expitaxial-emitter and implanted-emitter diodes

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A New Process for the Fabrication of SiC Power Devices and Systems on SiCOI (Silicon Carbide On Insulator) Substrates

International audienceFeasibility of 4H-SiC epitaxy on SiCOI substrates has been demonstrated, with high quality of obtained layers. Power Schottky diodes were designed and fabricated on these new structures, and exhibited very interesting electrical performance, particularly in reverse mode, with V br ~ 1000 V. This technology is very promising for the realization of monolithic SiC power systems

Hydrogen implantation-induced blistering in diamond : towards diamond layer transfer by the Smart CutTM technique

International audienceThe effect of H$^+$ implantation and annealing of diamond (100) monocrystalline substrates has been studied by ToFSIMS,cathodoluminescence, transmission spectroscopy and TEM. Blistering conditions suitable for the Smart Cut$^{TM}$technology have been identified in monocrystalline diamond, using two sets of hydrogen implantation and annealing.A first hydrogen implantation followed by a first annealing leads to amorphization of a buried layer without hydrogenexodiffusion. Blisters and exfoliations appear at the surface of the diamond samples after a second hydrogen implantationinside the pre-amorphized diamond layer and a final annealing, as evidenced by TEM and optical microscopy.Demonstration of hydrogen-induced blistering is a major step to adapt the Smart Cut$^{TM}$ process on diamond material.This process is compatible with wafer bonding before the second annealing and therefore open the way for thin diamondlayer transfer, still not achieved to date