The epitaxial growth of germanium on silicon leads to the self-assembly of SiGe nanocrystals by a process that allows the size, composition and position of the nanocrystals to be controlled. This ...level of control, combined with an inherent compatibility with silicon technology, could prove useful in nanoelectronic applications. Here, we report the confinement of holes in quantum-dot devices made by directly contacting individual SiGe nanocrystals with aluminium electrodes, and the production of hybrid superconductor-semiconductor devices, such as resonant supercurrent transistors, when the quantum dot is strongly coupled to the electrodes. Charge transport measurements on weakly coupled quantum dots reveal discrete energy spectra, with the confined hole states displaying anisotropic gyromagnetic factors and strong spin-orbit coupling with pronounced dependences on gate voltage and magnetic field.
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IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
We describe a process for transferring a 200 nm thick, 200 mm wide monocrystalline silicon (mono c-Si) thin film from a silicon-on-insulator onto a flexible polymer substrate. The result is a ...stretchable and flexible ultra-thin semi-conductor film that can be subjected to tensile stress experiments. The process uses off-the-shelf 200 mm wafers and standard polymer temporary bonding techniques. The backside substrate and buried oxide are removed using grinding and wet etching processes. No cracks or wrinkles are observed on the film prior to the tensile stress experiments. The stretching of the flexible structure results in up to 1.5% uniaxial tensile elastic strain on the thin mono c-Si film.
Abstract
This article deals with Si/Ge heterostucture manufacturing using covalent bonding, and its application to the layer transfer of a thin germanium film. At first, bow simulations of the ...heterostructure are discussed, in order to determine the temperature that should be used during bonding. Then, the covalent bonding process used to manufacture the heterostructure is described and characterized. At the end, a layer transfer process and observations of a thin germanium film are presented.
Spin-selective tunneling of holes in SiGe nanocrystals contacted by normal-metal leads is reported. The spin selectivity arises from an interplay of the orbital effect of the magnetic field with the ...strong spin-orbit interaction present in the valence band of the semiconductor. We demonstrate both experimentally and theoretically that spin-selective tunneling in semiconductor nanostructures can be achieved without the use of ferromagnetic contacts. The reported effect, which relies on mixing the light and heavy holes, should be observable in a broad class of quantum-dot systems formed in semiconductors with a degenerate valence band.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We report an electric-field-induced giant modulation of the hole g factor in SiGe nanocrystals. The observed effect is ascribed to a so-far overlooked contribution to the g factor that stems from the ...mixing between heavy- and light-hole wave functions. We show that the relative displacement between the confined heavy- and light-hole states, occurring upon application of the electric field, alters their mixing strength leading to a strong nonmonotonic modulation of the g factor.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The presented work concerns the manufacturing of very thin silicon wafers for a 3D Integrated Circuit industrial purpose. One of the key parameters of the 3D integration is the adherence of the ...bonded structure which involves silicon wafers and a polymer adhesive as an intermediate layer. The scope of the paper is to determine the suitable adherence of the stack for a successful manufacturing onto industrial tools. For this purpose the dismounting capacity of the fully automated equipment EVG®850DB depending on the adherence energy is studied. Direct and polymer bonded silicon pairs are prepared. Their energies of adherence cover a large range of energy: from 0.3 to 14 J/m2. The automatic mechanical dismounting process is successful when the stack adherence is 1.2 J/m2 or lower. This value does not depend on the bonded structure type: direct bonded pairs or thinned polymer bonded pairs exhibit the same behavior regarding the dismounting capacity. And we demonstrate that the industrial manufacturing of 70 μm thin silicon wafers is possible if the adherence is 0.4 J/m2 to 1.2 J/m2.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The study deals with the handling of thin wafers in 3D integration. It concerns the fabrication of 300 mm wafers in industrial tools. Usually, the manufacturing is based on a temporary bonding ...process performed at 200 °C using a thermoplastic adhesive. In that condition bonding, thinning and dismounting are satisfactory. Moreover, the adhesive flattening during bonding results in an excellent thickness uniformity of the bonded pairs, with a small total thickness variation (TTV) value suitable for 3D integration. If the temperature is 150 °C or lower, the adhesive thickness uniformity is not acceptable anymore. An innovative temporary bonding process at low temperature has thus been developed. It consists in a carrier fabrication with highly uniform adhesive thickness. The standard coated adhesive is flattened with a first reversible temporary bonding at 210 °C. After a first dismounting, this carrier is then bonded to the target device wafer with a low bonding temperature, from 110 °C to 150 °C. Due to the pre-flattening, 80 μm thick silicon films with an excellent TTV value can thus be obtained even with a low bonding temperature required by the device wafer. Moreover, after the device wafer thinning, the final dismounting can be performed without any antisticking layer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hybrid integration of III-V materials onto silicon by direct bonding technique is a mature and promising approaches to develop advanced photonic integrated devices into the silicon photonics ...platform. In this approach, the III-V material stack is grown on an InP wafer in a unique epitaxial step prior to the direct bonding process onto the silicon-on-insulator wafer. Currently, no additional epitaxial regrowth steps are implemented after bonding. This can be seen as a huge limitation as compared to the III-V on III-V wafer mature technology where multi-regrowth steps are most often implemented. In this work, we have studied the material behavior of an InP membrane on silicon (InPoSi) under epitaxial regrowth conditions by metal-organic vapor phase epitaxy (MOVPE). MOVPE requires high-temperature elevation, typically above 600 °C. We show for the first time the appearance of voids at 400 °C in an InP seed (100 nm) directly-bonded onto a thermally oxidized Si substrate despite the use of a thick SiO
oxide (200 nm) at the bonding interface. This phenomenon is explained by a weakening of the bonding interface while high-pressurized hydrogen is present. A kinetic study of the hydrogen lateral diffusion is carried out, enabling the assessment of its lateral diffusion length. To overcome the void formation, highly efficient outgassing trenches after bonding are demonstrated. Finally, high-quality AlGaInAs-based multi-quantum well (MQW) heterostructure surrounded by two InP layers was grown by MOVPE on InPoSi template patterned with outgassing trenches. This process is not only compatible with MOVPE regrowth conditions (650 °C under PH
) but also with conventional fabrication processes used for photonic devices.
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