The Alestle - Vol. 58 No. 66 - 07/26/2006

Vol. 58 No. 6

Deep germanium etching using time multiplexed plasma etching

Abstract : There is a growing need for patterning germanium for photonic and photovoltaics applications. In this paper, the authors use a time multiplexed plasma etch process (Bosch process) to deep etch a germanium substrate. They show that germanium etching presents a strong aspect ratio dependent etching and that patterns present scallops mostly on the upper part (aspect ratio below 0.8). Passivation layers are formed during the passivation step by neutrals’ deposition and are reinforced during the etching step by the redeposition of sputtered fluorocarbon species from the etch front. When the sidewalls are passivated, reactive neutrals diffuse through Knudsen-like diffusion down to the bottom of the pattern to etch the germanium. The Knudsen-like diffusion is responsible for the aspect ratio dependent etching and makes difficult the etching of holes with aspect ratios above 10 while trenches with aspect ratio of 17 are still etched faster than 2 lm/min

The Alestle - Vol. 57 No. 1 - 08/24/2004

Vol. 57 No.

Selective dry etching of TiN nanostructures over SiO2 nanotrenches using a CI2/Ar/N2 inductively coupled plasma

Abstract : An inductively coupled plasma etch process for the fabrication of TiN nanostructures over nanotopography is presented. Using a Cl2/Ar/N2 plasma, a selectivity of 50 is achieved over SiO2. The effect of N2 flow rate on the etch rates and the nonvolatile residues on TiN sidewalls is investigated. As N2 flow rate is increased up to 50 sccm, a change in the deposition of the nonvolatile residues on TiN sidewalls is observed. The current density–voltage characterizations of TiN devices fabricated with TiN nanostructure sidewalls are presented. The measured current densities of two different samples etched with low and high N2 flow rate, respectively, demonstrated the presence after cleaning of an insulating layer deposited on the sidewalls for low N2 flow rate only

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Economic Contributions of Venezuelan Protected Areas: The Tragedy of the Commons and Perspectives.

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Wafer-scale detachable monocrystalline Germanium nanomembranes for the growth of III-V materials and substrate reuse

Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronic, photovoltaic, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, weight reduction, limitation of waste, and cost effectiveness. Herein, we introduce the Porous germanium Efficient Epitaxial LayEr Release (PEELER) process, which consists of the fabrication of wafer-scale detachable monocrystalline Ge NMs on porous Ge (PGe) and substrate reuse. We demonstrate monocrystalline Ge NMs with surface roughness below 1 nm on top of nanoengineered void layer enabling layer detachment. Furthermore, these Ge NMs exhibit compatibility with the growth of III-V materials. High-resolution transmission electron microscopy (HRTEM) characterization shows Ge NMs crystallinity and high-resolution X-ray diffraction (HRXRD) reciprocal space mapping endorses high-quality GaAs layers. Finally, we demonstrate the chemical reconditioning process of the Ge substrate, allowing its reuse, to produce multiple free-standing NMs from a single parent wafer. The PEELER process significantly reduces the consumption of Ge during the fabrication process which paves the way for a new generation of low-cost flexible optoelectronics devices.Comment: 17 pages and 6 figures along with 3 figures in supporting informatio

Plasma Etching in Microelectronics

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Les Procédés par Plasmas Impliqués dans l'Intégration des Matériaux SiOCH Poreux pour les Interconnexions en Microélectronique

To increase the integrated circuits pace and decrease the devices size, interconnects must be isolated by porous SiOCH. Because of porous SiOCH degradation by plasma exposure, the integration of narrow trenches into porous SiOCH necessitates to re-develop plasma processes (etching, striping and pore sealing). This thesis addresses plasmas/materials interactions during the integration of porous SiOCH into narrow trenches (The hybrid material and the dense SiOCH present similar etch mechanisms with a fluorocarbon-based plasma. The TiN and the organic material present other etch mechanisms, assuring a good selectivity. The process defined for narrow trenches etching with an organic hard mask leads to straight profiles. On the contrary, profiles distortions due to etch by-products deposits, bow profiles and dielectric lines buckling are obtained with a TiN hard mask. Both porous and hybrid materials are modified by post-etch plasma treatments.Pour réduire la taille des dispositifs et les temps de commutation en microélectronique, les lignes d'interconnexions doivent être isolées par du SiOCH poreux. Cependant, la réalisation de tranchées étroites dans le SiOCH poreux nécessite de revoir les différents procédés par plasmas (gravure, traitements post-gravure) et les schémas d'intégration, puisque ce matériau est facilement dégradé lorsqu'il est exposé à un plasma.Cette thèse porte sur les interactions plasmas/matériaux pour l'intégration des SiOCH poreux dans des tranchées très étroites (Avec un plasma fluorocarboné, le matériau hybride présente des mécanismes de gravure similaires à ceux d'un SiOCH dense. Le TiN et le matériau organique ont des mécanismes de gravure différents de ceux des diélectriques, ce qui assure une bonne sélectivité. Le procédé de gravure optimisé pour le masque organique permet la gravure de tranchées très étroites avec un profil quasiment vertical. Par contre, le contrôle dimensionnel de tranchées étroites est plus difficile avec un masque en TiN, en raison de dépôts métalliques sur les flancs, de profils en forme de tonneaux, et du flambage des lignes. Après l'étape de gravure, les matériaux poreux et hybrides sont modifiés par les plasmas post-gravure

Introduction

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