Fabrication and optimization of bimorph micro probes for the measurement of individual biocells

This paper deals with a novel structure for single-cell characterization which makes use of bimorph thermal actuators combined with electrical sensor device and integrated micro channel. The goal of this device is to capture and characterize individual biocells or micro particles. After analysis of actuation by numerical modeling and simulation, practical fabrication of prototype probes is realized. Finally, we optimize the dimension of cantilevers and integrated parallel probe systems with microfluidic channels.     

Optimization of SiNX:H films deposited by PECVD for reliability of electronic, microsystems and optical applications

This paper presents the correlation between the optical properties and the chemical and electrical properties of amorphous silicon nitride (SiN_X:H) films prepared by reactor Plasma-Enhanced Chemical Vapor Deposition (PECVD). The effects of temperature and mixture of gases (NH₃/SiH₄/N₂) on these dielectric films are investigated in this study. Silane (SiH₄) and ammonia (NH₃) are used as the reactive species, while nitrogen (N₂) is used as a dilution gas. A particular focus is made on the improvement of the electrical properties that are strongly correlated to the physicochemical bonds films properties. The incorporation of the N₂ dilution leads to the deposition rate and hydrogen content reductions in the film. An optimal gases mixture with N₂ is obtained to improve the breakdown voltage at low temperature, 200 °C. Fundamental properties of these fabricated films are characterized by their elemental composition, chemical specification, residual stress, optical and electrical properties. The results experimentally show that this film can be used to improve some of the key deposition parameters for the reliability of semiconductor, microsystems and optical applications.     

Thermal and electrostatic reliability characterization in RF MEMS switches

The reliability of RF MEMS switches is closely linked to their operational and environmental conditions. This paper examines the reliability of five different capacitive switch designs by a combined use of modeling and experimental tools. Three-dimensional multiphysics finite element analysis was performed to estimate the actuation voltage and deflection vs. temperature variations of the micro-switches. The effect of temperature and temperature cycles on switch dilatation and pull-in voltage are studied, as well as the influence of different operational signals on switch reliability.     

Electron beam nanolithography in AZnLOF 2020

We present a lithography process using electron beam lithography with an optical resist AZnLOF 2020 for pattern transfer. High-resolution 100 keV electron beam lithography in 400 nm layers of negative resist AZnLOF 2020 diluted 10:4 with PMGEA is realized. After the electron beam lithography process, the resist is used as a mask for reactive ion etching. We performed the transfer of patterns by RIE etching of the substrate allowing a final resolution of 100 nm. We demonstrate the patterning in an insulating layer, thus simplifying the fabrication process of various multilayer devices; proximity correction has been applied to improve pattern quality and also to obtain lines width according to their spacing. This negative resist is removed by wet etching or dry etching, could allow combining pattern for smallest size down to 100 nm by EBL techniques and for larger sizes by traditional lithography using photomask.     

Mechanical characterization of aluminium nanofilms

The mechanical properties (Young’s modulus, hardness, wear resistance) of aluminium nanofilms on silicon substrate are studied. Size effect on these mechanical properties are exhibited. Young’s modulus, hardness and wear resistance increases when the thickness is reduced. Experimental investigations have been led by atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. Compared to the bulk values, hardness and wear resistance of one aluminium nanofilm (thickness = 100 nm) have increased by a factor ∼7 whereas the Young’s modulus only increased by a term ∼15%. By comparing mechanical properties between high and low melting point materials, we conclude that high melting point materials have a decreasing behaviour of the Young’s modulus with size whereas low melting point materials have an increasing one.     

Optimization of ohmic contact and adhesion on polysilicon in MEMS-NEMS wet etching process

This paper presents the optimization of polysilicon doping and metallization to form ohmic contact with etching resistance. Indeed, polysilicon doped by ion implantation and ohmic contacts are an important and interesting part of integrated circuit technology or MEMS and NEMS. LPCVD-polysilicon doping parameters, such as ion energy, dose, and annealing were investigated. In particular a superficial implantation realized after a deep implantation enables one to slightly decrease the polysilicon resistivity while the contact resistance is reduced. And ohmic contacts with wet etching resistance were realized by depositing the different metallization stacks. We demonstrate that ohmic contact pad Cr/Pt/Au has provided a good adhesion on LPCVD-polysilicon after wet etching.