The metallization technique is usually aimed at (but not limited to) the fabrication of electrical contacts of prototypes and devices for extracting the produced signals. Usually metals are deposited with a thickness ranging from few monolayers to few µm, depending on the specific application. ISM proposes three techniques for metallization: magnetron sputtering, electron-beam evaporation, and pulsed laser deposition, all located in the DiaTHEMA Lab of Montelibretti Section.
In the magnetron sputtering, ionized particles due to the activation of a plasma of an inert gas (e.g. Ar) are forced to impact onto a target (the material to be deposited) causing the ejection of atoms and/or molecular clusters, that later condense on the substrate surface for the metal coating formation. This setup is generally used in the deposition of films with thickness > 20 nm. Derived from a commercial unit (Leybold LH Z400), the available system is dedicated to the deposition of materials up to 4-inch size.
The electron beam evaporation is a physical vapor deposition in which high-energy electrons impinge on the material to be deposited, typically in the form of rods or pellets, inducing its sublimation and the following deposition on a substrate. Inside the vacuum chamber, the metal is placed in a pocket crucible where it is easily irradiated by the electron beam. The system employs a multi-crucible system that allows the deposition of multilayers. To improve the homogeneity of deposition, the substrates are mounted on a rotating holder whose speed can be controlled by the operator.
The pulsed laser deposition is based on the vaporization from a target due to the interaction with a high-power laser beam. The evaporated material gives shape to a dense cloud of ionized species, of different nature, known as plume. The plume, formed by atoms, ions, particles and small atomic aggregates (i.e. clusters), has its origin on the surface of the target irradiated by the laser and condenses on the surface of the deposition substrate. The available laser source is the Lambda COMPex 102, capable of producing a pulsed beam (with a single pulse duration equal to 30 ns) operating in Q-switching mode and with a wavelength of 193 nm.

Leybold LH Z400 IONVAC EVPK 500EBK ns-PLD (@193 nm)

Micro and nanomaching of materials and devices are performed with techniques that physically modify their surface and/or the bulk, such as Reactive Ion Etching (RIE) and fs-Laser Patterning, differing in the physical mechanisms producing the modifications and in the processing logics.  
RIE is used to etch various materials under vacuum in the presence of reactive ions. The purpose of the RIE machine is usually to etch patterns of materials by using a chemically reactive gas in plasma state. The plasma is generated by an electromagnetic field and directed towards a substrate patterned with photo-lithographic technique or a hard mask.  High-energy ions from the plasma can physically and/or chemically etch the material under treatment or react with its surface to remove atoms from the target material with high anisotropy. Etched depths of tens of micrometers with resolution correlated with the used lithographic technique can be obtained with the setup available at the DiaTHEMA Lab in the Montelibretti Section.
Laser patterning is a technique based on the direct writing of the materials at the the micro- and the nanoscales. The modifications provided by the interaction with the ultrashort-pulse laser beam can be used for controlling the surface properties as well as can be employed for fabricating complex 3D channels into the bulk of solid materials. The achievable resolution is sub-micrometric and the applications can be in optics, photonics, microfluidics, electronics. The setup consists of the Ti:sapphire femtosecond laser (pulse length of about 100 fs) and the nanoresolution workstation Newport MicroFab, located in the Tito Scalo Section and managed by FemtoLAB and DiaTHEMA Lab.

RIE uFAB - Micro & Nano fabrication

The Electrospray Ionization (ESI) technique, allows to bring large molecules as intact and isolated units in the gas phase. Its ability to generate sprays of monodisperse charged particles can be exploited to deposit thin and uniform coating films of fine particles of different materials. The ESI technique uses a low-concentration solution of the molecule of interest flowing in a small capillary toward a metallic emitter held at high voltage (typically a few kV).  
At the tip of the emitter, the competition of the surface tension of the liquid and the high field results in the so-called 'Taylor cone', inside which Coulomb explosion creates a spray of charged droplets with sizes down to nanometers. As the solvent evaporates the size of the droplet deceases and at the end a gas of molecular ions is formed. This approach provides dry depositions at ambient pressure or in controlled atmosphere and can be easily automatized and applied on a large scale. The system is available in the DepEST lab of the Montelibretti Section.

DEPEST LAB

Two optical lithography techniques are available: 1) Ultraviolet lithography also known as photolithography, which is the most common used patterning technique in microfabrication, 2) 2-photon lithography, which is a high resolution 2D and 3D structuring process of a photosensitive material induced by an ultrashort pulse laser with radiation intensity sufficiently over a defined threshold.
In the case of photolithography, the photoresist (a photosensitive material) is spin-coated onto a substrate and illuminated with UV light through a photomask containing the geometric patterns. After the required exposition and development of the sample, the desired pattern is transferred on the photoresist. DiaTHEMA Lab of ISM, located in the Montelibretti Section, has a setup composed by a Karl Süss MA6 mask aligner, able to reach a resolution of about 1 μm, and a SUSS MicroTec LabSpin spin coater, with maximum speed of 5000 rpm. The setup is mounted in a clean room to improve the cleanliness of lithography process. It is possible to use both positive and negative photoresist, with thickness up to 30 μm.
In case of 2-photon lithography, 2D or 3D mask-less patterns can be obtained by direct-writing with the ultrashort-pulse laser beam, that can be focused down to the sub-micrometer resolution. Features of a few hundreds of nanometers are achievable thanks to the existence of intensity threshold, which allow pushing the resolution over the laser spot size. The setup consists of the Ti:sapphire femtosecond laser (pulse length of about 100 fs) and the nanoresolution workstation Newport MicroFab, located in the Tito Scalo Section and managed by FemtoLAB and DiaTHEMA Lab.

Photolitography 1µm 2 Photon lithography