A. Beaurain

Improved release strategy for UV nanoimprint lithography

The adhesion between the fused silica mold and the resist remains a key issue in ultraviolet nanoimprint lithography (UV-NIL), especially in step and repeat processes. In this paper, we present results on antisticking layers (ASLs) of tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (F13-TCS) deposited in vapor phase and of a commercial product, Optool DSX™, from Daikin Chemical, deposited in liquid phase. The antisticking properties and structural morphologies of the formed self-assembled monolayer are investigated using contact angle, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy (XPS) measurements. Obtained surface energies are as low as 10mN∕m for both types of ASL. The stability of these formed layers during the UV-NIL process remains the main important issue. It was tested on an EVG® step and repeat UV-NIL equipment using acrylate-based resists. After only 50 prints, we observed a high increase in the surface energy of the mold, which indicates a drastic degradati...

Double-anchoring fluorinated molecules for antiadhesion mold treatment in UV nanoimprint lithography

In this work, the authors evaluate a new type of perfluoropolyether molecule (FLUOROLINK® S10) to be used as an antisticking mold treatment in UV nanoimprint lithography. Unlike currently used ones, this molecule has two anchoring ends groups allowing two covalent grafting sites of the molecule to the mold surface. Obtained results on this molecule are compared to Optool DSX’s ones. Using contact angle measurement, x-ray photoelectron spectroscopy, and electron spin resonance, the authors carried out chemical analysis of the evolution of antisticking treatments as a function of the number of imprints. It is found that both molecules have a roughly equivalent behavior. FLUOROLINK® S10 has shown less chemical resistance, attributed to its larger number of C–O bonds in the molecule, but an improved mechanical resistance, attributed to the double grafting mechanism.

Passivated TiN nanocrystals/SiN trapping layer for enhanced erasing in nonvolatile memory

We present chemical vapor deposition of titanium nitride nanocrystals (ncs) on silicon nitride (SiN). Ncs are passivated in situ by a silicon shell and encapsulated in SiN. High density (3×1012 cm−2), crystalline and isolated ncs are observed by transmission electron microscopy and characterized by x-ray photoelectron spectroscopy. TiN ncs/SiN are integrated as charge trapping layer in a nonvolatile memory. Devices show large memory window (10 V) and fast erasing compared to devices using pure SiN trapping layer, explained by enhanced electrical field in SiN. Acceptable reliability in terms of cycling and data retention is also demonstrated.

Enhanced cell-material interactions on medium-pressure plasma-treated polyhydroxybutyrate/polyhydroxyvalerate

In this article, a medium-pressure DBD plasma treatment is used to improve the cell-material interaction of a polyhydroxybutyrate/polyhydroxyvalerate (PHB/PHV) film. PHB/PHV is a biodegradable natural polyester, used for different biomedical applications, including sutures, repair devices, and bone marrow scaffolds. The cell adhesion onto PHB/PHV is far less than optimal due to inadequate surface properties, and a surface modification is usually necessary to be able to use the full potential. Medium-pressure plasma treatments, in different atmospheres, are used to change the surface properties of a PHB/PHV foil. The hydrophilic character could be increased, as shown by water contact angle measurements. X-ray photoelectron spectroscopy (XPS) revealed an increased oxygen and nitrogen content. Cell culture test with human foreskin fibroblasts showed that the plasma was able to improve cell adhesion (both quantitatively and qualitatively). Both an increase in the number of adherent cells and an improved morphology were obtained after plasma treatment. After 7 days, a confluent cell layer could be observed on plasma-treated samples. The differences between the three discharge gases are negligible when looking at the improved cell-material interactions. From economical point of view, treatments in air are thus the best choice.