Christophe Peroz

Step and repeat UV nanoimprint lithography on pre-spin coated resist film: a promising route for fabricating nanodevices

A step and repeat UV nanoimprint lithography process on pre-spin coated resist film is demonstrated for patterning a large area with features sizes down to sub-15 nm. The high fidelity between the template and imprinted structures is verified with a difference in their line edge roughness of less than 0.5 nm (3σ deviation value). The imprinted patterns residual layer is well controlled to allow direct pattern transfer from the resist into functional materials with very high resolution. The process is suitable for fabricating numerous nanodevices.

Obtaining nanoimprint template gratings with 10 nm half-pitch by atomic layer deposition enabled spacer double patterning.

A strategy for fabricating nanoimprint templates with sub-10 nm line and 20 nm pitch gratings is demonstrated, by combining electron beam lithography and atomic layer deposition. This is achieved through pitch division using a spacer double-patterning technique. The nanostructures are then replicated using step-and-repeat ultra-violet assisted nanoimprint lithography.

Printable planar lightwave circuits with a high refractive index

We report a novel nanofabrication method to fabricate printable integrated circuits with a high refractive index working in the visible wavelength range. The printable planar ligthwave circuits are directly imprinted by ultra-violet nanoimprinting into functional TiO2-based resist on the top of planar waveguide core films. The printed photonic circuits are composed of several elementary components including ridge waveguides, light splitters and digital planar holograms. Multi-mode ridge waveguides with propagation losses around 40 dB cm(-1) at 660 nm wavelength, and, on-chip demultiplexers operated in the visible range with 100 channels and a spectral channel spacing around 0.35 nm are successfully demonstrated.

High-Resolution Spectrometer-on-Chip Based on Digital Planar Holography

Digital planar holography enables the creation of a new generation of integrated photonic circuits with desired transfer function. We give here, for the first time, the basis for designing computer-generated planar holograms and demonstrate their application for spectroscopy-on-chip. Nanospectrometer chips are demonstrated with unmatched spectral resolution of up to 2 ·105. A specific configuration is demonstrated for easy integration of planar holograms into the full spectrometer system. The ultraminiaturization and very high performances of the devices are a breakthrough in spectroscopy and open a novel route for the digital processing of light.

Multilayer lift-off process for sub-15-nm patterning by step-and-repeat ultraviolet nanoimprint lithography

Numerous studies report the importance of nanoscale metallic features to increase the sensitivity of gas sensors, biodetectors, and for the fabrication of the new-generation plasmonic devices. So far, nanoimprint lithography has not shown the capability to pattern a metallic structure that would both be sub-15 nm and sufficiently thick to ensure electrical conductance. To overcome these limitations, we report a step and repeat nanoimprint lithography (SR-NIL) on a pre-spin-coated layer stack. This work reports the fabrication of sub-15-nm lines that are 15-nm thick and have a 50-nm-half-pitch grating with 35-nm-thick metal, which represents the new state of the art for SR-NIL.

Fabrication of novel digital optical spectrometer on chip

A novel type of digital optical spectrometer on chip is proposed and first results of their fabrication and characterization are reported. The devices are based on computer-designed digital planar holograms which involves millions of lines specifically located and oriented in order to direct the output light into the designed focal points according to the wavelength. Spectrometers were fabricated on silicon dioxide and hafnium dioxide planar waveguides using electron beam lithography and dry etching. The optical performances of the first devices with up to 1000 channels for a central wavelength of 660 nm are reported.

Optical metasurfaces for high angle steering at visible wavelengths

Metasurfaces have facilitated the replacement of conventional optical elements with ultrathin and planar photonic structures. Previous designs of metasurfaces were limited to small deflection angles and small ranges of the angle of incidence. Here, we have created two types of Si-based metasurfaces to steer visible light to a large deflection angle. These structures exhibit high diffraction efficiencies over a broad range of angles of incidence. We have demonstrated metasurfaces working both in transmission and reflection modes based on conventional thin film silicon processes that are suitable for the large-scale fabrication of high-performance devices.

Printable photonic crystals with high refractive index for applications in visible light

Nanoimprint lithography (NIL) of functional high-refractive index materials has proved to be a powerful candidate for the inexpensive manufacturing of high-resolution photonic devices. In this paper, we demonstrate the fabrication of printable photonic crystals (PhCs) with high refractive index working in the visible wavelengths. The PhCs are replicated on a titanium dioxide-based high-refractive index hybrid material by reverse NIL with almost zero shrinkage and high-fidelity reproducibility between mold and printed devices. The optical responses of the imprinted PhCs compare very well with those fabricated by conventional nanofabrication methods. This study opens the road for a low-cost manufacturing of PhCs and other nanophotonic devices for applications in visible light.

Step-and-repeat nanoimprint on pre-spin coated film for the fabrication of integrated optical devices

Abstract. A step-and-repeat nanoimprint lithography (SR-NIL) process on a pre-spin-coated film is employed for the fabrication of an integrated optical device for on-chip spectroscopy. The complex device geometry has a footprint of about 3  cm2 and comprises several integrated optical components with different pattern size and density. Here, a new resist formulation for SR-NIL was tested for the first time and proved effective at dramatically reducing the occurrence of systematic defects due to film dewetting, trapped bubbles, and resist peel-off. A batch of 180 dies were imprinted, and statistics on the imprint success rate is discussed. Devices were optically characterized and benchmarked to an identical chip that was fabricated by electron-beam lithography. The overall performance of the imprinted nanospectrometers is well-aligned with that of the reference chip, which demonstrates the great potential of our SR-NIL for the low-cost manufacturing of integrated optical devices.

Nanoimprint planarization of high aspect ratio nanostructures using inorganic and organic resist materials

Planarization is often crucial to the implementation of three-dimensional devices and systems. By using a pressing process analogous to nanoimprint, the authors show that moderate to high aspect ratio (⩾3) photonic nanostructures in the form of one-dimensional and two-dimensional photonic crystals can be effectively planarized with thermally cured sol-gel or uv-curable nanoimprint resist materials. The planarization results are strongly dependent on parameters such as pressing pressure, hydrophobicity of feature surface, spin conditions for sol-gel, and dispense volume for uv-curable. High degree of planarization and complete filling of open features can be achieved through optimization of imprint parameters. Nanoimprint planarization may thus offer a simple, low cost, fast, and viable alternative planarization methodology.