Stanford
nano@stanford
Diffractive Optical Lens made on the Raith Voyager
NNCI and nano@stanford present:

The Advanced Lithography UnSymposium, 2021

9 am - noon, PST
Jan. 21/22, 2021

Event overview

Abstracts

Michael Kahl, Raith GmbH

Nanofabrication for quantum computing

Quantum computing technologies have become a hot topic in academia and industry receiving much attention and financial support from all sides. Many quantum devices and related research are based on nanotechnology, which is a key enabling technology for this application. Nanofabrication with charged particles is one of the major patterning techniques in nanotechnology, since it allows flexible generation of nanostructures with precision in the range of nanometers. In this presentation several examples are given where electron beam lithography and ion beam implantation are used for building quantum devices and related research.

Dr. Sven Preuss, Director of Technical Sales, Heidelberg Instruments

The MLS300: Making a case for a Maskless Stepper Alternative

With the enduring success Maskless Aligners such as the MLA150 and the uMLA, direct write laser lithography has entered the lithography playing field as an alternative to MaskAligners. The MLA tools as most suitable  for applications with a moderate requirements in precision, but with the need for high throughput. Based on our technology for high precision photomasks we propose a system that meets the specification for structure fidelity and position accuracy that thus far has been provided by I-line steppers. 

Anja Voigt, micro resist technology, GmbH

Highlights in Resist & Photopolymer Development for advanced micro & nano patterning technologies, Part 1

In the 1st part of our contribution, we will review different generic methods for the manufacture of high resolution 2D and 3D features which require a wide range of material solutions based on innovative photoresist chemistry. As a commercial material supplier, micro resist technology aims at providing such solutions tailored for diverse lithography processes, comprising both materials and technology support.

Tero Kulmala, Heidelberg Instruments Nano

Transfer and replication of NanoFrazor patterns

All the common approaches to pattern transfer (lift-off, etching etc.) are compatible with NanoFrazor lithography and devices and structures with superior performance have been demonstrated. For example, ohmic contacts to single-layer MoS2 and nanometer-accurate 3D metal wave profiles have recently been fabricated with the technique. Examples of nanometer precise replication of the patterns via nanoimprinting will also be presented.

Dr Nils Goedecke, Heidelberg Instruments Nano

NanoFrazor thermal scanning probe lithography

NanoFrazor thermal scanning probe lithography uses a heatable ultrasharp silicon tip to locally decompose polymer resists and to generate ultrahigh-resolution 2D and 3D geometries on both conducting and insulating substrates. In addition, the technique offers a superior markerless alignment accuracy without exposing the sample to high-energy charged particles. For true mix & match lithography, a laser can be used to pattern and to seamlessly align larger area features to the high-resolution pattern without the need for any intermediate processing steps.

Jan Klein, micro resist technolgy, GmbH

Highlights in Resist & Photopolymer Development for advanced micro & nano patterning technologies, Part 2

In the 2nd part of our contribution, we will broaden the view on emerging micro- and nanoscale manufacturing alternatives using replication processes. As alternative patterning techniques for 2D and 3D features transferred from innovative concepts to the industrial environment, we will briefly show why holistic material concepts for advanced photopolymers are required in replication processes for lab and fab applications.

Niels Wijnaendts van Resandt, Director Sales N. & S. Americas/Dr. Christian Pies, Head of Process & Application Lab, Heidelberg Instruments

Tips and Tricks from our Process Applications Lab (PAL)

Heidelberg Instruments operates multiple process and applications labs (PAL) around the world for the purpose of internal process development, benchmarking, confirming process compatibility of our tools to various industrial customers as well as for training. In this talk we would like to share some lessons we learned over the last years in our PAL in our Headquarters in Heidelberg. We will also highlight some inventive processes we have used in the past.  

Benjamin Richter, Nanoscribe GmbH

Two-photon grayscale lithography

In this presentation we introduce two-photon grayscale lithography (2GL®). In contrast to one-photon grayscale lithography, for 2GL®, the exposed volume pixel is strongly confined to the vicinity of the laser focus allowing for a truly 3-dimensional dose control with very high spatial resolution (see Figure 1). Discrete and accurate steps as well as essentially continuous topographies can be printed with increased throughput, on any substrate, and without the need for additional lithography steps or mask fabrication.
As demonstrators, we design, fabricate, and characterize diffractive optical elements (DOE) as continuous topographies (see Figure 2). The DOE topography is printed by modulating the exposure dose and associated voxel height, thus not limited anymore to a few levels that required a printed layer each, and strongly decreasing the print time while required high lateral and axial resolutions are still met. Such DOEs can be used either directly as prototypes or as masters for tooling production.
The 2GL® process is also applied to smooth surfaces of refractive micro-optical elements, by eliminating the stair casing effect when adding layers on top of each other (see Figure 1). This allows higher distances between layers and proportionally decreases print times, an important factor in industrial environment. The resulting structures are characterized by confocal and electron-beam microscopy. They show surface roughness below 10nm with high shape accuracy, without requiring any post-processing steps.
This printing approach is compatible with micro-lens arrays with 100% fill factor, free form shapes and high aspect ratios.

Roger McKay, GenISys, Inc.

Electron Beam Lithography Software for Enabling Quantum Devices

Li Wang, Eulitha AG

Multiple Exposure Printing Strategies with Displacement Talbot Lithography for Resolution Enhancement and Generation of Different Pattern Symmetries

Displacement Talbot Lithography is a technique based on interference of multiple beams diffracted by a periodic pattern on a mask. For example, a hexagonal array of features on a mask typically produces six diffracted beams that interfere in the substrate plan to expose again a hexagonal array. Linear (line/space), square, rectangular, rhombic arrays are examples of patterns that can be printed directly in this way. Further pattern geometries or higher resolution patterns can be obtained by exposing a substrate multiple times with DTL while displacing or rotating the substrate between the different exposures. Examples of patterns that can be obtained in this way include quasiperiodic patterns with high rotational symmetry or honeycomb arrays. This greatly expands the available pattern types that can be printed on DTL tools for many applications.

Harun Solak, Eulitha AG

Patterning for Photonics with Displacement Talbot Lithography

High-resolution periodic patterns such as gratings or two-dimensional arrays are required in many applications, especially in photonics devices such as near eye displays (AR/VR), DFB lasers or plasmonic or diffraction based biosensors. In order to address this growing need, Eulitha introduced a photolithography technique called Displacement Talbot Lithography (DTL) that enables low-cost patterning of large areas. DTL offers resolution well below 100nm, which is sufficient even for the most demanding applications that require sub-wavelength resolution such as wire-grid polarizers or anti-reflection surfaces. Eulitha provides tools for research and industrial use of DTL in various fields.

Roger McKay, GenISys, Inc.

Automated Feature Measurements from SEM Images with ProSEM

Matthieu Opitz, Alvéole

Engineering Custom and Relevant Cellular Microenvironments with Maskless Photopatterning PRIMO System

In vitro cell experiments confront researchers with many challenges, such as the recurring reproducibility issues, reliability in term of physiological relevance, but also ease of use and efficiency. Here we present one photopatterning system PRIMO - base on the LIMAP* technology - performing three techniques that can be used separately or in synergy and which all aim at answering those labs daily challenges:

(1) MICROPATTERNING allows to precisely control cell adhesion to isolate them or place them in reproducible conditions for standardized assays. Several of our users research works show the advantages of PRIMO contactless micropatterning - at single cell, cell population and high throughput levels: Cell positioning within EM grids for Cryo-et, airway smooth muscle cells patterning on gel for contraction study.

(2) MICROFABRICATION: One key advantage of PRIMO maskless DMD-based photopatterning system is that it can perform greyscale photolithography on greyscale resists (collaboration with Physico-Chimie Curie UMR 168 and UMS-IPGG) and therefore create complex 3D molds such as ramps, curving wells, microfluidic chips for organ-on-a-chip applications.

(3) HYDROGEL POLYMERIZATION: PRIMO can also polymerize and photo-scission most commonly used hydrogels for applications such as 3D cell culture within micro-niches or permeable hydrogel membranes polymerization within microfluidic chips.

*Multiprotein Printing by Light-Induced Molecular Adsorption. P.-O. Strale et al., Advanced Materials, 2016

Torsten Richter, Raith GmbH

Universal Ion Sources for FIB nanopatterning on a lithography platform

Nanofabrication by means of focused ion beam (FIB) technology has specific requirements in terms of patterning resolution and stability. In addition, the type of ion defines the nature of interaction mechanism with the sample and thus has significant consequences on the resulting nanostructures. [1].

Therefore, Raith has extended its FIB technology towards the stable delivery of multiple ion species selectable into a nanometer scale focused ion beam by employing a liquid metal alloy ion source (LMAIS) [2]. Many elements of the periodic table are made accessible in FIB technology because of continuous research in this area [3]. This range of ion species with different mass or charge can be beneficial for various nanofabrication applications. Recent developments make these sources available to an alternative technology for nanopatterning challenges. We will introduce universal ion sources that are feasible to tailor the physical and chemical properties of the resulting nanostructures. [4], [5]

 

References:

[1] L. Bruchhaus, P. Mazarov, L. Bischoff, J. Gierak, A. D. Wieck, and H. Hövel, Comparison of technologies for nano device prototyping with a special focus on ion beams: A review, Appl. Phys. Rev. 4, (2017) 011302.

[2] L. Bischoff, P. Mazarov, L. Bruchhaus, and J. Gierak, Liquid Metal Alloy Ion Sources – An Alternative for Focused Ion Beam Technology, Appl. Phys. Rev. 3 (2016) 021101. 

[3] J. Gierak, P. Mazarov, L. Bruchhaus, R. Jede, L. Bischoff, Review of electrohydrodynamical ion sources and their applications to focused ion beam technology, JVST B 36 (2018) 06J101.

[4] W. Pilz, N. Klingner, L. Bischoff, P. Mazarov, and S. Bauerdick, Lithium ion beams from liquid metal alloy ion sources, JVSTB 37(2), (2019) 021802.

[5] Nico Klingner, Gregor Hlawacek, Paul Mazarov, Wolfgang Pilz, Fabian Meyer, and Lothar Bischoff, Imaging and milling resolution of light ion beams from helium ion microscopy and FIBs driven by liquid metal alloy ion sources, Beilstein J. Nanotechnol. 2020, 11, 1742–1749.

Benjamin Richter, Nanoscribe GmbH

3D Microfabrication and the Importance of Dedicated Resins

3D printing is one of the most powerful technologies in the 21st century. It is widely used in all kind of industries and opened also new emerging fields. The association with 3D printing is typically for big bulky parts but to tailor the properties of these parts a much smaller substructure is required.
In 1997, Shoji Maruo (Osaka University, Japan) and coworkers published their pioneering work based on two-photon absorption which allowed the fabrication of 3D structures with sub micrometer features via the solidification of photopolymers. This marked the birth of 3D micro-/nanoprinting and is also often called direct laser writing or two-photon polymerization (2PP). Here, a femto-second laser beam is focused into a photosensitive liquid material (a mixture of monomeric matrix molecules and a photo initiator). In the focal volume of the focused laser beam a simultaneous absorption of two photons by the photo initiator leads to an excitation into a higher state and the generation of free radicals. This causes a highly localized chemical polymerization event that is confined to the focal volume of the laser due to the non-linearity of the 2PP process and allows tailored fabrication of advanced functional structures.
This talk will summarize the state‐of‐the art regarding 3D microfabrication and will explore the importance of new dedicated resins. One application can be found in cell biology, where low fluorescence is the key for high resolution fluorescent microscopy of single cells. Further, numerous other material properties are of large importance, depending on the respective application. This includes biocompatibility or cytotoxicity for life science, mechanical properties in general, and refractive index or dispersion for optical devices.