Nanolithography

The production of an electronic device will often require many stages of photolithography. Photolithography is the process of defining a pattern on the surface of a device material slice. By sequentially using such patterns to define metal contacts or etched areas a complete device is gradually built up.

In this article, nanolithography is discussed, what it is and what its applications are and how to utilize it fully.

Extreme ultraviolet lithography (also known as EUV or EUVL) is a lithography (mainly chip printing/making aka "fabricating") technology using a range of extreme ultraviolet (EUV) wavelengths, roughly spanning a 2% FWHM bandwidth about 13.5 nm.

by The Chinese University of Hong Kong (CUHK)

Single-walled carbon nanotubes (SWCNTs) are considered pivotal components for molecular electronics. Techniques for SWCNT lithography today lack simplicity, flexibility, and speed of direct, oriented deposition at specific target locations. In this paper SWCNTs are directly drawn and placed with chemical identification and demonstrated orientation using fountain pen nanolithography (FPN) under ambient conditions. Placement across specific electrical contacts with such alignment is demonstrated and characterized. The fundamental basis of the drawing process with alignment has potential applications for other related systems such as inorganic nanotubes, polymers, and biological molecules.

It may soon be possible to manufacture the miniscule structures that make up transistors and silicon chips rapidly and inexpensively. EPFL scientists are currently investigating the use of dynamic stencil lithography, a recent but not yet perfected method, for creating nanostructures.

The Dutch firm ASML spent $9 billion and 17 years developing a way to keep making denser computer chips.

“The qubit systems we have today are a tremendous scientific achievement, but they take us no closer to having a quantum computer that can solve a problem that anybody cares about. It’s akin to trying to make today’s best smartphones using vacuum tubes from the early 1900s. You can put 100 tubes together and establish the principle that if you could somehow get 10 billion of them to work together in a coherent, seamless manner, you could achieve all kinds of miracles,” Sankar Das Sarma recently wrote in MIT Review.

Fountain pen nanolithography for nanometric chemical writing

Integrated circuits, and devices fabricated using the techniques developed for integrated circuits, have steadily gotten smaller, more complex, and more powerful. The rate of shrinking is astonishing - some components are now just a few dozen atoms wide. This book attempts to answer the questions, "What comes next?" and "How do we get there?" Nanolithography outlines the present state of the art in lithographic techniques, including optical projection in both deep and extreme ultraviolet, electron and ion beams, and imprinting. Special attention is paid to related issues, such as the resists used in lithography, the masks (or lack thereof), the metrology needed for nano-features, modeling, and the limitations caused by feature edge roughness. In addition emerging technologies are described, including the directed assembly of wafer features, nanostructures and devices, nano-photonics, and nano-fluidics. This book is intended as a guide to the researcher new to this field, reading related journals or facing the complexities of a technical conference. Its goal is to give enough background information to enable such a researcher to understand, and appreciate, new developments in nanolithography, and to go on to make advances of his/her own.

ASML Fellow Simon Mathijssen explains how he and his colleagues ensure layers of microchips align with nanometer accuracy.

Femtosecond Projection Two-photon Lithography (FP-TPL) printing technology increases the printing speed by 1,000 – 10,000 times, and reduces the cost by 98%. It controls the laser spectrum via temporal focusing, the laser 3D printing process is performed in a parallel layer-by-layer fashion instead of point-by-point writing. This is a technological breakthrough that leads nanoscale 3D printing into a new era. Conventional nanoscale 3D printing technology, i.e., two-photon polymerization (TPP), operates in a point-by-point scanning fashion. As such, even a centimeter-sized object can take several days to weeks to fabricate (build rate ~ 0.1 mm3/hour). The process is time-consuming and expensive, which prevents practical and industrial applications. To increase speed, the resolution of the finished product is often sacrificed. Professor Chen and his team have overcome the challenging problem by exploiting the concept of temporal focusing, where a programmable femtosecond light sheet is formed at the focal plane for parallel nano-writing; this is equivalent to simultaneously projecting millions of laser foci at the focal plane, replacing the traditional method of focusing and scanning laser at one point only. In other words, the FP-TPL technology can fabricate a whole plane within the time that the point-scanning system fabricates a point. What makes FP-TPL a disruptive technology is that it not only greatly improves the speed (approximately 10 100 mm3/hour), but also improves the resolution (~140 nm / 175 nm in the lateral and axial directions) and reduces the cost (US$1.5/mm3). Professor Chen pointed out that typical hardware in a TPP system includes a femtosecond laser source and light scanning devices, e.g., digital micromirror device (DMD). Since the main cost of the TPP system is the laser source with a typical lifetime of ~20,000 hours, reducing the fabrication time from days to minutes can greatly extend the laser lifetime and indirectly reduce the average printing cost from US$88/mm3 to US$1.5/mm3 a 98% reduction. Due to the slow point-scanning process and lack of capability to print support structures, conventional TPP systems cannot fabricate large complex and overhanging structures. The FP-TPL technology has overcome this limitation by its high-printing speed, i.e., partially polymerized parts are rapidly joined before they can drift away in the liquid resin, which allows the fabrication of large-scale complex and overhanging structures, as shown in Figure 1 (G). Professor Chen said that the FP-TPL technology can benefit many fields; for example, nanotechnology, advanced functional materials, micro-robotics, and medical and drug delivery devices. Because of its significantly increased speed and reduced costs, the FP-TPL technology has the potential to be commercialized and widely adopted in various fields in the future, fabricating meso- to large-scale devices. Brian Wang is a prolific business-oriented writer of emerging and disruptive technologies. He is known for insightful articles that combine business and technical analysis that catches the attention of the general public and is also useful for those in the industries. He is the sole author and writer of nextbigfuture.com, the top online science blog. He is also involved in angel investing and raising funds for breakthrough technology startup companies. He gave the recent keynote presentation at Monte Jade event with a talk entitled the Future for You.  He gave an annual update on molecular nanotechnology at Singularity University on nanotechnology, gave a TEDX talk on energy, and advises USC ASTE 527 (advanced space projects program). He has been interviewed for radio, professional organizations. podcasts and corporate events. He was recently interviewed by the radio program Steel on Steel on satellites and high altitude balloons that will track all movement in many parts of the USA. He fundraises for various high impact technology companies and has worked in computer technology, insurance, healthcare and with corporate finance. He has substantial familiarity with a broad range of breakthrough technologies like age reversal and antiaging, quantum computers, artificial intelligence, ocean tech,  agtech, nuclear fission, advanced nuclear fission, space propulsion, satellites, imaging, molecular nanotechnology, biotechnology, medicine, blockchain, crypto and many other areas.

With the help of immersion lithography and multiple patterning, photolithography has been the key technology over the last decade in manufacturing of ICs, microchips and MEMS devices. Continuous rapid shrinking of feature size made the authorities to seek alternative patterning methods that can go beyond classic photographic limits. Some promising techniques have been proposed as next generation lithography and further technological progress are required to make them significant and reliable to meet the current demand. EUVL is considered as the main candidate for sub-10 nm manufacturing because of its process simplicity and reduced operating cost. Remarkable progress in EUVL has been made and the tools will be available for commercial operation soon. EBL, FIB and X-ray lithography are used for patterning in R&D, mask/mold fabrication and low volume chip design. DSA have already been realized in lab and further effort will be needed to make it as NGL solution. NIL has emerged attractively due to its simple process-steps, high-throughput, high-resolution and low cost and become one of the commercial platforms for nanofabrication.

In new work, an international team of researchers describes the drawing and Raman characterization procedure developed for placing single-walled carbon nanotubes (SWCNTs), proof of SWCNT alignment, optimization of the drawing parameters, and the subsequent placement in predefined lithographic structures for the demonstration of electrical conductivity. In essence, the team developed a simple nanopen for drawing and placing aligned single or multiple rod like molecules nanometrically.