Interview with Kenneth E. Gonsalves (Distinguished Professor at the Indian Institute of Technology Mandi, India).

Kenneth Gonsalves
Kenneth Gonsalves

In the race to develop ever smaller and better performing chips, several technological limitations need to be overcome. Today, the bottlenecks to continue this trend lie mainly in techniques for manufacturing electronic circuits of less than 10 nanometers (nm). Among the techniques being improved to manufacture the next generation of chips, one of the most promising is extreme ultraviolet lithography (EUVL). This technology takes advantage of the very short wavelength of extreme ultraviolet radiation to pattern nanoscale circuits on the chip with the intermediation of the so-called “resists” – thin layers of radiation sensitive material that cover the chip substrate during nanofabrication.

At the XVI B-MRS Meeting, a plenary lecture will discuss an important contribution that the materials field can make to the next generation of chips: the development of suitable resists for the fabrication of electronic circuits of less than 10 nm through EUVL.

The subject will be presented by Kenneth E. Gonsalves, Distinguished Professor of the Indian Institute of Technology Mandi (IIT Mandi), a teaching and research institution created in 2009, where Gonsalves arrived in 2012 as a visiting professor.

Gonsalves obtained his BS in Chemistry from the University of Delhi (India) followed by an MS also in Chemistry from Boston College (USA) and a PhD from the University of Massachusetts at Amherst (USA) with a doctoral thesis on polymer synthesis. Then he performed a postdoctoral specialization on polymer ceramics at MIT (USA). From 2001 to 2014, Gonsalves was the Celanese Acetate Distinguished Professor of Polymer Materials at the University of North Carolina at Charlotte (USA).

Together with his research group at IIT and his collaborators from the United States, India, Brazil, Taiwan and Europe, Gonsalves carries out research and development on resists for advanced nanofabrication techniques, with support of major companies in the electronics segment, and on polymer scaffolds for tissue engineering.

Here follows a brief interview with the researcher.

B-MRS newsletter: – Tell us a little bit about your main scientific/ technological contributions up to the moment.

Kenneth Gonsalves: – My research has centered on polymers with an emphasis on synthesis of novel materials. For the last 20 years I have focused on resist technology for IC (integrated circuit) fab. This is a fascinating area as it has significant technological applications in the development of integrated circuits, solid state devices. In addition it can also be used successfully for cell and tissue engineering of scaffolds for biotechnologies.

B-MRS newsletter: – About the resists you are working on, what skills and expertise are needed to develop them, in your opinion? When this next generation of chips is expected to be available?

Kenneth Gonsalves: – Resist R&D is multifaceted and extremely complex. It requires extensive collaborations between chemists with organic, inorganic and polymer backgrounds. In addition, interaction with physicists and electrical/electronic engineers is essential. The next generation of chips at the 14 nm node are currently available. Sub 7 nm node technology is expected by 2018 onwards.

B-MRS newsletter: – Describe in the simplest and briefest possible way the process of EUVL, without forgetting to mention the role of resists.

Kenneth Gonsalves: – The EUV photons are generated by a plasma or synchrotron source operating at a wavelength of 13.5 nm. Through a series of special mirrors and a mask, the predesigned template for the IC fab is projected onto photosensitive materials such as polymers as well as inorganics. This is all conducted in vacuum, a challenge for the IC fab industry as it is a drastic change from current photolithography fab, which functions under ambient conditions. The extremely short EUV wavelength is a prerequisite for patterning features at the sub 20 nm scale. The challenges for resists that can meet the sub 7 nm node requirements are enormous. A new paradigm is paramount – hybrid resists, that are partially inorganic may provide solutions to patterning at these scales. Inorganic hardmasks are another alternative. The sensitivity of these photoresists has to be enhanced drastically in order to meet the mass volume production of chips. There are several other critical parameters that have to be met for a successful resist system. Again, this requires multidisciplinary, multi institutional, industry collaboration on a global scale.


More information

On XVI B-MRS Meeting website, click on the photo of Kenneth Gonsalves and see his mini CV and the abstract of his plenary lecture:

Interview with Prof. Susan Trolier-McKinstry (Penn State), MRS President.

foto susan
Prof. Susan Trolier-McKinstry

Piezoelectric materials convert mechanical energy into electric energy and vice versa. They are widely used now for ultrasonic imaging, ink jet printers, sonar systems, sensors, and in precise positioning. Thin film piezoelectric microelectomechanical systems (MEMS) already enable cell phone communications, and offer the possibility of many additional technological changes with the potential for strong social impact. The field of MEMS has already started to generate microscopic machines that are able to capture data from the environment, to process them and to carry out operations involving movement.

This subject will be addressed in a plenary lecture of the XVI B-MRS Meeting by Professor Susan Trolier-McKinstry, who leads a research group at The Pennsylvania State University, USA (Penn State) with expertise in the study and development of piezoelectric thin films and their use in MEMS. In the lecture, the scientist will reveal how she improves the performance of her piezoelectric thin films to use them as sensors, actuators and energy harvesters (that capture small amounts of mechanical energy from the environment to transform them into electrical energy for use them in low-power devices).

At Penn State, Susan Trolier-McKinstry is the Steward S. Flaschen Professor of Ceramic Science and Engineering, Professor of Electrical Engineering, and Director of the Nanofabrication facility. She is also the current president of the Materials Research Society (MRS), which has an international and interdisciplinary membership of about 14,000 people. Previously, Trolier-McKinstry was president of IEEE Ultrasonics, Ferroelectrics and Frequency Control Society and Keramos National Professional Ceramic Engineering Fraternity.

Susan Trolier-McKinstry was born in Syracuse, New York, USA. After completing her primary and secondary studies in public schools in the bordering states of New York and Pennsylvania, she entered Penn State to study Ceramic Science and Engineering. In 4 years of studies, which included her first research work on piezoelectric ceramics, she obtained her B.S. and M.S. degrees. Shortly thereafter, in 1987, she began her doctoral studies in Ceramic Science, also at Penn State, which included a research internship at Hitachi’s Central Research Laboratory in Tokyo, Japan. In both master’s and doctoral works, Troiler-McKinstry was supervised by Professor Robert E. Newnham, an expert in minerals and crystallography who created, in the late 1970s a piezoelectric composite transducer that is now widely used for ultrasound imaging. Susan Troiler-McKinstry received her PhD in 1992 and, at the same year, she began her academic career at Penn State.

Professor Troiler-McKinstry is an associate editor of the journal Applied Physics Letters. She is a fellow of the American Ceramic Society, IEEE and Materials Research Society and a scholar of the World Academy of Ceramics. She has received numerous awards and honors for her research and teaching work, such as the IEEE Ferroelectrics Achievement Award, the Ceramic Education Council’s Outstanding Educator Award, and the Robert L. Coble Award for Young Scholars from the American Ceramic Society, among others. In addition, her biography was included in the book “Successful Women Ceramic and Glass Scientists and Engineers: 100 Inspirational Profiles”, released in 2016.

Besides having developed a distinguished trajectory in research, with more than 12,000 citations to her papers and an h-index=56 according to Google Scholar, Professor Troiler-McKinstry loves teaching and is very proud of the students she has supervised.

Here follows a brief interview with this scientist.

B-MRS Newsletter: – In your opinion, what are your main scientific contributions to the field of piezoelectric thin films? Describe briefly and feel free to share references.

Susan Trolier-McKinstry: – My research group works in three main areas: 1) understanding the factors that control the magnitude of the dielectric and piezoelectric responses of materials, 2) Processing science of electroceramic films, 3) demonstration of low voltage microelectromechanical systems for actuator arrays, sensors, and energy harvesting. In the fundamental area, we have studied the role that domain structure and domain walls play in controlling the properties of high strain piezoelectric films based on ferroelectric compositions. We demonstrated the length scale over which domain walls move collectively, and have quantified the role that grain boundaries and defect chemistry have in influencing wall mobility of lead zirconate titanate. We also contributed to the development of materials that have piezoelectric coefficients that are several times larger than conventional thin films, as well as films that have energy harvesting figures of merit that exceed those of conventional films by ten times. In many cases, it has been necessary to invent and calibrate new tools for assessing the piezoelectric properties (including wafer flexure tools, and mapping interferometers for quantitative piezoelectric measurements on clamped and released parts). Once interesting materials are developed, we then work on understanding how to scale the deposition to large substrate sizes, alternate substrates such as polymers, glasses, and metals. It is also critical to be able to laterally pattern the piezoelectric films without degrading their properties. Thus, the group also studies methods to pattern at length scales ranging from 100 nm to 200 mm. Because the properties of high strain piezoelectric materials are a strong function of the composition and the crystallinity, it is imperative to develop patterning processes that do not degrade either of these factors. Finally, we have made microelectromechanical systems over a wide range of application space, including adaptive optics, rf switches, acceleration sensors, energy harvesters, and CMOS – replacement switches.

B-MRS Newsletter: – Why use piezoelectric materials in MEMS technology?

Susan Trolier-McKinstry: – Many MEMS devices are intended to either generate or sense motion. Piezoelectric materials allow this to be done with very high sensitivities in sensors, and with low voltages in actuators. Thus, it is possible to replace high voltage electrostatic devices with low voltage piezoelectric counterparts. This, in turn, simplifies the electrical system, and allows significant miniaturization of devices. For example, we are now working on a medical ultrasound system for imaging which is small enough that the whole device (including all of the electronics) can be put in a pill and swallowed for investigation of the gastrointestinal tract.

B-MRS Newsletter: – Your research group has already manufactured piezoelectric MEMS devices. Have any of these systems left the lab to be commercialized? Describe in few words, please.

Susan Trolier-McKinstry: – The field of piezoelectric MEMS is exploding now. Thus, many of the materials developments that we have made over the years are being utilized in systems being commercialized now.

B-MRS Newsletter: – What are, in your opinion, the main challenges or goals that material research societies have today?

Susan Trolier-McKinstry: – Scientific societies play crucial roles in improving scientific communication and in helping their members have productive careers. The materials research societies underpin essential interdisciplinary communication through meetings and publications because our field sits at the juncture of chemistry, physics, and engineering. Thus, it is common to see colleagues from different disciplines meeting together and discussing key issues that cross fields at materials research meetings. Key to our future is fostering the diversity of people and fields covered by the society.

B-MRS Newsletter: – In your view, how could the MRS and B-MRS communities enhance their interactions in a productive way?

Susan Trolier-McKinstry: – There are many possibilities here. Good examples might be to identify a particular joint program around an education, outreach or communication goal. One possibility would be to establish a joint program to translate education materials from one language to another to increase the quality of materials education around the world. Other possibilities might be joint programming of a symposium at a meeting, or utilizing publication vehicles like MRS Advances to make work presented at B-MRS meetings more widely available. All of these will hinge on good interactions between the people and societies involved.

On XVI B-MRS Meeting website, click on the photo of Susan Trolier-McKinstry and see her mini CV and the abstract of her plenary lecture:

Featured paper: Designing structures to manipulate light.

[Paper: Oxide-cladding aluminum nitride photonic crystal slab: Design and investigation of material dispersion and fabrication induced disorder. Melo, EG; Carvalho, DO; Ferlauto, AS; Alvarado, MA; Carreno, MNP; Alayo, MI. Journal of Applied Physics 119, 023107 (2016). DOI: 10.1063/1.4939773.]

Designing structures to manipulate light

Photonic crystals are nanostructures capable of manipulating visible light and other forms of electromagnetic radiation by organizing its structure in periodic patterns.

In addition to the natural materials with these characteristics, such as opal, photonic crystals are man-made and are generally classified as metamaterials. Its characteristics (shape, size and composition) are designed to control light waves. Through nanofabrication processes these become tangible structures and are used in many “nanophotonic” devices. Nevertheless, producing these structures is by no means a simple task.

The authors of the article. From left to right, at the laboratory: Prof. Marcelo Nélson Paez Carreño, Emerson Gonçalves de Melo, Maria Elisia Armas Alvarado and Prof. Marco Isaías Alayo Chávez. At the insets: Daniel Orquiza de Carvalho (left), André Santarosa Ferlauto (right).

With a study based on computer simulations, a team of Brazilian scientists headed by researchers from the Polytechnic School of the University of São Paulo (EPUSP) presented scientific contributions that can be used to improve the production of photonic crystals to enhance their performance of manipulating light. According to Emerson Melo, the first author of a paper on the study that was recently published in the prestigious Journal of Applied Physics (JAP) “the work presents a detailed analysis of the effects caused by nanofabrication processes on the optical properties of planar photonic crystals produced on silicon dioxide-cladding aluminum nitride”.

“The idea emerged from the opportunity of combining the excellent optical and physical characteristics of aluminum nitride (AlN), such as transparency over a wide wavelength range (from the near infrared to the ultraviolet range), its non-linear effects, great stability and temperature variations, with the advantages provided by photonic crystals, such as the construction of high-efficiency waveguides, curves and resonant cavities in nanoscale dimensions, in addition to the various optical effects of photonic crystals, such as very low group velocity and low-intensity nonlinear effects of the materials”, adds Emerson,  who is a doctoral student in Microelectronics – Photonics in EPUSP, within the Group of New materials and Devices of the Microelectronics Laboratory of the Department of Electronic Systems Engineering. Emerson`s doctoral research, whose advisor is Professor Marco Isaías Alayo Chávez, enquires into the study, production and characterization of nanophotonic devices such as waveguides, resonant cavities, optical modulators and switches in aluminum nitride photonic crystals.

The study that resulted in the paper published in the JAP began with an experimental stage. Thin films of aluminum nitride and silicon dioxide (SiO2) were manufactured by the EPUSP group, and with the research collaboration from UFMG and UNESP they were analyzed by the Variable Angle Spectroscopic Ellipsometry (VASE) technique to determine the dielectric functions, which was later used as the theoretical research data.

On the left, a diagram of a photonic crystal structure with some of the manufacturing defects studied. On the right, a diagram of the unit cell of the ideal photonic crystal designed by the scientists.

Then, the EPUSP group designed a photonic crystal, ideal in terms of performance and manufacturing possibilities, consisting of a layer of aluminum nitride between two silicon dioxide layers, with round holes arranged in a repeating pattern along the “sandwich” material. Using analytical and numerical methods, the USP researchers simulated some of the “side effects” of the photonic crystal manufacturing processes of this type (e.g., variations of size and location of holes) and theoretically analyzed how these imperfections affect the performance of the photonic crystal.

The theoretical research of Emerson and the other researchers of EPUSP focused on the imperfections generated in the two main stages of the nanofabrication process normally used in photonic crystals such as the one studied: electron-beam lithography and plasma-assisted dry etching. “The results presented allow to assess that the electron-beam lithography process has greater effect on the performance of devices that explore the dispersion of electromagnetic radiation through the photonic crystal, such as prisms, optical switches and modulators”, says Emerson. “However, the quality of the dry etching process has a more profound impact on the characteristics of devices into which linear or exact defects are introduced in the periodic network of the photonic crystal to insert harmonic modes within the photonic band gap. In this case, the dry etching has to be extremely well controlled for manufacturing the devices where waveguides and resonant cavities are among its main elements”.

In addition to making headway in understanding the role of nanofabrication processes of photonic crystals in the performance of nanophotonic devices, the authors of the paper were able to define a method to design planar photonic crystals with core and cover in thin film dielectric materials. “The methodology includes determining the dielectric function of the material by the spectroscopic ellipsometry technique to analyze the dispersion effects of the materials,  determining the geometrical parameters that maximize the photonic band gap and the analysis of the impacts caused by deviations introduced in the manufacturing process”, explains Emerson.

The research received financial support from the National Council for Scientific and Technological Development (CNPq) and from the Financier of Studies and Projects (Finep).

The authors of the article. From left to right, at the laboratory:.