Peter Trefonas

Last updated
Peter Trefonas
Born1958 (age 58–59)
Residence Medway, Massachusetts, U.S. [1]
Nationality United States
Alma mater University of New Orleans, University of Wisconsin-Madison
AwardsACS Heroes of Chemistry 2014, Perkin Medal 2016
Scientific career
Fields Lithography
Institutions Dow Chemical
Doctoral advisor Robert West
External video
Nuvola apps kaboodle.svg “Peter Trefonas: Chemistry is key player in lithography process”, Micro/Nano Lithography, SPIE
Nuvola apps kaboodle.svg “Dow Chemical - Dow AR™ Fast Etch Organic Bottom Antireflectant Coatings“, ACS

Peter Trefonas (born 1958) is a DuPont Fellow (a senior scientist) at DuPont, where he works on the development of electronic materials. He is known for innovations in the chemistry of photolithography, particularly the development of anti-reflective coatings and polymer photoresists that are used to create circuitry for computer chips. This work has supported the patterning of smaller features during the lithographic process, increasing miniaturization and microprocessor speed. [2] [3]

DuPont American chemical company

DuPont de Nemours, Inc., commonly known as DuPont, is an American company formed by the merger of Dow Chemical and DuPont on August 31, 2017, and then subsequent spinoffs of Dow Inc. and Corteva. Prior to the spinoffs it was the world's largest chemical company in terms of sales. Within 18 months of the merger the company was split into three publicly traded companies with focuses on the following: agriculture, materials science, and specialty products. The agriculture division is named Corteva, the materials science spin-off is named Dow Inc., and the specialty products division is named DuPont. Jeff Fettig is executive chairman of the company, and Edward Breen is the CEO. The merger has been reported to be worth an estimated $130 billion. DowDuPont ranked No. 35 in the 2019 Fortune 500 list of the largest United States corporations by total revenue.

Chemistry of photolithography

Photolithography is a process in removing select portions of thin films used in microfabrication. Microfabrication is the production of parts on the micro- and nano- scale, typically on the surface of silicon wafers for the production of microelectromechanical systems (MEMS). Photolithography makes this process possible through the combined use of hexamethyldisilazane (HMDS), photoresist, a spin or spray coater, photomask, an exposure system and other various chemicals. By carefully manipulating these factors it is possible to create nearly any geometry microstructure on the surface of a silicon wafer. The chemical interaction between all the different components and the surface of the silicon wafer makes photolithography an interesting chemistry problem. Current science has been able to create features on the surface of silicon wafers between 1 and 100 µm.

Anti-reflective coating

An antireflective or anti-reflection (AR) coating is a type of optical coating applied to the surface of lenses and other optical elements to reduce reflection. In typical imaging systems, this improves the efficiency since less light is lost due to reflection. In complex systems such as telescopes and microscopes the reduction in reflections also improves the contrast of the image by elimination of stray light. This is especially important in planetary astronomy. In other applications, the primary benefit is the elimination of the reflection itself, such as a coating on eyeglass lenses that makes the eyes of the wearer more visible to others, or a coating to reduce the glint from a covert viewer's binoculars or telescopic sight.



Peter Trefonas is a son of Louis Marco Trefonas, also a chemist, and Gail Thames. [4] He was inspired by Star Trek and the writings of Isaac Asimov, and created his own chemistry lab at home. [2] Trefonas attended the University of New Orleans, receiving his Bachelor of Science in chemistry in 1980. [1]

Star Trek is an American media franchise based on the science fiction television series created by Gene Roddenberry. The first television series, simply called Star Trek and now referred to as "The Original Series", debuted in 1966 and aired for three seasons on NBC. It followed the interstellar adventures of Captain James T. Kirk and his crew aboard the starship USS Enterprise, a space exploration vessel built by the United Federation of Planets in the 23rd century. The Star Trek canon includes The Original Series, an animated series, five spin-off television series, the film franchise, and further adaptations in several media.

Isaac Asimov American science-fiction and non-fiction writer

Isaac Asimov was an American writer and professor of biochemistry at Boston University. He was known for his works of science fiction and popular science. Asimov was a prolific writer who wrote or edited more than 500 books and an estimated 90,000 letters and postcards. His books have been published in 9 of the 10 major categories of the Dewey Decimal Classification.

University of New Orleans public university in New Orleans, Louisiana; part of the University of Louisiana System

The University of New Orleans, often referred to locally as UNO, is a medium-sized, metropolitan, public research university located on the New Orleans lakefront within New Orleans, Louisiana, United States. It is a member of the University of Louisiana System and the Urban 13 association.

While an undergraduate, Trefonas earned money by writing early computer games for personal computers. These included Worm, the first version of Snake to be written for a personal computer, and a clone of Hustle. Both were based on the Blockade arcade game. [5] [6] Trefonas also wrote a game based on Dungeons and Dragons. [7]

Personal computer Computer intended for use by an individual person

A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or technician. Unlike large costly minicomputer and mainframes, time-sharing by many people at the same time is not used with personal computers.

Blockade is a monochrome arcade maze game developed by Gremlin and released in October 1976. Using four directional buttons, each player moves their character around leaving a solid line behind them, turning at 90 degree angles. To win, a player must last longer than the opponent before hitting something, with the first person to hit something losing. The game ends after one player gains six wins.

Arcade game Coin-operated entertainment machine

An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are video games, pinball machines, electro-mechanical games, redemption games or merchandisers. While exact dates are debated, the golden age of arcade video games is usually defined as a period beginning sometime in the late 1970s and ending sometime in the mid-1980s. Excluding a brief resurgence in the early 1990s, the arcade industry subsequently declined in the Western hemisphere as competing home video game consoles such as the Sony PlayStation and Microsoft Xbox increased in their graphics and game-play capability and decreased in cost. The eastern hemisphere retains a strong arcade industry.

Trefonas studied at the University of Wisconsin-Madison with Robert West, [1] completing a Ph.D. in inorganic chemistry in late 1984. [2] Trefonas became interested in electronic materials after working with West and chip makers from IBM to create organosilicon bilayer photoresists. [2] His thesis topic was Synthesis, properties and chemistry of organosilane and organogermane high polymers (1985). [8]

Robert C. West is E. G. Rochow Professor of Chemistry Emeritus at the University of Wisconsin–Madison; Director of the Organosilicon Research Center, University of Wisconsin–Madison 1999–present; President, Silatronix, Inc. (2007–present; Distinguished Professor, Yonsei University, 2007–2011.

IBM American multinational technology and consulting corporation

International Business Machines Corporation (IBM) is an American multinational information technology company headquartered in Armonk, New York, with operations in over 170 countries. The company began in 1911, founded in Endicott, New York, as the Computing-Tabulating-Recording Company (CTR) and was renamed "International Business Machines" in 1924.


Trefonas joined MEMC Electronic Materials in late 1984. In 1986, he and others co-founded Aspect Systems Inc., utilizing photolithography technology acquired from MEMC. [2] Trefonas worked at Aspect from 1986-1989. Then, through a succession of company acquisitions, he moved to Shipley Company (1990-2000), Rohm and Haas (1997-2008), to The Dow Chemical Company (2008-2019), and finally to DuPont (2019-current). [9] [10] [11] [2]

Rohm and Haas company

Rohm and Haas Company is a manufacturer of speciality chemicals for end use markets such as building and construction, electronic devices, packaging, household and personal care products. Headquartered in Philadelphia, the company is organised into three business groups of Specialty Materials, Performance Materials and Electronic Materials, and also has two stand-alone businesses of Powder Coatings and Salt. Formerly a Fortune 500 Company, Rohm and Haas employs more than 17,000 people in 27 countries, with its last sales revenue reported as an independent company at US$8.9 billion. Dow Chemical Company bought Rohm and Haas for $15 billion in 2009.

Trefonas has published at least 115 journal articles and technical publications. He has received 103 American patents, and has more than 25 active patent applications pending. [12] [13]


Throughout his career, Trefonas has focused on materials science and the chemistry of photolithography. By understanding the chemistry of photoresists used in lithography, he has been able to develop anti-reflective coatings and polymer photoresists that support finely-tuned etching used in the production of integrated circuits. These materials and techniques make it possible to fit more circuits into a given area. [13] [3] Over time, lithographic technologies have developed to allow lithography to use smaller wavelengths of light. Trefonas has helped to overcome a number of apparent limits to the sizes that are achievable, developing photoresists that are responsive to 436-nm and 365-nm ultraviolet light, and as small as 193 nm deep. [14] [15]

In 1989, Trefonas and others at Aspect Systems Inc. reported on extensive studies of polyfunctional photosensitive groups in positive photoresists. They studied diazonaphthoquinone (DNQ), a chemical compound used for dissolution inhibition of novolak resin in photomask creation. They mathematically modeled effects, predicted possible optimizations, and experimentally verified their predictions. They found that chemically bonding together three of the molecules of DNQ to create a new molecule containing three dissolution inhibitors in a single molecule, led to a better feature contrast, with better resolution and miniaturization. [16] These modified DNQs became known as "polyfunctional photoactive components" (PACs). This approach, which they termed polyphotolysis, [17] [18] [19] has also been referred to as the "Trefonas Effect." [14] [20] The technology of trifunctional diazonaphthoquinone PACs has become the industry standard in positive photoresists. [20] Their mechanism has been elucidated and relates to a cooperative behavior of each of the three DNQ units in the new trifunctional dissolution inhibitor molecule. Phenolic strings from the acceptor groups of PACs that are severed from their anchors may reconnect to living strings, replacing two shorter polarized strings with one longer polarized string. [21]

Trefonas has also been a leader in the development of fast etch organic Bottom Antireflective Coating (BARC) [22] BARC technology minimizes the reflection of light from the substrate when imaging the photoresist. Light that is used to form the latent image in the photoresist film can reflect back from the substrate and compromise feature contrast and profile shape. Controlling interference from reflected light results in the formation of a sharper pattern with less variability and a larger process window. [23]

In 2014, Trefonas and others at Dow were named Heroes of Chemistry by the American Chemical Society, for the development of Fast Etch Organic Bottom Antireflective Coatings (BARCs). [22] In 2016, Trefonas was recognized with The SCI Perkin Medal for outstanding contributions to industrial chemistry. In 2018, Trefonas was named as a Fellow of the SPIE for "achievements in design for manufacturing & compact modeling." Peter Trefonas was elected to the National Academy of Engineering in 2018 for the "invention of photoresist materials and microlithography methods underpinning multiple generations of microelectronics".

Awards and honors

Related Research Articles

Microelectromechanical systems technology of very small devices

Microelectromechanical systems is the technology of microscopic devices, particularly those with moving parts. It merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are also referred to as micromachines in Japan, or micro systems technology (MST) in Europe.

Photolithography, also called optical lithography or UV lithography, is a process used in microfabrication to pattern parts of a thin film or the bulk of a substrate. It uses light to transfer a geometric pattern from a photomask to a photosensitive chemical photoresist on the substrate. A series of chemical treatments then either etches the exposure pattern into the material or enables deposition of a new material in the desired pattern upon the material underneath the photoresist. In complex integrated circuits, a CMOS wafer may go through the photolithographic cycle as many as 50 times.


A photoresist is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronic industry.

Photomask opaque plate or film with holes or transparencies that allow light to shine through in a defined pattern

A photomask is an opaque plate with holes or transparencies that allow light to shine through in a defined pattern. They are commonly used in photolithography.

Immersion lithography photolithography technique for manufacturing integrated circuits

Immersion lithography is a photolithography resolution enhancement technique for manufacturing integrated circuits (ICs) that replaces the usual air gap between the final lens and the wafer surface with a liquid medium that has a refractive index greater than one. The resolution is increased by a factor equal to the refractive index of the liquid. Current immersion lithography tools use highly purified water for this liquid, achieving feature sizes below 45 nanometers. ASML and Nikon are currently the only manufacturers of immersion lithography systems. The idea for immersion lithography was first proposed by Burn J. Lin and realized in the 1980s. Immersion lithography is now being extended to sub-20nm nodes through the use of multiple patterning.

Chris Mack is an expert in photolithography. He received multiple undergraduate degrees from Rose-Hulman Institute of Technology in 1982, a master of science degree in electrical engineering from the University of Maryland, College Park in 1989, and a PhD in chemical engineering from The University of Texas in 1998.

Extreme ultraviolet lithography a next-generation lithography technology using an extreme ultraviolet (EUV) wavelength, currently expected to be 13.5 nm.

Extreme ultraviolet lithography is a next-generation lithography technology using a range of extreme ultraviolet (EUV) wavelengths, roughly spanning a 2% FWHM bandwidth about 13.5 nm. EUV is currently being developed for high volume use by 2020.

In semiconductor fabrication, a resist is a thin layer used to transfer a circuit pattern to the semiconductor substrate which it is deposited upon. A resist can be patterned via lithography to form a (sub)micrometer-scale, temporary mask that protects selected areas of the underlying substrate during subsequent processing steps. The material used to prepare said thin layer is typically a viscous solution. Resists are generally proprietary mixtures of a polymer or its precursor and other small molecules that have been specially formulated for a given lithography technology. Resists used during photolithography are called photoresists.

Nanoimprint lithography (NIL) is a method of fabricating nanometer scale patterns. It is a simple nanolithography process with low cost, high throughput and high resolution. It creates patterns by mechanical deformation of imprint resist and subsequent processes. The imprint resist is typically a monomer or polymer formulation that is cured by heat or UV light during the imprinting. Adhesion between the resist and the template is controlled to allow proper release.

SU-8 photoresist

SU-8 is a commonly used epoxy-based negative photoresist. Negative refers to a photoresist whereby the parts exposed to UV become cross-linked, while the remainder of the film remains soluble and can be washed away during development.


LIGA is a German acronym for Lithographie, Galvanoformung, Abformung that describes a fabrication technology used to create high-aspect-ratio microstructures.

Color filter array

In photography, a color filter array (CFA), or color filter mosaic (CFM), is a mosaic of tiny color filters placed over the pixel sensors of an image sensor to capture color information.

Multiple patterning is a class of technologies for manufacturing integrated circuits (ICs), developed for photolithography to enhance the feature density. It is expected to be necessary for the 10 nm and 7 nm node semiconductor processes and beyond. The premise is that a single lithographic exposure may not be enough to provide sufficient resolution. Hence additional exposures would be needed, or else positioning patterns using etched feature sidewalls would be necessary.

Bitumen of Judea, or Syrian asphalt, is a naturally occurring asphalt that has been put to many uses since ancient times. It is a light-sensitive material in what is accepted to be the first complete photographic process, i.e., one capable of producing durable light-fast results. The technique was developed by French scientist and inventor Nicéphore Niépce in the 1820s. In 1826 or 1827, he applied a thin coating of the tar-like material to a pewter plate and took a picture of parts of the buildings and surrounding countryside of his estate, producing what is usually described as the first photograph. It is considered to be the oldest known surviving photograph made in a camera. The plate was exposed in the camera for at least eight hours.

Diazonaphthoquinone chemical compound

Diazonaphthoquinone (DNQ) is a diazo derivative of naphthoquinone. Upon exposure to light, DNQ converts to a derivative that is susceptible to etching. In this way, DNQ has become an important reagent in photoresist technology in the semiconductor industry.

Multiphoton lithography

Multiphoton lithography of polymer templates has been known for years by the photonic crystal community. Similar to standard photolithography techniques, structuring is accomplished by illuminating negative-tone or positive-tone photoresists via light of a well-defined wavelength. The fundamental difference is, however, the avoidance of reticles. Instead, two-photon absorption is utilized to induce a dramatic change in the solubility of the resist for appropriate developers.

Three-dimensional (3D) microfabrication refers to manufacturing techniques that involve the layering of materials to produce a three-dimensional structure at a microscopic scale. These structures are usually on the scale of micrometers and are popular in microelectronics and microelectromechanical systems.

Melinda H. Keefe

Melinda H. Keefe is a research and development manager at the Dow Chemical Company, where she works on architectural coatings. She helped to develop the award-winning Evoque pre-composite polymer platform, reducing TiO


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