Peter Trefonas

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

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. Trefonas also wrote a game based on Dungeons and Dragons.

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

Trefonas joined MEMC Electronic Materials in late 1984. In 1986, he and others co-founded Aspect Systems Inc., utilizing photolithography technology acquired from MEMC. 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), and finally to The Dow Chemical Company (2008-).

Trefonas has published at least 99 journal articles and technical publications. He has received 61 American patents, and has more than 25 active patent applications pending.

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. 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.

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. These modified DNQs became known as as "polyfunctional photoactive components" (PACs). This approach, which they termed polyphotolysis,has also been referred to as the "Trefonas effect." The technology of trifunctional diazonaphthoquinone PACs has become the industry standard in positive photoresists. 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.

Trefonas has also been a leader in the development of Bottom Antireflective Coating (BARC) and Developable Bottom Antireflective Coating (DBARC) Technology. BARC and DBARC technology minimize the reflection of light from the substrate when developing the photomask. Light that is used to develop the photomask can reflect back from the substrate and compromise feature contrast. Controlling interference from reflected light results in the etching of a sharper line with less variability. DBARC uses anti-reflective coatings on the substrate that can be removed from the substrate as the novolak resin is dissolved off after photoimaging.

Developable bottom antireflective coatings (DBARC) and bottom antireflectant coatings (BARCs) are made of cross-linkable polymers that can minimize back-reflection of light during the process of etching the wafer surface. The technology is based on polystyrene derivatives that effectively absorb light at the wavelengths used in the photomasking technology. DBARC technology places the anti-reflective coating on the substrate and removes it from the substrate as the novolak resin is dissolved off after photoimaging. By creating polymers that are easy to remove once the pattern transfer step is finished, damage to the pattern and unevenness in the resist film thickness are minimized, improving electrical performance and reducing waste. The DBARC and BARC processes afford similar control of substrate reflectivity, but the DBARC process also offers process simplification by eliminating the need for a BARC open etch step.

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).

• 2016, Perkin Medal, from the Society of Chemical Industry
• 2014, ACS Heroes of Chemistry, from the American Chemical Society (one of thirteen scientists from the Dow Chemical Company credited with the development of Dow AR™ Fast Etch Organic Bottom Antireflectant Coatings)
• 2013, SPIE C. Grant Willson Best Paper Award in Patterning Materials and Processes jointly with researchers at Dow and Texas A&M University, from SPIE for the paper "Bottom-up / top-down high-resolution, high-throughput lithography using vertically assembled block brush polymers".