Sogang University Team Uncovers Key to Advanced Semiconductor Material Performance

A research team led by Professor Kim Sang-yeop at Sogang University's Department of Mechanical Engineering has identified the crucial importance of 'thermal history' in spin-on carbon (SOC) hardmasks, a key material for next-generation semiconductor ultra-fine processes. Their findings, published in the prominent materials and polymer journal 'Polymer Testing,' were the result of a joint industry-academia project with Samsung Electronics.

The study focused on SOC hardmasks, essential for precisely transferring patterns in ultra-fine semiconductor processes. While their planarization capabilities are expanding their application, they have historically shown lower etch resistance compared to amorphous carbon films produced by chemical vapor deposition (CVD). Previous research primarily concentrated on designing precursor molecular structures or simply adjusting the final heat treatment temperature.

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The importance of the kinetic path of the heat treatment that the material undergoes, in addition to the carbonization of the hardmask, was proven.

However, the Sogang University team emphasized that the material's cumulative 'thermal history', the entire process of reaching a specific temperature, determines its final performance, not just the peak temperature. They developed a 3-component dispersed activation energy model (DAEM) to design heat treatment paths that theoretically achieve the same carbonization degree under different temperature conditions.

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We hope this becomes a practical guideline for managing the competitive reactions of surface oxidation and bulk carbonization to ensure the productivity and quality of semiconductor micro-processes.

Experiments revealed that a high-temperature, short-duration treatment (700°C for 1 minute), which minimized the exposure of the film surface to residual oxygen in the vacuum chamber, improved etch resistance by 26.4% and reduced surface defect density by 6.5% compared to a low-temperature, long-duration treatment (650°C for 112 minutes) that reached the same carbonization degree. Spectroscopic analysis confirmed this difference was due to the dominance of surface oxidation over bulk carbonization as the heat treatment time increased.

This research offers a new kinetic design standard for optimizing materials in next-generation semiconductor processes, moving beyond a simple central approach. It provides practical guidelines for achieving the required etch resistance even in the residual oxygen environments common in industrial settings, paving the way for enhanced process productivity and quality. Song Jin-woo, the first author and a master's-Ph.D. integrated student, expressed the significance of proving the kinetic importance of the heat treatment path, stating, "We hope this becomes a practical guideline for managing the competitive reactions of surface oxidation and bulk carbonization to ensure the productivity and quality of semiconductor micro-processes."

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I am deeply grateful to Professor Kim Sang-yeop for his generous guidance throughout the research process and to the Samsung Electronics joint research team for discussing on-site challenges.