A new insight from ARCNL researchers into how intense light causes damage in materials could help control light-induced damage in applications like wafer metrology. Rather than it being driven solely by direct energy absorption, underlying nanoscale processes also appear to play a significant role in the onset of the damage.
Light-induced damage is a crucial limiting factor in semiconductor devices exposed to intense light. Existing models typically explain this damage through thermal effects or direct energy absorption, but they don’t account for how other observed damage processes occur.
Materials behave predictably as long as the light intensity remains below a certain threshold. If that intensity is exceeded, other, nonlinear processes can occur that lead to damage. As chip structures continue to shrink while being processed with high light intensities, the threshold is reached more quickly, creating new forms of light-induced damage.
As an example, wafers use markers to determine the position via diffraction of light. Smaller markers save wafer surface. As a result, higher light intensities must be used, both when making and reading these markers. Under these conditions, classic thermal effects and other, nonlinear processes can play a role.
The researchers at ARCNL, in collaboration with ASML, describe these processes in a perspective paper. There, they combine different damage mechanisms and underlying physical processes in one framework. This should help improve the understanding of light-induced damage and enable more targeted control, especially in wafer metrology, where materials are exposed to intense light. The researchers argue that with their insights, small, measurable changes could be detected early in the process, which can help prevent irreversible damage during inspection.
