The demand for even denser semiconductor devices is driving efforts to reduce pattern dimensions in semiconductor
lithography. It has been found that 193-nm immersion lithography technology can achieve smaller patterns without
having to modify the infrastructure technology of existing state-of-the-art 193-nm dry lithography. This has made
193-nm immersion lithography a promising technology for next-generation mass production processes. It is now under
full-scale development and is about to enter a commercial stage applicable to mass production.
In 193-nm immersion lithography, the space between the optical projection system and silicon wafer is filled with
liquid thereby immersing the resist film in de-ionized water during exposure. This generates a number of concerns, such
as the penetration of moisture into the resist, the leaching of resist components into deionized water, and the presence of
residual moisture, all of which can lead to defects that can affect post-processing. It has been reported; however, that
rinse processing before and after exposure can be effective in reducing such defects . Also, the trend toward finer
patterns has resulted in large aspect ratios that can lead to pattern collapse, but the application of a surfactant has been
found to ease this problem. Controlling the drying process after rinsing has also been found to reduce residue adhering to
The stability of process data is considered to be a crucial factor in the adapting of 193-nm immersion lithography to
mass production. In this report, we obtain long-term data on defects and critical dimension (CD), examine this data for
process stability, and discuss the applicability of 193-nm immersion lithography to mass production.