Everything you ever wanted to know about why the semiconductor industry needs a high-refractive index photoresist but were afraid to ask: Part I

The lithography prognosticator of the early 1980's declared the end of optics for sub-0.5μm imaging. However, significant improvements in optics, photoresist and mask technology continued through the mercury lamp lines (436, 405 & 365nm) and into laser bands of 248nm and to 193nm. As each wavelength matured, innovative optical solutions and further improvements in photoresist technology have demonstrated that extending imaging resolution is possible thus further reducing k₁. Several authors have recently discussed manufacturing imaging solutions for sub-0.3k₁ and the integration challenges. Our industry will continue to focus on the most cost effective solution. What continues to motivate lithographers to discover new and innovative lithography solutions? The answer is cost. Recent publications have demonstrated sub 0.30 k₁ imaging. The development of new tooling, masks and even photoresist platforms impacts cost. The switch from KrF to ArF imaging materials has a significant impact on process integration. This paper will focus on the need to increase the refractive index of ArF photoresist systems to enhance process capability for ultra-high NA's that are near the limitation of the immersion fluid. Data will be presented demonstrating the impact of higher refractive index photoresist systems have on the further extension of ArF Immersion. Advanced RET's will be incorporated to further explore improvements in critical imaging levels along with dominant mask effects.