Tailorable BARC system to provide optimum solutions for various substrates in immersion lithography

Abstract

It is common knowledge that the semiconductor industry continues to shrink the features contained in integrated circuits to increase speed and density. Each time the critical dimension (CD) shrinks, new challenges arise to impede the progress to attain smaller feature sizes, and control over surface reflectivity becomes even more important. Single-layer bottom anti-reflective coatings (BARCs) have been used in photolithography processes for years to reduce substrate reflectance, thus reducing or eliminating CD swing, reflective notching, and standing waves. Continued use of this solution is highly advantageous because it is well-known and cost-effective. This paper will describe a cutting-edge BARC system that has tailorable optical constants designed specifically to greatly improve immersion lithography process latitude. This BARC system can be easily modified to make formulations that match many different substrates that are being used in new devices, including highly absorbing substrates (nitrides), reflective substrates (oxide), metal layers, and hardmasks. The optimum optical parameters for this BARC system can be easily achieved through simulations. This paper will exhibit the correlation between optical simulations and lithography results.