As optical lithography is extended to the sub-90 nm nodes, more stringent requirements are placed on the mask critical dimension and registration budget. Errors in image placement (IP) due to exposure-induced thermal loading of the optical reticle can be a significant contribution to the overlay error budget. Thermal loading on the mask is primarily caused by the chrome pattern that absorbs a large fraction of exposure light. The effects of the chrome pattern density, local pattern distribution, and chrome reflectivity were studied using three-dimensional finite-element models for both 193 and 157 nm technologies. It was found that the chrome pattern density has a stronger influence on the thermomechanical response than the pattern distribution. Also, it was found that as the chrome reflectivity increases, the reticle maximum temperature rise decreases, thus it follows a linear relationship. In addition, various reticle/chuck mounting designs were investigated to identify what type of configuration is nec...