Masks for laser ablation technology: New requirements and challenges

Laser ablation is used as a dry patterning process in which an intense beam of light from an excimer laser is used to pattern a material directly, This process has found extensive application in the microelectronics industry for patterning of polymer materials, A typical laser ablation tool is very similar to a conventional optical lithography projection tool; the primary difference is the wavelength and the intensity of the light used in the ablation process, Conventional chromium-coated quartz masks are incompatible with Ix laser ablation tools because the chromium layer is rapidly damaged, This paper discusses a mask technology which has been developed specifically for excimer laser ablation, The mask consists of a quartz substrate with a stack of dielectric films which have been selected for the laser ablation wavelength, Mask fabrication is accomplished with standard microelectronic processes and equipment, Such masks have been used in IBM manufacturing since 1987 and have met all process specifications such as resolution, defect density, and damage resistance.