Photoresist technology for 0.25-um lithography

It has been the general opinion of device manufacturers that deep ultraviolet (DUV) imaging will be the imaging method required to produce 250nm and sub-250nm geometries for 256Mb-DRAMs and related logic technology. Traditional I-line lithography may not be capable of manufacturing at these geometry's and the use of DUV radiation with 'chemically amplified' photoresists will be required for these device programs. Issues regarding the problems that researchers are combining or have not yet considered in the evolutionary chain of DUV photoresist development and implementation will be discussed. As researchers continue developing environmentally stable materials, there is a series of issues that device manufacturers need to resolve today as new quarter micron fabs are currently under construction. Fab designers may need to consider additional space for specialty tools or processes in order to produce quarter micron lithography. The issues concerning materials, process, reflectivity control, manufacturing facilities, quality control, photoresist manufacturing, photoresist cost and a proposed roadmap for the next several years of development will be discussed. The author will also provide a brief overview of current I-line photoresists and their capability to the 300nm geometry region along with some basic chemistry regarding the principles of DNQ's and chemically amplified photoresists.