Over the past 30 years the world market for semiconductors has grown at an average annual rate of approximately 15%. This growth has been maintained by the industry's unique ability to consistently provide over this time frame higher device performance at lower cost (achieving a 25-30% per-year cost reduction per function). Microlithography is the key technological driving force for this; in large part, the overall rate of progress in microelectronics is controlled by the rate of advances in microlithographic tools, methods, and materials. Today, the photolithographic technologies that have served the microelectronics community since its inception are widely viewed to be nearing their limits of extendibility. If the historical growth rate is to be maintained in the future, new imaging technologies with the capability of forming features with sub-100 nm dimensions must be devised and refined. In this paper we provide an overview of the issues to be considered for patterning in the sub-100 nm regime and describe the imaging technologies which are currently being evaluated for such use.