Design Strategies for Future Lithographic Technologies (or, OPC Will Never Die)
Resolution Enhancement Technologies (RETs) have extended the life of optical lithography well into the regimes of k1 = 0.3. Although there are a number of RETs widely in use now, all involve some degree of optical and process correction (OPC). This puts additional strain on the data handling and management capabilities for process calibration and mask preparation.
Alternative lithographic technologies, such as Extreme UV (EUV), electron projection lithography (EPL), direct-write maskless lithography (MLL), and even nanoimprint techniques have been proposed and are under rapid development. All these alternatives create patterns using a wavelength (or the dimension of the writing tool itself) smaller than the desired feature. Since these should comfortably increase k1 back to the values enjoyed many years ago, it is generally assumed that the issues associated with OPC and the data management for RETs will go away.
This is not true. Although these will no longer have “optical proximity” effects to compensate, each of these processes introduces its own signature of distortions, which in turn will require compensation and the associated data management. In this paper, we will inventory the state of development for each of these technologies, and outline the expected compensations and requirements placed on data management that are associated with the adoption of the technology. These effects include electron proximity effects and pattern stitching for EPL, Flare induced proximity effects for EUV, gray scale mapping for various maskless techniques, and even local process biasing for various nanoimprint approaches.
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