CURRENT ISSUES AND FUTURE PROSPECTS OF LITHOGRAPHY

The resolution limit of optical lithography now looms on the horizon. We are using very complicated masks and sophisticated exposure tools with very low k1 factors. To deal with this situation, liquid immersion lithography is now under intensive development. It can extend the application of the optical lithography for one or two generation, but the k1 factor remains very small. To obtain a significantly larger k1 value, we shall move to the non-optical lithography techniques. EUV lithography is the strongest candidate. Many problems of EUV still remain though we have remarkable achievements recently. In addition to the mass production technology, methods such as maskless lithography (ML2) and nano-imprint lithography were also developed for small-scale production and some other applications.