MAPPER: High throughput maskless lithography

摘要

Maskless electron beam lithography, or electron beam direct write, has been around for a long time in the semiconductor industry and was pioneered from the mid-1960s onwards. This technique has been used for mask writing applications as well as device engineering and in some cases chip manufacturing. However because of its relatively low throughput compared to optical lithography, electron beam lithography has never been the mainstream lithography technology. To extend optical lithography double patterning, as a bridging technology, and EUV lithography are currently explored. Irrespective of the technical viability of both approaches, one thing seems clear. They will be expensive.MAPPER Lithography is developing a maskless lithography technology based on massively-parallel electron-beam writing with high speed optical data transport for switching the electron beams. In this way optical columns can be made with a throughput of 10-20 wafers per hour. By clustering several of these columns together high throughputs can be realized in a small footprint. This enables a highly cost-competitive alternative to double patterning and EUV alternatives. In 2007 MAPPER obtained its Proof of Lithography milestone by exposing in its Demonstrator 45 nm half pitch structures with 110 electron beams in parallel, where all the beams where individually switched on and off .In 2008 MAPPER has taken a next step in its development by building several tools. The objective of building these tools is to involve semiconductor companies to be able to verify tool performance in their own environment. To enable this, the tools will have a 300 mm wafer stage in addition to a 110-beam optics column. First exposures at 45 nm half pitch resolution have been performed and analyzed. On the same wafer it is observed that all beams print and based on analysis of 11 beams the CD for the different patterns is within 2.2 nm from target and the CD uniformity for the different patterns is better than 2.8 nm.