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 systems together high throughputs can be realized in a small footprint. This enables a highly cost-competitive alternative to double patterning and EUV alternatives [1].In 2009 MAPPER shipped two systems one to TSMC and one to CEA-Leti. Both systems will be used to verify the applicability of MAPPER's technology for CMOS manufacturing.This paper presents a status update on the development of the MAPPER system over the past year. First an overview will be presented how to scale the current system to a 10 wph machine which can consequently be used in a cluster configuration to enable 100 wph throughputs.Then the results of today's (pre-) alpha systems with 300 mm wafer capability are presented from the machines at MAPPER, TSMC and CEA-Leti.
Currently, three MAPPER multi-electron beam lithography tools are operational. Two are located at customers, TSMC and LETI, and one is located at MAPPER. The tools at TSMC and LETI are used for process development. These tools each have 110 parallel electron beams and have demonstrated sub-30 nm half pitch resolution in chemically amplified resists [5].One important step towards the high volume tool is the capability to stitch the exposure of one electron beam to the next. The pre-alpha tool at MAPPER has been upgraded with an interferometer to enable exposures with a scanning stage and demonstrate first beam-to-beam stitching. A scan of 200 micrometers has been used to create a stitch area of 50 x 3 microns. The stitch error over all stitches was found to be below 25 nm.The electron beam position stability during the 10 seconds required for beam-to-beam stitching showed a contribution to the stitch error of 2.3 nm. The beam separation measurement, used to correct the static error, adds about 2.2 nm and the stage stability and linearity adds another 5 nm in the scan (interferometer) direction. In the perpendicular direction the stage instability gives the largest contribution to the stitch error (15 nm) due to the use of capacitive sensors.Overall, the electron beam stability and the beam position correction method work correctly and with sufficient accuracy for the high volume tool, 'Matrix'. The wafer stage for the Matrix system will incorporate full interferometer control to attain the needed positioning accuracy and stability.
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 [1].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 [2].In 2008 MAPPER has taken a next step in its development by building several tools. A new platform has been designed and built which contains a 300 mm wafer stage, a wafer handler and an electron beam column with 110 parallel electron beams. This manuscript describes the first patterning results with this 300 mm platform.
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