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Traditionally, e-beam direct write lithography has been too slow for most lithography applications. E-beam
direct write lithography has been used for mask writing rather than wafer processing since the maximum blur
requirements limit column beam current - which drives e-beam throughput. To print small features and a fine
pitch with an e-beam tool requires a sacrifice in processing time unless one significantly increases the total
number of beams on a single writing tool. Because of the uncertainty with regards to the optical lithography
roadmap beyond the 22 nm technology node, the semiconductor equipment industry is in the process of
designing and testing e-beam lithography tools with the potential for high volume wafer processing. For this
work, we report on the development and current status of a new maskless, direct write e-beam lithography
tool which has the potential for high volume lithography at and below the 22 nm technology node.
A Reflective Electron Beam Lithography (REBL) tool is being developed for high throughput electron beam
direct write maskless lithography. The system is targeting critical patterning steps at the 22 nm node and
beyond at a capital cost equivalent to conventional lithography. Reflective Electron Beam Lithography
incorporates a number of novel technologies to generate and expose lithographic patterns with a throughput
and footprint comparable to current 193 nm immersion lithography systems. A patented, reflective electron
optic or Digital Pattern Generator (DPG) enables the unique approach. The Digital Pattern Generator is a
CMOS ASIC chip with an array of small, independently controllable lens elements (lenslets), which act as an
array of electron mirrors. In this way, the REBL system is capable of generating the pattern to be written
using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage
concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve
the capability of high throughput for sparse pattern wafer levels. The lens elements on the DPG are fabricated
at IMEC (Leuven, Belgium) under IMEC's CMORE program. The CMOS fabricated DPG contains ~
1,000,000 lens elements, allowing for 1,000,000 individually controllable beamlets. A single lens element
consists of 5 electrodes, each of which can be set at controlled voltage levels to either absorb or reflect the
electron beam. A system using a linear movable stage and the DPG integrated into the electron optics module
was used to expose patterns on device representative wafers. Results of these exposure tests are discussed.
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