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Maskless Nanowriter (NANOWRITER)

The goal of the Maskless Nanowriter program is to produce a maskless electron-beam-direct-write (EBDW) lithography tool using a novel Reflection Electron Beam Lithography (REBL) concept invented by KLA-Tencor. A critical component of the Maskless Nanowriter program is the use of a reflective electron beam pattern generator that converts design data for an integrated circuit into a column of 1 million electron beams, controlled and modulated individually, to write the circuit pattern directly onto the wafer at very high throughput. This tool will be designed for nanolithography at the 45 nm node with a technology that can be scaled to the 32 nm node and beyond. Success in the development of the REBL technology will eliminate costly mask sets and increased economic viability for small lot production (1 – 20 wafers) of state-of-the-art custom ASICs (Application-Specific Integrated Circuits), NEMS/MEMS devices, and nanophotonic devices for DoD applications. The EBDW technology developed during this program will also result in maskless lithography tools that can be installed in the Trusted Foundry to enable affordable production of small lots of state-of-the-art DoD nanosystems for a broad spectrum of DoD applications. Additionally, the technology will find wide application in the commercial sector for nanopatterning masks for DUV lithography and templates for imprint lithography, thus defraying tool infrastructure costs to the DoD.

The spatially uniform, low energy spread electron beam is created on a thermionic cathode, accelerated to high energy (50 kilovolt), and rotated 90o via a magnetic prism toward a metal plate known as the dynamic pattern generator (DPG). The DPG features a 256 x 4000 array of micron-scale metal pixels, each pixel capable of individual biasing, that modulate the electron beams by biasing particular pixels of the array at either a low negative voltage (-2.1 volts) or at ground potential. When pixels are biased at -2.1 volts, the local electron beam is reflected; when pixels are biased at ground potential, the local electron beam is absorbed at very near zero energy. The patterned, reflected electron beam is then reaccelerated to 50 keV, rotated 90o by the magnetic prism, demagnified by a factor-of-50 in a magnetic optical system, and used to pattern the resist on the surface of the wafer.

The REBL tool to be developed in the Maskless Nanowriter program allows high throughput, greatly simplifies the electron optics required, and utilizes existing IC technology for easy addressing of the individual pixels. With a total beam current of 20 mA at the DPG (11 mA at the wafer), 5-to-7 300 mm-wafer-levels can be patterned in 1 hour, representing a write speed more than 100 times faster than available from existing single electron beam, direct-write technology. By delivering patterning performance compatible with the 45 nm node and beyond at several wafers per hour without the requirement for masks, Nanowriter will enable affordable and timely production of state-of-the art ICs in small lots entirely within secure facilities. In addition, it provides a commercially viable EBDW tool to ensure continued availability of custom ASICs for DoD applications.