Electron-beam lithography is promising for future manufacturing technology because it does not suffer from wavelength
limits set by light sources. Since single electron-beam lithography systems have a common problem in throughput, a
multi-electron-beam lithography (MEBL) system should be a feasible alternative using the concept of massive
parallelism. In this paper, we evaluate the advantages and the disadvantages of different MEBL system architectures,
and propose our novel Massively Parallel MaskLess Lithography System, MPML2.
MPML2 system is targeting for cost-effective manufacturing at the 32nm node and beyond. The key structure of the
proposed system is its beamlet array cells (BACs). Hundreds of BACs are uniformly arranged over the whole wafer area
in the proposed system. Each BAC has a data processor and an array of beamlets, and each beamlet consists of an
electron-beam source, a source controller, a set of electron lenses, a blanker, a deflector, and an electron detector. These
essential parts of beamlets are integrated using MEMS technology, which increases the density of beamlets and reduces
the system cost. The data processor in the BAC processes layout information coming off-chamber and dispatches them
to the corresponding beamlet to control its ON/OFF status. High manufacturing cost of masks is saved in maskless
lithography systems, however, immense mask data are needed to be handled and transmitted. Therefore, data
compression technique is applied to reduce required transmission bandwidth. The compression algorithm is fast and
efficient so that the real-time decoder can be implemented on-chip. Consequently, the proposed MPML2 can achieve 10
wafers per hour (WPH) throughput for 300mm-wafer systems.
Ge/SiGe quantum well electroabsorption modulators grown on silicon through relaxed SiGe buffers had shown strong
quantum-confined Stark effect (QCSE), even though Ge is an in-direct band gap semiconductor. The absorption
characteristic near the direct band gap edge can be tuned by applying an electric field. QCSE is the most efficient optical
modulation mechanism through direct light absorption and promising for reducing the device size and power
consumption. The device fabrication here is based on Ge-rich SiGe technology, which is also commonly used for various
silicon photonics applications. Here we will discuss Ge QCSE electroabsorption modulators as well as the consideration
of SiGe process integration for optical interconnects.
Monolithic integration of both electronic and optic components into a silicon-based platform will provide high-speed optical interconnects and solve the power-bandwidth limitations. However, the lack of strong optical effects in silicon has limited the progress in the transmitter-end applications. Recently our research had demonstrated strong quantum-confined Stark effect (QCSE) in germanium quantum-well modulators on silicon. This first strong physical mechanism for group-IV photonics has a comparable behavior to III-V material systems. With proper quantum well structure design, we also demonstrated QCSE in C-band for long distance communications with CMOS-operational temperatures. The device fabrication is also compatible with standard silicon chip processes. Since the QCSE, a type of electroabsorption effect, requires much shorter optical length, it is suitable for device miniaturizations and possible for use in both lateral and vertical modulator configurations. Moreover, silicon-germanium electroabsorption modulators are inherently photodetectors, this advantage will enable efficient transmitter/receiver applications for optical interconnects.