Proceedings Article | 25 October 2016
KEYWORDS: Photomasks, Lithography, Electronic design automation, Computing systems, Data processing, Printing, Data conversion, Raster graphics, Germanium, Distributed computing
According to the 2013 SEMATECH Mask Industry Survey,i roughly half of all photomasks are produced
using laser mask pattern generator (“LMPG”) lithography. LMPG lithography can be used for all layers at
mature technology nodes, and for many non-critical and semi-critical masks at advanced nodes. The
extensive use of multi-patterning at the 14-nm node significantly increases the number of critical mask
layers, and the transition in wafer lithography from positive tone resist to negative tone resist at the 14-nm
design node enables the switch from advanced binary masks back to attenuated phase shifting masks that
require second level writes to remove unwanted chrome. LMPG lithography is typically used for second
level writes due to its high productivity, absence of charging effects, and versatile non-actinic alignment
capability. As multi-patterning use expands from double to triple patterning and beyond, the number of
LMPG second level writes increases correspondingly. The desire to reserve the limited capacity of
advanced electron beam writers for use when essential is another factor driving the demand for LMPG
capacity.
The increasing demand for cost-effective productivity has kept most of the laser mask writers ever
manufactured running in production, sometimes long past their projected lifespan, and new writers continue
to be built based on hardware developed some years ago.ii The data path is a case in point. While state-ofthe-
art when first introduced, hardware-based data path systems are difficult to modify or add new features
to meet the changing requirements of the market. As data volumes increase, design styles change, and new
uses are found for laser writers, it is useful to consider a replacement for this critical subsystem.
The availability of low-cost, high-performance, distributed computer systems combined with highly
scalable EDA software lends itself well to creating an advanced data path system. EDA software, in routine
production today, scales well to hundreds or even thousands of CPU-cores, offering the potential for
virtually unlimited capacity. Features available in EDA software such as sizing, scaling, tone reversal, OPC,
MPC, rasterization, and others are easily adapted to the requirements of a data path system.
This paper presents the motivation, requirements, design and performance of an advanced, scalable
software data path system suitable to support multi-beam laser mask lithography.
