MNS Synova vFinal DR 27/6/08 10:28 Page 14
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MICRONANOSYSTEMS
Laser Microjet and
Semiconductor manufacturing
The semiconductor manufacturing industry is being faced with many problems
in today’s fast paced and ever accelerating demand for smaller and more sophisticated
devices, to fill the requirements of the global electronics industry. Added to this
is the present worldwide shortage of adequate supplies of silicon wafers.
Keith Stay, Technical Writer, Synova explains.
M
anufacture of integrated
circuits from silicon or other
raw material (GaAs, Ge,
SiC, etc.) is a complicated process, with many
steps before the final parts emerging from the
production line. During this process, the risks of
producing defect parts increases as the geometry of
the parts decreases. Minimising the risks during
the cutting process, where both mechanical and
thermal material stress can play a significant
negative role on productivity, is one area where
improvements are eagerly being sought.
Implementing improved wafer-cutting methods
with the aim of reducing wastage and maximising
yield, is also very high on the agenda for
semiconductor fabs.
The main competing methods used today for
cutting are diamond blade saws and conventional
lasers. The diamond blade saw functions well for
cutting simple bulk silicon, but becomes more and
more unsuitable as the wafer thickness decreases, Fig. 1. Basic principle
is a multi-layered device, or composed of brittle of the water Solving the problem
low-k materials. There are also the added negative jet guided laser The Synova water jet-guided laser system, also
effects of crack formation or chipping as a result known as the Laser MicroJet (LMJ), is a relatively
of the mechanical stress applied to the material new solution to these problems, which is finding
during the cutting process. The economics of increasing acceptance within the semiconductor
using blade saws also has to be taken into manufacturing industry. The advantages to be
consideration, especially with low-k materials, gained in cutting semiconductor material using this
where blade wear is extremely high due to the technology are a fast, flexible and economical
hardness of the material. process, capable of cutting both thin and thick
Conventional lasers could have provided the materials to any shape required, with no remnant
solution, except for their inherent problems of heat contamination, no thermal damage and minimal
damage and associated chipping, deposition of changes to the material structure.
ablated material, brittle recast layers as well as The principle of this patented technology is to
the poor quality cut for thick materials, due to couple a high-power pulsed laser beam into a
beam divergence, all points which rule out their hair-thin, low-pressure water jet as shown in Fig.1.
use as a viable choice. The laser source can vary from flash-lamp-
www.micronanosystems.info July 2008
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