Customer Feedback
wings. These systems are highly valued not only
for their dependability but also for efficient use
of expensive precursor gas.
The ALD process deposits thin films of
precursor materials onto substrates one atomic
layer at a time to impart such properties as
conductivity, chemical resistance and strength.
With help from Swagelok ALD valves,
Cambridge NanoTech has designed gas delivery
Issue VI 2009
assemblies that achieve precise, controlled
square4
delivery of precursor gas.
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One reason for the precise timing is the
ability of one ALD valve to perform two
functions – precursor delivery and purging. The
alternative would be to construct a subassembly
of several valves, which can introduce timing
variability. Inconsistent precursor and purge gas
delivery times result in an increase in the
oasiasemiconductor
quantity of precursors consumed, which, in turn
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leads to higher cost of ownership.
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In its most basic form, the ALD valve design For example, Cambridge NanoTech offers Cambridge
consists of three ports. Carrier gas enters its customers the option to expand the number NanoTech’s ALD
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through one port and exists through another. of heated precursor lines in an ALD system system
Precursor gas enters through a third port, which without increasing the unit’s footprint. The
is a small, precise orifice that delivers minimum company’s Savannah family of ALD systems
chemical volume. This three-port configuration typically accommodates up to six precursor lines
works by delivering a steady flow of carrier gas all capable of handling gas, liquid or solid
into the ALD chamber. At precisely timed precursors. However, these lines may be
intervals the carrier gas flow is interrupted by a subdivided, enabling users to experiment with
brief pulse (<15 milliseconds) of precursor gas. up to 12 precursors in a single system.
The carrier gas moves the precursor into the This versatility is made possible through
deposition chamber where precursor atoms custom-engineered Swagelok components, such
attach to the substrate being coated. as valve manifolds. Swagelok has designed
“Through precise delivery of precursor gas, manifolds for Cambridge NanoTech and other
nearly all of the gas is used in the deposition customers that accommodate multiple process
process,” Becker said. “The delivery is so precise lines. Multiple manifolds may be connected to
that a system running at full capacity 24/7 may multiple precursors but may draw from a
take three months or longer to use a 25-cc common purge line. Swagelok engineers also
cylinder of precursor.” adjust port sizes to provide the most efficient
delivery of chemistries. A small port may be
Custom Configurations. appropriate for liquid precursors, while a larger
An objective of Cambridge NanoTech is to port may be appropriate for a precursor with low
provide ALD tools that are versatile, expandable vapor pressure.
and tailored to the specific needs of the ALD technology is undergoing rapid
customer. evolution, which means that the components
“It doesn’t matter if we offer 25 different that service it must evolve as well. For example,
configurations. There will be customers who increased use of liquid precursors prompted
want a different version. The fact that Swagelok Swagelok to develop the liquid injection valve,
will move a gland and reconfigure the valve is which vaporizes liquid precursors inside the valve
huge and allows for us as a vendor to offer these body. Precise heat control – without cold spots
solutions to our end customers,” Becker or temperature variability – has for some time
explains. been a critical ALD valve specification. More
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