Louis, MO). All
tubingwas tested
as 100 foot coils
of
1
/
4
" OD x 0.020"
wall 316L stain-
less steel.
Electropolished tubing had a surface roughness
of 10 to 15microinches. Siltek
®
treated tubing
(Restek Performance Coatings, Bellefonte, PA)
is finishedwith 5µm of amorphous silicon,
followed by a surface functionalization that
increases inertness and hydrophobicity.
Wet-up curves for Siltek
®
treated electropol-
ished, electropolished, and standard tubing are
compared in Figure 1.Treated electropolished
tubing reached the 98% saturation limit in 30
minutes, compared to 60minutes for electropol-
ished tubing. Standard tubing could only achieve
a 96% uptake, after 180minutes.
ImproveMoistureDry-Downand
CorrosionResistance
Economical solutions for
ultra-highpurity streams
Restek surface treatment extends the lifetimes
of steel and steel alloy systems, while
maintaining high dimensional tolerances, high
temperature capability, and leak-free conditions.
•Up to three times faster wet-up or dry-down
than electropolished or conventional surfaces.
•Corrosion resistance improved tenfold, or
more—increases component lifetime and
maintains pure product stream.
•Custom services: can be applied to existing
equipment.
ApplicationsNote
110Benner Circle • Bellefonte, PA 16823
800-356-1688•814-353-1300• fax: 814-353-1309
Restek
Performance
Coatings
Restek treated tubingand system
componentsoffer improved
analytical reliabilityand longer lifetimes.
Introduction
Gas transfer systems serving the semiconductor
industry often require lowmoisture content and
retention, and high resistance to corrosion.The
current substrate of choice in semiconductor
manufacturing, electropolished VIM/VAR
(vacuum inductionmelt/vacuum arcmelt) 316L
stainless steel, frequently is insufficient in these
capacities, increasing periodicmaintenance,
prolonging equilibration times, and allowing
system contamination and inaccurate analytical
results. In contrast, surface treatments avail-
able through the Restek Performance Coatings
Group provide significant added value to con-
ventional stainless steel substrates, by greatly
acceleratingwet-up and dry-down times and
dramatically improving corrosion resistance.
Restek surface treatments deposit an amor-
phous silicon based layer onto, and into, the
steel surface through a chemical vapor deposi-
tion (CVD) process in vacuum at 400°C.There
are no line of sight limitations; all exposed sur-
faces are coated. Layer depth iswell controlled
and, for corrosion resistance, is optimized at 5
to 10microns.The amorphous silicon layer can
be further functionalized using the patented
Siltek
®
process (US Patent#6,444,326), which
has been optimized to reducemoisture hold-up
and improve surface inertness.
Data for wet-up and dry-down experiments,
measuring the relative response time formois-
ture content change in treated electropolished
stainless steel tubing, untreated electropolished
stainless steel tubing, and standard 316L stain-
less steel tubing, demonstrate a significant
advantage in treated versus untreated sub-
strates.
1
Tubing used in thewet-up / dry-down
experimentswas supplied by Cardinal UHP (St.
Figure1
Restek treatedelectropolished
tubing stabilizes at 1ppmmoisturemuch faster
than conventional surfaces.
1
for
more
info
Formore information about the anti-corrosive
properties of Silcosteel
®
-CR treatment, request
packet 59048, or visit us online.
Figure2
Restek treatedelectropolished
tubingdriesmuch faster than conventional
surfaces.
1
Table I
Restek treatedelectropolished tubingprovides the shortest drying times.
1
Time Required toDetect Change (min.)
Moisture
Treated
Untreated
Concentration
Electropolished
Electropolished
Standard
From
To
Tubing
Tubing
Tubing
10ppm*
5ppm
4
5
13
5ppm
1ppm
22
46
71
1ppm
500ppb
40
63
96
500ppb
100ppb
80
103
153
100ppb
50ppb
98
121
---
*Initial moisture concentration.
