Preventing Particles on Wafers and Increasing Process
Throughput by Installing the Pall ChamberKleen™ Diffuser
Anthony Ricci
About the Purge Cycle in Semiconductor
Manufacturing
The rapid introduction and removal of wafers
from process chambers is performed in load
lock and transport chambers. In order to
maintain process chamber cleanliness and
vacuum integrity the load lock chamber is
pumped down to a similar pressure as the
process chamber prior to wafer delivery. After
processing, the wafer is delivered back to the
load lock for placement in the wafer pod. The
load lock is then pressurized to atmospheric
pressure by introduction of a purge gas, and the
wafer is delivered to the front opening unified
pod (FOUP).
The purge cycle process consists of a
pressurization step followed by a
depressurization step. Purge cycle time impacts
total wafer processing time and, ultimately, tool
throughput. The rapid flow characteristics of the
ChamberKleen™ 1100 and 5500 Series diffusers
make them well suited for applications where
large volumes of gas are flowing in a short
Figure 1. ChamberKleen™ 1100 Diffuser Flow Rate
1100 Series Diffuser Pressure vs. Vent-Up Time
25
25
20
20
Vent-Up Time (s/l)
Vent-Up Time (s/l)
1100 Series Diffuser Pressure vs. Vent-Up Time
15
10
5
15
10
5
0
0
0
20
10
Pressure (psig)
30
0.5
0
1.0
Pressure (bar)
1.5
2.0
Figure 2. ChamberKleen™ 5500 Diffuser Flow Rate
5500 Series Diffuser Pressure vs. Vent-Up Time
5500 Series Diffuser Pressure vs. Vent-Up Time
3.0
3.0
2.5
2.5
Vent-Up Time (s/l)
Vent-Up Time (s/l)
Application Bulletin
ABG-104-0305
2.0
1.5
1.0
0.5
2.0
1.5
1.0
0.5
0
0
0
20
10
Pressure (psig)
30
0
0.5
1.5
1.0
Pressure (bar)
2.0
amount of time. The rapid vent-up times offered
by these diffusers result in shorter purge cycle
times, translating to increased tool throughput.
Why Uniform and Clean Gas Flow is Critical
As a load lock chamber is put through the
purge cycle, the rapid changes in pressure
(either from introduction of purge gas or a
high-vacuum environment) can result in
turbulent flow. This turbulent flow condition
can deposit particles within the chamber onto
wafers. Particulate contamination within the
purge and process gas must be kept at a
minimum in order to reduce the number of
particles within load lock chambers. Also,
reduction in flow turbulence during venting
diminishes the disturbance of any particles
within the chamber. Introduction of uniform
and clean purge gas will result in lower onwafer particle defects.
The Pall ChamberKleen™ Diffusers
The Pall ChamberKleen™ 1100 and 5500 Series
diffusers combine a stainless steel filter and a
unique diffuser membrane that allows for 360°
circular flow. This combination allows large
volumes of gas to flow in a uniform manner.
The 1100 Series is for 200 mm chambers and
the 5500 Series is for 300 mm chambers.
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The 316L stainless steel filter medium removes
particles down to 3 nm in size, and optimizes
gas flow. Figures 1 & 2 show the fast vent
times that the Pall ChamberKleen™ 1100 and
5500 Series diffusers can achieve.
In conclusion, the ChamberKleen™ 1100 and
5500 Series diffusers’ fast vent-up times
demonstrate that they can be used in
applications where large volumes of gas are
flowing in a short amount of time. In particular,
ChamberKleen™ 1100 and 5500 Series
diffusers are ideal for load lock, transfer and
process chamber applications.
In addition to offering greater cleanliness and
uniformity of gas flow, the ChamberKleen™
1100 and 5500 Series diffusers increases tool
throughput. The more uniform and cleaner
gas effluent from the Pall diffusers results in
the prevention of on-wafer particle defects.
References
Gas Filtration Metal Data Sheet A45a
ChamberKleen™ Diffuser
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