| Pumps for Semiconductor Industry
A New Standard for Magnetically
Levitated Centrifugal Pumps
Levitronix has developed a Bearingless
Centrifugal Pump for the semiconductor industry
based on proprietary magnetic levitation technology.
With the Levitronix technology, a pump rotor is suspended
and driven by the magnetic field of a motor/bearing
stator through the wall of the pump housing without
mechanical contact. A signal processor-based electronic
control unit allows precise regulation of the speed,
pressure or flow rate.
Product Features
Designed for Highest Purity
The Levitronix BPS pump systems are designed for high-purity
fluid applications where low particle shedding and metal
contamination are required. The pump heads are made
from high-purity fluorocarbon resins (PTFE, PFA, ECTFE,
PVDF) and can be easily cleaned or exchanged resulting
in less down time and lower maintenance costs.
Chemical Resistant Design
Each bearingless motor is completely potted, the housing
is coated with ETFE and all cables are FEP jacketed.
As a result, our systems are impervious to aggressive
chemicals and can be utilized even in submersible applications.
 |
| Figure 1: Design
of bearingless pump system BSP-1 |
|
 |
 |
| Figure 2: Design
of bearingless pump system BSP-3 |
|
 |
|
| Figure 3: Design
of bearingless pump system BSP-4 |
|
Extremely Low Particle Generation
An important advantage resulting from contact-free levitation
of the rotating impeller is that the system can be operated
with extremely low particle generation. Tests conduced
by an independent test laboratory show that particle
generation of a Levitronix pump during operation is
significantly less than that of a bellows pump of comparable
hydraulic performance (detailed report available).
 |
| Figure
4: The Levitronix pump not only generates
fewer particles than bellows pumps but also
flushes up to 100 times faster compared to
typical bellows-type pumps due to the smaller
wetted surface area! |
|
Download
Particle contamination test reports.
Extremely low Metal Contamination
The wetted components of Levitronix pumps are fabricated
from ultra-high purity fluorocarbon materials. Independent
tests have verified that the area normalized surface
metal contamination is well below industry standards.
Since other leading high-purity pump manufacturers use
comparable high purity fluorocarbon materials, and process
these materials with the same high degree of care, the
area normalized surface metal contamination values
for their products match those of the Levitronix pump.
However, since the wetted surface area of a Levitronix
pump is about 30 times smaller compared to a
typical bellows pump, the total metal contamination
which bellows-type pumps introduce into a system is
30 times higher compared to a Levitronix pump.
Surface Metal Contamination of Levitronix
BPS-3 Pump:
|
 |
|
| Figure
5: Levitronix® redundant layer magnet
encapsulation concept |
|
|
Element
|
Normalized Mass Extracted
(ng/cm2)
|
|
Fe
|
1.44
|
|
B
|
0.24
|
|
Ca
|
0.18
|
|
K
|
0.12
|
|
Na
|
0.12
|
|
Al
|
0.09
|
|
Zn
|
0.09
|
|
Misc.
|
0.22
|
|
Total
|
2.5
|
|
Industry Standard
|
<20 ng/cm2
|
|
Download
Trace metal extraction reports.
Hermetic Rotor Encapsulation
In order to assure minimal metallic contamination over
time, the rotor-magnet is encapsulated and protected
by two polymeric layers. The first layer is a proprietary
coating with extremely low permeability, and the second
is a ultra high-purity PFA layer to enhance chemical
resistance. The rotor-magnet is then embedded within
the high purity fluorocarbon body of the impeller.
Levitronix's redundant layer magnet encapsulation
concept has been validated by long-term chemical
compatibility tests as well as metal extraction tests
at independent test laboratories.
Download
long-term trace metal extraction report.
Download
chemical compatibility test report.
Electronic Control and Interfacing
Levitronix pump systems are digitally controlled with
a powerful digital signal processor (DSP) and incorporate
multiple analog and digital interface options. This
allows easy interfacing to PLC systems, host computers
and systems controllers. Our systems are also designed
to interface with a variety of flow, pressure, temperature,
viscosity and fluid density sensors. Levitronix provides
software modules which allow closed-loop flow control,
pressure control and process control systems without
additional hardware. Since each system is equipped with
sensors for speed, torque and rotor position, multiple
process parameters can be monitored or controlled without
the use of external sensors. Levitronix provides extensive engineering support
to implement these and other features into your process.
Electronic control features
- Continuous
flow or custom defined flow patterns
- Precise
electronic control of flow rate or pressure
without throttle valves—better process
control, fewer system components, higher systems
efficiency
- Monitoring
of fluid viscosity
- Monitoring
of filter life in a flow control loop
|
 |
|
| Figure
6: Systems block diagram |
|
 |
|
| Figure
7: Block diagram
of a flow control loop with the ability of
monitoring filter life |
|
Download
Closed-Loop Flow-Control Manual.
 |
|
| Figure 8: Block diagram
of a pulse-free fluid delivery loop with pressure
control |
|
Pump Applications
The Ideal Pump for Single Wafer
Processing
Levitronix pumps operate in a
pulse-free mode making them ideally suited for use in
single wafer wet-processing tools. A single pump can
feed several process chambers and produce a constant,
homogenous flow on the Wafer. Electronic control helps
to maintain the flow at a precise, constant rate independent
of the state of a filter. Our electronic control system
can also be used to diagnose the status of a filter
and indicate when it needs to be exchanged. Levitronix
pumps are much smaller than bellows or diaphragm pumps
with comparable flow-rates without the need for pulse-dampers.
This helps to build your new tool smaller than ever
before.
The Ideal Plating Pump
Due to its unique design, the Levitronix pump has no
bearings, valves, or membranes, which can plate out
when used in plating processes.
Levitronix pumps are the best choice
for the following electrochemical plating (ECD) processes:
- Gold
ECD
- Copper
Damascene
- Patterned
Copper ECD
- Permalloy
ECD (GMR heads)
- Nickel
ECD (packaging, MEMs)
- Solder
ECD (bumping)
|
The Ideal Pump for CMP Slurries
and Other Sensitive Fluids
Levitronix is a leading expert
in low shear pump design. The company's medical
blood pumps have been shown to cause minimal damage
to the blood cells as demonstrated by a low rate of hemolysis
(red blood cell destruction). The hemolysis rate associated
with the Levitronix blood pump is approximately 50% of
the industry standard device, and is also less than any
peristaltic pump. The same low-shear blade design has
also been applied to our high-purity fluid pumps. The
low-shear blade design, combined with avoidance of small
fluid gaps, translates to lower shear force acting on
the fluids and prevents the creation of hot spots. By
generating continuous pulseless flow, the Levitronix pump
is ideally suited for pumping sensitive fluids such as
CMP slurries. Particle distribution, as well as zeta potential,
has been shown to remain constant over 3000 tank turnovers
(detailed report available). For the same reason, the
Levitronix pump creates fewer bubbles than bellows pumps
in sensitive fluids like Triton-X 100 solutions.
Download Slurry test report.
Watch the CMP movie
|
|
|
| Figure 9: Effect of
a Levitronix BPS-3 pump operated at 7600 rpm,
5 gpm and 30 psi on particle size in SemiSperse®
12 slurry (Cabot Microelectronics Corporation,
Aurora, IL). |
|
|
|
|
| Figure 10: Effect
of a Levitronix BPS-3 pump operated at 7600
rpm, 5 gpm and 30 psi on Zeta potential in
SemiSperse® 12 slurry (Cabot Microelectronics
Corporation, Aurora, IL). |
|
| 
Contact Us
Printable Version
