3M CMP User Manual

Betapure™
CMP Series

CMP Filter Cartridges

Superior Reduction Of Large Particle
Counts For Improved Yields

Betapure™ CMP filter cartridges are high capacity depth filters optimized for oxide and metal
slurries used in chemical mechanical planarization (CMP) applications. Betapure CMP filters are
composed of all-polypropylene components and features a multi-zone "graded-porosity" design
for the optimum level of particle classification. This novel construction provides enhanced flow
characteristics, including low pressure drop, to minimize shearing of the slurry while providing
superior service life.

The objective of a slurry lter is for the majority of particles to pass through it unchanged,

while only removing the undesired or “oversized” particles. The oversized particle population
is commonly referred to as large particle counts (LPC) and they typically form over time when
the suspended particles in the slurry settle forming aggregates, agglomerates, and gels. Large
particles can also be the result of ad verse shipping conditions, shearing, slurry drying, and

interaction with other distribution loop components such as ttings, tanks, piping, valves, and

pumps. These large particles can scratch metal and inter-level dielectrics potentially causing

wafer defects. The Betapure CMP lter reduces large particle counts that can potentially

reduce yields while maintaining the polishing characteristics of the slurry.

Applications

Semiconductor Oxide/Low-k Dielectrics, Shallow Trench

Features & Benefits

Graded Porosity Design



Superior removal of hard and soft gel contaminants, for reduced defectivity

and improved yields



High contaminant holding capacity reduces downtime and increases overall

equipment effectiveness



The filters are "matched" to the slurry providing the optimum level of

performance needed to dramatically reduce defect causing particles



Provides a low pressure drop reducing the potential for fluid shear of the slurry

100% Polypropylene



Low cartridge extractables, free of adhesives, binders, and surfactants



Excellent chemical compatibility with low and high pH slurries

Quality Manufacturing



ISO certified quality management system



Non-contact welding reduces a potential source for contamination



Manufactured and double-bagged in a clean environment to provide superior downstream cleanliness out of the package

Built to Exacting Specifications



Provides a consistent quality of slurry enabling repeatability of the planarization process

Data Storage Magnetic Heads, Nickel and Glass

Data Transmission Optical Fiber

Compound Semiconductor Light Emitting Diodes (LED)

Isolation (STI), Inter-level Dielectric (ILD),
Polysilicon, Tungsten, and Copper

Substrates

1

Particle Size Distribution

The filtration of CMP slurries is a unique and challenging process as compared to the filtration of high purity chemicals used in electronics
manufacturing. High purity chemical filtration is typically performed using 0.2 micron or tighter membrane filters that have a sharp particle
removal cut-off at the rated pore size. The majority of CMP slurries contain a de sired mean particle size that ranges from 0.03 - 0.2 microns.
Consequently, the filter that was specifically designed for particle clarification of high purity chemicals would strip out the de sired particles and
adversely affect the polishing characteristics of the CMP slurry. Over sized particles in the slurry typically greater than 0.5 micron are undesired
and represent the “tail” (Figure 1) of the particle size distribution (PSD). Betapure™ CMP filters remove the PSD tail while allowing the majority
of desired or “target” size particles to pass through it unchanged

.

Particle Removal Efficiency is the Best Measure of Filter Performance

Figure 1 com pares the PSD of colloidal-silica slurry and a lab oratory test dust which is typically used by filter suppliers to establish depth filter
ratings. The data shows that test dust has a broader PSD above 0.5 micron proving that it is not a true representation of the types of particles in
CMP slurry. A wide variation in performance also exists from one filter supplier to the next because there is no industry accepted standard for
rating retention of depth filters. Furthermore, Absolute and Nominal filter ratings are both used to specify particle removal efficiency which
only serves to confuse the situation while not providing the application specific information needed. In Figure 2, particle removal efficiency is
compared for the same grade of CMP filters from 3M Purification. The filters were challenged using both a lab oratory test dust and colloidal
silica slurry. There is a significant difference in particle removal efficiency, which is a direct result of the contaminant PSD distribution. The
broad PSD of the test dust yields significantly higher particle removal efficiency than achieved when tested with slurry. Therefore, test dust is not

representative of slurry and ratings based on test dust will likely be over stated and meaningless for CMP slurry applications. In Figure 3, particle

removal efficiency is compared for equivalent rated CMP filters from 3M Purification Inc., Competitor P, and Competitor M in colloidal silica
slurry. The data clearly shows that equivalent rated filters from different manufacturers does not deliver equivalent performance and reinforces
the fact that the “rating” generated in a lab using test dust is not meaningful in predicting actual performance. Based on this information particle
removal efficiency generated in slurry is the best measure of filter performance. Other important factors in selecting the appropriate slurry filter
include particle classification, pressure drop, and filter lifetime..

Number of Particles per ml

Figure 1. - Particle Size Distribution > 0.5 micron - Colloidal Silica Slurry & ISO Test Dust

200000

Colloidal Silica Slurry

150000

100000

ISO Test Dust

50000

0

0.5 1 2 105

Particle Diameter (microns)

2

Betapure™ CMP Series

CMP Filter Cartridges

Particle Removal Efficiency

Colloidal Silica vs. ISO Test Dust

Betapure CMP560 - Colloidal Silica
Betapure CMP560 - ISO Test Dust

100

80

60

40

20

0

Particle Removal Efficiency (%)

Figure 2. - Particle Removal Efficiency Figure 3. - Comparative Particle Removal Efficiency in Colloidal Silica

Particle Size > 0.54 micron

Superior Particle Retention through
Graded Porosity Design

Betapure™ CMP filter media was specifically engineered to provide a low
porosity, downstream section with a sharp retention cut-off that closely aligns
to the size distribution of undesired particles to be removed. This sharp removal
cut-off will not alter per cent solids (Figure 4) or re move de sired or “target” size
particles thus preserving the polishing characteristics of the slurry. In contrast,
competitive point-of-use filters (Figure 4) that have a broad removal range can in
fact retain particles smaller than the PSD. Re moving these “target” size particles
can alter the per cent solids of the slurry which in turn reduces filter lifetime
because more particles are being re moved than required in the application.
The multiple higher porosity layers on the upstream section (Figure 5) provide
effective pre-filtration of over sized particles resulting in higher contaminant
removal capacity and increased filter life-time. This novel graded porosity
(Figure 5) design also provides a tortuous downstream path and low pressure
drop which is ideal for gel capture and reduced shear effect on the slurry.

Particle Removal Efficiency

for Equivalent Rated Filter Cartridges

Betapure CMP

Competitor P

Competitor M

100

80

60

40

20

0

Particle Removal Efficiency (%)

> 0.54 micron > 1.01 micron

Percent Solids - Colloidal Silica

Influent

Effluent

0.5

0.4

0.3

0.2

0.1

Percent Solids (%)

0

Competitor P Betapure CMP

Figure 4. - Percent Solids Comparison

TM

Superior Particle Retention through
Graded Porosity Design

Large particles, greater than 0.5 micron, can scratch metal and interlevel dielectrics
potentially causing wafer defects. Variations in particle size distribution and
particle counts in the slurry can affect re peat ability of the planarization process.
In both cases, major reductions in large particle counts can be associated to proper
filtration, resulting in reduced defectivity (Figure 6) and an increase to yields. Proper
filtration also provides a consistent quality of slurry which enables repeatability
of the planarization process. The ideal slurry filter will have a retention curve that
closely aligns to the PSD of “undesired” particles to be removed. By matching that
characteristic, Betapure CMP filters are able to maintain the polishing characteristics
of the slurry, maximize contaminant holding capacity, and increase filter lifetime.

3

Flow Direction

Inner

Outer

Medium

Figure 5. - Graded Porosity Design

Medium