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Rocky Mountain Laboratories, Inc.
 800-PRO-LABS (776-5227) |
Ten Different Ways to Measure Thickness
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Dear Tom,
Time for more helpful information from your colleagues at Rocky Mountain Labs. We would like to share a number of data images with you, that were selected by our staff. They all involve the measurement of material structures: whether surface coatings, buried structures, or multi-film stacks. Please let us know if you find this newsletter useful or if there is any topic that you would like us to discuss in a future issue. Comments can be sent to info@rockymountainlabs.com.
Sincerely,
Rocky Mountain Labs' Staff
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The analysis
thicknesses of our various analytical techniques affect the ultimate film
thickness that can be measured by that technique. Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) can measure the thinnest films.
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Generic Three-film System
 Auger sputter depth profiling offers a rapid method of characterizing thin film structures. This example is of a multilayer system employed in the past for a hard disk for data storage. The structure is:
C/Cr oxide/CoNi/NiP |
Passivation on Stainless Steel
The measurement of the chromium oxide film on a
properly-passivated stainless steel surface is easily accomplished with Auger
Sputter Depth Profiling (AES-SDP).
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Thin Fluorocarbon Lubricant Coating
 Films in the range of 1-100 Å can be measured by X-ray
Photoelectron Spectroscopy (XPS/ESCA).
The technique makes use of the short, finite escape depth of the
electrons that are measured. Electrons
cannot escape through more than a ~100 Å thick surface layer. For layers < 100 Å thick, electrons from
the substrate begin to be detected. The
smaller the substrate signal, the thicker the overlayer film. The
thickness of the fluorocarbon film in this example is 3.5 nm.
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Multilayer Antireflective Coating
 Optical components such as these in our FTIR instrument are
designed, e.g., to reflect or transmit a specific wavelength of light; in this
case infrared. The optical response is
designed by depositing various sequences of films with a multitude of chemical
compositions, on a thick substrate.
Devices can be reverse engineered to reveal their thin film
composition. Insulating materials such
as these are profiled by XPS.
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Infrared Detector Diode
 This thickness measurement was
accomplished by scanning an electron beam across a cross-section of an infrared
detector diode and monitoring Auger electron signals for each element of
interest.
Easy, except that the sample
was held at typical operating cryogenic temperatures, cleaved in
ultra-high vacuum just prior to analysis, and was electrically wired to
simultaneously provide the Electron Beam Induced Current (EBIC) to correlate
with the compositional data.
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Polished Cross Sections
 Polished cross sections are prepared by mounting samples in
epoxy and grinding and polishing them to a mirror-like finish.
 Rocky Mountain Labs has in-house capabilities for preparing
cross-sections of a broad range of materials.
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Drug-eluting Arterial Stent
 An estimated $24 billion in
stents have been sold in the U.S. over the past fifteen years.
 This sample of a stent, which is manufactured with a very
soft organic coating on a metal substrate, was prepared as a polished cross
section. The exterior and interior
surfaces of the drug-eluting film are highlighted by proprietary RML
techniques.
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Organic Coating on Micro-wire
 The thickness and uniformity of this organic coating on a
wire is depicted by SEM observation of a polished cross section. The interfaces are accentuated by RML proprietary techniques.
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UV Mirror
Field Emission Scanning Electron Microscopy (FESEM) is
required for observation of very thin layers.
This image is of a polished cross section of a multilayer optical
component. Original magnification equal
to 40,000X.
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Aluminum Wire to Gold-film Bond
This optical image shows the cross section of an aluminum
wire bond to a gold-coated substrate.
The thickness of the gold coating can be measured. Original magnification 1,000X.
EDS mapping of an expanded view of the wire bond depicts
thin-film thickness by the elemental image of the metal stack in cross section.
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Fiber/Adhesive Interface
RML is experienced in preparing
cross-sections by many methods; including this Instant PrepSM of a
fabric/adhesive system.
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Polyimide Coating on Display Chip
 Atomic Force Microscopy (AFM) is used to accurately measure
film thicknesses in the
0-5µm range. We sometimes calibrate our instrument by observing the 4 Å lattice steps
in cleaved GaAs.
3-D imaging and thickness calculations can characterize films
with various surface morphologies.
This polyimide coating on a silicon substrate is measured to
be 55 nm in thickness.
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All data presented in this newsletter are actual data obtained from our instruments and modified with presentation tools.
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Free Pocket Size Periodic Table
 Please contact us if you would like to receive one. |
About Rocky Mountain Laboratories, Inc.
Rocky
Mountain Labs has provided surface and micro-analysis services to the
international community since 1983. We proudly provide analysis to
manufacturing, medical device, pharmaceutical, photovoltaic, academic,
aerospace, defense, research, and other industries around the world.
Rocky Mountain Laboratories, Inc.602 Park Point Dr., Suite 101
Golden, CO 80401 USA800-PRO-LABS (800-776-5227)
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Copyright © 2009 Rocky Mountain Laboratories, Inc.
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Screws of various lengths are used in back surgery. These titanium screws are color coded for
easy identification of their length in the operating room. Different colors are achieved by
manufacturing different thicknesses of titanium oxide on the surface.
