TECHNIQUES
Analytical and Preparation Techniques
AES/SAM
XPS/ESCA
SEM
OM
Precision Cutting
Micro-Sectioning
A. Technique: Auger Electron Spectroscopy (AES), Scanning Auger Microscopy (SAM)
Equipment: PHI 680 Scanning Auger Nanoprobe
Feature: A combination of surface sensitive Auger Electron Spectrometer (AES) and high resolution Field Emission Scanning Electron Microscope (FESEM)

 

Capabilities

  • Nanoscale compositional analysis and imaging (with probe size down to 10nm)
  • Large area surface analysis using scan mode
  • Elemental Depth profiling with ion sputter gun
  • Thin film thickness measurements with calibrated ion sputtering rate Elemental mapping and line scanning
  • Dimensional measurement with calibrated scale

 

Specifications

Target Signal:  Auger electrons from 5-10nm of the sample topmost surface
Elements covered: All except H & He
Detection Limits: 0.1-1at% depends on element
Lateral Resolution: 10-40nm
Image modes:  Secondary Electron (SEM), Auger Electron (Elemental mapping) 

 

Theory behind

Auger Electron Spectroscopy (AES) is a quantitative analytical technique that utilizes a finely focused high energy electron beam (up to 20keV) as an excitation source to eject Auger electrons from the surfaces of solid materials. The in-situ electron energy analyzer is used to measure the kinetic energy (KE) and number of electrons that escape from the surface. From the kinetic energy and intensity of an Auger peak, the elemental identity and quantity of a detected element can be determined. The average analysis depth of Auger electrons approximately 5 nm which make AES is extremely surface sensitive. The electron beam size is as small as 10 nm which make this technique have very high lateral spatial resolution, high definition elemental line scanning and mapping can be obtained with the scanning function. With equipping ion sputtering gun, elemental distribution against sputter depth (i.e. depth profile) at the surface of a material can be monitored. 

B. Technique: X-Ray Photoelectron Spectroscopy / Electron Spectroscopy for Chemical Analysis (XPS / ESCA)
Equipment: PHI Quantera Scanning X-ray Microprobe
Feature: A X-ray photoelectron spectrometer with finely focused scanning X-ray probe which could provide not only single point analysis but also imaging and elemental mapping. 

 

Capabilities

  • Surface analysis of organic and inorganic materials, stains, corrosion or discoloration
  • Determination of chemical state of the detected elements [e.g, Cu(0), Cu(I) & Cu(II)]
  • Elemental and chemical state mapping
  • Depth profiling for thin film composition
  • Thin film thickness measurements with calibrated ion sputtering rate

 

Specifications

Target Signal:  Photoelectrons from 5-10nm of the sample topmost surface
Elements covered: All except H & He

Chemical state information:

Yes
Detection Limits: 0.1-1at% depends on element
Image modes: Scanning X-ray Induced secondary electron (SXI), Photoelectron (Elemental and Chemical state mapping)
Lateral Resolution: 9 - 200 µm

 

Theory behind

X-ray Photoelectron Spectroscopy (XPS) or Electron Spectroscopy for Chemical Analysis (ESCA) is a quantitative spectroscopic technique that measures the elemental composition and chemical states of the elements that exist in a material.  XPS spectra are obtained by irradiating a material with a beam of monochromatic Aluminum X-ray (Al Kα) causing photoelectrons to be emitted from the sample surface. The in-situ electron energy analyzer is used to measure the kinetic energy (KE) and number of electrons that escape from the top 5 nm of the material. From the binding energy (deduced from KE) and intensity of a photoelectron peak, the valuable information about the elemental identity, chemical state and relative amount of the detected elements can then be determined. XPS detects all elements with atomic number (Z) greater than 3, this implies that XPS cannot detect hydrogen (Z=1) and helium (Z=2). With equipping ion sputtering gun, elemental distribution against sputter depth (i.e. depth profile) at the surface of a material can be monitored; the change in chemical state of particular element can also be tracked. 

C. Technique: Scanning Electron Microscopy (SEM)
Equipment: PHI 680 Scanning Auger Nanoprobe

 

Capabilities

  • High magnification image with spatial resolution down to 10nm
  • Dimensional measurement down to submicron level with calibrated scale

 

Specifications

Target Signal:  Secondary & backscattered electrons
Lateral Resolution: 10nm at 20kV

 

Theory behind

Scanning Electron Microscopy (SEM) is one of the most widely used analytical tools today. It provides high-resolution and long-depth-of-field images of the sample surface that optical microscopy cannot provide. The Secondary Electron (SE) and Backscattering Electron (BSE) images are formed by scanning the sample with a high energy electron beam (up to 20kV). The primary electrons interact with the sample and generate low energy secondary electrons and back-scattered electrons, these electrons are collected by corresponding electron detectors and the surface topography of the sample can be constructed.

D. Technique: Optical Microscopy (OM)
Equipment: Nikon MM-400 measuring microscope & SK-HZM digital microscope

 

Capabilities

  • High magnification color image with spatial resolution down to 1μm
  • Dimensional measurement down to micron level with calibrated scale

 

Specifications

Target Signal:  Visible light
Lateral Resolution: down to 1μm
Image resolution: 5 Megapixel

 

Theory behind

Optical Microscopy is a widely used technique for inspection of surface feature and morphology under visible light with wide range of magnifications; with combination of micro-sectioning, the internal feature of the specimen could also be revealed and inspected. With proper scale calibration, optical microscope can be used for dimension measurement such as plating thickness and particle size.

E. Technique: Precision cutting
Equipment: MTI SYJ-200 precision cutting saw

 

Specifications

Target material: All types of solid
Blade selection: Diamond, Silicon Carbide or Aluminum Oxide
Feed speed: 1 -20mm/min
Blade speed: 300-3500 RPM 
Precision: 0.01mm

 

Description

Precision cutting is a useful sample preparation technique. When sectioning small, delicate, or extremely hard materials, a thin metal bonded diamond blade is used for cutting, the cut piece will have more precise cut, less material loss and less induced deformation than other types of cutting.

F. Technique: Micro-sectioning
Equipment: MTI EQ-Unipol-820 dual platens grinder/polisher

 

Specifications

Mounting medium: Epoxy resin
Grinding tool: Silicon Carbide abrasive papers
Polishing aid: Diamond or Aluminum Oxide suspension
Wheel speed: 50-600 RPM

 

Description

The micro-sectioning is multi-stage sample preparation process for revealing coating layer structure/uniformity, thickness in plating finishes, or ascertaining the internal failure in the bond pad/junction/joint at Printed Circuit Board and electronic packages. The isolated area of interest from the sample is firstly encapsulated into a mounting medium (e.g., epoxy resin) within a mould and is left to solidify. On solidification, the mounted specimen (or micro-section) is subjected to a number of grinding/polishing stages to generate a final polished specimen free of deformation and suitable for optical and/or electron microscopy analysis.