AZtecLive and Ultim Max

Sensor Area

Ultim Max is available with multiple sensor area options. Larger sensor areas deliver higher sensitivity because they collect more of the X-rays emitted from a sample.

Using the same conditions, Ultim Max 170 mm² detectors will collect up to 17 times more data than a conventional 10 mm² SDD detector. Therefore, 17 times more of a sample can be mapped in the same time.

X-ray maps collected with different sensor areas using the same microscope conditions. Count rates increase from 88,000cps for 10 mm² to 1,500,000cps for 170 mm². Therefore, for the same data quality, map resolution increases from 128x128 pixels for 10 mm² to 512x512 pixels for 170 mm² sensor areas, revealing much more of the sample in the same time.

Low Noise X-ray Detection

Ultim Max incorporates Extreme Electronics. These electronics were developed to detect Lithium by EDS, which was achieved in 2012 for the first time (Burgess et al. 2013) and are being used to analyse Li-battery materials with X-Max Extreme and new Ultim Extreme windowless detectors.

Extreme Electronics provide the lowest noise signal detection and processing available for SDD. They ensure excellent energy resolution and spectrum quality is achieved at the high count rates that are easily achieved by large area Ultim Max detectors. With a 100 mm² detector, 130,000cps can be generated with around 1nA at 20kV, yet the resolution achieved is typically less than 125eV at MnKα.

Spectrum collected at <1nA, 20kV from FeS₂ using an Ultim Max 100. Count rate was 130,000cps, resolution measured at MnKα was 124.2 eV.

Spectrum collected from LiAl Oxide in lithium battery solid electrolyte using Ultim Extreme. This corresponds to the orange area in the layered X-ray map where LiK is yellow and AlL red.

Bellows SEM Interface

All Ultim Max detectors use a bellows interface to the microscope. This guarantees vacuum integrity is maintained during detector insertion and retraction.

Motorised Slide

All Ultim Max detectors include an integrated motorised slide. This means the detector can be easily and rapidly inserted and retracted using software control from the AZtecLive software, or using the buttons on the detector housing.

Quantitative Analysis at >400,000CPS

Only the combination of Ultim Max detectors and AZtec Live software can deliver the same accurate standardless quantitative analysis results at over 400,000cps as those achieved at low count rate.

Ultim Max sensors and Extreme electronics provide the stability and fidelity of signal required for accurate processing and production of a spectrum with count rate independent shape and relative peak intensity.

AZtecLive includes unique Tru-Q technology, required to turn this spectrum automatically into a reliable quantitative result. Tru-Q consists of:

• FLS – Robust algorithm for removing the X-ray background from the spectrum and fitting peak profiles of the identified elements to calculate peak areas that does not require any user set up.
• QCAL – New and unique approach to determining the precise position, resolution and shape of all element peak profiles to bring a new level of accuracy to both the calculation of peak area and the intensity relative to that of a pure element (“k-ratio”).
• XPP – The Matrix correction algorithm to convert k-ratios to element concentrations that has been proven to give more accurate results on all types of samples
• PPC – Improved version of our special algorithm for predicting pile-up X-rays present at very high count rates and putting them back in their correct place in the spectrum

Spectrum collected at over 400,000cps with Ultim Max 100 from an Orthoclase standard sample. The original spectrum has been corrected using pulse pile-up correction in AZtecLive to produce the spectrum in yellow. In addition to the removal of sum peaks, the X-ray events have been replaced at their correct energies, correcting the intensity of the real characteristic X-ray peaks.

Comparison of spectra collected at over 400,000cps (yellow) and 4,000cps (red) from an Orthoclase Standard sample. Once automatic pulse pile-up correction is applied, no difference in peak position, shape or intensity can be seen between the two spectra.

Composition of an Orthoclase standard calculated from spectra collected at 400,000cps and 4,000cps.

X-ray Mapping at >1,000,000CPS

Ultim Max maintains excellent spectral resolution and signal stability at count rates over 1,000,00cps. The new X4 pulse processor has been designed to work with Ultim Max to process signals at this very high rate to deliver ultra-fast mapping for AZtecLive.

Sub-1 second mapping is used in AZtecLive for real-time chemical images aiding sample navigation and feature confirmation. At 1,500,000cps, an X-ray map collected in as little as 5 seconds provides a detailed picture of the elemental make-up of a region of interest, with sufficient data for automatic phase analysis.

X-ray maps collected from a mineral sample at 1,500,000cps for 5 seconds

Size Really Matters

Maximising sensitivity requires collecting as many X-rays as possible. The number of X-rays that a detector can collect is determined by its solid angle, which is proportional to sensor area and the inverse of the square of the distance between sensor and sample.

Ultim Max uses new innovative designs to place the largest sensors as close as possible to the sample. This means solid angles of up to 2x greater than previous generation X-Max^N detectors are achieved.

Maximising sensor area and solid angle offers a number of vital benefits when using EDS in practice. Benefits include:

• Maximising productivity by collecting the same data faster
• Maximising sensitivity by collecting more data in the same time
• Maximising sample integrity by minimising sample damage and contamination
• Maximising image quality by using lower beam currents when X-ray mapping
• Maximising spatial resolution for nano-analysis by maintaining signal at low accelerating voltage

The larger the sensor area the more capable an EDS detector becomes.

Schematic image of 10 mm² and 170 mm² detectors, showing that as sensor area increases the number of X-rays that a detector can collect increases.

Sensor Independent Performance

Ultim Max detectors have guaranteed spectrum resolution which is the same independent of sensor size. All standard spec. detectors are guaranteed to achieve 127eV or better at MnKa measured at 130,000cps on installation, and during user operation.  Typical resolution achieved by both sensor sizes is better than 125eV. All sensors also have excellent low energy performance with guaranteed resolution at Carbon of 56eV or better, also measured at 130,000cps. No special operation modes are required to achieve this performance.

This means when choosing an Ultim Max detector you don’t need to accept any loss in detector performance or data quality when choosing a detector with a larger sensor. Choosing a detector with a larger sensor therefore will mean you gain the benefits of size while accepting no compromises.

Mn spectra collected under the same microscope conditions by 100 and 170 mm² sensors. Increasing sensor area means higher count rate with no compromise in detector resolution or performance

Sample Damage

The majority of beam damage arises from three sources, ionization of the specimen by the electron beam, electron induced heating, and specimen charging. These damage mechanisms are primarily dependent on two factors, electron energy and beam current. To minimize specimen damage, a balance must be achieved between current and electron energy for each particular type of specimen.

The large sensor sizes and high sensitivity of Ultim Max ensure that X-rays can be collected at the conditions required to minimise beam damage in a specimen. Sensor sizes of up to 170 mm² allow the use of 17x less beam current than a conventional 10 mm² detector or working at much lower electron energies.

Electron images collected from a Li battery electrolyte specimen collected before and after the acquisition of a 10 minute EDS map. At 5kV the sample is significantly damaged. The high sensitivity of Ultim Max allows the use of electron energies of 2.5kV where damage is significantly reduced.

Sample Contamination

Build up of contaminant during long exposure to an electron beam is always an issue when acquiring X-ray maps or high resolution images. The large sensor sizes of Ultim Max allow the same data to be collected in as little as 1/17th of the time. This minimises exposure to the electron beam and therefore minimises the amount of contamination build up. This ensures that you analyse the specimen and not the contamination.

Electron image of a spinner bowl sample showing contamination build up after EDS map acquisitions of 1 minute and 17 minutes.

TruMap

TruMap gives the true picture of element variation in a sample. It accurately removes common artefacts responsible for errors in X-ray maps in real-time during data collection. As a result only real spatial variation of elements is shown, independent of variations in the X-ray spectrum.

At every pixel in the map the spectrum is processed so the X-ray background is removed and the peaks of all elements are separated. This means that element signals are correctly separated when peaks overlap in the spectrum. In addition, apparent minor element variation which is often caused by different background intensity from different phases is also removed.

Where peaks overlap, e.g. where Mn (MnKα) is present with Cr (CrKb), conventional X-ray mapping will show significant errors, because all X-ray counts in an energy window for each element are combined.

Mn and Cr maps in this sample look identical, however this is due to the dominance of the Cr signal. TruMap separates MnK from CrK to show the real underlying Mn variation without changing the real Cr variation.

Highlight Real Chemical Variation

X-ray maps collected at 100 of thousands or millions of counts per seconds using SDD detectors, often shows an immense amount of fine low intensity detail. This detail is more often due to variation in the X-ray background intensity than real element variation.

X-ray background intensity is related to the mean atomic number of a phase. The heavier the phase the more background X-rays it will emit. Therefore gold particles in an oxide matrix will appear to have higher element intensities where the particles are present than in the surrounding matrix. High count rate X-ray maps from this sample will show apparent variations for every element in the periodic table, due to the phases having significantly different mean atomic number.

Therefore for accurate mapping of low intensity signals the background signal must be removed. TruMap uses the Tru-Q FLS technique, meaning the background is removed automatically, without the need to model the background for each phase. This allows the real variation of minor elements to be determined.

X-ray spectra collected under the same conditions for Au, Fe, SiO₂ and BN. Intensities in the energy window used to calculate Ti maps (red) vary widely due to the different background intensities from the different materials.

X-ray map of minor levels of Ti in a sample. Despite no elements overlapping with Ti in this sample, TruMap shows there are significant errors in the traditional X-ray map, caused by the background intensity change between Cr/Fe particles and the surrounding oxide matrix.

Mapping Low Concentrations

Combining Ultim Max and AZtecLive offers the unique capability to map minor element variations. Ultim Max is sensitive enough to rapidly provide enough counts to achieve sufficient precision to image changes on the 0.1wt% level. Variations due to peak overlaps and background intensity are automatically and accurately removed by TruMap.

TruMaps for Mn and Ti in this sample reveal real variations in minor elements which have been confirmed by WDS. Variations in Mn between 0 and 0.3wt% and Ti between 0 and 0.1wt% are clearly visible.

Light Element Analysis

For light elements with X-ray energies less than 1keV, count rates are reduced by the presence of an X-ray window no matter what the material properties of that window. The Larger sensor sizes of Ultim Max ensure that more of the low energy X-rays generated in the sample are collected. Extreme electronics allow more of those low energy X-rays to be counted. This powerful combination maximises sensitivity for light elements.

For ultimate light element sensitivity Ultim Extreme uses windowless operation, to increase light element sensitivity by up to 8x.

Low kV Analysis

To improve the spatial resolution of EDS the incident energy of the electron beam must be reduced. As electron landing energy is reduced the number of X-rays generated also decreases. To overcome this, the large sensor sizes of Ultim Max ensure maximum counts are achieved under the most demanding conditions. Sensor sizes of 100 mm² and 170 mm² allows a consistent count rate to be achieved as you decrease electron landing energy from 5kV to 3.5 kV.

For the ultimate spatial resolution in bulk samples Ultim Extreme allows practical count rates to be achieved at electron energies of 1.5kV and lower. 

TruMaps of N, O and Si from a de-layered semiconductor device collected with constant acquisition time showing increasing spatial resolution with decreasing incident electron energy. Count rate is maintained at low kV by increasing solid angle, and using windowless collection in the case of Ultim Extreme.