Allalin

Blazing fast quantitative cathodoluminescence microscope

The Allalin is a nanometer resolution spectroscopy instrument, based on a disruptive technology known as quantitative cathodoluminescence that integrates a light microscope and a scanning electron microscope (SEM) into one tool.

Allalin-Picture-Without-Background-Attolight-Blazing-Fast-Quantitative-Cathodoluminescence-Microscope

The Allalin allows for “No Compromise” large field/fast scanning simultaneous SEM imaging with hyperspectral or panchromatic CL maps. The system was constructed from the ground up to attain the best cathodoluminescence performance without sacrificing the SEM performance: the light microscope and the objective lens of the SEM are carefully integrated so that their focal planes match each other; the light microscope is machined with sub-micrometer precision so as to an achromatic, high numerical aperture (N.A. 0.71) detection with superior photon collection efficiency over a large field of view  — up to 300µm — compared with traditional CL technologies. As a result, quantitative cathodoluminescence, where instrument related artifact can intrinsically be ruled out as an explanation for a spectral feature or a contrast, becomes conceivable for the first time.

The Allalin is built for those who need to follow a tight technology roadmap and quickly access very precise spectroscopic information that has been out of reach for traditional methods.

In semiconductor Failure Analysis, Development & Research, the Allalin’s spectroscopic measurement capabilities offer an unparalleled solution for fast and reliable defect detection and localization. Proven use cases include measurement of dislocation density, material composition fluctuations, strain, dopant type and concentration; and a wide range of other applications.

In scientific research, the Allalin’s ability to create spectroscopic maps with nanometer resolution makes it the ultimate tool to acquire a deep understanding into the physics of nanoscale objects.

The Allalin features a comprehensive set of options to optimize the tool’s performance for your application : various choices of detectors to cover the UV – IR wavelength range, an stable low temperature stage, and a high sensitivity EBIC (Electron Beam Induced Current) detection solution.

Key benefits

Designed from the ground up as an integrated CL-SEM system


  • Puts optical collection within the electron column
  • Requires ZERO optical alignment for CL
  • Highest collection efficiency over a field of view (FOV) of 300μm
  • Ensures CL uniformity and reproducibility, making the system quantitativeas well asqualitative. Quantitative: the photon collection efficiency is constant (+- 1%) over a large FOV of 300 μm (no vignetting); a 300 μm mapis performed without any displacement of the specimen: cathodoluminescence results are reproducible and comparable.
  • Uses lower beam dosages, reducing the possibility for beam damage to sensitive samples
  • Fast! Single hyperspectral CLmap measurement time ranges from 18 s to30 min compared to the competition’s 30 min – multiple hours
  • Simultaneous generation of a SEM image and a hyperspectral CL image with no degradation of the electron probe size
  • Schottky FEG for high current densities from: 30pAto 300nA
  • Highest resolution SEM inCL mode: down to 3nm
  • Intuitive User Interface and specialized software
  • Touch screen control with easy to navigate context based GUI that does not require anexpert to operate the tool
  • Dedicated Attomaphyperspectral analysis software (see separate brochure)
  • High precision nanopositioning stage with low temperature option (10K to room temperature)
  • Highly versatile: Optical hub for integration of the Attolight CL instrument in a larger spectroscopic system or complement its functionality

System Configurations

Schematic setup of an Allalin system showing the main components.

Fast hyperspectral mapping allows to fully characterize a region of interest with speeds as fast as 1 ms per spectrum, a good quality hyperspectral map (128 x 128 pixel) can be obtained in under 18s. This detector covers the emission range of most commonly used semiconducting materials such as gallium nitride, gallium arsenide, diamond, gallium oxide and compounds.

Fast hyperspectral mapping extension to detect emission in the near infrared domain. This extension is especially useful for CL applications on Silicon and Silicon related compound materials.

Panchromatic detection allows for ultrafast mapping of the CL intensity within a specified wavelength range (bandpass). Measurement times per pixel can be as low as 100ns which means that a 4k map can be registered in under one second. Attolight provides detectors and bandpasses that are adapted to the user application. Panchromatic detection is particularly useful to determine defect densities in different materials such as GaN, SiC, or GaAs.

The helium cryostat system is compatible with the nanopositioning stage and allows to carry out measurements at precise temperatures (+-0.1K) between 10K and room temperature. A copper braid between the cold head of the cryostat and the sampleholder allows to limit vibrations enough to guarantee the best imaging resolution at low temperatures. The cryostat’s versatile design allows it to be used with liquid helium and liquid nitrogen. The cryostat option is extremely useful to separate thermal contribution to the a emission spectrum or to study spectral variations depending on thermal activation.

EBIC & EBAC measure the electrical currents induced in the structure under test. EBIC & EBAC are complementary to CL since they measure non radiative effects, whereas CL looks mostly at radiative effects. EBIC/EBAC signals and CL can be measured simultaneously, even at low temperature

TRCL allows to measure CL decay times with resolutions below 10ps. Please refer to the Attolight Chronos brochure for a detailed description of TRCL options.
Attolight can add up to two spectrometers per CL system, this allows for a total of four detectors connected to the CL setup. Switching between the detectors is computer controlled and does not need any hardware re-configuration.

Specifications

  • Schottky thermal field emission gun
  • Beam energy 1keV – 10keV
  • Smallest electron spotsize: 3 nm at 10 kV
  • Optimal working distance 3mm
  • High sensitivity SE detector
  • Field-upgradable to picosecond pulsed photoelectron gun (see Chronos specifications for more information)
  • Electron probe current: 30 pA to 300 nA
  • Field of view up to 300 μm
  • Integrated light collection: 30% of the photons emitted by a lambertian emitter exit the microscope (constant over the whole field of view)
  • Achromatic reflective objective from 180 nm to 1.6 μm
  • Numerical aperture: NA 0.71 (f/0.5)
  • Dispersive spectrometer with two imaging exits (320 mm focal length) and a 3-grating turret (Attolight provides a large collection of diffractions gratings to optimally fit your application), motorized entrance and exit slits
  • High speed CCD camera for UV-Visible (200nm – 1100 nm) detection, highest speed > 900 spectra per second
  • InGaAs camera for near infra-red (600nm – 1700nm) detection, highest speed > 180 spectra per second
  • Panchromatic detection in the range 200nm – 1700nm using different detectors, highest speed > 50ns per pixel
  • Low noise EBIC electronic board
  • Current measurement limit of 100fA
  • Gain 10^4 to 10^15 V/A
  • Bandwidth up to 100kHz
  • Oil-free pumping system: Ion getter pumps for electron gun and electron column and turbo molecular pump for the specimen chamber
  • Typical specimen exchange time: 20 min
  • Electrical feedthroughs on vacuum door
  • 6 degrees of freedom for arbitrary movements (compatible with the cryostat)
  • Travel range: 25 mm (X and Y), 3 mm (Z), 3° tilt (X and Y), 10° rotation (Z)
  • Smallest increment: 1 nm
  • Repeatability of 100nm over full travel range
  • Coordinate system for easy and precise navigation
  • Temperature range from 10K – room temperature with 0.1K precision
  • Advanced digital temperature controller
  • Less than 300nm drift per hour at a temperature of 10K
  • simultaneous CL (hyperspectral or panchromatic mapping), SEM, and EBIC mapping
  • capability for semi-automated operation
  • Intuitive touch screen based graphical user interface (GUI) for quick sample navigation & realtime data illustration to check measurement status
  • Maximum image resolution of 4k, maximum resolution of a hyperspectral map 512 x 512 pixel, minimum electron beam dwell time of 50ns per pixel

Sampleholder overview created by the user. This overview is created for every sample load and facilitates the navigation to the region of interest on any given sample. The software tracks the location in a metadata file which makes data analysis easier and removes potential sample identifications errors.

Standard screen during hyperspectral mapping. The user can choose spectral bands and control in realtime the quality of the measurement.

Data analysis

  • Attolight provides Attomap a powerful analysis and reporting solution. Please refer to the separate Attomap brochure for more information.
  • Tool configuration and CL data is saved simultaneously for easy reproduction of the tool configuration
  • Easy password protected user access to measurement data over the network
  • Export to open data format to give maximum flexibility to users to choose their preferred data analysis software

System layout

Layout example with Helium Dewar for low temperature operation and operator desk.