Specification3000 times higher sensitivity than conventional LEIS instruments Quantitative, elemental characterisation of the top atomic layer Spectroscopy, imaging and depth profiling capabilities Time-of-flight mass filtering for improved sensitivityAnalysis of rough and non-conductive materialsApplicationThe stand-alone version of the Qtac is based on a field-proven instrument platform. The modular design is ideal for customisation and the integration of a large variety of UHV preparation techniques. It is also possible to couple the Qtac100 to other floor standing instruments.
The Qtac is a high sensitivity low energy ion scattering (LEIS) instrument. It is extremely surface sensitive, providing elemental and structural characterisation of the top atomic layer. This new generation instrument has been developed to include small spot analysis, surface imaging, and both static and dynamic depth profiling. Its unique surface sensitivity makes the Qtac the perfect tool to study surface processes. The Qtac provides valuable information in many production and research areas on materials such as catalysts, semiconductors, metals, polymers, fuel cells, and biomaterials. Key features are:
- 3000 times higher sensitivity than conventional LEIS instruments
- Quantitative, elemental characterisation of the top atomic layer
- Spectroscopy, imaging and depth profiling capabilities
- Time-of-flight mass filtering for improved sensitivity
- Analysis of rough and non-conductive materials
Many interactions of a solid surface with other solids, liquids or gases involve only the atoms in the first monolayer. To obtain a clear understanding of these processes the analysis of the first atomic layer is crucial.
The significant advantages of low energy ion scattering (LEIS) are extreme surface sensitivity and quantification. Contrary to many other established surface analysis techniques such as XPS or AES, which generally integrate over several atomic layers, LEIS characterises individual atomic layers. These features make the Qtac100 an extremely valuable instrument when information about the composition of the first atomic layer is required. Static depth profiling is used to analysis the sub-surface atomic layers and to determine layer thicknesses.
The Qtac100 extends the range of LEIS applications to surface imaging and dynamic sputter depth profiling.
For catalysis the characterisation of the top surface layer of atoms is essential and the Qtac100 is the perfect tool for this application
By using a low-energy sputter ion source, fitted to the Qtac100, in a dual beam mode with LEIS analysis, high-resolution chemical depth profiles are obtained. In contrast to SIMS, there is no need to use reactive sputter species, which lead to changes in sputter rate and ionisation yield close to the surface. The Qtac100 provides easy quantification even in the first few nanometers.
Ultra-thin Film Analysis
In the semiconductor industry ultra-thin films such as diffusion barriers and high-k materials are increasingly manufactured by atomic layer deposition (ALD). The example below shows five different LEIS spectra taken after an increasing number of deposition cycles of WNxCy on silicon.
By monitoring the decreasing silicon and the increasing tungsten signal it can clearly be seen that 40 ALD deposition cycles are necessary for a closed layer of WNxCy. The peak shape on the left side of the tungsten surface peak also shows the growth of multiple layer islands before reaching full coverage.
Segregation of Cu
The alloy Constantan consists of nickel and copper. At higher temperatures the Cu segregates to the surface. The formed Cu monolayer contains Cu and Mn, a contaminant which also segregates to the surface during the heat treatment.
Langmuir-Blodgett Film on Gold
By evaluating the static depth profiling information of the LEIS spectrum thicknesses of organic films can be measured. In this example the thickness of Langmuir-Blodgett films was determined by measuring the energy shift of the gold signal.
LEIS Sputter Gun
The Qtac can be equipped with a high current ion optical column fitted with an electron impact gas ion source operable with rare gase or Oxygen. This ion gun is used for ultra-low energy sputtering in combination with LEIS analysis. It includes differential pumping, a service valve for separate venting, a three-lens ion column with deflection units, a mass separating pulsing system, a Wien filter, and fully computer controlled high voltage power supplies.
The Qtac100 is available with two different sample introduction systems:
SINGLE STAGE INTRO
A single stage sample introduction system including a rapid pumpdown HV loadlock fitted with a
turbomolecular pump and a horizontal sample transfer system fully integrated into the logic of the Qtac100 vacuum control system. Provision for the attachment of heating and process gas treatment of the sample in the loadlock. The loadlock chamber is prepared to accept various sample preparation devices, such as an atomic Hydrogen/Oxygen source.
DUAL STAGE INTRO
A dual stage sample introduction system including a rapid pumpdown HV loadlock, an UHV preparation chamber fitted with a turbomolecular pump, and a horizontal sample transfer system fully integrated into the logic of the Qtac100 vacuum control system. Provision for the attachment of heating and process gas treatment of the sample in the introduction system. The UHV chamber is prepared to accept various sample preparation devices, such as an atomic Oxygen/Hydrogen source.
The modular design of our instruments is ideal for customisation. The Qtac is available in three different standard versions:
The stand-alone version of the Qtac is based on a field-proven instrument platform. The modular design is ideal for customisation and the integration of a large variety of UHV preparation techniques. It is also possible to couple the Qtac100 to other floor standing instruments.
Qtac – TOF.SIMS 5 Combination
For many samples, including those with sensitive surfaces, the in-situ transfer between analytical techniques is very useful, avoiding contamination between analyses, and permitting direct comparison of results. The combination of the Qtac with the time-of-flight secondary ion mass spectrometer TOF.SIMS 5 makes a very effective tool for inorganic and organic surface analysis. The combination provides top atomic layer analysis, surface chemical mapping, static and dynamic depth profiling, 3D chemical imaging, layer thickness measurement, and quantification.
Qtac Bolt-on Module
Many manufacturing, surface treatment, and thin layer deposition techniques benefit from on-line quality control.
For coverage and layer thickness measurements, the Qtac makes an ideal addition. The Qtac is available as a bolt-on system, tailored to individual requirements, for laboratory instruments or industrial tools. ALD and MBE instrumentation are typical examples.