Final Results
Development and manufacturing of materials
CHALLENGES started with the manufacturing/acquisition of the test samples needed for the characterization work in subsequent
work packages. The choice of test samples was pivotal for the success of the project, and it has been based on the needs of the industrial
partners, about manufacturing requirements and characteristics.
Two sets of test samples were benchmarked using standard industrial characterization methods, to guarantee the compliance with the expected specifications:
- Samples to validate the new plasmonic materials and be able to isolate and fully characterize each physical quantity of interest (“standard samples”)
- Industrial semi-finished (or finished) products to be used for developing and testing the inline metrology and adapting it to the specific requirements of each application (“industriallyrelevant samples”).
Both standard and industrial samples were provided for the following targeted applications:
• Semiconductor Industry: CMOS electronics (representative picture)
• Photovoltaics (representative picture)
• 2D Materials
Development of clean room compliant tips
One of the main results of CHALLENGES has been the development of advanced plasmonic tips, which are fully compatible with industry production lines. These tips ensure high reliability and performances in terms of plasmonic amplification, resolution and stability. Moreover, these performances have been obtained using materials which are not ‘poisonous’ when used in microelectronic industrial environments: these requirements inhibit the use of standard SNOM tips which employs noble metals.
Therefore, CHALLENGES has implemented two different strategies:
• coating of standard glass SNOM tips with not noble metals
• manufacturing of advanced tips with or without grating systems
The approach followed required a “circular” interaction between the theoretical activities of simulation of advanced tip structures and prediction of their performances, the practical activities of industrial realization of the designed probes, and the experimental characterization and verification of their performances.
The design of advanced tips was performed on the basis of needed specifications, by UNISAP and TIBERLAB who combined different approaches, i.e., finite element analysis or first-principle calculation, for the simulation of tip-laser interaction, in order to optimize
their shape and materials.
The practical realization of tips on the basis of the results of the simulation activities was carried out by SCANSENS and NANONICS.
The actual performances of the realized tips was assessed using conventional instrumentations by NANONICS and UNISAP.
Instrumentation development
We developed the two main components of the instrument:
• AFM components (NANONICS);
• spectroscopy components for Raman and mid-IR (SOL Instruments).
1. The AFM components
Were able to provide the following advantages in terms of capabilities and optical integration:
• Measurement of phase and amplitude
• Normal and lateral force
• High resolution stage
• Fully integrate with upright microscope
• Inverted microscope if needed
• Optical, Electrical and Thermal measurement without artifact of feedback
2.The spectroscopy components
Spectrometer developed by SOL instruments is designed to solve a wide range of routine and research tasks related to registration and processing of spectra, quantitative and multi-component analysis, as well as kinetic measurements.
The spectrometer features:
• high optical throughput and sensitivity of illumination and detection channels
• high spectral resolution. Spectral resolution of Raman spectra – 0.16 cm-1 (excitation wavelength 532 nm, Echelle grating 75 l/mm, 45-th order)
• possibility to operate with the laser wavelengths necessary to trigger the plasmonic resonance on the AFM tips
• high long-term spectral stability (there is the integrated the reference light source for spectral calibration and validation)
• far field confocal spatial resolution that is the closest possible to the theoretical diffraction limit
• fully automated device
Application and validation
Definition of specifications of test samples for the validation activities
• Definition of material for different analyses
• New ‘standard’ materials (SiGe epitaxial layers on Si, prepared by CEA)
Validation with TEM and X-Ray based characterization techniques:
• TEM sample preparation by FIB: design and realization to preserve strain configuration
• TEM imaging and strain analysis on DIVA structures, Photovoltaics samples and SiGe standards
• X-ray analysis crystal quality and strain measurements on Photovoltaics samples and laser annealed Si crystalline samples from ST-C
Validation with Optical-based characterization techniques:
• Raman analysis of strain, crystal order and defect analysis on DIVA samples, Photovoltaics samples and laser annealed Si crystalline samples and SiGe standards
• PL measurements for Crystal quality and Band-gap analysis on on DIVA samples and Photovoltaics samples
Plasmonic, TERS and TEPL measurements with standard and new tips:
• TERS strain analysis on DIVA samples
• TERS and TEPL Crystal quality and defect analysis on Photovoltaics samples and laser annealed Si crystalline samples and SiGe standards
Development of measurement protocols
The main objective was to set up a framework for establishing metrological support of the CHALLENGES methodologies by identifying and qualifying industrial samples as calibration specimens.
A subset of test samples was selected and used for a statistically strong metrological basis. For traceability and validation purposes, an appropriate set of samples was also selected from outside the consortium to support the metrological work within the consortium. In particular, appropriate SixGe1-x epitaxial samples of different composition have been identified and showed a compositional dependence of strain/stress parameters. The latter corresponds to wavenumber shifts of relevant bands in Raman spectroscopy.
Using conventional and new characterization techniques and standard samples, we were able to assess the reliability of novel approaches proposed in CHALLENGES, in particular linked to baseline precision and accuracy of lab instrumentation.
The results underpin the choice of Si WP6 provides the main elements to set the stage for the after-project exploitation of the solutions proposed by CHALLENGES, including an assessment of sustainability both from the economic and the environmental points of view.
Exploitation and environmental impact
The main elements to set the stage for the after-project exploitation of the solutions proposed by CHALLENGES, including an assessment of sustainability both from the economic and the environmental points of view.
Key Exploitable results:
We have developed exploitation routes for the Key exploitable results (KER), following two different strategies which depend on the type of interest:
EXPLOITATION of technologies and tools as TECHNOLOGY PROVIDERS:
• Plasmonic tips made of not noble metals materials (SCANSENS)
• Automated AFM-based tool, optimized for plasmonic enhancement of optical signals in industrial production environments (NANONICS)
• Raman and Luminescence spectrometer (SOL)
• Machine learning algorithms between tip enhanced tools and far field metrology tools (NOVA)
• Data management system for Raman spectrometers (TIBERLAB)
EXPLOITATION of technologies and tools as ENDUSERS:
• New insights into the formation and reorganization of porous silicon for the growth of epitaxial silicon wafers for photovoltaic devices (IMEC)
• Evaluation of TERS technic to characterize advanced semiconductor device and materials and round robin between partners on standard Raman technics on CEA’s samples (CEA)
• SI-traceable Raman spectroscopic procedure to measure and quantify stress/strain at the surface of semiconductors and 2D materials and experimental set-up for SItraceable Raman-band measurement and Raman spectrometer calibration (PTB)
• Introduction of the Raman spectroscopy analysis into the PV field (AMAT)
• Test Raman spectroscopy analysis on advanced CMOS structures and evaluate calibration protocol for quality industrial requirements (ST_C)
• Industrial in-line Quality Control method for graphene wafer production line (GRAPHENEA).