Strain at the nanoscale is one of the critical parameters affecting physical properties (i.e., electric or mechanical) of microelectronic devices. While uncontrolled strain can be detrimental as it may dramatically modify devices conductibility, engineered strain can be used to tune electric properties of semiconductors to overcome the limits of standard technologies in terms of miniaturization. The availability of nondestructive analytical techniques to characterize local strain at the nanoscale and to map strain field in larger areas is required, which should be integrated in industrial production lines. Electron microscopy represents a well-established tool for strain analysis in microelectronic devices, but it is destructive, not easily used on large areas, and difficult to be really integrated in industrial production lines. Tip Enhanced Raman Spectroscopy (TERS) is a promising technique for nondestructive characterization of strain in semiconductors, which we recently demonstrated on a real 3D semiconductor device made via a standard industrial process. Validation of accurate and reliable TERS-based methods, requires the optimization of the experimental parameters and comprehensive approaches for data analysis. The present project STRESS, the first step of a project submitted to the Horizon 2020 Framework Programme (Call H2020-NMBP-2016-2017, proposal: 760888 - SINAPSI), positively evaluated at the first step with a score of 9.5/10 and also at the second step with a score of 13/15 (threshold:12) but not funded, aims at developing, validating, optimizing, and consolidating a TERS-based methodology for the characterization of strain in real 3D microelectronic devices ready for the integration in production line. Taking advantage of the industrial and academic partnership, TERS will be developed on two different experimental setups and validated with standard electron microscopy based approaches using real industrially produced 3D microelectronic devices.
The final purpose of the SINAPSI project was the development of an Open Environment for strain characterization at the nanoscale, which includes novel and optimized analytical methodologies as well as an accessible platform for data analysis. The envisaged repercussions are expected to be transferable in many other fields. Nano-strain engineering can be applied for instance to improve thermoelectric effects, to tailor piezoelectric response, to tune opto-electronic properties of 2D materials or to modify the magneto-electric properties in materials for future spintronics.
METROLOGICAL ADVANCEMENTS
The present SINAPSI-step1 aims at developing, validating, consolidating and standardizing the use of TERS for strain analysis in semiconductors, which is one of the main metrological goals of the project, the other ones including the improvement of TEM-based methods. The improvement of TERS is aimed at its integration in the industrial production chain. The technology readiness level of such nano-scale evolution of consolidated techniques is TRL4. Such validation clearly requires a cross-correlation with consolidated experimental techniques, which is a primary goal of SINAPSI. By the end of the project, the expected TRL of both techniques will be TRL6. Overall, the methodology proposed in SINAPSI will allow to overcome the actual limitation of the strain measurement experimental techniques. Moreover, in order to extract quantitative information from TERS signals (i.e. modification of the spectral parameters in terms of line shifting and profile), atomic level simulations are required and model validation by independent techniques is mandatory for a correct result interpretation.
In addition to the use of TERS for strain study in semiconductors, among the potential scientific repercussions of SINAPSI.step1, there is development of a feasible analytical methodology ready to be adapted to different characterization challenges and materials, e.g., the study of strain effects in graphene.
Particularly relevant in SINAPSI is the fine tuning and metrological validation of TERS for nondestructive strain characterization, which can pave the way for in-line mapping of strain below 100 nm for rapid process control.
The proposing group has recently obtained excellent results with TERS and the ambition now is to improve the system resolution up to 40 nm. To this purpose, we has already set up a collaboration with major TERS developers worldwide, like Horiba (Japan), and components suppliers such as Renishaw (UK) and Bruker (Germany). Upon specific agreements, the TERS system developed by SINAPSI.step1 could represent the basis to develop a new commercial tool.
INDUSTRY-ACADEMIA COLLABORATIONS
One of the typical obstacles in an academia-industry collaboration is the distance between their objectives. While the industry is looking for tangible results, performance and marketable products on a short time scale, the researchers are focusing on fundamental understanding of phenomena without time constraint and without any barrier to imagination and creativity. A successful and sustainable collaboration is possible only if both parties can achieve their objectives and will result in benefits for both, which means developing a ¿win-win¿ strategy. Convergence of the objectives is therefore critical for a fruitful collaboration. SINAPSI is expected to promote the successful collaboration between industry and academia since the scientific objectives remain coherent with industrial needs and perspectives to get i) reliable data and models to make strain prediction for material and device optimization, ii) novel tools for fast in-line strain monitoring at suitable (nano) scales, iii) effective and robust metrological protocols, all-in-all integrated into one very well-conceived platform.
Overall, the primary expected result of SINAPSI.step1 is a metrological improvement of TERS for the nanoscale study of strain in semiconductors. The finally optimized TERS technique is expected to:
- allow nondestructive accurate mapping of strain in semiconductors with enhanced spatial resolution;
- be ready for the integration in the industrial production chain;
- be adaptable for different experimental contexts (e.g., study of graphene);
- provide the experimental basis for the development of an Open Environment for strain characterization at the nanoscale.
In case of approval, the activities will start from the date of approval. Activities and expenses will be reported within 36 months from the date on which funding will be actually available.