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| Spatially Resolved Chemical Characterization of Optoelectronic and Semiconductor Systems |
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| Objective: |
| To develop the measurement tools to chemically characterize next generation, nanoscale optoelectronic and semiconductor devices. |
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| Description: |
| Electronic and advanced materials are increasingly impacted by compositional changes on the submicron length scale. This is routinely seen in the semiconductor area where the ever-shrinking size of device features continues to allow the industry to realize Moore 's Law – the exponential increase in transistor density on a chip. Efforts span thin-film characterization, surface chemical growth mechanisms, and novel nanostructures for the electronics industry. Increased interest in optoelectronics can be seen in the activities of this program, with increased efforts being directed toward the development of measurement techniques that address needs which range from those of the Semiconductor Industry Association (SIA) roadmap to the determination of contaminants in starting materials and finished products. |
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| Area(s) of Application: |
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| Accomplishments: |
- In-Situ Characterization of Additives Governing Copper Electrodeposition : This research team adapted a commercially available spectroscopic ellipsometer to evaluate the effect of additives on metal substrates in liquid-based environments to mimic the electrolytic plating baths used in the industry.
- Improved Energy Stability in the NIST Microcalorimeter X-ray Detector: The drift in energy scale of the microcalorimeter x-ray detector has been a major limitation to the commercial development and marketing of this type of detector. CSTL research team investigated the sources of energy scale drift in the NIST-developed microcalorimeter x-ray detectors and has addressed the most critical elements. The detector is cooled to a substrate temperature of only 70 mK and maintained at its operating point by a complex feedback control system connected to a large superconducting magnet.
- Chemical Characterization of SiGe Single Crystal Specimens and SiGe Films on Silicon with Electron Probe Microanalysis : The CSTL-led research team provided the semiconductor industry with a reference material for evaluation of SiGe components. Secondary-ion mass spectrometry (SIMS) and ellipsometry revealed a circular halo-like region around the disk material center that was thicker than for the rest of the disk thus suggesting specimen-to-specimen heterogeneity. With this knowledge, specimens were selected from a region in the wafer where the specimen-to-specimen thickness variation was expected to be minimal.
- Characterization of Silicon Semiconductor Electronics Using SIMS Backside Depth Profile Analysis: Researchers developed a backside sample preparation method that uses mechanical grinding and polishing to remove the silicon substrate prior to SIMS analysis. The method can be applied to a variety of different samples including fully processed, patterned wafers. This should extend the utility of SIMS measurements to the characterization of future generation semiconductor electronic devices.
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| Future Plans: |
- In-Situ Characterization of Additives Governing Copper Electrodeposition: Additional studies on more complex systems are planned to build on the insights already gained. Additionally, the use of other materials such as ruthenium as substrates for copper electrodeposition applications will be examined
- NIST Microcalorimeter X-ray Detector : Additional measures to stabilize the operating temperature are possible. Once realized, we can carry out a demonstration of the microcalorimeter detector with an electron microscope for quantitative microanalysis. We also anticipate replacing the actual detector element with higher resolution (< 4 eV) versions, which have been developed at NIST, Boulder . Combined with the achieved stability of the energy scale, we can start to look at characterizing chemical states of some elements by the energy of their fluorescence lines.
- Data from the standard materials will be used in conjunction with Monte Carlo calculations to determine the optimum voltage and corrections procedures for microprobe analysis of the thicker films. Once the data analysis is completed, the materials will be released to the industry for distribution as consensus standards (Interactive Materials).
- SIMS Backside Depth Profile Analysis : Future plans include combining backside sample preparation with cluster ion SIMS depth profiling to further improve the depth resolution of SIMS measurements.
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| Recent publications: |
- M. L. Walker, L. J. Richter and T. P. Moffat, “ In-Situ Ellipsometric Study of PEG/Cl - Co-adsorption on Cu, Ag and Au”, submitted to J. Electrochemical Soc.
- E. Windsor, G. Gillen, D. Bright, P. Chi, A. Fahey and J. Batteas, “Techniques for Improving SIMS Depth Resolution: C 60 + Primary Ions and Backside Depth Profile Analysis” Proceedings of the 2005 International Conference on Characterization and Metrology for ULSI Technology, American Institute of Physics Press, in press.
- Marinenko, R.B., Armstrong, J.T., Turner, S. Steel, E.B., and Stevie, F.A., “ Characterization of SiGe Bulk Compositional Standards with Electron Probe Microanalysis ,” American Inst. of Physics (AIP) Conference Proceedings of ULSI 2003 Meeting, Austin, TX, Mar. 24-28, (2003).
- Gillen, J.G., Wight, S.A., Chi, P.H., and Fahey, A. J., “Bevel Depth Profiling SIMS for Analysis of Layer Structures,” Characterization and Metrology for Ultra Large Scale Integration, American Institute of Physics (in press).
- Jach, T.J., Dura, J.A., Nguyen, N.V., Swider, J.R., Cappello, G., and Richter , C.A. , “Comparative Measurements of SiO 2 /Si Films for Thickness Less than 10 nm,” Surface and Interface Analysis, 36, 23, (2004).
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| Other related project work: |
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| External Collaborators: |
- Chemical Characterization of SiGe: F. Stevie ( North Carolina State University )
- Characterization of Silicon Semiconductor Electronics: J. Bennett (International SEMATECH)
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| Principal Investigator:
Dave Simons |
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