Role of Post-Deposition Annealing on Defectivity in 2D Materials
Faculty Mentor Information
Elton Graugnard, Boise State University; Steven Hues, Boise State University; and Dmitri A. Tenne, Boise State University
Presentation Date
7-2023
Abstract
With the increasing complexity of microelectronics, the development of new forward-looking materials and processes has become imperative to enable their functionality. Among the potential pathways to further miniaturize devices, two-dimensional (2D) materials offer great promise due to their outstanding electrical properties even at the atomic level. Molybdenum disulfide (MoS2) is a notable example of a 2D material that exhibits these desirable characteristics and can be synthesized through chemical vapor deposition (CVD) at elevated temperatures. For deposition temperatures below 300°C, atomic layer deposition (ALD) shows promise for synthesis of MoS2 films, but film quality is generally lower than CVD films, and ALD films often employ post-deposition annealing (PDA) to improve their quality.
Ultimately, electrical performance of 2D materials is of primary interest, yet device fabrication can be time consuming and expensive. Thus, there arises a need for the ability to rapidly evaluate the quality of ALD thin films prior to test device fabrication. Raman spectroscopy, a powerful analytical technique widely employed for the characterization of 2D thin films, presents itself as a promising approach for efficient metrology. Variations in the crystallinity and defect density of MoS2 can induce peak shifts or broadening in the corresponding Raman spectra. Establishing a quantitative correlation between these changes and the film properties would enable a swift and non-destructive method for characterizing thin films to evaluate which processing conditions produce films of sufficient quality for device fabrication. To establish this approach, ALD MoS2 films will be deposited on a variety of substrates and subsequently subjected to various annealing conditions, including different temperatures, durations, and environments. The Raman spectra of the annealed samples will be evaluated using deconvolution of the phonon modes giving rise to the peaks in the spectra. These data, along with processing conditions, will be correlated with defect densities acquired through transmission electron and scanning probe microscopies and film conductivity. This approach will establish a quantitative relationship between Raman spectral features and film mobilities, which will enable high-throughput metrology for ALD process development of high quality 2D materials.
Role of Post-Deposition Annealing on Defectivity in 2D Materials
With the increasing complexity of microelectronics, the development of new forward-looking materials and processes has become imperative to enable their functionality. Among the potential pathways to further miniaturize devices, two-dimensional (2D) materials offer great promise due to their outstanding electrical properties even at the atomic level. Molybdenum disulfide (MoS2) is a notable example of a 2D material that exhibits these desirable characteristics and can be synthesized through chemical vapor deposition (CVD) at elevated temperatures. For deposition temperatures below 300°C, atomic layer deposition (ALD) shows promise for synthesis of MoS2 films, but film quality is generally lower than CVD films, and ALD films often employ post-deposition annealing (PDA) to improve their quality.
Ultimately, electrical performance of 2D materials is of primary interest, yet device fabrication can be time consuming and expensive. Thus, there arises a need for the ability to rapidly evaluate the quality of ALD thin films prior to test device fabrication. Raman spectroscopy, a powerful analytical technique widely employed for the characterization of 2D thin films, presents itself as a promising approach for efficient metrology. Variations in the crystallinity and defect density of MoS2 can induce peak shifts or broadening in the corresponding Raman spectra. Establishing a quantitative correlation between these changes and the film properties would enable a swift and non-destructive method for characterizing thin films to evaluate which processing conditions produce films of sufficient quality for device fabrication. To establish this approach, ALD MoS2 films will be deposited on a variety of substrates and subsequently subjected to various annealing conditions, including different temperatures, durations, and environments. The Raman spectra of the annealed samples will be evaluated using deconvolution of the phonon modes giving rise to the peaks in the spectra. These data, along with processing conditions, will be correlated with defect densities acquired through transmission electron and scanning probe microscopies and film conductivity. This approach will establish a quantitative relationship between Raman spectral features and film mobilities, which will enable high-throughput metrology for ALD process development of high quality 2D materials.