Development of SiGe Indentation Process Control for Gate-All-Around FET Technology Enablement

Spectral interferometry for fully integrated device metrology

“…Workhorse OCD tools used in logic manufacturing today employ high-intensity broadband light sources (within the wavelength range from ∼200 to 1000 nm), which allow for sensitive and versatile measurements of semiconductor device architectures, such as gate-all-around nanosheet transistors. 9 In certain scenarios, shorter wavelengths toward EUV and x-rays would be desired for increased sensitivity to weak parameters of interest, roughness, precise shape analyses, or measurements of optically opaque materials. [10][11][12] In contrast, longer wavelengths in the infrared or terahertz would be beneficial for contactless electrical transport property characterization of patterned materials.…”

“…17 Additionally, with increasing device complexity, the number of floating parameters required to account for statistical process variations can quickly reach double digits and increasing parameter correlations will negatively impact the analysis. 9 Furthermore, the optical constants of nanometer thin and patterned materials can change with thickness and dimensions due to quantum confinement effects and electron-phonon interactions, so neither bulk nor properties of very thin but continuous films may be appropriate. In addition, compositional variations as well as strain have an effect on the dielectric function and must be considered appropriately for accurate analyses.…”

“…For example, in the inner spacer module, such volumes may be comparable to some rounding or footing that would have been previously approximated with a slant. 9 With this in mind, it is important to work also on solutions that reduce the modeling complexity. One opportunity, which is applied to some extend already, is a methodology that may be called design metrology co-optimization (DMCO).…”

“…Machine learning can enable scatterometry solutions without the need for a geometrical model and may even allow for the prediction of parameters that are inaccessible with traditional model solutions. 7,9,25,26,30 However, the required reference data are not always easy to obtain. It may also be very time-consuming and expensive if, for example, only cross-sectional TEM reference metrology is an option.…”

“…Such approximations are also accepted because of lower computational efforts, especially because some trade-offs regarding RCWA calculations may have to be made for stacks with intricate architectures in terms of the number of slices and harmonics 17 . Additionally, with increasing device complexity, the number of floating parameters required to account for statistical process variations can quickly reach double digits and increasing parameter correlations will negatively impact the analysis 9 . Furthermore, the optical constants of nanometer thin and patterned materials can change with thickness and dimensions due to quantum confinement effects and electron–phonon interactions, so neither bulk nor properties of very thin but continuous films may be appropriate.…”