Metrology for directed self-assembly block lithography using optical scatterometry

Metrology for block copolymer directed self-assembly structures using Mueller matrix-based scatterometry

“…For experimental MMSE data collected at a 45 deg azimuthal angle, due to nonzero offdiagonal Mueller matrix elements, it is observed that α ≠ 0, β ≠ 0, γ ≠ 0 in the wavelength range of 250 to 500 nm for perfectly oriented PS line-space patterns, and an increase in disorientation of self-assembled PS lines are correlated with a decrease in the value of α and β (to 0), while the value of γ increased to 1. 16 This trend of change in anisotropy coefficients can be correlated to a change in intensity of the off-diagonal Mueller elements with a change in the degree of alignment of PS line-space patterns as shown in Fig. 8(b).…”

“…The differences in MSE values are large enough to routinely distinguish among ordered, partially disordered, and fingerprint-like patterns. 16 The wafer map for etched samples with respect to the MSE obtained from scatterometry analysis and the structural model are seen in Figs. 9 and 10, respectively.…”

“…It was previously reported that for all azimuthal directions, the depolarizing coefficient value increases as structural order decreases. 16 The increase in depolarization coefficient is due to certain nonidealities present in PS patterns, i.e., bridging defects, wiggles, or dislocations. The wafer map showing this increase in the depolarization coefficient value at 260 nm wavelength of light is seen in Fig.…”

Characterizing Patterned Block Copolymer Thin Films with Soft X-rays

“…The combination of “top-down” and “bottom-up” approaches to nanofabrication have the potential to produce systems with well-controlled length scales and long-range order. The directed self-assembly (DSA) of block copolymers (BCPs) is an example of this combined approach in which the long-range orientation is controlled by a lithographically patterned guide and the minimum length scale is defined by the pitch ( L 0 ) of the BCP. − BCP DSA is being explored as a lithographic resolution enhancement technique to cost effectively pattern magnetic storage media and semiconductor devices. , Understanding the limits of the parameter space that lead to the assembly of BCP thin films with orientation and morphology suitable for lithography applications is critical for implementation of this approach, particularly given the limitations of current in-line metrologies. − The chemical composition of the template and template geometry, including topography and width of the guiding stripe ( W ) relative to L 0 , all are known to impact the quality of the assembled film. − The assembly quality is typically assessed via scanning electron microscopy (SEM), which is used to evaluate the alignment and registration with the underlying template. , The SEM analysis is necessary for refining assembly conditions but cannot provide any information on variations in the internal morphology of the film. These subsurface shifts in morphology have been predicted by coarse-grained Monte Carlo (CGMC) simulations and have the potential to disrupt the etch transfer to the underlying wafer .…”

Modeling ellipsometric measurement of three-dimensional structures with rigorous coupled wave analysis and finite element method simulations

“…4 When the figure-of-merit (usually mean square error) is minimized, the structural parameters are determined and compared again to other metrology tools for value confirmation, although some variation is expected depending on the method used for comparison. 5 The most common simulator type for ellipsometry-based OCD tools is rigorous coupled wave analysis (RCWA). As for ellipsometry, RCWA has found favor in industry for its fast computation time and accuracy for typical samples.…”