- Start
- Sensitivity Analysis for Grating Reconstruction
Sensitivity Analysis for Grating Reconstruction
Angebote / Angebote:
Periodic structures, called diffraction gratings,
play an important role in optical lithography. When
the incident field and the shape of a grating is
known, the diffracted field can be computed by using
the rigorous coupled-wave analysis (RCWA) or the C
method. These so-called forward models solve
Maxwell's equations for time-harmonic fields by
transforming them into algebraic eigensystems.
The reconstruction of a grating shape starts with an
initial guess of its shape. The diffracted field is
computed with the forward model and compared to
actual measurements. The difference between them
determines how the shape parameters should be
adjusted. This will be repeated iteratively until an
optimal solution has been found.
The focus of this work lies in finding the first-
order derivatives of the diffracted field with
respect to the physical parameters. This can be done
by finite differences, but straightforward
differentiation of the relations within RCWA gives a
more accurate and faster way to find these
derivatives.
Folgt in ca. 5 Arbeitstagen