OPTIMIZING COMPUTATIONAL EFFICIENCY BY MULTIPLE TRUNCATION OF SPATIAL HARMONICS

摘要

Methods and systems are presented for solving measurement models of complex device structures with reduced computational effort and memory requirements. The computational efficiency of an electromagnetic simulation algorithm based on a truncated spatial harmonic series is improved for a periodic target that exhibits a fundamental space period and one or more approximate periods that are integer fractions of the fundamental space period. Spatial harmonics are classified according to each distinct period of the target exhibiting multiple periodicity. A separate truncation order is chosen for each group of spatial harmonics. This approach produces an optimal sparse truncated order sampling pattern and ensures that only harmonics that make significant contributions to the approximation of the target are selected for calculation. Metrology systems utilizing these techniques are configured to measure process parameters and structural and material properties associated with different semiconductor manufacturing processes.