Nicholas E Keller

US Patent:

20220357286, Nov 10, 2022

Filed:

May 5, 2021

Appl. No.:

17/308949

Inventors:

- Wilmington MA, US
Nicholas James KELLER - La Jolla CA, US

International Classification:

G01N 21/956
G01N 21/95
G06F 30/3308
G01N 21/21
G06F 30/347

Abstract:

Characteristics of a standard logic cell, e.g., a random logic cell, are determined using an effective cell approximation. The effective cell approximation is smaller than the standard logic cell and represents the density of lines and spaces of the standard logic cell. The effective cell approximation may be produced based on a selected area from the standard logic cell and include the same non-periodic patterns as the selected area. The effective cell approximation, alternatively, may represent non-periodic patterns in the standard logic cell using periodic patterns having a same density of lines and spaces as found in the standard logic cell. A structure on the sample, such as a logic cell or a metrology target produced based on the effective cell approximation is measured to acquire data, which is compared to the data for the effective cell approximation to determine a characteristic of the standard logic cell.