Method of identifying an extreme interaction pitch region, methods of designing mask patterns and manufacturing masks, device manufacturing methods and computer programs
First Claim
1. A computer-implemented method of identifying an extreme interaction pitch region when designing a mask pattern for transferring a lithographic pattern onto a substrate by use of a lithographic apparatus, said method comprising the steps of:
- (a) determining a first pitch between certain features in said mask pattern and a first illumination map of an illumination source of said lithographic apparatus,(b) determining an illumination intensity at an image plane of said lithographic apparatus corresponding to said first pitch of said certain features and said first illumination map,(c) repeating steps (a) and (b) after varying one or more of said first pitch and said first illumination map;
(d) identifying one or more extreme interaction pitch regions based on a plurality of determined illumination intensities from step (c); and
(e) adjusting the mask pattern based on the identified one or more extreme interaction pitch regions,wherein steps (a) to (e) are implemented by the computer.
1 Assignment
0 Petitions
Accused Products
Abstract
Optical proximity effects (OPEs) are a well-known phenomenon in photolithography. OPEs result from the structural interaction between the main feature and neighboring features. It has been determined by the present inventors that such structural interactions not only affect the critical dimension of the main feature at the image plane, but also the process latitude of the main feature. Moreover, it has been determined that the variation of the critical dimension as well as the process latitude of the main feature is a direct consequence of light field interference between the main feature and the neighboring features. Depending on the phase of the field produced by the neighboring features, the main feature critical dimension and process latitude can be improved by constructive light field interference, or degraded by destructive light field interference. The phase of the field produced by the neighboring features is dependent on the pitch as well as the illumination angle. For a given illumination, the forbidden pitch region is the location where the field produced by the neighboring features interferes with the field of the main feature destructively. The present invention provides a method for determining and eliminating the forbidden pitch region for any feature size and illumination condition. Moreover, it provides a method for performing illumination design in order to suppress the forbidden pitch phenomena, and for optimal placement of scattering bar assist features.
14 Citations
16 Claims
-
1. A computer-implemented method of identifying an extreme interaction pitch region when designing a mask pattern for transferring a lithographic pattern onto a substrate by use of a lithographic apparatus, said method comprising the steps of:
-
(a) determining a first pitch between certain features in said mask pattern and a first illumination map of an illumination source of said lithographic apparatus, (b) determining an illumination intensity at an image plane of said lithographic apparatus corresponding to said first pitch of said certain features and said first illumination map, (c) repeating steps (a) and (b) after varying one or more of said first pitch and said first illumination map; (d) identifying one or more extreme interaction pitch regions based on a plurality of determined illumination intensities from step (c); and (e) adjusting the mask pattern based on the identified one or more extreme interaction pitch regions, wherein steps (a) to (e) are implemented by the computer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
Specification