| 摘要 |
In the present invention, a BARC stack comprising at least a first BARC layer and at least a second BARC layer is optimized for reducing substrate reflectivity in lithographic processing applications. The first BARC layer is positioned adjacent the resist layer, while the second BARC layer is positioned adjacent the first BARC layer. The optical parameters of the first BARC layer are determined to be slightly different from the optical parameters of the resist, thus resulting in a small optical step at the interface resist/first BARC. Furthermore, the second BARC may be selected to have optical parameters such that the optical step at the interface first BARC/second BARC is slightly larger but still relatively small compared to the optical step between resist and substrate. The thicknesses for the BARC layers can be determined from substrate reflectivity calculations. The latter allows obtaining a low substrate reflectivity for various pitches in a pattern to be printed.
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