Fixing the focus shift caused by 3D mask diffraction

Bayram Yenikaya; Constantin Chuyeshov; Onur Bakir; Youngae Han

doi:10.1117/12.2045682

31 March 2014 Fixing the focus shift caused by 3D mask diffraction

Bayram Yenikaya, Constantin Chuyeshov, Onur Bakir, Youngae Han

Proceedings Volume 9052, Optical Microlithography XXVII; 905217 (2014) https://doi.org/10.1117/12.2045682
Event: SPIE Advanced Lithography, 2014, San Jose, California, United States

Abstract

As the feature sizes printed with optical lithography get smaller, Kirchhoff’s thin mask approximation used in full chip optical proximity corrections (OPC) fails to yield acceptable accuracy due to thick mask diffraction effects. One of the most observed effects of the thick mask diffraction is that it creates different focus shift for different patterns. When Bossung curves (CD plots with respect to defocus) of various patterns are observed from rigorous simulations and from actual wafer data one can notice that each pattern has a different best focus. Depending on the pattern, Bossung curves can be offset in either positive or negative direction. This significantly reduces the common depth of focus (DOF) for which all patterns print with acceptable fidelity. Even though each pattern by itself may have an acceptable DOF, the common DOF may not be acceptable. Several extensions to the thin mask approximation have been developed that model this behavior accurately, such as boundary layer approximations and domain decomposition methods. These methods provide a more accurate approximation than the thin mask model while still being computationally efficient to be useful for full chip OPC. Even though these approximations model and predict the focus shift accurately, to the best knowledge of the authors no method has been published to use these modeling capabilities to automatically fix this focus shift during OPC. In this paper we provide an optimization method to significantly reduce focus shift due to 3D mask effects during OPC. We show that our 3D mask model can predict this focus shift fairly accurately and we also demonstrate how we use this model in OPC to reduce focus shift, which significantly improves the common DOF for the entire layout.

Citation Download Citation

Bayram Yenikaya, Constantin Chuyeshov, Onur Bakir, and Youngae Han "Fixing the focus shift caused by 3D mask diffraction", Proc. SPIE 9052, Optical Microlithography XXVII, 905217 (31 March 2014); https://doi.org/10.1117/12.2045682

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available