Patterning challenges in the fabrication of 12 nm half-pitch dual damascene copper ultra low-k interconnects

J. S. Chawla; K. J. Singh; A. Myers; D. J. Michalak; R. Schenker; C. Jezewski; B. Krist; F. Gstrein; T. K. Indukuri; H. J. Yoo

doi:10.1117/12.2048599

28 March 2014 Patterning challenges in the fabrication of 12 nm half-pitch dual damascene copper ultra low-k interconnects

J. S. Chawla, K. J. Singh, A. Myers, D. J. Michalak, R. Schenker, C. Jezewski, B. Krist, F. Gstrein, T. K. Indukuri, H. J. Yoo

Author Affiliations +

Proceedings Volume 9054, Advanced Etch Technology for Nanopatterning III; 905404 (2014) https://doi.org/10.1117/12.2048599
Event: SPIE Advanced Lithography, 2014, San Jose, California, United States

Abstract

Earlier [1, 2] work highlighted an integrated process for electrically functional 12 nm half-pitch copper interconnects in an ultralow-k interlayer dielectric (ILD). In this paper, we focus on understanding and reducing undesired effects such as pattern asymmetry/distortion, and line undulation/ collapse. Key defect modes and possible solution paths are discussed. Line undulation can occur when the ILD feature changes shape under the stress of the sacrificial hard mask(s) (HM) during patterning, resulting in “wavy” instead of straight features. The amount of undulation is directly related to mechanical properties such as elastic modulus, residual stresses of patterned HMs and the ILD, as well as the dimensions and aspect ratio of the features. Line collapse is observed post wet-clean processing when one or more of the following is true - Insufficient ILD mechanical strength, excessive pattern aspect ratio, or non-uniform drying. Pattern asymmetry, or unequal critical dimensions (CD) of trenches defined by the same backbone, is a typical problem encountered during spacer-based pitch division. In pitch quartering (P/4), three different trench widths result from small variations in backbone lithography, spacer CD and etch bias. Symmetric patterning can be achieved through rigorous control of patterning processes like backbone definition, spacer deposition and downstream etches. Plasma-based ash and energetic metal deposition were also observed to degrade patterning fidelity of ultra low-k film, and also need to be closely managed.

Citation Download Citation

J. S. Chawla, K. J. Singh, A. Myers, D. J. Michalak, R. Schenker, C. Jezewski, B. Krist, F. Gstrein, T. K. Indukuri, and H. J. Yoo "Patterning challenges in the fabrication of 12 nm half-pitch dual damascene copper ultra low-k interconnects", Proc. SPIE 9054, Advanced Etch Technology for Nanopatterning III, 905404 (28 March 2014); https://doi.org/10.1117/12.2048599

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