Abstract
A lithographic test pattern, the phase shift grating (PSG) z monitor, is introduced. Through the use of phase shift techniques, position errors of images in the z-direction translate into lateral shifts in the printed pattern. The lateral shifts are easily measurable using an overlay metrology tool. Each z monitor pattern in a test mask can be directly read for the sign and magnitude of the z error. When the experimental conditions, namely, the period of a PSG and a coherent factor of the lithography tool simultaneously satisfies a criterion of the asymmetric two-beam interference between the zeroth-order ray and either of the two first-order rays of diffraction, the linearity of a z-vs-overlay curve is always complete and the slope of the curve is constant everywhere in the image field. Using state-of-the-art overlay metrology tools, we realized subnanometer-order accuracy in the z measurement.
Similar content being viewed by others
References
T. Brunner, A. Martin, R. Martino, C. Ausschnitt, T. Newman, and M. Hibbs: Proc. SPIE 2197 (1994) 541.
J. Kirk and C. Progler: Proc. SPIE 3679 (1998) 70.
J. Kirk, G. Kunkel, and A. Wong: Proc. SPIE 4346 (2001) 8.
H. Nomura: Proc. SPIE 4346 (2001) 25.
H. Nomura: Opt. Rev. 8 (2001) 184.
H. Nomura: Jpn. J. Appl. Phys. 40 (2001) 6316.
B. LaFontaine, M. Dusa, J. Krist, A. Acheta, J. Kye, H. Levinson, C. Luiten, C. Sager, J. Thomas, and J. van Praagh: Proc. SPIE 4691 (2002) 315.
B. LaFontaine, J. Hauschild, M. Dusa, A. Acheta, E. Apelgren, M. Boonman, J. Krist, A. Khathuria, H. Levinson, A. Fumar-Pici, and M. Pieters: Proc. SPIE 5040 (2003) 570.
B. Roberts, M. McQuillan, N. Louka, T. Zavecz, P. Reynolds, and M. Dusa: Proc. SPIE 5377 (2004) 1929.
M. McQuillan and B. Roberts: Proc. SPIE 6154 (2006) 30.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Nomura, H. Subnanometer-accuracy z-position monitor mask for optical lithography. OPT REV 17, 499–506 (2010). https://doi.org/10.1007/s10043-010-0090-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10043-010-0090-8