Error-budget paradigms and laser mask pattern generator evolution

Conference: EMLC 2009 - 25th European Mask and Lithography Conference
01/12/2009 - 01/15/2009 at Dresden, Germany

Proceedings: EMLC 2009

Pages: 4Language: englishTyp: PDF

Personal VDE Members are entitled to a 10% discount on this title

Hamaker, H. Christopher; Jolley, Matthew J.; Berwick, Andrew D. (Applied Materials, Inc., 21515 NW Evergreen Pkwy., Hillsboro, OR, USA 97231)

The evolution of the ALTA(R) series of laser mask pattern generators has increased the relative contribution of intensity errors on critical-dimension (CD) control to those from placement errors. This paradigm shift has driven a change in rasterization strategy wherein aerial image sharpness is improved at the cost of a slight decrease in the averaging of column-to-column placement errors. Print performance evaluation using small-area CD test patterns show improvements in stripe-axis local CD uniformity (CDU) 3sigma values of 15–25% using the new strategy, and systematic brush-error contributions were reduced by 50%. The increased importance of intensity errors, coupled with the improvement of ALTA system performance, has also made the mask-blank and process-induced errors a more significant part of the overall error budget. A simple model based on two components, a pattern-invariant footprint and one related to the exposure density ρ(x, y), is shown to describe adequately the errors induced by these sources. The first component is modeled by a fourth-order, two-dimensional polynomial, whereas the second is modeled as a convolution of ρ(x, y) with one or more Gaussian kernels. Implementation of this model on the ALTA 4700 system shows improvements in global CDU of 50%