Flare-variation compensation for 32nm line and space pattern for device manufacturing on extreme-ultraviolet lithography

Abstract

One of the critical issues in extreme-ultraviolet lithography (EUVL) is flare, which degrades the contrast of aerial images and control of the critical dimension (CD) across the exposure field and is related to the density of the absorber layout. It is necessary, therefore, to determine a process window under flare-variation compensation (FVC), taking into account residual FVC error and estimated resist properties. In this article, the authors specify a process window for 32nm line/space patterns under a FVC framework based on rigorous aerial-image simulations. FVC, by means of proper mask resizing, can provide an exposure latitude of up to 23% or more. A 0.5nm grid can be used for mask-data preparation due to the low mask-enhancement error factor of EUVL. In addition, resist blur, estimated by convolving a Gaussian function to aerial images, has a significant impact and the standard deviation of the blur needs to the kept below 7nm to obtain a usable process window, considering mask CD error and the process margin for flare levels of 0%–10%.