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20 October 2006 Required mask specification for mass production devices below 65-nm design node
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In the photo-lithography process, a mask is one of the most important items because CD error from its imperfection is transferred to the CD error on the wafer. And the CD error amplification from the mask CD to the wafer CD is denoted by Mask Error Enhancement Factor (MEEF). As the device shrinks so fast, MEEF increases conspicuously and massive OPC is necessary to secure the target pattern CD and the proper process margin on the wafer. Therefore the mask CD uniformity and the just mean-to-target (MTT) are very important to minimize the CD variation on the wafer level. In most cases, MTT and CD uniformity for a certain device are not defined exactly. What we know is that the smaller, the better. Because just small value of MTT and CD uniformity is not the reasonable guideline for the mask fabrication and inducing high mask cost, defining the logical MTT and CD uniformity prospect for a certain device or layer is very important. As the necessity of the low k1 process increases, MTT and CD uniformity specifications become tighter and tighter. However the proper mask specification for sub-65nm real device has not been defined yet and not been studied considering the mask fabrication and MEEF. In this study, MTT and CD uniformity specification of the sub-65nm real device patterns are discussed with respect to the mask pattern linearity and MEEFs. Mask linearity is one of the typical items for the mask fabrication and strongly related to MTT and CD uniformity. MTT and CD uniformity tolerance also follows OPC tolerance, and OPC tolerance is directly related to the pattern layouts and MEEF. To define the mask specification for the sub-65nm device, an example of mask linearity effect is shown; MEEFs of the critical pattern designs are calculated and compared with each other; MTT, CD uniformity and MEEF relationship is commented.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dongseok Nam, Soohan Choi, Jonggul Doh, Young-hwa Noh, Hojune Lee, Yu-jeung Sin, Bo-hye Kim, Man-kyu Kang, Byunggook Kim, Seong-woon Choi, and Woosung Han "Required mask specification for mass production devices below 65-nm design node", Proc. SPIE 6349, Photomask Technology 2006, 634928 (20 October 2006); doi: 10.1117/12.686534;


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