Impact of mask absorber and quartz over-etch on mask 3D induced best focus shifts

Bouma, Anita; Miyazaki, Junji; Veen, Marieke van; Finders, Jo

doi:10.1117/12.2068155

Cited by 1 publication

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“…The 3D mask effects are mainly subject to the morphology of the mask absorber including mask absorber thickness and absorber profile. Related research has indicated that mask absorber thickness (MAT) and the absorber sidewall angle (SWA) have a big impact on critical dimension (CD), best focus (BF), and depth of focus (DOF) [4][5][6][7][8][9]. However, mask absorber errors are inevitably introduced by the imperfect etching process in mask fabrication and measurement [10,11].…”

Section: Introductionmentioning

confidence: 99%

Mitigating the Impact of Mask Absorber Error on Lithographic Performance by Lithography System Holistic Optimization

Sheng

Sun

et al. 2019

Applied Sciences

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The non-ideal mask absorber can cause an increase in critical dimension error (CDE) and decrease in process window (PW). However, the random mask absorber errors induced during mask fabricating and measuring are not considered in computational lithography. The problem cannot be neglected as the continuous scaling of lithography technology node. In this work, for the first time to our knowledge, a source, numerical aperture (NA), and process parameters co-optimization (SNPCO) method is developed to reduce the CDE induced by absorber errors and improve the PW. First, the source is represented by Zernike polynomials to balance computational burden and flexibility of source. Then a weighted cost function containing CDE and PW that incorporates the influences of absorber errors is created. Finally, a statistical optimization method is used to optimize the lithographic system parameters. Simulations of 1D mask pattern show that for the system with extreme absorber errors, the pattern errors of the proposed method are reduced by 62.1% and 58.9%, and the PWs are increased by 40.3% and 36.4%, respectively. The results illustrate that this method is effective in mitigating the CDE caused absorber errors and improving process robustness.

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