Investigation of pupil-fill factors as process window indicators for dry optical lithography

Chua, Jeun Kee; Murukeshan, Vadakke Matham; Tan, Sia Kim; Lin, Qun Ying

doi:10.1016/j.optlastec.2007.03.001

Cited by 2 publications

(1 citation statement)

References 14 publications

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“…Some studies have proposed the use of an overlap ratio given by the ratio between the first ͑and higher͒ and zeroth order light as a metric for illumination optimization 13,14 given by…”

Section: That Mostmentioning

confidence: 99%

Forbidden pitch improvement using modified illumination in lithography

Ling

Tay

Quan

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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In lithography, forbidden pitch refers to pitch that suffers degradation in the process window due to the application of off-axis illumination ͑OAI͒. Destructive light field interference of diffracted light from a mask at forbidden pitch causes reduction in image contrast and depth of focus ͑DOF͒ and limits the pitch range to be patterned. In this paper, a modification to conventional OAI shape is proposed to minimize the effect of forbidden pitch. The modification is based on the interaction of illumination source with pattern density. The modified source employs double annular illumination. Simulation is carried out to investigate the effect of the modified source for one dimensional line and space pattern with a pitch varying from 130 to 500 nm. Results shows that the maximum critical dimension fluctuation is around 3% compared to 13% in conventional annular illumination. Furthermore, the degradation in DOF is within 21% of DOF compared to 49% in conventional annular illumination.

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“…Some studies have proposed the use of an overlap ratio given by the ratio between the first ͑and higher͒ and zeroth order light as a metric for illumination optimization 13,14 given by…”

Section: That Mostmentioning

confidence: 99%

Forbidden pitch improvement using modified illumination in lithography

Ling

Tay

Quan

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

View full text Add to dashboard Cite

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Micromirror array allocation algorithm based on deconvolution

Liu

Yang

et al. 2020

Appl. Opt.

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Freeform illumination is one of the necessary techniques in 28 nm technology nodes and beyond. The micromirror array (MMA) has been widely used in lithography freeform illumination systems due to its programmability and high free degree. The MMA allocation algorithm is the key to generate the target freeform illumination source. Its computational speed and precision affect the generation speed and precision of the target illumination source as well as the process window size of the generated illumination pupil directly. In this paper, an MMA allocation method based on deconvolution is proposed. The target freeform illumination source can be obtained directly with the deconvolution and quantization processes. Without the iterative optimization process, the computational speed of the proposed method is much faster than that of the traditional method. The numerical simulation results show that the difference between the target source and the MMA source generated using the proposed method is less than 0.2%. Compared with the process window loss of the target source, the process window loss of the MMA source generated by the proposed deconvolution method is less than 0.5%. Compared with the traditional allocation method, the runtime of the proposed method is less than 0.05 s and has improved by 1463 times.

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Investigation of pupil-fill factors as process window indicators for dry optical lithography

Cited by 2 publications

References 14 publications

Forbidden pitch improvement using modified illumination in lithography

Forbidden pitch improvement using modified illumination in lithography

Micromirror array allocation algorithm based on deconvolution

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