High-resolution etching of MoSi using electron beam patterned chemically amplified resist

Mueller, Mark; Komarov, Serguei; Baik, Ki‐Ho

doi:10.1117/12.504195

Cited by 3 publications

(1 citation statement)

References 6 publications

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“…However, mask absorber errors are inevitably introduced by the imperfect etching process in mask fabrication and measurement [10,11]. In addition, the MAT error and tapered SWA deformation of the absorber are increased by repeated mask cleaning process [12,13]. Recently, Sturtevant et al and Rudolph et al studied the impact of photomask uncertainties on computational lithography [4,14,15].…”

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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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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Photomask plasma etching: A review

Wu¹

2006

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

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Investigation of etching properties of metal nitride/high-k gate stacks using inductively coupled plasma Photomask plasma etching was thoroughly reviewed over wide topics including history, equipment, etchant, absorbers, phase shifters, thermodynamics, and kinetics. Plasma etch obtained industrial applications for photomask fabrication in the 1990s and presently is a critical fabrication step for the "enabling" photomask industry. Among all types of photomasks ͑binary, embedded attenuated phase-shift mask, and alternating aperture phase-shift mask͒, chromium ͑Cr͒ containing material etching has been the basis and fundamental for all photomask etches. The main technological challenges for Cr etch occur on ͑isolated͒ dark features of a high load photomask due to the etch critical dimension ͑CD͒ bias dependence on the local loading. It determines the CD features on the Cr layer, phase shifter MoSi layer, and fused silica ͑quartz͒ layer. The CD deviation on pattern layers from the nominal value has been a challenge, especially for the Cr state-of-the-art 65 nm node photomasks even though data sizing exists. Inductively coupled plasma plus bias power using radio frequency wavelength is the dominant configuration of the photomask plasma etcher, with improved loading and CD mean-to-target potential. Thermodynamic applications ͑Gibbs energy minimization method͒ on photomask plasma etch provide a quick, easy, and low cost method to estimate the plasma etch feasibility and defect reduction at different plasma gas input conditions. Empirical relationships between operational parameters and etch properties significantly improve the only design of experiment procedure for etch process optimization.

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Pseudo actinometry for the measurement of reactive species density

Kang

Jang

et al. 2017

Opt. Lett.

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To compensate for the effect of plasma parameters in the signal of optical emission spectroscopy, we should normalize the emission intensity from the species against that of an inert gas (i.e., the actinometer). In many plasma processes in the semiconductor industry, plasma etching without using a neutral gas for the actinometer has become popular to achieve better critical dimension uniformity. We propose "pseudo actinometry" for normalization in the absence of an inert gas in the process plasma. Based on the theory of optical actinometry, we define a correction factor as the ratio of the emission intensity to the number density of the inert gas. As we reduced the density of the inert gas, we experimentally determined the correction factor by taking its convergence when the concentration of the inert gas was zero. As proof of concept, we applied pseudo actinometry to measure the density distribution of atomic chlorine in a photomask etching process without an inert gas. By comparing the distributions of chlorine radicals and the etch rate as measured by an ellipsometer, we calculated the correlation coefficient between the distributions. The correlation coefficient rapidly decreased to 0.60 when we used the correction factor determined at a flow rate for the inert gas of 20 standard cubic centimeters per minute at STP. By using pseudo actinometry, we successfully determined the distribution of chlorine radicals with a correlation coefficient of 0.98 in a plasma etching process without an inert gas.

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High-resolution etching of MoSi using electron beam patterned chemically amplified resist

Cited by 3 publications

References 6 publications

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

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

Photomask plasma etching: A review

Pseudo actinometry for the measurement of reactive species density

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