Kuen-Yu Tsai

Publications (12) View all

• Article: In situ beam drift detection using a two-dimensional electron-beam position monitoring system for multiple-electron-beam–direct-write lithography

  Sheng-Yung Chen, Kuen-Yu Tsai, Philip C. W. Ng, Hoi-Tou Ng, Chun-Hung Liu, Yu-Tian Shen, Chieh-Hsiung Kuan, Yung-Yaw Chen, Yi-Hung Kuo, Cheng-Ju Wu, Jia-Yush Yen
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  ABSTRACT: Electron-beam lithography is one of the promising candidates to replace optical projection lithography due to its high resolution and maskless direct-write capability. In order to achieve the throughput requirement for high-volume manufacturing, miniaturized electro-optics elements are utilized to drive massively parallel beams simultaneously. In high-throughput multiple-electron-beam systems, beam positioning drift problems can become quite serious due to several factors such as thermal distortion and fabrication errors of electron optics. In single-beam systems, periodic recalibration with reference markers on the wafer can be utilized to achieve beam placement accuracy. This technique is not easy for multiple-beam systems. In this article, an innovative in situ two-dimensional electron-beam position monitoring system for multiple-electron-beam lithography is studied. An array of miniaturized electron detectors to measure scattered electrons from the substrate is placed above the wafer. It is assumed that the detector array signals are correlated with the distribution of electron trajectories, and the change of trajectory distortion due to the beam drift can be predicted by Monte Carlo electron-scattering simulation. A standard quadrant detection (SQD) method and a linear least-squares (LLS) method are used to estimate the beam drift from the detector array signals. Simulation results indicate that while the estimation uncertainty of both methods can be reduced substantially when the number of detected electrons is large enough. The LLS method always outperforms the SQD one regardless the detected electron numbers.
  Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 08/2011; · 1.34 Impact Factor
• Article: Impact of Process-Effect Correction Strategies on Variability of Critical Dimension and Electrical Characteristics in Extreme Ultraviolet Lithography

  Philip C. W. Ng, Sheng-Wei Chien, Bo-Sen Chang, Kuen-Yu Tsai, Yi-Chang Lu, Jia-Han Li, Alek C. Chen
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  ABSTRACT: The conventional correction strategy used to compensate for imaging errors in extreme ultraviolet (EUV) lithography is accomplished by incorporating independent corrections in which rule-based corrections are used to compensate for EUV-specific imaging effects such as mask shadowing, and a model-based correction is used to compensate for proximity effects. Because most rule-based corrections are empirically developed by using simple Manhattan patterns, some of the simplified approximation approaches would not be applicable in a circuit layout with complicated geometric patterns. These kinds of approximation approaches can lead to ineffective corrections of EUV-specific imaging effects, resulting in inaccurate patterns printed on a wafer which will significantly alter the electrical characteristics of fabricated circuits. In order to prevent the problems due to rule-based corrections, a promising correction strategy has been proposed to simultaneously deal with EUV-specific imaging effects and proximity effects. In this study, the impact of two different correction strategies on the critical dimension (CD) variation caused by defocus and the deviation of electrical characteristics from the design intent is explored. Numerical experiments indicate that the variability of CD and electrical characteristics is significantly improved by the proposed correction strategy.
  Japanese Journal of Applied Physics 05/2011; 50(6). · 1.06 Impact Factor
• Article: Stochastic simulation of photon propagation in Si for extreme-ultraviolet mask-defect inspection

  Ting-Hang Pei, Kuen-Yu Tsai, Jia-Han Li
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  ABSTRACT: Extreme-ultraviolet (EUV) light is used to inspect the Si photomask by analyzing the reflective photons. We demonstrated the re-emitting EUV photons from the flat Si surface and a two-dimensional semicircular Si defect by using the Monte Carlo method with a Gaussian phase function, respectively. The results of a model based on the Feynman path integral matches those of the Monte Carlo method very well by multiplying a correction function. The intensity of re-emitting photons from the defect can offer enough signals at the angle intersecting the surface less than 20°.
  Applied Physics Letters 08/2010; 97(6):061108-061108-3. · 3.84 Impact Factor
• Conference Proceeding: A new method to improve accuracy of parasitics extraction considering sub-wavelength lithography effects.

  Kuen-Yu Tsai, Wei-Jhih Hsieh, Yuan-Ching Lu, Bo-Sen Chang, Sheng-Wei Chien, Yi-Chang Lu
  Proceedings of the 15th Asia South Pacific Design Automation Conference, ASP-DAC 2010, Taipei, Taiwan, January 18-21, 2010; 01/2010
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  Available from: Kuen-Yu Tsai

  Conference Proceeding: A new method to improve accuracy of leakage current estimation for transistors with non-rectangular gates due to sub-wavelength lithography effects.

  Kuen-Yu Tsai, Meng-Fu You, Yi-Chang Lu, Philip C. W. Ng
  2008 International Conference on Computer-Aided Design (ICCAD'08), November 10-13, 2008, San Jose, CA, USA; 01/2008