1. CASE 2010 Analysis of Circular Cluster Tools: Transient Behavior and Semiconductor Equipment Models Analysis of Circular Cluster Tools: Transient Behavior and Semiconductor Equipment Models Younghun Ahn and James R. Morrison, Department of Industrial and Systems Engineering, KAIST, Daejeon, KoreaMotivation Semiconductor wafer fabrication is arguably the most complex of manufacturing processes with facility costs rising toward US $4 billion. Anticipate an increase in transient behavior, but little research focus. Want rigorous models of wafer cycle time in cluster tool that include wafer transport robot and address transient behavior. System Description Concluding Remarks Exact equation: Transient analysis is possible. Cyclic approximation has less errors than existing approximations (PMGC, PM approximation). Our models are good candidates for use in semiconductor manufacturing modeling and simulation. Assumptions Contact Information Younghun Ahn and James R. Morrison, KAIST E-mail: eraan@kaist.edu,eraan@kaist.edu E-mail: james.morrison@kaist.edu CASE 2010 KAIST Websites KAIST general: http://www.kaist.eduhttp://www.kaist.edu Industrial and Systems Engineering: http://iedhcp.kaist.ac.kr/english/main.htmhttp://iedhcp.kaist.ac.kr/english/main.htm xS3D Laboratory: http://xs3d.kaist.edu Wafer available at the input loadlock as soon as the robot is available. Constant robot move time independent of source/destination. The robot proceeds immediately to next action site. Backward sequence in steady state & transition.,. Option 1: Complete simulation Exact & slow. Cycle Time Analysis Options Theorem: Exact equation for the cycle time. Approximation: Cyclic approximation for cycle time. The cycle time in an N chamber cluster tool for W wafers is approximately * T. Perkinson, P. McLarty, R. Gyurcsik, and R. Cavin, “Single-wafer cluster tool performance: An analysis of throughput,” IEEE Transactions Semiconductor Manufacturing, 7(3), pp. 369–373, 1994. * P. van der Meulen, “Linear semiconductor manufacturing logistics and the impact on cycle time,” in Proceedings of the 18th Ann. IEEE/SEMI Adv Semiconduct. Manuf. Conf., Stresa, Italy, 2007. 6 th IEEE Conference on Automation Science and Engineering (CASE) Option 2: Reduced complexity simulation Jump from key event to key event Exact, faster(10x) Option 3: Approximation based on Option 2 More than 99.7% accuracy Even faster(6x) Our contribution Note: Includes robot movement Expresses robot or process bound regions. Existing approximations have 15-30% error. W: The number of wafers, N: The number of chambers, δ: Robot move time, ε: Robot get/put time, ΔR M,0,I (i): Duration of time between the arrival of the robot to the input loadlock on the i th and i+1 th visit, ΔR P,W,O (i): Duration of time between the completion of the put to the output loadlock, Wc i (W j ): Duration of time the robot waits at chamber i before it gets wafer j. Application: Semiconductor wafer cluster tools. Table 2: Percent error in TBLD based on Approximation 1-3 in Example 4. C i : Process chamber (P i is process time of chamber C i ). VEC: Vacuum Exchange chamber. WTR: Wafer Transport Robot (Single gripper robot). Measurement: The average time between lot departures(TBLD). TBLD(i)= min{CT i, E i -E i-1 }. TS (Train size): The number of lots that are run consecutively. Example: The chamber tool model has N=4, P 1 =80, P 2 =70, P 3 =110, P 4 =90, δ =1 and ε=1. Exact solution for TBLD in Example Percent error in TBLD in Example Each approximation is faster than the exact equation (6x, 4x, 60x respectively). PM approximation can give 30% error in robot bound region. Circular cluster tool Our contribution