Design of run to run controller with stochastic metrology delay
WANG Hai-yan
PAN Tian-hong
TAN Fei
GAO Zhan-tao
Abstract：Run to run control (RtR) is an effective algorithm for semiconductor manufacturing process. Due to the limitation of measurement methods and cost,it is difficult to measure wafer quality in time(i.e.,metrology delay)during the manufacturing process.In general,metrology delay is random and time-varying,which directly deteriorate the performance of RtR controller. To overcome this issue,a novel disturbance estimation integrated into exponentially weighted moving average(EWMA)algorithm is presented in this paper. Firstly,taking the probability of measurement into consideration, the formulation of disturbance estimation with the probability of metrology delay is established. Then,the probability of metrology delay is estimated by expectation maximization(EM)algorithm.Thirdly,the stability is analyzed and the static offset existing in the system is compensated. As a result,an EWMA algorithm resolving the stochastic metrology delay is formed.Finally,the simulation cases demonstrate the effectiveness of the proposed algorithm.
Keywords：run-to-run controlmetrology delayEWMA algorithmEM algorithm
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：8( 531-538 )