Patent Document ID: 20170083008
Application ID: 14918577
Patent Flag: 0

Claim One:
1. A computer-implemented method for scheduling a tree-like multi-cluster tool to generate a one-wafer cyclic schedule, the multi-cluster tool comprising K single-cluster tools denoted as C i , i=1, 2,. .. , K, the single-cluster tool C i having a robot R i for wafer handling, the multi-cluster tool being decomposable into a plurality of cluster-tool-chains (CTCs) each having a serial topology, an individual CTC consisting of single-cluster tools C i , C i+1 ,. .. C i′ being denoted as CTC[i,i′], the method comprising: determining values of ω ij , i=1, 2,. .. , K, and j=0, 1,. .. , n[i], such that: 
 θ lm =θ aƒ =Θ, m∈Ω n[l] and ƒ∈Ω n[a] ; 
 τ l(b[l,a]) ≧4λ a +3μ a +ω a(n[a]) ; and 
 τ a0 ≧4λ l +3μ l +ω l(b[l,a]−1) ; are satisfied for any pair of C l and C a , in which l, a∈N K , C a being an immediate downstream tool of C l ; wherein: processing steps performed by C i are indexed from 0 to n[i], an initial processing step of C i having an index 0 and being a step of loading a wafer from a loadlock or a buffer module of C i to R i ; b[l,a] is an index denoting a step of putting a wafer in C l to a buffer module shared by C l and C a ; ω ij is a robot waiting time for R i to wait at an m-th step in C i before unloading a wafer held by R i to a next step; 
 θ ij =τ ij +4λ i +3μ i +ω i(j−1) , i∈N K and j∈N n[i] ; 
 θ i0 =τ i0 +4λ i +3μ i +ω i(n[i]) , i∈N K ; Θ is a cycle time of the multi-cluster tool; τ ij is a wafer sojourn time at the j-th step in C i ; λ i is a time taken by R i to load or unload a wafer in C i ; μ i is a time taken by R i to move between process modules of C i for transiting from one processing step to another; N L ={1, 2,. .. , L} for a positive integer L; and Ω L =N L ∪{0}.