TY - GEN
T1 - Scheduling in-line mulitple cluster tools
T2 - 2012 9th IEEE International Conference on Mechatronics and Automation, ICMA 2012
AU - Kim, Hyun Jung
AU - Lee, Jun Ho
AU - Kim, Chulhan
AU - Baik, Sun Hee
AU - Lee, Tae Eog
PY - 2012
Y1 - 2012
N2 - We examine a new scheduling problem of in-line multiple cluster tools. A cluster tool has been popularly used for wafer fabrication processes such as lithography, etching, deposition, and inspection. It consists of several processing modules (PMs), a wafer handling robot, and loadlocks. Each cluster tool also has its equipment front-end module (EFEM) that helps keep the cluster tool in a vacuum state. An EFEM has an aligner, a robot, and loadports where wafer cassettes arrive. Since overhead hoist transfers (OHTs) move wafer cassettes containing 25 wafers between EFEMs and there are a huge number of manufacturing tools in a fab, it is extremely complicated to schedule OHTs. Moreover, an arrival delay of cassettes can cause wafer quality degradation significantly. Therefore, fabs tend to reduce transportation tasks by arranging tools in a line with a buffer. In this paper, we address the new in-line multiple cluster tools' scheduling problem to minimize the makespan of a lot with 25 identical wafers. Since the problem is NP-complete, we decompose it into two parts; a PM assignment problem and a robot task sequence decision problem. We first develop mixed integer programming (MIP) models to decide the number of wafers that each PM processes based on the workloads and to assign each wafer to PMs. With the assignment information, we find a best robot task sequence priority experimentally.
AB - We examine a new scheduling problem of in-line multiple cluster tools. A cluster tool has been popularly used for wafer fabrication processes such as lithography, etching, deposition, and inspection. It consists of several processing modules (PMs), a wafer handling robot, and loadlocks. Each cluster tool also has its equipment front-end module (EFEM) that helps keep the cluster tool in a vacuum state. An EFEM has an aligner, a robot, and loadports where wafer cassettes arrive. Since overhead hoist transfers (OHTs) move wafer cassettes containing 25 wafers between EFEMs and there are a huge number of manufacturing tools in a fab, it is extremely complicated to schedule OHTs. Moreover, an arrival delay of cassettes can cause wafer quality degradation significantly. Therefore, fabs tend to reduce transportation tasks by arranging tools in a line with a buffer. In this paper, we address the new in-line multiple cluster tools' scheduling problem to minimize the makespan of a lot with 25 identical wafers. Since the problem is NP-complete, we decompose it into two parts; a PM assignment problem and a robot task sequence decision problem. We first develop mixed integer programming (MIP) models to decide the number of wafers that each PM processes based on the workloads and to assign each wafer to PMs. With the assignment information, we find a best robot task sequence priority experimentally.
KW - cluster tool
KW - in-line architecture
KW - mixed integer programming
KW - scheduling
UR - http://www.scopus.com/inward/record.url?scp=84867591143&partnerID=8YFLogxK
U2 - 10.1109/ICMA.2012.6284366
DO - 10.1109/ICMA.2012.6284366
M3 - Conference contribution
AN - SCOPUS:84867591143
SN - 9781467312776
T3 - 2012 IEEE International Conference on Mechatronics and Automation, ICMA 2012
SP - 1544
EP - 1549
BT - 2012 IEEE International Conference on Mechatronics and Automation, ICMA 2012
Y2 - 5 August 2012 through 8 August 2012
ER -