This definition produces a dynamic weight function having the desired properties, i.e., γ→ 0 if W >>τandγ→ 1 if W <<τ.
Observe that PSA+ may not be defined for all lots. In particular, if the lot is at a bottleneck step or at a step at the end of the process, for which there is no future visit to the bottleneck, the priority function is undefined. For these two exceptions lots are displaced according to SRPT.
8.TB+(Lou and Kager, 1989)
If the actual output of each layer < expected output and actual inventory of each layer < predetermined inventory level, the job will be a candidate. The candidates have the largest value of weight of product × weight of layers × difference in output will be assigned high priority.
2.4 Rework Rules
1. Lock-step(Zager, 1995)
In this rule, the child lot must be defaulted as a hot lot that can directly be reworked in photolithography process without having to enter the queuing line.
The mother lot shall wait to remerge with the child lot to become the original lot when rework is completed before continuing with the follow-up processes.
Since the mother lot needs to wait for the rework on child lot, the total processing time for the wafer lot will be extended significantly.
2. Lot-split (Zager, 1995)
In this rule, the mother lot shall continue with follow-up processes without having to wait for the child lot. Since the mother lot does not need to wait for the child lot, the child lot remains as an ordinary lot without having to be defaulted as a hot lot and shall enter the queuing line waiting to be reworked.
The reworked child lot will become a new independent lot to proceed with the follow-up processes.
3. Rendezvous (Sha et al. 2001)
The mother lot does not need to wait for the child lot in order to shorten the processing time and the child lot shall be defaulted as a hot lot without
having to queue up for rework in order to remerge with the separated mother lot. So, the mother lot shall proceed with follow-up processes and the child lot shall be reworked immediately after they separate. The child lot shall then follow the original mother lot to the next process where they shall remerge into the original lot.
附錄三、LIST OF PREDICTION FACTORS
Main Class Subclass Factors
1.1 Shop status (8)
1. total WIP in the shop
2. total remaining workload in the shop 3. total WIP of DRAM in the shop 4. total WIP of SRAM in the shop 5. total WIP of LOGIC in the shop
6. total remaining workload of DRAM in the shop 7. total remaining workload of SRAM in the shop 8. total remaining workload of LOGIC in the shop 1. System Condition
1.2 Bottleneck status (10)
9. number of lots in the bottleneck
10. total remaining workload in the bottleneck
11. total remaining workload of DRAM in the bottleneck 12. total remaining workload of SRAM in the bottleneck 13. total remaining workload of LOGIC in the bottleneck 14. total WIP of DRAM in the bottleneck
15. total WIP of SRAM in the bottleneck 16. total WIP of LOGIC in the bottleneck
17. number of shot-down machine in the bottleneck 18. total remaining workload of the bottleneck in the shop
Main Class Subclass Factors
1.System Condition 1.3Constraint resource status (50)
19. number of WIP in the IMPLANTER_H 20. number of WIP in the RCA_CLEAN 21. number of WIP in the GATE_OXIDE 22. number of WIP in the LPCVD_POLY 23. number of WIP in the N_DOPE
24. total remaining workload in the IMPLANTER_H 25. total remaining workload in the RCA_CLEAN 26. total remaining workload in the GATE_OXIDE 27. total remaining workload in the LPCVD_POLY 28. total remaining workload in the N_DOPE 29. the WIP of DRAM in the IMPLANTER_H 30. the WIP of SRAM in the IMPLANTER_H 31. the WIP of LOGIC in the IMPLANTER_H 32. the WIP of DRAM in the RCA_CLEAN 33. the WIP of SRAM in the RCA_CLEAN 34. the WIP of LOGIC in the RCA_CLEAN 35. the WIP of DRAM in the GATE_OXIDE 36. the WIP of SRAM in the GATE_OXIDE
Main Class Subclass Factors
1.System Condition 1.3 Constraint resource status (50)
37. the WIP of LOGIC in the GATE_OXIDE 38. the WIP of DRAM in the LPCVD_POLY 39. the WIP SRAM in the LPCVD_POLY 40. the WIP LOGIC in the LPCVD_POLY 41. the WIP of DRAM in the N_DOPE 42. the WIP of SRAM in the N_DOPE 43. the WIP of LOGIC in the N_DOPE
44. total remaining workload of DRAM in the IMPLANTER_H 45. total remaining workload of SRAM in the IMPLANTER_H 46. total remaining workload of LOGIC in the IMPLANTER_H 47. total remaining workload of DRAM in the RCA_CLEAN 48. total remaining workload of SRAM in the RCA_CLEAN 49. total remaining workload of LOGIC in the RCA_CLEAN 50. total remaining workload of DRAM in the GATE_OXIDE 51. total remaining workload of SRAM in the GATE_OXIDE 52. total remaining workload of LOGIC in the GATE_OXIDE 53. total remaining workload of DRAM in the LPCVD_POLY 54. total remaining workload of SRAM in the LPCVD_POLY 55. total remaining workload of LOGIC in the LPCVD_POLY 56. total remaining workload of DRAM in the N_DOPE 57. total remaining workload of SRAM in the N_DOPE 58. total remaining workload of LOGIC in the N_DOPE 59. number of shot-down machine in the N_DOPE
60. number of shot-down machine in the IMPLANTER_H
Main Class Subclass Factors
1.3 Constraint resource status (50)
61. number of shot-down machine in the RCA_CLEAN 62. number of shot-down machine in the GATE_OXIDE 63. number of shot-down machine in the LPCVD_POLY 64. total remaining workload of IMPLANTER_H in the shop 65. total remaining workload of RCA_CLEAN in the shop 66. total remaining workload of GATE_OXIDE in the shop 67. total remaining workload of LPCVD_POLY in the shop 68. total remaining workload of N_DOPE in the shop 1.System
Condition
1.4 Recently completed orders (8)
69. average flow time of three lots which had only just finished
70. average flow time (three lots) of SRAM, which had only just finished.
71. average flow time (three lots) of DRAM, which had only just finished.
72. average flow time (three lots) of LOGIC, which had only just finished.
73. average waiting time (three lots) in the shop which had only just finished
74. average waiting time (three lots) of DRAM in the shop which had only just finished
75. average waiting time (three lots) of SRAM in the shop which had only just finished
76. average waiting time (three lots) of LOGIC in the shop which had only just finished
Main Class Subclass Factors
2.Order Characteristics (8)
77. total workload of the order
78. total workload on the bottleneck of the order 79. total workload on the IMPLANTER_H of the order 80. total workload on the RCA_CLEAN of the order 81. total workload on the GATE_OXIDE of the order 82. total workload on the LPCVD_POLY of the order 83. total workload on the N_DOPE of the order
84. product type of the order (1.DRAM, 2.SRAM 3.LOGIC)
3.1 PSP status (4)
85. number of lots in the pre-shop-pool
86. number of lots of DRAM in the pre-shop-pool 87. number of lots of SRAM in the pre-shop-poop 88. number of lots of LOGIC in the pre-shop-poop
3.PSP Condition
3.2 Recently Completed orders (4)
89. average waiting time (three lots) in the pre-shop-pool which had only just finished
90. average waiting time (three lots) of DRAM in the pre-shop-pool which had only just finished
91. average waiting time (three lots) of SRAM in the pre-shop-pool which had only just finished
92. average waiting time (three lots) of LOGIC in the pre-shop-pool which had only just finished
附錄四、LIST OF WORKSTATIONS IN THE WAFER FAB.
Workstation No. of
machine Workstation No. of
machine Workstation No. of machine .total of workstation is 87, total of machine is 488
.Total Output per month=46,000 pcs