Dynamic lot dispatching required turn rate factory control system and method of operation thereof

• US 5,818,716 A
• Filed: 10/18/1996
• Issued: 10/06/1998
• Est. Priority Date: 10/18/1996
• Status: Expired due to Term

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Lin, Kuo-Chen, Wang, Jiann-Kwang, Huang, Sheng-Rong, Chin, Wen-Cheng
• Primary Examiner(s): Voeltz, Emanuel Todd
• Assistant Examiner(s): Musgrove, Richard H.
• Application Number:
  US08/735,059
• Time in Patent Office: 718 Days
• Field of Search: 364/468.01-468.02, 364/468.05-468.12, 364/468.28
• US Class Current: 700/100
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/31395 Process management, specification, process and production data, middle level
• CPC Class Codes: G05B 2219/31407 Machining, work, process finish time estimation, calculation
• CPC Class Codes: G05B 2219/31428 Production management for lot production and for individual components of lot
• CPC Class Codes: G05B 2219/32088 Master production planning, highest level
• CPC Class Codes: G05B 2219/32256 Due dates, pieces must be ready, priority of dates, deadline
• CPC Class Codes: G05B 2219/32266 Priority orders
• CPC Class Codes: G05B 2219/32267 Dynamic throughput maximization
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

In a semiconductor manufacturing fabrication plant with production to-order type operation, hundreds of devices and various processes are managed. To provide short cycle time and precise delivery to satisfy customer expectations is a major task. A dispatching algorithm named "Required Turn Rate (RTR)" functions according to the level of current wafers in process (WIP) algorithm revising the due date for every lot to satisfy the demand from Master Production Scheduling (MPS). Further the RTR algorithm calculates the RTR of each lot based on process flow to fulfill the delivery requirement. The RTR algorithm determines not only due date and production priority of each lot, but also provides RTR for local dispatching. The local dispatching systems of each working area dispatch the lots by using required turn rate to maximize output and machines utilization.

Claims

1. A method of operating an automated factory management of a fabrication plant using a computer with a Master Production Scheduling (MPS) system providing demand information, said method comprising the steps as follows:

providing lot data including a plurality of lot due dates (LDDS) collected from said fabrication plant and stored in A data storage device to a central processing unit and a current Work in Progress (WIP) list,

a) revising each said LDD for a said lot by the steps as follows;

i) calculating the remaining process time to a LDD of said LDDs for each lot,

ii) sorting said current WIP list using said remaining process time to produce a sorted WIP list,

iii) revising said LDDs to satisfy current demand data from said MPS system according to said sorted WIP list,

b) calculating critical ratios (CRs) for said lots, and

c) sorting said lots based upon said critical ratio to determine lot priority, and

d) calculating a required turn rate (RTR) for each lot.

2. A method in accordance with claim 1 wherein said critical ratio between a Due Date and Now is calculated by the formula as follows:

##EQU7##

3. A method in accordance with claim 1 wherein a said Required Turn Rate RTR is determined in accordance with the formula as follows:

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1

where X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU8##

4. A method in accordance with claim 1 wherein said critical ratio is calculated by the formula as follows:

##EQU9## and said Required Turn Rate RTR is determined in accordance with the formula as follows;

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1;

where

X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU10##

5. A method in accordance with claim 1 wherein a plurality of priorities are provided as a function of critical ratios CRs as follows:

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratios.

6. A method in accordance with claim 1 wherein said critical ratio between a Due Date and Now is calculated by the formula as follows:

##EQU11## and a plurality of priorities are provided as a function of critical ratios CRs as follows;

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratios.

7. A method in accordance with claim 1 wherein a said Required Turn Rate RTR is determined in accordance with the formula as follows:

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1, where

X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU12## and a plurality of priorities are provided as a function of critical ratios CRs as follows;

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratios.

8. A method in accordance with claim 1 wherein said critical ratio between a Due Date and Nowis calculated by the formula as follows:

##EQU13## said Required Turn Rate RTR is determined in accordance with the formula as follows;

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1, where

X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU14## and a plurality of priorities are provided as a function of critical ratios CRs as follows;

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratios.

9. A method in accordance with claim 1 wherein said method includes a Master Production Scheduling (MPS) algorithm for revising said lot due dates which commences by sorting of the Work In Progress (WIP) in which the lots being processed are sorted according to said lot due dates,

performing a function choosing the lot with the shortest remaining process time, and if a lot is completed, reporting the fact that a lot is completed on line to an MPS net demand function, said MPS net demand function combining inputs from a current wafer out input and a MPS Demand input,

testing whether said MPS net demand is greater than zero,

when said MPS net demand is not greater than zero, then going to a slow down function which leads back to said function of choosing a lot,

when said MPS net demand is greater than zero, then revising one of said lot due dates as the latest requirement date on said MPS schedule and updating said MPS net demand data function, and

said MPS demand function supplying check demand status data to a reporting and action function.

10. A method in accordance with claim 8 wherein said method includes a Master Production Scheduling (MPS) algorithm for revising said due date which commences by sorting of the Work In Progress (WIP) in which the lots being processed are sorted according to the due date,

performing a function choosing a lot with the shortest remaining process time, and if a lot is completed, reporting the fact that a lot is completed on line to an MPS net demand function, said MPS net demand function combining inputs from a current wafer out input and a MPS Demand input,

testing whether said MPS net demand is greater than zero,

when said MPS net demand is not greater than zero then going to a slow down function which leads back to said function of choosing a lot,

when said MPS net demand is greater than zero then revising one of said lot due dates as the latest requirement date on said MPS schedule and updating said MPS net demand data function, and

said MPS demand function supplying check demand status data to a reporting and action function.

11. A system for operating an automated factory management of a fabrication plant using a computer system with a Master Production Scheduling (MPS) system providing demand information, said method comprising as follows:

means for providing lot data including a plurality of lot due dates (LDDs) collected from said fabrication plant and stored in a data storage device to a central processing unit and a current Work in Progress (WIP) list,

a) means for revising each said LDD for a said lot by the means as follows;

i) means for calculating the remaining process time to the LDD for each lot,

ii) means for sorting said current WIP list using said remaining process time to produce a sorted WIP list,

iii) means for revising said LDD to satisfy current demand data from said MPS system according to said sorted WIP list,

b) means for calculating critical ratios (CRs) for said lots,

c) means for sorting said lots based upon said critical ratio to determine lot priority, and

d) means for calculating a required turn rate (RTR) for each lot.

12. A system in accordance with claim 11 wherein said critical ratio between a Due Date and Now is calculated by the formula as follows:

##EQU15##

13. A system in accordance with claim 11 wherein a said Required Turn Rate RTR is determined in accordance with the formula as follows:

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1, where

X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU16##

14. A system in accordance with claim 11 wherein said critical ratio is calculated by the formula as follows:

##EQU17## and said Required Turn Rate RTR is determined in accordance with the formula as follows;

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1, where

X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU18##

15. A system in accordance with claim 11 wherein a plurality of priorities are provided as a function of critical ratios CRs as follows:

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratio.

16. A system in accordance with claim 11 wherein said critical ratio between a Due Date and Now is calculated by the formula as follows:

##EQU19## and a plurality of priorities are provided as a function of critical ratios CRs as follows;

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratio.

17. A system in accordance with claim 11 wherein a said Required Turn Rate RTR is determined in accordance with the formula as follows:

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1, where

X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU20## and a plurality of priorities are provided as a function of critical ratios CRs as follows;

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratio.

18. A system in accordance with claim 11 wherein said critical ratio between a Due Date and Now is calculated by the formula as follows:

##EQU21## said Required Turn Rate RTR is determined in accordance with the formula as follows;

space="preserve" listing-type="equation">RTR=X.sub.n -X.sub.o +1, where

X_o ;

current stage number

X_n ;

next nth-stage number; and

##EQU22## and a plurality of priorities are provided as a function of critical ratios CRs as follows;

space="preserve" listing-type="tabular">______________________________________ CR order Priority ______________________________________ First 25% 1 25%-50% 2 50%-75% 3 Last 25% 4 ______________________________________

whereby said system has priorities ordered by said critical ratio.

19. A system in accordance with claim 11 wherein said system includes a Master Production Scheduling (MPS) algorithm for revising said lot due dates which commences by sorting of the Work In Progress (WIP) in which the lots being processed are sorted according to said lot due dates,

means for choosing a lot with the shortest remaining process time, and if a lot is completed, reporting the fact that a lot is completed on line to an MPS net demand function, said MPS net demand function combining inputs from a current wafer out input and a MPS Demand input,

means for testing whether said MPS net demand is greater than zero,

means for slowing down when said MPS net demand is not greater than zero then which leads back to said function of choosing a lot,

means for revising one of said lot due dates as the latest requirement date on said MPS schedule and updating said MPS net demand data function when said MPS net demand is greater than zero, and

said MPS demand function supplying check demand status data to a reporting and action function.

20. A system in accordance with claim 18 wherein said system includes a Master Production Scheduling (MPS) algorithm for revising said due date which commences by sorting of the Work In Progress (WIP) in which the lots being processed are sorted according to the due date,

means for choosing a lot with the shortest remaining process time, and if a lot is completed, reporting the fact that a lot is completed on line to an MPS net demand function, said MPS net demand function combining inputs from a current wafer out input and a MPS Demand input,

means for testing whether said MPS net demand is greater than zero,

means for slowing down when said MPS net demand is not greater than zero then which leads back to said function of choosing a lot,

means for revising one of said lot due dates as the latest requirement date on said MPS schedule and updating said MPS net demand data function when said MPS net demand is greater than zero, and

said MPS demand function supplying check demand status data to a reporting and action function.