Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory
We consider the lead time of priority lots in a semiconductor factory. The main cause of delays is waiting for repairs of failed machines, and the failures are mainly caused by power disturbances. This can be modeled as an exogenous time-dependent failure process, and we develop a probabilistic mode...
| Main Author: | |
|---|---|
| Format: | Working Paper |
| Language: | en_US |
| Published: |
Massachusetts Institute of Technology, Operations Research Center
2004
|
| Online Access: | http://hdl.handle.net/1721.1/5226 |
| _version_ | 1826191679030296576 |
|---|---|
| author | Bonvik, Asbjoern M. |
| author_facet | Bonvik, Asbjoern M. |
| author_sort | Bonvik, Asbjoern M. |
| collection | MIT |
| description | We consider the lead time of priority lots in a semiconductor factory. The main cause of delays is waiting for repairs of failed machines, and the failures are mainly caused by power disturbances. This can be modeled as an exogenous time-dependent failure process, and we develop a probabilistic model of the system based on this. Using this model, a convolution algorithm for finding the lead time distribution is described. We describe a method of creating synthetic samples of the lead time from historical failure and repair data collected in the factory. Based on such a sample from the MIT Integrated Circuits Laboratory, we approximate the distribution of lead times by a gamma probability density function shifted by the smallest possible lead time for the product type. The parameters of the gamma distribution are found by using a maximum likelihood estimator. The resulting distribution gives good agreement with the synthetic data for values less than two standard deviations above the mean lead time. Since our procedure only depends on a description of the process and the failure and repair history of the factory, it can also be used to obtain lower bounds on the lead time for new product types. |
| first_indexed | 2024-09-23T08:59:39Z |
| format | Working Paper |
| id | mit-1721.1/5226 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:59:39Z |
| publishDate | 2004 |
| publisher | Massachusetts Institute of Technology, Operations Research Center |
| record_format | dspace |
| spelling | mit-1721.1/52262019-04-10T20:07:24Z Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory Bonvik, Asbjoern M. We consider the lead time of priority lots in a semiconductor factory. The main cause of delays is waiting for repairs of failed machines, and the failures are mainly caused by power disturbances. This can be modeled as an exogenous time-dependent failure process, and we develop a probabilistic model of the system based on this. Using this model, a convolution algorithm for finding the lead time distribution is described. We describe a method of creating synthetic samples of the lead time from historical failure and repair data collected in the factory. Based on such a sample from the MIT Integrated Circuits Laboratory, we approximate the distribution of lead times by a gamma probability density function shifted by the smallest possible lead time for the product type. The parameters of the gamma distribution are found by using a maximum likelihood estimator. The resulting distribution gives good agreement with the synthetic data for values less than two standard deviations above the mean lead time. Since our procedure only depends on a description of the process and the failure and repair history of the factory, it can also be used to obtain lower bounds on the lead time for new product types. 2004-05-28T19:28:59Z 2004-05-28T19:28:59Z 1994-05 Working Paper http://hdl.handle.net/1721.1/5226 en_US Operations Research Center Working Paper;OR 293-94 1545854 bytes application/pdf application/pdf Massachusetts Institute of Technology, Operations Research Center |
| spellingShingle | Bonvik, Asbjoern M. Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory |
| title | Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory |
| title_full | Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory |
| title_fullStr | Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory |
| title_full_unstemmed | Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory |
| title_short | Estimating the Lead Time Distribution of Priority Lots in a Semiconductor Factory |
| title_sort | estimating the lead time distribution of priority lots in a semiconductor factory |
| url | http://hdl.handle.net/1721.1/5226 |
| work_keys_str_mv | AT bonvikasbjoernm estimatingtheleadtimedistributionofprioritylotsinasemiconductorfactory |