Improving the Cycle Time of Semiconductor Manufacturing
- Detailed Technology Description
- This technology is an algorithm used for scheduling semiconductor wafer fabrication in multiproduct manufacturing plants.
- Countries
- United States
- Application No.
- 5706200
- *Abstract
-
This technology is an algorithm used for scheduling semiconductor wafer fabrication in multiproduct manufacturing plants. This new method prioritizes the processing of competing, incomplete lots by available tools at a workstation.
DESCRIPTION/DETAILS
This technology is software containing an algorithm used for computerized scheduling in wafer fabrication plants that manufacture multiple products. It efficiently schedules the wafer lots and reduces the mean cycle time as well as its variance. This is done by more efficient prioritization of competing lots for processing by available tools at workstations.
How It Works
One of the common methods of mass production used in the semiconductor industry is a process called re-entrant line processing. In this method, each incomplete product, in the form of numerous wafers, is conveyed through a series of workstations while undergoing several cycles of cleaning, oxidation, deposition, metallization, etching, ion implantation, stripping, etc., before completion. At any particular time in the process, the buffers for the various workstations may contain many incomplete products in varying stages of completion, vying for the same finite resources. This new technology uses a new policy to generate a priority variable for each waiting lot. In addition, this method adapts itself to actual changes in production system performance. It does not require a model of the plant; rather, all it requires is the sequence of stations visited by various lot types.
Why It Is Better
This technology provides a scheduling method that can be used in multiple-product production or fabrication. It does not require fabrication plant modeling before application. Existing methods also are particularly sensitive to discrepancies between simulation models and actual systems and cannot be easily adapted to change. This new technology is more robust, stable, and adaptable via its use of a normalized slack policy method to determine the priority of each lot waiting the queue.
APPLICATIONS
- Wafer fabrication plant scheduling
BENEFITS
This technology has reduced the average queuing time by roughly 19%, has reduced the standard deviation of the cycle time by approximately 49%, and has accomplished both simultaneously. By reducing mean cycle time and the variance in cycle time, this technology enables:
- Faster production
- Improved ability to meet due dates
- Decreased work in process
- Faster prototyping
- Shorter response time to market
- Decreased product costs
- Increased product yield
- Reduced exposure to contaminants in manufacturing
For more information about this technology, please contact the University of Illinois at Urbana-Champaign Office of Technology Management at otm@illinois.edu.
- *IP Issue Date
- None
- *IP Type
- Utility
- Country/Region
- USA
