Optimized operations by extended X-factor theory including unit hours concept

Abstract

The relationships between tool performance, cycle time, and throughput have been described to achieve the highest productivity. Though tool utilization is low for manually operated tools, long waits prior to product processing lead to a productivity loss in our production line. We focus on operator efficiency in the CMP (chemical mechanical polishing) operation, which, as a typical manually operated tool, influences cycle time. This paper introduces an online/offline unit hour analysis method, which has been designed to optimize operator allocation and headcount in our production line, using -factor theory in order to achieve the shortest cycle time. By using online/offline unit hour analysis with -factor theory, the root cause of waiting time can be identified and the relationship between operator headcount and cycle time can be described. The waiting time can be reduced by 35% and the cycle time can be reduced by 25%, according to a simulator with optimized operator allocation and headcount based on online/offline unit hour analysis.

Capacity pricing mechanism for wafer fabrication

“…The three stages are explained in detail as follows. Because the production cycle time of wafer fabrication is very long, the ratio of production cycle time to theoretical processing time, or X-factor, is practically adopted to control the production progress (see also Kishimoto et al, 2001). In other words, by using layer theoretical cycle time and X-factor of each order, we can control the processing step in each layer to be finished in a given time.…”

“…Production cycle time for each layer is different due to the difference in machine units, utilization rates, and operation times of the workstation type specified in a product's process plan. The ratio of production cycle time to theoretical processing time of a product is called X-factor, which is usually used as a reference for production progress control (Kishimoto, Ozawa, Watanabe, & Martin, 2001). Therefore, based on X-factor and theoretical processing time of a layer, layer cycle time for a product can be estimated.…”

Long-term tool elimination planning for a wafer fab

“…Kishimoto, Ozawa, Watanabe, and Martin (2001) used manufacturing simulator ''ManSim'' to evaluate the manufacturing performance and modified the basic X-factor equation as follows.…”

An operator staffing and assignment model for foundry fabs

“…The above LP formulation, an extension of a generalized assignment problem (GAP) [10], is distinguished by the inclusion of constraint set Eq. 4.…”