Capacity planning model: The important inputs, formulas, and benefits

In today's world, as the need and demand for semiconductor products increases, the goals of a high volume manufacturing facility are to supply customers and to stay economically competitive. To accomplish this, full factory utilization and efficient product mixing is required. Wider product range and the ability to be flexible to variations of product mixes are main factors in gaining market share and profit maximization. White Oak Semiconductor (located in Richmond, VA) is a DRAM manufacturing facility of Infineon Technologies AG (Munich, Germany). Since White Oak Semiconductor was founded in 1997, the demand of the DRAM market has caused the factory to set ever-higher output goals and to far exceed the original planned capacity. These outputs and goals are only achievable with careful planning of equipment capacity, equipment utilization, and continuous verification of achieved throughput versus planned throughput. Using Microsoft Excel (TM) a capacity prediction model was developed to fulfill the planning requirements. Input parameters for this model include: tool availability, tool utilization, process throughput (in wafers per hour), numbers of tools, and product mix predictions. The model is a working document that constantly changes due to process changes (throughput, equipment set), product mix, and total wafer starts per week. Once the inputs are entered, tool need can be calculated out per process and per technology and overall wafer starts per week capacity is calculated. By using multiple worksheets and the graphing features of Microsoft Excel (TM), the effects of tool availability, tool utilization, process throughput, numbers of tools, and product mix can easily be seen. This paper describes the creation of the capacity planning model and how it has been and will continue to be an important part of the success of the ramp-up of a high volume semiconductor manufacturing facility.