Improving process yield by utilizing smart SPC rules
MAX International Engineering Group
Tel: (201) 295-2953
Fax: (201) 295-3255
Keywords: SPC, Quality, Yield Improvement, Operational Controls
The purpose of Statistical Process Control is to create dynamic measures that track our manufacturing, and assures that our process remains stable. Typically, there is a high cost associated with implementing a full-blown SPC mechanism both in system purchasing cost and in management overhead. The article will give an overview of SPC, from original Shewhart charts to more recent SPC schemes like Western electric rules. We will demonstrate that most SPC tools relay on assumptions that are not valid in most compound semiconductors manufacturing fabs. However we will show that by creating good operational process control, and scrutinizing SPC measures it is possible to achieve excellent process control by just staying with a basic set of control charts, such as X Bar and R plotted for specific products, operations, and tools. Furthermore we will show the relationship between reaction times to discrepancy events and overall yield losses. Remembering that our target is to reduce discrepancies and not to manufacture charts is the clear advocate for an operational approach to controls.