Cramer, Harlan C.; Spurgeon, Susan P. (1989, ASQC) Westinghouse Electric Corp., Baltimore, MD
Statistical Process Control (SPC) is an essential technique in the reduction of variability. Reduced process variability is required to produce and optimize more complex semiconductor devices. Types of variability related to semiconductor devices are described. A four step program for SPC implementation on a specific, existing process is presented. The steps of the program are demonstrated by application to silicon nitride deposition for ion implantation anneal encapsulation, one of the many processes necessary to build a gallium arsenide monolithic microwave integrated circuit. The work on the nitride deposition process resulted in a 50% decrease in process variability and eliminated a trend that would have jeopardized the product. The clear objective of reducing variability within all processes resulted in saving the cost of SPC implementation within the first eight months of operation due to higher yields and more effective utilization of equipment. The implementation of SPC on the nitride deposition and other processes in the gallium arsenide fabrication area provides a stabilized process base for further development in an emerging product line.