Title :
SHEWMA: an end-of-line SPC scheme using wafer acceptance test data
Author :
Fan, Chih-Min ; Guo, Ruey-Shan ; Chang, Shi-Chung ; Wei, Chih-Shih
Author_Institution :
Dept. of Electr. Eng., Nat. Taiwan Univ., Taipei, Taiwan
fDate :
8/1/2000 12:00:00 AM
Abstract :
In this paper, an end-of-line quality control scheme based on wafer acceptance test (WAT) data is presented. Due to the multiple-stream and sequence-disorder effects typically present in the WAT data, an abnormal process shift caused by one machine at an in-line step may become vague for detection using end-of-line WAT data. A methodology for generating robust design parameters for the simultaneous application of Shewhart and EWMA control charts to WAT data is proposed. This SHEWMA scheme is implemented in a foundry environment and its detection and diagnosis-enhancing capabilities are validated using both numerical derivations and fab data. Results show that the SHEWMA scheme is superior to the current practices in detection speed. Its use is complementary to the existing in-line SPC for process integration
Keywords :
fault diagnosis; integrated circuit manufacture; moving average processes; production testing; quality control; statistical process control; EWMA control charts; SHEWMA; Shewhart control charts; detection speed; diagnosis-enhancing capabilities; end-of-line SPC scheme; foundry environment; multiple-stream effects; numerical derivations; quality control scheme; robust design parameters; sequence-disorder effects; wafer acceptance test data; Analysis of variance; Circuit testing; Control charts; Fabrication; Manufacturing processes; Process control; Quality control; Robust control; Semiconductor device manufacture; Stability;
Journal_Title :
Semiconductor Manufacturing, IEEE Transactions on
