Case study : Wafer Map Study to Reduce Electrical Parameters Variation – (Semiconductor)
Electrical properties of wafer are tested at the end of manufacturing process to determine the yield of final product. Electrical parameter measurements such as drive current, threshold current, leakage current etc. need to be within their specifications. Out of spec wafer can lead to scrap. A study is conducted by a process engineer to reduce electrical parameter variations.
Base on the e-test results, wafer map (contour plot) is created through JMP 9 software to analyze the variation of various electrical parameters. One of the parameters which is leakage current (LCH 250) is analyzed as follow :
Interpretation of Analysis Results
The wafer map (contour plot) is a convenient representation of the variation in performance across the wafer, since the distribution of those variations may be a clue as to their cause. As indicates above, the red color zone indicates that the value of LCH 250 is above 4.6. The location of the red zone can become an important clue for process engineer to find out the possible root causes of excessive electrical parameters variation.