| In semiconductor manufacturing,WAT(Wafer Acceptance Test)is the electrical test for various test structures on wafers after all processes finished.WAT test is used to monitor process stability and identify issues from semiconductor manufacturing process so as to help engineers to fine-tune process and improve yield.In view of WAT data importance,we need a set of scientific and effective quality control methods to assist engineers to judge WAT data non-conformance rapidly and precisely.Starting from analyzing current status of WAT control and the deficiency of existing control methods,this study aims to discover a more scientific and effective WAT parameter control method and develop corresponding system to make it use into real production.The paper is divided into three parts: The first part is theoretical deduction and simulation of control method on the basis of using manufacturing data of the past 3 years and 190 WAT parameter types so as to design SPC(Statistical Process Control)control charts suited for WAT.The second part is the verification of control methods by analyzing various WAT parameter types and employing newly-designed SPC charts to control data of the past six months to trace their effectiveness.The last part is BWS(Best WAT Set)system development.Through above data analysis methods and various SPC charts,BWS system is developed to achieve intelligent control and auto identification of WAT parameters and free choice of SPC charts to make corresponding result simulation.BWS system has been put into use since 2016,and we can evaluate the system efficiency according to the data from 2013 to 2016: it can prevent 1825 wafers scrap annually and reduce 52 man-power for routine inspection every month. |
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