在現今之半導體製造業裡，對於元件的微小化，製造的尺寸也越來越小，因此製程的準確度要求要越來越高，晶圓經過電性的測試(WAT)，用來判斷產品的品質好壞。WAT的英文全名是 Wafer Acceptance Test，晶圓接受測試，它是晶圓在完成製程前, 能否從晶圓廠出貨到下一流程的依據。
主要是測試擺在晶圓切割道上的測試， 測試鍵通常設計有許多元件， 如: N型(NMOS)及P型(PMOS)電晶體的電容，電阻，飽和電流(Saturated current,Isat)，臨限電壓(threshold voltage ,Vt)，P contact， Poly contact，Metal line，...。
半導體廠在某特定幾個製程結束後會有抽樣量測的動作，量測晶圓與此製程相關位置的長度、寬度、深度(Critical dimension ,CD)，作為該製程晶圓品質的依據，在某些製程沒有量測。
我們採用多變項共變異分析(MANCOVA)，以找到的重要參數及對電性有影響的CD當作共變數，並且以較有影響的製程機台為因子建立模型。

[1] Braatz,R. et al ,Multiscale systems engineering with application to microelectronics ,in:AIChE Annual Meeting ,San Francisco ,CA,2003
[2] Burnett ,D. et al, Implications of Fundamental Threshold Voltage Variations for High-Density SRAM and Logic Circuits .
[3] Cherry, G. et al , Multiblock principle component analysis base on a combined index for semiconductor fault detection and diagnosis , IEEE Trans. Semi. Manuf. ,submitted for publication.
[4] Garling, L.K. , Woods, G.P. , Enhancing the Analysis of Variance (ANOVA)Technique with Graphical Analysis and its Application to Wafer Processing Equipment , IEEE TRANSACTIONS ON COMPONENTS. HYBRIDS, AND MANUFACTURING TECHNOLOGY-PART A, VOL. 17, NO. 1, MARCH 1994 .
[5] KAMATA,Y. et al, Influences of Annealing Temperature on Characteristics of Ge p-Channel Metal Oxide Semiconductor Field Effect Transistors with ZrO2 Gate Dielectrics , Japanese Journal of Applied Physics , Vol. 45, No. 7, 2006, pp. 5651–5656
[6] McCray, T.A. et al, Stepwise Regression for Identifying Sources of Variation in a Semiconductor Manufacturing Process , IEEE Advanced Semiconductor Manufacturing Conference ,2004
[7] Pierret ,R.F. , SEMICONDUCTOR DEVICE FUNDAMENTALS , School of Electrical and Computer Engineering Purdue University.
[8] Saito ,K. et al, Application of Statistical Analysis to Determine the Priority for Improving LSI Technology , IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING, VOL. 5. NO. I , FEBRUARY 1992 .
[9] Spanos, C.J. ,Coping with variability in semiconductor manufacturing ,in:AIChE Annual Meeting , Austin , TX ,2004
[10] Qin ,S.J. et al ,Determining the number of principal components for best reconstruction ,Journal of Process Control 10(2000) 245-250 .
[11] Qin ,S.J. et al , Semiconductor manufacturing process control and monitoring :A fab-wide framework ,Journal of Process Control ,16 179-191,2006
[12] 黃俊英，多變量分析，華泰圖書文物公司，1986
[13] 呂學士，半導體製程，台北圖書有限公司，2003
[14] 吳宗正，變異數分析-理論與應用，華泰書局，1999