以Alignment mark的選擇作為改善黃光製程上的OVL budget之研究

Abstract

學生在半導體製造工作有七年的經驗，工作以來全部浸淫在黃光微影製程的環境裡。半導體黃光製程的重心一直以來都在於線寬的縮小，眾多的論文研究無不在討論如何縮小線寬、提高解像力、增加景深(DOF depth of focus)。所以眾多相關的技術被開發出來，例如：OPC光罩、短波長雷射的應用、新光阻開發、泡水機(immersion)的出現。 的確在製程開發之初是線寬的縮小是個大挑戰，但是在產品到生產線上大量生產時，與本層與前層的重合對準不佳的問題佔了每天不良貨(NG lot)六、七成的比重。這也是學生在半導體工廠每天重複不斷遇到最多的問題。 本篇論文是在這樣子的出發點下寫出。希望藉由對準指標(alignment mark)與重合指標(overlay mark)的選取，來趨近實際產品的重合趨勢。以期達到增加積體電路在本層疊對前層時的對準的能力，從而減少不良產品(NG lot)的出現及重工(rework)，提升有效產能及品質。 學生論文提出二個可能是增加重合餘裕的方法，希望能作為以後重合指標(overlay mark)選取或者是本層前層機台間配對(machine mix matching)的參考。

I have worked about seven years experiment in semiconductor manufacture. All jobs are related to the photolithography process. The point about semiconductor photolithography process is the shrinkage of the line pitch. Numbers of articles have been devoted to the study of how to reduce the line pitch, enhanced the resolution, increase the DOF (depth of focus). Thus numerous technology have been developed, example of those are: OPC (optical proximity correction) reticle, application of short wavelength LASER, development of new photo resist, appearance of immersion scanner. It is really a huge challenge that shrink the line pitch at the beginning of the new photolithography process develop, however, when the product release to the manufacture line for mass production, there are sixty to seventy percentages of the trouble lots is the current layer is not fine overlap to the previous layer. This is I met the most problems in the manufacture FAB repeatedly everyday. This thesis is been written with this staring-point. I wish by the selection of the alignment marks and overlay marks to approach the products overlay trend for achieving an objective that increases the overlay ability of current layer aligns previous layer. And thereupon, diminish the NG lot and lot rework to improve the effective throughputs. This thesis provides two methods which might actually improve the overlay margin. It is a chance to be a consult of overlay mark selection or current layer to previous layer machine mix and matching.