半導體微影覆蓋誤差的控制策略

Abstract

本論文研究方向為，透過微影製程條件的最佳化，及增加曝光對準精確度來降低微影覆蓋誤差。藉由適當對準策略的應用，對準取樣記號數目選擇及對準取樣記號分佈分散且對稱，可有效增加對準精確度及穩定性，再經由調整曝光機台之設定參數去補償對準覆蓋誤差，進而降低覆蓋誤差，提升產品良率。此外，探討了微影製程條件對微影覆蓋誤差造成影響的可能原因，並透過實驗設計(DOE) 驗證之。我們由實際半導體廠所量得資料，比較不同對準抽樣策略下之覆蓋誤差補償效果，新的對準曝光程式證明比半導體廠現有方式為佳，實驗資料發現可降低36.4%的覆蓋誤差，減少微影製程重工(Rework)率

This paper aimed to minimize the overlay error model by optimizing process factor and increasing the alignment accuracy. We designed the alignment sampling strategies including the number of sampling points and sampling position to increase the alignment accuracy, then, the overlay errors can be corrected by exposure stage and the lens element of equipment. Furthermore, we studied the entire process factors that were overlay related, and optimized the process recipe by DOE methods. We compared the proposed alignment sampling strategy with alternative sampling strategies including the existing alignment strategies based on the model adequacy of alignment and the overlay residual errors. The proposed model and alignment sampling strategy are validated by empirical studies conducted in a fab. From the experiment result we got an excellent overlay improvement .The results demonstrated the practical viability of the proposed approach.