| 摘要: | 光罩製造過程中，接觸窗層(Contact Hole Layer)是一種以正方形孔洞圖形為主的層別，有時候因為曝光、顯影或蝕刻過程的微塵粒子污染因素，導致應該曝寫出來的圖形未曝出，稱之為瞎窗(Missing Contact Hole)。 使用特定的缺陷修補(Defect Repair)機台修補後，該缺陷的關鍵尺寸(Critical Dimension, CD)雖符合光罩出貨品質規格，但晶圓廠使用光罩曝寫晶圓片時，往往未能找到可以工作的適當照射-離焦範圍(Exposure-Defocus Window, E-D Window)，造成光罩必須報廢與重新製作，影響成本的損失與晶圓廠生產作業的延遲。 本文提出一種「過度修補(Over Repair)」的方法，藉由增加修補的次數或提高修補的能量，來改善瞎窗缺陷修補後的外形，並解決原本瞎窗缺陷修補後仍無法達到預期使用功能的問題。 本實驗使用SEIKO/SIR-3000X及FEI/Accura 850兩種不同條件的聚焦離子束(Focus Ion Beam, FIB)修補機台，針對瞎窗缺陷採取過度修補(比修補機台原本計算與定義的正常修補次數或能量還要高)方法，研究在不同條件下過度修補結果的特性，並使用模擬成像機台(Aerial Image Measurement System, AIMS)進行模擬，探討關鍵尺寸(CD)、光強度(intensity)與照射-離焦範圍(E-D Window)的差異，找出修補瞎窗缺陷的最佳條件，該條件可提供晶圓廠曝寫晶圓片時最寬裕的製程空間。 從實驗結果得知，我們得到以下的結論：對於SEIKO/SIR-3000X修補機台來說，採取掃描次數增加約74%左右的過度修補方法，可得到最佳化的照射-離焦範圍；相較之下，FEI/Accura 850修補機台，目前由機台自行計算與定義的修補條件已是最佳化，無需採用過度修補方法來進行改善。 未來我們將應用本文的結論於光罩瞎窗缺陷修補作業，改善特定聚焦離子束修補機台對於瞎窗缺陷的修補結果，並提升修補機台的效能。 In mask manufacture,“Contact Hole Layer” is a hole layer which has square shape used for pattern design. Sometimes it is not well exposed because of particle issue come from exposure, develop or etching process, and we call it “Missing Contact Hole”. Although the Critical Dimension(CD) value for the repaired defect meets mask shipping specification after repaired the missing contact hole by specific repair tools, it is still a main issue to find a suitable Energy-Defocus Window(E-D Window) for wafer exposure in wafer fabrication(Fab). The impacts will lead to extra mask remaking needed, mask scrapped, cost increased, and wafer production delay. In the thesis we brought up an ”Over-Repair” idea. By means of increasing repair times or repair energy to improve repaired missing contact hole profile, the idea also solve the existing problem on failing to provide expected function as normal pattern by repaired missing contact hole. We use two different Focus Ion Beam(FIB) repair tools, and apply “Over-Repair”(The repair frequency or dosage is more than “Normal Repair” which is calculated and defined by repair tool itself.) method on programmed defects, to study the characteristics of different repair conditions. Then we use Aerial Image Measurement System (AIMS) simulation tool to confirm the difference of CD, intensity and E-D window, and find out the best condition for missing contact hole repairing in mask manufacture. This condition will provide ample space for wafer exposure process window in Fab. According to the experiment result, we have a conclusion as follows: For SEIKO/SIR-3000X repair tool, we could get the best E-D Window condition by increasing repair frequency about 74%. For FEI/Accura 850 repair tool, the repair condition calculated and defined by repair tool itself is already the best condition for missing contact hole repairing, it is no need to implement over repair method. In the future we will apply our conclusion on missing contact hole repairing, to improve repair result for specific FIB repair tool, then enhance the efficiency of repair tools. |
