晶圓邊緣光阻殘留缺陷改善

Improvement of Photoresist Residuals Induced Wafer Edge Defects

葉鎮熠(Chen-Yi Yeh)

指導教授 ： 林佑昇

國立暨南國際大學/科技學院/光電科技碩士學位學程在職專班/碩士(2017年)

摘要

光阻顯影的目的為在維持可接受的光阻黏著性下，於光阻層中正確的複製出光罩中圖案，將具有深次微米及幾何圖案的光阻成功顯影的能力，對於先進IC製程而言，是相當重要的指標之一。本研究針對化學放大型光阻，曝光後顯影製程發生晶圓邊緣產生光阻殘留而做實驗，然而化學放大型光阻則需要曝光後加熱的步驟（通常是以90∼140oC加熱一至二分鐘），才能有效地進行將薄膜溶解度變更的去保護反應。這是因為光阻曝光後所形成的化學物質是一種酸性催化劑，這種物質在曝光後烘烤（Pre-Exposure bake，PEB）的過程中會引發光阻內許多功能群（Functional Group）的反應，而本身卻不會被消耗掉。
不同光阻特性以及曝光圖形密度高低，皆會影響曝完光後溶出光阻的多寡，顯影製程包含顯影液與光阻反應及純水洗淨，本研究是以Rinse次數與顯影的最佳程式加以分析，並利用多次實驗與交叉比對方式尋找最佳Rinse條件，並在實驗過程中密切觀察原圖形的解析度。另外，曝光前後的溫度控制也是必須留意的條件之一，當烘烤溫度較低，表示光阻含溶劑成份較多，此時顯影速度快，對線寬較不易控制；反之，若光阻內溶劑較少，需要更大的曝光能量，對線寬較易控制。且在實驗完成後所得到的缺陷較低，良率與先前比較後，提升了2.8%。

關鍵字

光阻殘留 ； 顯影 ； 化學放大型光阻 ； 純水洗淨

並列摘要

The purpose of photoresist development is to duplicate patterns on masks into photoresist layers and develop the patterns of photoresist accurately when sustaining acceptable adherence of photoresist. For advanced IC processes, this ability is a crucial index. This research focuses on cleaning chemical amplification photoresist remained at wafer edge during development processes after exposure. Chemical amplification photoresist requires a heating step after exposure (normally with temperature between 90 to 140 oC for one to two minutes) to alter the solubility of the film effectively. As the chemical generated after photoresist being exposed is an acid catalyst, this chemical could induce functional group reaction within photoresist during the process of post exposure bake (PEB) and not be consumed.
Different photoresist characteristics and pattern density will affect the amount of photoresist dissolved after exposure. Development processes include developers reacting with photoresist and water clean. This research analyzes the number of times rinsed and the optimal development recipe to seek for the best rinse condition. Resolution of the original patterns was also closely watched during the experiments. Moreover, temperature control before and after exposure also needs to be careful. If the baking temperature is lower, photoresist will contain more solvent and will be developed rapidly. The critical dimension will not be easily controlled. On the other hand, if the photoresist contains less solvent, a higher exposure dose is required and the control of critical dimension could be more easily. After the completion of this experiment, particles are reduced and the yield is improved for 2.8 %.

並列關鍵字

Photoresist residue ； development ； chemical amplification photoresist ； pure water cleaning

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