以臭氧去除光阻的機制研究

Abstract

以臭氧去除光阻的機制研究 研究生：陳志偉 指導教授：羅正忠 博士 國立交通大學 電子工程學系 電子研究所碩士班 摘 要 臭氧已被研究於替代傳統半導體工業中以硫酸/雙氧水溶液去除顯影後晶片表面殘餘光阻的製程，由研究結果顯示出臭氧能夠快速將光阻清除，因此具有應用於半導體製程中的價值。但是相關研究中對臭氧在去光阻反應中的機制缺乏系統性的說明。本論文即是來探討這些反應的機制，用以提出更佳的製程條件以增加反應速率、減少製程時間、降低生產成本。 一開始我們先提出臭氧與光阻間擴散層理論來說明掌控兩者反應速率的機制。驗證的方式先藉由臭氧溶於水以產生臭氧水與晶片上光阻的化學反應速率變化結果探討。實驗中我們控制臭氧水的臭氧濃度、流量、及PH值研究臭氧分子在擴散層間流量變化。由結果顯示，水中臭氧具有快速的氧化能力，因反應受限於臭氧分子的擴散，因此需要提高水中臭氧濃度來提高反應速率；這是因為臭氧分子與光阻反應時，需藉由水中臭氧分子擴散至光阻層表面，因此，要提高反應速率必須增加水中臭氧與光阻之間擴散層的分子擴散速率。在這個製程下，提高光阻表面的臭氧擴散速率是這個製程的主要關鍵。 最後，我們藉由超音波震盪等機械方式來加速臭氧與光阻的反應速率。不同於提高臭氧濃度來加速擴散速率，這個方式是利用縮小整個擴散層的厚度以加速反應的進行。我們發現可大幅提高臭氧與光阻的反應速率，有效的縮短製程時間。由實驗的結果歸納，提高臭氧水中濃度，降低水中PH值，並配合超音波震盪等方式可使臭氧有效綠地清除光阻。

The Study of Photoresist Removal Mechanism by Ozone Student：Ji-Wei Chen Advisor：Dr. Jen-Chung Lou Department of Electronics Engineering & Institute of Electronics National Chiao Tung University Abstract Ozone has been studied in replacement of the mixture of sulfuric acid and peroxide used to remove residual photoresist after lithography in traditional IC process. Researches indicated that ozone is capable of quickly stripping photoresist so that ozone may be beneficial to apply in IC process. Due to the lack of systematic illustrations related to the photoresist removal mechanism by ozone, we will thoroughly investigate this mechanism so that we can propose the better conditions of photoresist stripping process to increase the reaction rates, reduce process time and cost of ownership. In the beginning, we proposed mechanism of diffusion layer between ozone and photoresist to illustrate the key point of the reaction rates. In experiments, we changed the aqueous ozone concentrations, flow rate of ozonated water, and [OH－] to study the mass transfer of ozone through the boundary layer. The results indicated that although aqueous ozone is strong oxidant aqueous ozone concentration should be raised to increase the reaction rate limited by ozone diffusion. The reactions of ozone with photoresist take place by the mass transfer of ozone to the photoresist so the increase of mass transfer of ozone is necessary. In photoresist stripping process, it is critical to raise mass transfer of ozone to the photoresist through the diffusion layer. At last, we increased the reaction rates by megasonic agitation or stirring. Instead of raising the aqueous ozone concentrations, we conducted the reduced diffusion layer to increase the mass transfer so that a faster reaction rate was achieved. In conclusion, raising the aqueous ozone concentrations, reducing [OH－], plus megasonic agitation can effectively remove the photoresist.