深紫外光化學放大阻劑性質探討

Abstract

當曝光系統由I-線進展到深紫外光時，傳統Diazo-Novolak阻劑由於在深紫外光波長範圍的透光率太低，已無法適用。含光酸的化學放大阻劑除了改善透光率太低的缺點外，另具有靈敏度高、良好解像度及對比度的優點，是深紫外光光源曝光系統的主要阻劑系統。 本論文利用紫外光光譜儀探討負型化學放大阻劑之反應動力學，利用阻劑內化學活性基在紫外光光譜儀吸收峰的變化作為探討動力學反應的依據。論文主要分為兩部分。一、動力學模型部分：反應機制主要是以曝後烤光酸催化反應及光酸損失反應為基礎。藉由實驗數據求出曝後烤反應速率常數、光酸損失速率常數及反應級數，並探討其物理意義。二、環境安定性部分：對於曝光結束至曝後烤這段時間約延遲（曝後延），由於空氣中微量鹼性物質的擴散作用，會使負型阻劑輪廓產生圓形頂的情形。本論文利用人為的氨氣環境對阻劑的破壞，探討在氨氣破壞下阻劑的反應情形，並嘗試提出以弱酸防止鹼性空氣污染阻劑的方法。 化學放大阻劑是進入0.25微米製程的主流，藉由本論文的探討，對於動力學模型將有進一步的瞭解。本論文並對於曝後延所產生的鹼污染提出弱酸中和法。

When exposure system has advanced from I-line to Deep-UV, traditional Diazo-Novolak photoresist can not be used because of very low transmittance in Deep-UV wave length region. Chemically amplified resist (CAR) could improve the deficiency of lower transmittance, besides, CARs have high sensitivity, good resolution and high contrast, and are the major resist of Deep-UV exposure system. In this thesis, UV spectrometer was used to study the kinetic model of negative-tone chemically amplified photoresist, the change of absorbance of chemically active groups in photoresist were measured as the basis of kinetic reaction study. The thesis contains two parts: 1.Kinetic model: reaction mechanisms were based on the photoacid catalyzed reaction by post exposure bake and photoacid loss reaction. The photoacid catalyzed reaction rate constant, acid loss rate constant and photoacid catalyzed reaction order were obtained by experiments and their physical meanings were studied. 2.Environmental stability: between the exposure and PEB, post exposure delay, the contaminations in air diffusion into the negative-tone resist and induce-the round top profile. The paper studied the photoacid loss by the artificial NH3 contamination and tried to use weak acid to prevent this basic contamination. Chemically amplified resists are the main trend of resist to get into 0.25 micron processes. The kinetic model can be understood further from this thesis. This thesis also proposed the using of weak acid to neutralize basic contamination during post exposure delay.