半導體製程中，如清洗、沉積與蝕刻等過程皆需使用氣體。然而，目前多數製程系統主要控制氣體的壓力與流量，對於腔體內氣體分布與狀態變化之監測仍較為不足。隨著元件尺寸逐漸縮小至 2 奈米節點，製程中氣體分布的均勻性對製程結果的影響愈加顯著，因此氣體狀態的精準監測與控制成為關鍵。本研究建立一套光學式氣體折射率量測系統，用以量測半導體製程中腔體內氣體折射率之變化。由於氣體折射率與其密度具有對應關係，因此折射率量測結果可作為後續分析氣體密度變化之參考依據。在實驗設計上，本研究採用波長為 532 nm 的綠光雷射作為光源，並以一對稜鏡作為折射率分析之光學元件。雷射光經過擴束模組後，通過稜鏡與含有待測氣體的半導體腔體，最終聚焦至位置感測器（PSD）上。藉由解析 PSD 的輸出訊號，可得到光斑位置的偏移量，進而換算出氣體折射率的變化，藉此建立可反應反氣體密度變化之折射率量測方法。;Semiconductor processes such as cleaning， deposition， and etching involve the use of gases. However， most existing process systems mainly control the pressure and flow rate of gases， while the monitoring of gas distribution and gas-state variations inside the chamber remains insufficient. As device dimensions continue to scale down to the 2-nm node， the uniformity of gas distribution has an increasingly significant impact on process performance. Therefore， precise monitoring and control of gas conditions have become critical issues. In this study， an optical gas refractive index measurement system is developed to measure the variation of gas refractive index inside semiconductor process chambers. Since the refractive index of a gas is related to its density， the measurement results of refractive index can serve as a reference for subsequent analysis of gas density variation. In the experimental setup， a 532 nm green laser is used as the light source， and a pair of prisms is employed as the optical element for refractive index analysis. After passing through the beam-expanding module， the laser beam propagates through the prisms and the semiconductor chamber containing the target gas， and is finally focused onto a position-sensitive detector (PSD). By analyzing the output signals of the PSD， the displacement of the light spot can be obtained and further converted into the variation of gas refractive index. Accordingly， a gas refractive index measurement method capable of reflecting gas density variation is established.
