結合像散式輪廓儀高度成像之雷射直寫加工系統

Abstract

雷射直寫加工技術(Laser Direct Writing)具有構造簡單、加工快速、可控性高等優勢，是被廣泛運用在進行微奈米尺度下圖案刻劃和精細加工的重要技術；光學輪廓儀相較於接觸式表面輪廓儀，具有速度快、不會傷害樣品、不需使用耗材等優點，因此被廣泛運用在晶圓檢測和生醫工程等領域。其中像散式輪廓儀可使用市售光學讀取頭作為主要量測元件，不僅成本低、體積小，解析度亦相當優秀，可使用聚焦誤差訊號(Focus Error Signal, FES)與Z軸高度位置計算出樣品表面的反射率與高度。現有針對雷射直寫加工系統的加工成果量測，大多使用光學或電子顯微鏡觀察樣品表面影像，鮮少有結合加工與量測的系統可提供即時檢驗。因此本實驗提出一架設在倒立式顯微鏡上，結合雷射直寫加工技術與量測樣品表面結構高度和反射率的系統設計。本系統利用一共振式掃描器帶動讀取頭物鏡產生垂直位移，掃描成像同時以鎖相放大器擷取各像素點之聚焦誤差訊號與振幅大小，透過此振幅與反射率之間的正比關係推算獲得反射率成像，並藉由聚焦誤差訊號平均值與反射率，推算出樣品表面之高度成像。

Laser direct writing technique has advantages of simple configuration, fast processing, and high controllability, which has been widely used in patterning and fine processing at the micro-nano scale. Compared with the contact type surface profilometer, non-contact optical profilometer has advantages of fast measurement, no damage to the sample, and no need to use consumables, so it is widely used in the fields of wafer inspection and biomedical engineering. The astigmatic profilometer can use a commercial optical pickup head as the main measuring element. Optical pickup head has advantages of low cost, small size, and excellent resolution. The reflectivity and height of the sample surface can be calculated by the focus error signal(FES) and the Z-axis height position. Optical and electron microscopes are commonly used to examine the processing results of the laser direct writing. However, very few integrated systems are available for real-time examination. In this thesis, an integrated system between a laser direct writing system and an astigmatic profilometer was proposed based on an inverted microscope, which allows to measure the height and reflectivity of the surface structure of the sample. This system equips a resonant scanner to oscillate the pickup head objective lens in vertical direction, and uses a lock-in amplifier to capture the FES and amplitude at each image pixel. Due to the proportional relationship between the amplitude and reflectivity, reflectivity image can be calculated from the FES amplitude. Moreover, by using the average value of the FES and the reflectivity, the height image of the sample surface can also be calculated.