柔性基板上選擇性雷射燒結奈/微米混合矽顆粒

Abstract

矽基材料在半導體產業發展上扮演著相當重要的地位，隨著近年來智慧生活的興起，穿戴式電子元件的製造便是其中相當關鍵的技術，因此如何結合半導體材料於可撓性基板便成為一個相當重要的技術。有別於傳統製造矽薄膜需要高溫、高真空的環境，本研究欲採用波長532 nm脈衝持續時間為8 ns之脈衝雷射，藉由其極短的脈衝停留時間以及高能量密度，搭配振鏡的圖形化掃描，燒結矽奈米顆粒 (摻雜硼，濃度為5 × 1018 atom/cm3) 成為矽薄膜，來將在大氣下以選擇性雷射燒結的低溫製程技術應用於在柔性基板上。 透過針對最基本的單條線段進行不同掃描次數以及不同雷射能量下，其表面型態以及顆粒結晶狀況進行討論。並得出線段解析度約為130 µm之緻密的矽線段。並透過對不同線段重疊率之結果進行討論，找出路徑重疊率為70%時，能得出最均勻之面狀結構，之後對不同雷射能量密度下所產生之矽薄膜進行電性以及孔隙率上的討論。為提高矽薄膜之電性，我們提出透過摻入晶粒完整性較高之矽微米顆粒並優化了雷射製程參數，最後找出在80 wt% MPs之濃度下可得最佳電率約10 Ω-cm。 我們進一步提出透過二次沉積和燒結，降低薄膜的孔隙率並提升其電性以及可撓性，最後成功使電阻率下降12%，也透過彎曲測試證實其可撓性的提升。透過二次離子質譜儀觀察結果也證實該雷射燒結技術並不會改變原始的摻雜濃度，成功展現該雷射技術的可行性。

Silicon-based materials play a significant role in the development of the semiconductor industry. Recently, with the rise of an Intelligent Living System, wearable electronic devices are one of the key technologies. Therefore, how to apply semiconductor materials on flexible substrates has become a very important issue. Different from the traditional manufacturing of silicon thin film, which requires high temperature or high vacuum environment. This study uses a nanosecond pulse laser with a wavelength of 532 nm and a pulse duration of 8 ns to sinter p-type silicon nanoparticles. With its extremely short pulse dwell time、high energy density and the pattern control by galvanometer. We have successfully demonstrated laser sintering of a p-type Si nanoparticles (with dopant concentration of 5 × 1018 atom/cm3) on flexible substrates of PET in atmosphere environment. We investigated the surface morphology and particle crystallization states with different conditions of scanning times and laser energy density and found the optimal condition to form a silicon thin line. A dense Si line with width of about 130 µm was obtain. It is found that when the overlap ratio of line paths is 70%, the most uniform Si film can be obtained. Then the electrical properties and porosity of Si films under different laser energy density are analyzed. To further improve its electrical properties, we mixed Si micro-particles which compose large grains of Si with Si nanoparticles. The best resistivity of 10 Ω-cm can be achieved at the 80 wt% MPs. We also proposed to apply a second-time deposition of Si nanoparticles and laser sintering to reduce the porosity of Si film and improve its resistivity. The results showed a decrease of resistivity of 12% and better flexibility in the bending test. The SIMS analysis showed that the laser sintering process does not change the original doping concentration.