- 學位論文
嵌入式直接奈米壓印技術製作金屬/PMMA疊層光柵研究
The Fabrication of Nano-Scale Metal Gratings/PMMA Composite Stack Layer Using Insertion Nanoimprint
摘要
液晶螢幕背光模組中具偏振功能的導光板，結構為金屬光柵與透光性基材(PMMA)疊層的方式為主，以往此結構的導光板皆以黃光製程製作。本研究利用抗沾黏層結合直接金屬奈米壓印，於矽基板上製備金屬光柵，並將製作出之金屬光柵以熱壓方式嵌入PMMA使其成為金屬/PMMA疊層結構，希望能以藉著簡化製作程序製作出可適用於液晶螢幕之背光模組中導光板的穿透式偏振片(wire grid polarizer, WGP)。 由於金屬薄膜在直接金屬奈米壓印製作金屬光柵時必須黏著於矽基板上，而嵌入式奈米壓印時卻必須順利脫離矽基板嵌入至PMMA中，因此金屬薄膜與矽基板間接合能力為技術關鍵。本研究規劃多種疊層結構並探討出以金薄膜/鈦層/抗沾黏層/矽基板疊層符合製作需求。以線寬400nm光柵圖案矽模仁，壓印於金薄膜/鈦層/抗沾黏層/矽基板疊層，將成形後之金光柵薄膜以熱壓方式嵌入於PMMA中並藉抗沾黏層的作用剝離矽基板使其成為WGP偏振片。以聚焦離子束與電子束顯微系統(FIB/SEM)觀察壓印成形之光柵與嵌入PMMA後之形貌，量測其殘留層厚度並以光學多狹縫干涉實驗驗證光柵尺寸，進行穿透率量測得到光柵於殘留層尚未移除的試片透光率。受限模仁製作技術，線寬400nm光柵仍大於1/2可見光波長，尚無法產生偏振效果，但嵌入式直接奈米壓印的基本理念已經實現。
並列摘要
The structure of light guide plate with polarization function in LCD screen backlight module mainly consists of metal grating and translucent substrate made of PMMA. The laminated light guide plate having metal grating and PMMA stacking feature has been fabricated so far by using a series of photolithographic processes. In this research, metal grating was fabricated on a silicon substrate by direct metal nanoimprint. Between the metal grating and the silicon substrate, an anti-sticking layer was applied to ease a subsequent insert imprint process. Then we developed an insertion nanoimprint technique to embed the metal grating into the PMMA substrate to fabricate the metal grating/PMMA stack structure. By the simplified and time-saving fabrication technique, the wire grid polarizer applied to the LCD screen backlight guide plate, can be efficiently fabricated. The metal film must be attached to the silicon substrate during the direct metal nanoimprint process to form metal gratings. However, the imprinted gratings must be easily peeled from the silicon substrate after embedded into PMMA substrate. The adhesion of the metal film on the silicon substrate and the detachment of the imprinted grating from the silicon substrate are crucial to the success of the insert imprint processes. A variety of laminated structures to achieve above goal were tested, and the gold film / titanium layer / anti-sticking layer / silicon substrate stacking was proved to be most suitable for the insert imprint purpose. During the procedure, silicon mold of 400nm in pitch was applied to conduct direct imprint on gold film/titanium film/anti-adhesion layer/silicon substrate stack. Then the imprinted gold gratings were embedded into PMMA with insertion nanoimprint. The silicon substrate was then successfully separated from the imprinted gratings which were embedded in PMMA layer due to the existence of an anti-adhesion layer. SEM and FIB were used to investigate the thickness of residual layer of the gold grating and the cross-sectional morphology of the imprinted grating and the cross-section of the gold grating/PMMA substrate composite structure. The grating line width was verified by multi-slit interference experiment. The optical transmittance of the gold grating inserted in the PMMA substrate with residual layer was measured. Limited by the photolithographic technique, the line width of the mold for direct nanoimprint could not be made smaller than 1/2 wavelength of the visible light. Although polarization effect could not be achieved so far, yet the concept of direct nanoimprint and insert imprint has been realized.