傳統的印刷電路板(printed circuit board, PCB)微影製程中，主要以具有光罩的鄰近式(proximity)或接觸式(contact)的曝光方式在光阻上進行曝光製程。然而，製作光罩往往花費許多時間以及製程成本，若製作完成的光罩有不平坦或缺陷時，會造成PCB曝光不良的問題。為了減少光罩在PCB微影製程中所產生的問題以及成本，因此近年來發展了無光罩微影技術，例如電子束微影(electronic beam, E-beam)、雷射直接成像(laser direct imaging, LDI)以及數位光罩微影(digital mask lithography)。本研究主要探討以數位微反射鏡裝置(digital micromirror device, DMD)作為數位光罩取代傳統實體光罩，然而在空間中調變波長405 nm雷射光束強度並且將光束反射在PCB光阻表面上。目前產業以DMD投影式微影系統可印出最小線寬與特徵圖案大約為30-50 μm，為了進一步提升曝光線寬解析度，本系統採用點陣列曝光模式，以DMD設計點陣列光罩，並透過光學模組中微透鏡陣列(microlens array, MLA)聚焦最佳解析度的光點陣列，並進行曝光測試且與掃描平台做結合，探討光點陣列曝光形成掃描線，並增加曝光解析度之討論。本研究已成功利用所開發的數位光罩微影光學系統，以一個微反射鏡對應一個像素之方式形成點陣列之DMD光罩，並且運用脈衝寬度調頻(pulse width modulation, PWM)操作DMD光罩之開啟時序，有效的達到曝光劑量之控制，並已利用DMD的數位光罩微影製程中得到10 μm的曝光線寬。

In the conventional printed circuit board (PCB) lithography process, it often exposed the line pattern features on a resist-coated substrate in contact or proximity modes. The fabrication of photomask usually takes time and raises the overall running cost. The photomask also suffered the flatness issues during the lithography process and resulted in the low line pattern resolution. To eliminate the use of masks in the PCB lithography process, maskless lithography techniques have been developed in recent years such as the electronic beam (E-beam), laser direct imaging (LDI), and digital micromirror device (DMD) methods. The proposed method uses a digital micromirror device (DMD) to spatially modulate the beam intensity and reflect the beam at the wavelength of 405 nm onto a single photoresist layer. Currently, the minimum feature linewidth in the DMD-based digital maskless lithography system is between 30 and 50 μm. In order to improve the feature line width resolution in the PCB lithography process, this research is dedicated in designing an optical system with a H-line (405 nm) UV laser light source, projection optics, microlens array (MLA) and scanning stage. A point array scanning method is adapted for the exposure process. In addition, this research uses the pulse width modulation (PWM) technique to control DMD timing sequence for the pattern exposure. It is successfully exposure the line patterns with the 10 μm.

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