펨토초 레이저를 이용한 미세 PR 패터닝

손익부(Ik-Bu Sohn),고명진(Myeong-Jin Ko),김영섭(Young Seop Kim),노영철(Young-Chul Noh) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.6

Development of maskless lithography techniques can provide a potential solution for the photomask cost issue. Furthermore, it could open a market for small scale manufacturing applications. Since femtosecond lasers have been found suitable for processing of a wide range of materials with sub-micrometer resolution, it is attractive to use this technique for maskless lithography. As a femtosecond laser has recently been developed, both of high power and high photon density are easily obtained. The high photon density results in photopolymerization of photoresist whose absorption spectrum is shorter than that of the femtosecond laser. The maskless lithography using the two-photon absorption (TPA) makes micro structures. In this paper, we present a femtosecond laser direct write lithography for submicron PR patterning, which show great potential for future application.

Optical System with 4 μm Resolution for Maskless Lithography Using Digital Micromirror Device

이동희 한국광학회 2010 Current Optics and Photonics Vol.14 No.3

In the present study, an optical system is proposed for maskless lithography using a digital micromirror device (DMD). The system consists of an illumination optical system, a DMD, and a projection lens system. The illumination optical system, developed for 95% uniformity, is composed of fly’s eye lens plates, a 405 nm narrow band pass filter (NBPF), condensing lenses, a field lens and a 250W halogen lamp. The projection lens system, composed of 8 optical elements, is developed for 4 µm resolution. The proposed system plays a role of an optical engine for PCB and/or FPD maskless lithography. Furthermore, many problems arising from the presence of masks in a conventional lithography system, such as expense and time in fabricating the masks, contamination by masks, disposal of masks, and the alignment of masks, may be solved by the proposed system. The proposed system is verified by lithography experiments which produce a line pattern with the resolution of 4 µm line width.

Maskless lithography를 위한 MEMS 미러 레이저 스캐닝 시스템 설계

조준희(J. H. Jo),임형준(Hyungjun Lim),장원석(Won Seok Chang) 한국기계가공학회 2022 한국기계가공학회 춘추계학술대회 논문집 Vol.2022 No.12

Optical Proximity Corrections for Digital Micromirror Device-based Maskless Lithography

허준규,서만승 한국광학회 2012 Current Optics and Photonics Vol.16 No.3

We propose optical proximity corrections (OPCs) for digital micromirror device (DMD)-based maskless lithography. A pattern writing scheme is analyzed and a theoretical model for obtaining the dose distribution profile and resulting structure is derived. By using simulation based on this model we were able to reduce the edge placement error (EPE) between the design width and the critical dimension (CD) of a fabricated photoresist, which enables improvement of the CD. Moreover, by experiments carried out with the parameter derived from the writing scheme, we minimized the corner-rounding effect by controlling light transmission to the corners of a feature by modulating a DMD.

Maskless Lithography system을 이용한 TSP 검사 용 micro bump 제작에 관한 연구

김기범(Ki-Beom Kim),한봉석(Bong-Seok Han),양지경(Ji-Kyung Yang),한유진(Yu-Jin Han),강동성(Dong-Seong Kang),이인철(In-Cheol Lee) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.5

본 논문은 현재 개인 휴대기기 및 대형 디스플레이 장비의 제어에서 폭넓게 사용되고 있는 터치스크린 패널 (TSP; Touch Screen Panel)의 정상 작동 유무를 확인하기 위한 micro bump 제작 기술에 관한 연구이다. 터치스크린 패널은 감압식, 정전식 등의 여러 가지 방식이 있으나 지금은 편리성에 의하여 정전식 방식이 주도하고 있다. 정전식의 경우 해당하는 좌표의 접촉에 따라 전기적 신호가 변화하게 되고, 이를 통하여 접촉 위치를 확인할 수 있으며 따라서 접촉 위치에 따른 전기특성 검사가 필수적이다. 검사공정에서 TSP의 모델이 변경됨에 따라 새로운 micro bump를 제작이 및 검사 프로그램의 수정이 필수적이다. 본 논문에서는 새로운 micro bump 제작 시 mask를 사용하지 않아 보다 경제적이며 변화에 대응이 유연한 maskless lithography 시스템을 이용하여 micro bump 제작 가능성에 대하여 확인하였다. 이를 위하여 제작되는 bump의 pitch에 따른 전기장 간섭 시뮬레이션을 진행하였으며, maskless lithogrphy 공정을 적용하기 위한 패턴 이미지를 생성하였다. 이후 MEMS 기술에 해당하는 PR(Photo Resist) 패터닝 공정에서 노광(Lithography) 공정 및 현상(Developing) 공정을 통하여 PR마스크를 제작한 후 electro-plating 공정을 통하여 micro bump를 제작하였다. Touch Screen Panel (TSP) is a widely used personal handheld device and as a large display apparatus. This study examines micro bump fabrication technology for TSP test process. In the testing process, as TSP is changed, should make a new micro bump for probing and modify the testing program. In this paper we use a maskless lithography system to confirm the potential to fabricatemicro bump to reducecost and manufacturing time. The requiredmaskless lithography system does not use a mask so it can reduce the cost of fabrication and it flexible to cope with changes of micro bump probing. We conducted electro field simulation by pitches of micro bump and designed the lithography pattern image for the maskless lithography process. Then we conducted Photo Resist (PR) patterning process and electro-plating process that are involved in MEMS technology to fabricate micro bump.

Maskless lithography 응용을 위한 마이크로렌즈 어레이 개발

남민우,오해관,김근영,서현우,위창현,송요탁,양상식,이기근,Nam, Min-Woo,Oh, Hae-Kwan,Kim, Geun-Young,Seo, Hyun-Woo,Wei, Chang-Hyun,Song, Yo-Tak,Yang, Sang-Sik,Lee, Kee-Keun 한국마이크로전자및패키징학회 2009 마이크로전자 및 패키징학회지 Vol.16 No.4

마스크리스 리소그래피(maskless lithography)에 응용하기 위한 마이크로렌즈 어레이(microlens array, MLA)가 석영의 습식 식각과 UV 접착제(UV adhesive)의 코팅을 바탕으로 개발되었다. 제작된 MLA의 초점거리는 ${\sim}45\;{\mu}m$ 정도였으며, 집광되는 광선의 초점은 ${\sim}1\;{\mu}m$로 측정되었다. MLA를 통과하며 초점을 맺은 빔(beam)의 크기 및 세기가 charge coupled device (CCD) 카메라와 빔 프로파일러(beam profiler)를 이용하여 각각 측정되었으며, 일정한 세기의 점들이 초점면에서 고르게 관찰되었다. 초점거리는 코팅된 UV 접착제의 두께에 따라 변화하였으며, UV 접착제의 두께가 두꺼울수록 짧아지는 경향을 보였다. 일반적인 마스크 얼라이너(mask aligner)를 이용한 MLA의 UV 포커싱(UV focusing)이 감광막(photoresist, PR) 상에서 실시되었으며, MLA를 통과한 빛이 감광막 위에 일정하게 집광되었다. 마스크 얼라이너와 MLA 사이의 거리 변화에 따라 감광막에 구현된 패턴 사이즈가 조절 되었다. 고온에서 오랜 시간이 지난 후에도 소자의 특성은 전혀 변함이 없었다. A microlens array (MLA) was developed based on the wet-etched quartz substrate and coating of UV adhesive on the substrate for maskless lithography application. The developed MLA has the focal length of ${\sim}45\;{\mu}m$ and the spot size of ${\sim}1\;{\mu}m$. The spot size of the focused beam passing through the MLA was detected by CCD camera, and its intensity was monitored by beam profiler. Uniform spots with nearly identical intensities were observed on the focal plane when a beam passes through the fabricated MLA. The focal length was varied depending on thickness of the coated UV adhesive. The thicker the thickness of the UV adhesive was, the shorter the focal length of the MLA was. With a general mask aligner, UV beam focusing was tested onto photoresist (PR). The beams were well focused onto PR when UV passes through the MLA. Depending on the variable distances from the MLA, beam sizes onto PR were controlled. Even at high temperature for a long time, the performances of the MLA were not changed.

Maskless 노광공정을 위한 LDI(Laser Direct Imaging) 시스템 개발 및 단일 레이저 빔 에너지 분포 분석

이수진(Soo Jin Lee),김종수(Jong Su Kim),신봉철(Bong Cheol Shin),김동우(Dong Woo Kim),조명우(Meyong Woo Cho) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.6

Photo lithography process is very important technology to fabricate highly integrated micro patterns with high precision for semiconductor and display industries. Up to now, mask type lithography process has been generally used for this purpose; however, it is not efficient for small quantity and/or frequently changing products. Therefore, in order to obtain higher productivity and lower manufacturing cost, the mask type lithography process should be replaced. In this study, a maskless lithography system using the DMD(Digital Micromirror Device) is developed, and the exposure condition and optical properties are analyzed and simulated for a single beam case. From the proposed experimental conditions, required exposure experiments were preformed, and the results were investigated. As a results, 10 ㎛ spots can be generated at optimal focal length.

역학적 유체 리소그래피 기술

정수은,박욱,권성훈,Chung, Su-Eun,Park, Wook,Kwon, Sung-Hoon 대한의용생체공학회 2009 의공학회지 Vol.30 No.6

In this review paper, concepts in optofluidics are applied to an advanced manufacturing technology based on self-assembled microparts. The "optical" aspect of optofluidics will be described in the context of photolithography, and the "fluidic" aspect will be discussed in the context of self-assembly. First, optofluidic maskless lithography will be introduced as a dynamic fabrication method to generate microparticles in microfluidic channels. Next, the history and application of optofluidic lithography will be presented.

A rasterization method for generating exposure pattern images with optical maskless lithography

이진원,이형규,양정삼 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5

One of the core technologies used for high-density integration of electronic parts is a lithography method that draws a microcircuit by irradiating light onto photoresist. Because maskless lithography technology that employs a digital micromirror device (DMD) uses continuous exposure patterns, a huge amount of image frame data is required, and, moreover, a long calculation time is required to create exposure pattern images. In this paper, we propose a rasterization method that exposes continuous image frames onto a single overlay lithography image using GPU-accelerated path rendering and CPU parallel computing, creating a high-quality exposure pattern image at a high speed. This method enables effective rasterization using multiple CPU and GPU cores to create lithography image data. Additionally, it is possible to reduce the size of the data file by exposing a printed circuit board (PCB) in a single overlay image frame, rather than the conventional consecutive frames.

Fabrication of Passive Micromixer using a Digital Micromirror Device-based Maskless Lithography System

Cho, Yong-Kyu,Han, Tae-Heon,Ha, Seok-Jae,Lee, Jung-Won,Kim, Jong-Su,Kim, Sun-Min,Cho, Myeong-Woo Korean Society for Precision Engineering 2014 International Journal of Precision Engineering and Vol.15 No.7

We developed a maskless lithography system using a digital micromirror device (DMD). This system incorporates a light-emitting diode (LED) driver to generate ultraviolet (UV) light, illumination optics using a fly-eye lens, and telecentric projection optics to generate a parallel light source reflected from the DMD. The potential problems caused by using a mask (e.g., increased expense, increased time for processing, contamination, and alignment problems) can be circumvented with the proposed maskless system. Exposure energy intensity and the micropattern-generating performance were tested with the developed system. To investigate the performance of the developed system, a passive micromixer was fabricated using the soft lithography process. The molds for the micromixer were fabricated using the proposed DMD system and a conventional UV lithography system. Mixing experiments were performed in order to compare the performance of the micromixers fabricated using both approaches. The surface texture of the micromixer fabricated by the DMD system induced more vortex flow in the channel and thus the micromixer showed approximately 10% higher mixing performance.