High-resolution maskless lithography

Abstract

An innovative high-resolution maskless lithography system is designed employing a combination of low-and high-numerical-aperture (NA) projection lens systems along with integrated micro-optics, and using Texas Instruments' super video graphic array (SVGA) digital micromirror device (DMD) as the spatial and temporal light modulator. A mercury arc lamp filtered for the G-line (ϭ435.8 nm) is used as the light source. Exposure experiments are performed using data extraction and transfer software, and synchronous stage control algorithms derived from a point array scrolling technique. Each exposure scan produces a field width (W) of approximately 8.47 mm with a field length (longitudinal field) limited only by onboard memory capacity. DMD frame rates of up to 5 kHz (kframes/s), synchronized to the stage motion, are achievable. In this experiment, TSMR-8970XB10 photoresist (PR), diluted to 3.8 cP with PR thinner is prepared. The PR is spin-coated onto a chromecoated glass substrate to 1.0-m thickness with 0.1-m uniformity. A 0.4-m scan step is used and 27,000 DMD data frames are extracted and transferred to the DMD driver. Results indicate consistent 1.8-m line space (L/S) resolved across the entire field width of 8.47 mm. Given optimized exposure and development conditions, 1.5-m L/S is also observed at certain locations. The potential of this maskless lithography system is substantial; its performance is sufficient for applications in microelectromechanical systems (MEMS), photomasking, high-resolution LCD, high-density printed circuit boards (PCBs), etc. Higher productivity is predicted by a custom H-line (ϭ405 nm) lens system designed and used in conjunction with a violet diode laser systems and the development of a real-time driver. © 2003 Society of Photo-Optical Instrumentation Engineers.

Photolithography system with liquid crystal display as active gray-tone mask for 3D structuring of photoresist

“…On the contrary, the LCD is advantageous for high-resolution lithography. The minimum pixel size of commercially available LCDs is as small as 9.5 m, compared to that of the DMD pixel, 17 m [5,15]. Thus, an LCD based system is superior in terms of achieving high-resolution exposure by applying a low optical power projection system.…”

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

“…Nowadays, many new application fields for them have emerged. One of them is maskless lithography for semiconductor and Flat Panel Display (FPD) fabrication [3][4][5][6][7][8][9][10].…”

“…It is characterized by sufficient throughput for highly customized patterns, fine lithographic quality, efficiency in cost and time [9], and so on. Nevertheless, the micromirror based lithography is feasible if, and only if, each system developer could set up an excellent optic unit [10,11], and an accurate DMD control unit [3][4][5][6][7][8]12]. To fabricate lithographic patterns, millions of micromirrors on the DMD need to be addressed and adjusted, individually and instantaneously.…”

Detecting Digital Micromirror Device Malfunctions in High-throughput Maskless Lithography

“…Various maskless lithography techniques have been developed, such as plasmonic lithography [15], zone plate array lithography (ZPAL) [16,17], and nanoimprint lithography [18]. Among the various maskless lithography techniques, researchers have developed ML systems based on DMDs and subsequent applications since Chan et al had proposed a DMD-based ML system [8,9]. The DMDbased ML system has high throughput for highly customized patterns and is cost-and time-efficient.…”

“…A DMD has the advantages of high contrast ratio and throughput and a wide dynamic control range [2]. Because of this, DMDs have been widely used in various applications such as projectors [3,4], confocal microscopes [5][6][7], and maskless lithography [8][9][10][11][12][13][14].…”