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Markets continuously demand higher resolution and higher productivity in flat panel display (FPD) exposure systems. Our solution to improve resolution and productivity is the use of broadband wavelength illumination. A larger depth of focus (DOF) is also very important to achieve higher productivity because inadequate DOF can cause product defects. To obtain higher resolution and larger DOF, off axis illumination (OAI) conditions have been widely used. OAIs using a narrowband wavelength illumination are well documented and sufficiently studied. On the other hand, Canon FPD exposure tools use a broadband illumination source to achieve higher resolution and productivity. To obtain sufficient OAI effects in broadband exposure lithography, new technology should be developed with consideration of broadband wavelength because OAI effects are different between broadband and narrowband illumination. In this paper we introduce divided spectrum illumination (DSI), a new design concept proposed to achieve both high resolution and large DOF by optimizing the broadband illumination source wavelength band depending on the illumination angle. Experimental imaging results of line and space patterns with a line width of 1.0-μm and pitch of 2.0-μm showed that the DSI design improved resolution. Results showed that test patterns imaged using traditional narrowband OAI could not be resolved at the top of the resist even at the best focus, however resist profiles using DSI were sharp enough to retain pattern fidelity at the top of resist. DOF with DSI also improved 21 % compared to traditional OAI.

From late 1990s to 2000s, the demands for Flat Panel Displays (FPDs), represented by Liquid Crystal Displays (LCDs), were mainly for larger size and lower price. Consequently, the development of FPD exposure tools was focused on expansion of exposure area and high throughput. Today, however, due to rapid growth of application for mobile devices, such as Smartphones and Tablet PCs, high resolution FPDs are being needed, and exposure tools are being demanded to constantly print finer pattern than before. In order To meet such needs, in 2013, Canon has released MPAsp-E813 and MPAsp-H803 series, which can resolve 2.0μm Line and Space (L and S) pattern and 2.5μm Contact Hole (CH) pattern. However, FPD resolution for mobile devices is still getting higher and higher, and now extremely high resolution of 1.5μm L and S is already in great demand.

YCa4O(BO3)3 has been found to have the phase-matching points where the temperature variation of the phase-matching angle (dθobs/dT) becomes zero for type-1 second-harmonic generation at 0.5321 µm at θ=30.8° and =180°. We also found that the temperature sensitivity of the phase-matching angle in the zx plane differs between the =0° and =180° propagation directions in this material. In addition, the thermo-optic dispersion formula of YCa4O(BO3)3 is presented.

K2Al2B2O7 has been found to be phase matchable for type-1 sum-frequency generation (SFG) at 0.193 microm by mixing the Nd:YAG laser wavelength at 1.0642 microm and the SFG output of the RbTiOAsO4 optical parametric oscillator tuned at 0.2358 microm. An average power of 200 mW at 10 kHz was obtained in a 7-mm-long crystal. In addition, the Sellmeier equations and the thermo-optic dispersion formula, which predict well the phase-matching conditions and temperature phase-matching bandwidths (FWHM) for second-harmonic generation and SFG in the 0.193-0.669-microm range, are presented.