193nm ArF immersion microlithography has been used widely in high-volume manufacturing, and it is considered to be
the main solution below 32 nm node until extreme ultraviolet (EUV) lithography becomes ready. Laser systems are now
enlarging its function and capability to meet various applications. In this paper we report a newly developed solution for
focus drilling technique applied to increase the depth of focus (DoF) for patterning contacts, vias and trenches. The laser
light is stabilized at any E95 in the range from 0.3 pm to 2.5 pm, where E95 is defined as the width of the spectral range
that contains 95% of the integrated spectral intensity. The high-range bandwidth is realized by introducing a newly
developed line narrowing module (LNM) in the oscillator resonator. The bandwidth is measured with the on-board
Fabry-Perot etalon and well controlled. This technique is easy upgradable to Gigaphoton latest GT62A-1SxE with the
flexible output power (60W - 90W) and stabilized spectrum (E95=0.3pm). In comparison to another focus drilling
technique where the large DoF is achieved by tilting a wafer stage during scan, the increase of the bandwidth of light
source has much smaller impact on the required performance of the scanner such as productivity, overlay and critical
dimension uniformity (CDU). In the paper we present the data that indicate the increases in DoF with broadening of the
laser spectrum as well as imaging and overlay results obtained at high bandwidth.
In this paper we describe the basic principle of FlexWave, a new high resolution
wavefront manipulator, and discuss experimental data on imaging, focus and overlay.
For this we integrated the FlexWave module in a 1.35 NA immersion scanner. With
FlexWave we can perform both static and dynamic wavefront corrections. Wavefront
control with FlexWave minimizes lens aberrations under high productivity usage of the
scanner, hence maintaining overlay and focus performance, but moreover, the high
resolution wavefront tuning can be used to compensate for litho related effects.
Especially now mask 3D effects are becoming a major error component, additional
tuning is required. Optimized wavefront can be achieved with computational lithography,
by either co-optimizing source, mask, and Wavefront Target prior to tape-out, or by
tuning Wavefront Targets for specific masks and scanners after the reticle is made.
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