Specific Process Knowledge/Lithography/DUVStepperLithography/Optimization and Simulation: Difference between revisions
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== Optimization and Simulation in Deep UV lithography == | == Optimization and Simulation in Deep UV lithography == | ||
In order to accomplish the best fidelity of the produced pattern on the wafer, both the characteristics of the illumination system, the exposure process and the dimensions/ shapes of the designed structures on the reticle (mask for projection lithography) must be adjusted. Different techniques can be applied to improve the resolution and the depth of focus of the illumination tool for each individual pattern. Either the mask design will be optimized with the help of optical proximity corrections (OPC) or- in a second technique -the optical illumination system will be adapted to the respective pattern. Here relevant optical parameters as the coherence of the aerial image or the numerical aperture of the projection lens can be modified or alternatively off-axis illumination - as i.e. annular and quadrupole sources - can be used. | In order to accomplish the best fidelity of the produced pattern on the wafer, both the characteristics of the illumination system, the exposure process and the dimensions/ shapes of the designed structures on the reticle (mask for projection lithography) must be adjusted. Different techniques can be applied to improve the resolution and the depth of focus of the illumination tool for each individual pattern. Either the mask design will be optimized with the help of optical proximity corrections (OPC) or- in a second technique -the optical illumination system will be adapted to the respective pattern. Here relevant optical parameters as the coherence of the aerial image or the numerical aperture of the projection lens can be modified, or alternatively off-axis illumination - as i.e. annular and quadrupole sources - can be used. | ||
Both, optimizing the mask design and the illumination system are useful approaches that can be exerted to achieve resist structures on the wafer with the most accurate CD control, the preferred sidewall angles, the lowest corner rounding or line end shortening. Additionally, the impact of the reaction kinetics of the resist during exposure, post exposure bake and development must be considered in order to exceed the requirements of the device to be fabricated. | Both, optimizing the mask design and the illumination system are useful approaches that can be exerted to achieve resist structures on the wafer with the most accurate CD control, the preferred sidewall angles, the lowest corner rounding or line end shortening. Additionally, the impact of the reaction kinetics of the resist during exposure, post exposure bake and development must be considered in order to exceed the requirements of the device to be fabricated. | ||