Hydrogen silsesquioxane on SOI proximity and microloading effects correction from a single 1D characterization sample

Abstract

Designs patterned by electron beam lithography without applying process effect correction exhibit overexposed dense features and underexposed sparse features for most practical exposure scenarios. This is typified by the limited exposure latitude of hydrogen silsesquioxane resist on silicon-on-insulator substrates used for silicon photonics, which commonly display very high density features (vertical grating couplers, ring resonators) mixed with very sparse features (inverse tapered waveguides, lone waveguides) in a single pattern. The authors have optimized a proximity effect correction (PEC) based on our analysis of a single 1D process control monitor characterization sample. Our PEC verification sample, which includes electron backscatter and process-related microloading effects, achieved linewidths with an RMS error of ±5.0 nm for features with pattern densities spanning 1%–67%. Ignoring the pattern density-dependent microloading effect limits the resolvable pattern density span to a smaller range and degrades the linewidth error.

Parametric optimization of visible wavelength gold lattice geometries for improved plasmon-enhanced fluorescence spectroscopy

“…This scattering phenomenon ultimately results in either the enlargement and/or reduction of the designed feature sizes [208] and affects critical dimension accuracy. The proximity effect is usually observed when writing high-density features or repeating patterns, as reported by several groups [208][209][210][211][212][213]. The extent of the proximity effect has been shown to relate to the acceleration voltage of the electron beam.…”

“…Subsequently, the exposed or non-exposed regions of the resist are removed by a special solvent (i.e., development). EBL grants high-density micro-to nano-scale feature resolution and does not suffer from diffraction limitations characteristic of typical optical lithography methods such as photolithography [199][200][201][202][203][204][205][206][207][208][209][210][211][212][213][214][215]. Although EBL does have a wide variety of advantages, it is time consuming for some processes resulting in lower throughput [214][215].…”

“…At higher acceleration voltages (≥ 100kV) the effects seem to be worsened. At lower acceleration voltages (< 1kV), the proximity effects are significantly reduced, but with a tradeoff resulting in poor resist sensitivity and longer writing speeds [205][206][207][208][209][210][211][212][213][214][215] ( Figure 5.1). The JEOL JSM-7600F SEM system with EBL capabilities was used in conjunction with nanometer pattern generation system (NPGS) software to create the features upon which metal would be deposited.…”