scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Point exposure distribution measurements for proximity correction in electron beam lithography on a sub‐100 nm scale

01 Jan 1987-Journal of Vacuum Science & Technology B (American Vacuum Society)-Vol. 5, Iss: 1, pp 135-141
TL;DR: In this article, the authors demonstrate a technique, using a very high contrast resist, whereby the normalized point exposure distribution can be measured experimentally, both on solid substrates which cause backscattering, and on thin substrates where backscatter is negligible.
Abstract: The exposure distribution function in electron beam lithography, which is needed to perform proximity correction, is usually simulated by Monte Carlo techniques, assuming a Gaussian distribution of the primary beam. The resulting backscattered part of the exposure distribution is usually also fitted to a Gaussian term. In this paper we demonstrate a technique, using a very high contrast resist, whereby the normalized point exposure distribution can be measured experimentally, both on solid substrates which cause backscattering, and on thin substrates where backscattering is negligible. The data sets so obtained can be applied directly to proximity correction and represent the practical conditions met in pattern writing. Results are presented of the distributions obtained on silicon, gallium arsenide, and thin silicon nitride substrates at different beam energies. Significant deviations from the commonly assumed double Gaussian distributions are apparent. On GaAs substrates the backscatter distribution cannot adequately be described by a Gaussian function. Even on silicon a significant amount of exposure is found in the transition region between the two Gaussian terms. This deviation, which can be due to non‐Gaussian tails in the primary beam and to forward scattering in the resist, must be taken into account for accurate proximity correction in most submicron lithography, and certainly on the sub‐100 nm scale.
Citations
More filters
Book
24 May 2019
TL;DR: The second edition of this book as discussed by the authors was written to address several needs, and the revisions for the second edition were made with those original objectives in mind, and many new topics have been included in this text commensurate with the progress that has taken place during the past few years, and several subjects are discussed in more detail.
Abstract: Lithography is a field in which advances proceed at a swift pace. This book was written to address several needs, and the revisions for the second edition were made with those original objectives in mind. Many new topics have been included in this text commensurate with the progress that has taken place during the past few years, and several subjects are discussed in more detail. This book is intended to serve as an introduction to the science of microlithography for people who are unfamiliar with the subject. Topics directly related to the tools used to manufacture integrated circuits are addressed in depth, including such topics as overlay, the stages of exposure, tools, and light sources. This text also contains numerous references for students who want to investigate particular topics in more detail, and they provide the experienced lithographer with lists of references by topic as well. It is expected that the reader of this book will have a foundation in basic physics and chemistry. No topics will require knowledge of mathematics beyond elementary calculus.

508 citations

Journal ArticleDOI
TL;DR: This work investigated electron-beam lithography with an aberration-corrected scanning transmission electron microscope and achieved 2 nm isolated feature size and 5 nm half-pitch in hydrogen silsesquioxane resist.
Abstract: We investigated electron-beam lithography with an aberration-corrected scanning transmission electron microscope. We achieved 2 nm isolated feature size and 5 nm half-pitch in hydrogen silsesquioxane resist. We also analyzed the resolution limits of this technique by measuring the point-spread function at 200 keV. Furthermore, we measured the energy loss in the resist using electron-energy-loss spectroscopy.

381 citations

Journal ArticleDOI
TL;DR: In this article, the authors review the radiation chemistry of materials related to chemically amplified resist materials and discuss the imaging mechanisms from energy deposition to proton migration in resist materials are discussed.
Abstract: Historically, in the mass production of semiconductor devices, exposure tools have been repeatedly replaced with those with a shorter wavelength to meet the resolution requirements projected in the International Technology Roadmap for Semiconductors issued by the Semiconductor Industry Association. After ArF immersion lithography, extreme ultraviolet (EUV; 92.5 eV) radiation is expected to be used as an exposure tool for the mass production at or below the 22 nm technology node. If realized, 92.5 eV EUV will be the first ionizing radiation used for the mass production of semiconductor devices. In EUV lithography, chemically amplified resists, which have been the standard resists for mass production since the use of KrF lithography, will be used to meet the sensitivity requirement. Above the ionization energy of resist materials, the fundamental science of imaging, however, changes from photochemistry to radiation chemistry. In this paper, we review the radiation chemistry of materials related to chemically amplified resists. The imaging mechanisms from energy deposition to proton migration in resist materials are discussed.

254 citations

Journal ArticleDOI
TL;DR: In this article, the frequency mismatches between resonators significantly impact the spectral responses of coupled resonator filters, such as high-order microring filters, and the main approach consists of inducing small dimensional changes in the resonators through alteration of the electron-beam dose used to expose either the actual resonator on a wafer or its image on a lithographic mask to be later used in filter fabrication.
Abstract: Frequency mismatches between resonators significantly impact the spectral responses of coupled resonator filters, such as high-order microring filters. In this paper, techniques allowing fabrication of frequency-matched high-index-contrast resonators are proposed, demonstrated, and analyzed. The main approach consists of inducing small dimensional changes in the resonators through alteration of the electron-beam dose used to expose either the actual resonator on a wafer or its image on a lithographic mask to be later used in filter fabrication. Third-order microring filters fabricated in silicon-rich silicon nitride, with optical resonator frequencies matched to better than 1 GHz, are reported. To achieve this, the average ring-waveguide widths of the microrings are matched to within less than 26 pm of a desired relative width offset. Furthermore, optimization and calibration procedures allowing strict dimensional control and smooth sidewalls are presented. A 5-nm dimensional control is demonstrated, and the standard deviation of sidewall roughness is reduced to below 1.6 nm.

144 citations

Journal ArticleDOI
TL;DR: In this article, a chain scission model is combined with an empirical dissolution model to successfully describe the edge profile of a bar pattern, and a 40 nm period grating was defined in the 100 K resist.
Abstract: High-resolution lithographic performance of polymethyl methacrylate (PMMA) of molecular weights (MWs) of 50, 100, 496, and 950 K is compared. A chain scission model is used to analyze the behavior of the four molecular weight resists. The chain scission model is combined with an empirical dissolution model to successfully describe the edge profile of a bar pattern. Isolated linewidth data for the 100 and 496 K resists both fit a Monte Carlo code generated linespread function that was convolved with a Gaussian of standard deviation 9 nm. The width was comparable to that in the 950 K resist, but a factor of 3 narrower than that found for the 50 K resist. The higher molecular weight, 496 and 950 K resists showed more developer induced swelling than the lower molecular weight resists. In fact, the developer induced swelling limited the ability to develop 40 nm gratings in the 496 and 950 K resists. Reduction in developer strength produced some improvement. Etching of the supporting resist structure in the gratings was also observed, particularly in the 50 and 100 K resists. The 50 K MW resist exhibited the worst grating contrast upon development. Grating enhanced etching relative to 10 μm bar areas exposed with comparable area dose was observed. A 40 nm period grating was defined in the 100 K resist.

77 citations