The chemical changes in poly(methylmethacrylate) (PMMA) caused by irradiation with deep ultraviolet (UV), x-ray, electron, and proton beams were studied by gel permeation chromatography, Fourier-transform infrared, and UV spectroscopy. The quantitative analysis of spectroscopic changes (Beer’s law) demonstrated a 1:1 correspondence between the disappearance of ester groups and the generation of double bonds in the polymer chain by all types of radiation. The ratio of main chain scission to changes in the number of ester groups and unsaturated bonds was compared to determine the characteristics of degradation of PMMA by the different types of radiation. This ratio for deep UV data was very close to the quantum yield of main chain scission of PMMA as reported in the literature. High-energy radiation was ∼10× more efficient than deep UV in causing main chain scission with removal of fewer ester groups. Protons induced more main chain scission than electrons. X-ray irradiation was the most efficient at causing main chain scission of the four different types of radiation.
We report results from a measurement of the inclusive diffraction dissociation of photons on hydrogen, yp-Xp, in the range 7 5 < p , < 148 GeV/c, 0.02 < t I < 0.1 (G~v/c)', and M x 2 / s
X-ray lithography (XRL) has been under development since the early 1980s, and has reached a state of relative maturity. Numerous devices, including dense and complex integrated circuits, have been fabricated using XRL for one or more critical levels. While development of XRL technology itself continues, XRL is in use in several locations around the world for process development of advanced DRAM (1 Gb and beyond) and logic (0.18 μm and below) integrated circuits. Most of the tool set in use today comes from commercial vendors. Resolution using XRL has been demonstrated at dimensions down to 70 nm or below. Excellent critical dimension (CD) control results have been achieved in simple, single-layer, commercially available resists; for example, a total CD variation of 22 nm (3σ) has been achieved using a mask with a CD variation of 18 nm (3σ). Because of these capabilities, along with the experience and relative maturity of the technology, we believe that XRL is the technology best positioned to succeed optical lithography and be available for timely insertion into manufacturing for 0.13 μm ground rules, as well as to be extendible to 0.10 μm and below. In order to be accepted for manufacturing, however, significant work remains to be done. In particular, new e-beam mask writers and wafer aligners are needed, along with improved mask inspection and repair tools. Mask fabrication processes must also be advanced. The ability to satisfy these needs is not expected to be limited by fundamental physics, but rather is expected to depend on skilled engineering design and implementation.
Highly scaled FinFET SRAM cells, of area down to 0.128μm 2 , were fabricated using high-κ dielectric and a single metal gate to demonstrate cell size scalability and to investigate V t variability for the 32 nm node and beyond. A single-sided ion implantation (I/I) scheme was proposed to reduce V t variation of Fin-FETs in a SRAM cell, where resist shadowing is a great issue. In the 0.187μm 2 cell, at V d = 0.6 V, a static noise margin (SNM) of 95 mV was obtained and stable read/write operations were verified from N-curve measurements. σV t of transistors in 0.187μm 2 cells was measured with and without channel doping and the result was summarized in the Pelgrom plot. With the 22 nm node design rule, FinFET SRAM cell layouts were compared against planar-FET SRAM cell layouts. An un-doped FinFET SRAM cell was simulated to have significant advantage in read/write margin over a planar-FET SRAM cell, which would have higher σV t mainly caused by heavy doping into the channel region.
X-ray lithography ͑XRL͒ is a very promising technique with the potential to be available for integrated circuit manufacturing as early as the 130 nm generation. As a result of many years of development, the technology is relatively mature. Synchrotron sources have demonstrated performance and reliability; preproduction aligners are available from multiple vendors; significant improvements are being made in mask fabrication; and high resolution imaging has been demonstrated at 100 nm and below. Established vendors already have experience with almost all of the tools that are needed, although improved performance is required for most in order to satisfy the error budgets at 130 nm and below. Significant development activities are continuing in both the United States and Japan, and numerous complex integrated circuits have been fabricated using XRL for one or more critical levels. Nonetheless, there are challenges still to be met. Among the most important are the development and commercial availability of an improved e-beam mask writer; the ability to fabricate defect-free masks satisfying the image placement and critical dimension control requirements with good yields; the stability of the masks in usage ͑including the issue of possible radiation damage͒; the ability to correct for magnification errors; and the ability to satisfy the industry's desire for a technology extendible to 70 nm ground rules. These issues are primarily manufacturing issues, as opposed to issues related to demonstrating proof-of-concept or feasibility, although demonstrating extendibility is still needed before the industry can commit to using XRL at 70 nm ground rules. Because of the existing XRL facilities and experience, effective work to address these and other issues can be accomplished in a timely manner.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.