This paper presents the desigh fabrication and testing of capacitive RF MEMS switches with a new, low processing cost dielectric layer on high-resistivity silicon substrate. The dielectric can be spun on the wafer and its parameters (dielectric constant and loss) can be controlled during fabrication to achieve the desired values. Both bridge-and cantilever-type switches were fabricated on high-p silicon substrate using a simple low cost four-mask process. Measured results are presented
The extendability of conventional subtractive lithographic processing using spin-coated polymeric single layer resists (SLR) faces many challenges as feature sizes in microelectronics push below 100 nm. In addition, the opacity of the polymeric materials traditionally used as SLR resins to future exposure sources presents new challenges as the radiation penetration depth decreases (e.g. 157 nm, EUVL, low keV e-beam). One solution to these problems is the use of surface imaging materials and processes. In such surface imaging methods, exposure in only a thin surface layer is used to create a pattern in a substantially thicker etch barrier layer. Conventional surface imaging approaches have mainly focused on silylation techniques which have experienced a variety of problems. This paper presents an update on two novel surface imaging methods under investigation: (1) surface monolayer initiated polymerization (SMIP) and (2) organometallic-organic bilayer resists.The SMIP process involves using a monolayer that contains a polymerization initiator functionality. Exposure of the monolayer to radiation can deactivate the initiators in selected areas and the remaining initiators can subsequently be used to directly grow patterned polymer structures. This process allows complete decoupling of the imaging properties of the monolayer from the etch properties of the polymer etch barrier. In essence, the polymerization process is used to amplify the pattern initially formed in the monolayer. Recent results are presented that demonstrate the use of x-ray photoelectron spectroscopy in conjunction with dose array experiments to analyze the sensitivity of the initiators used for this process.The other novel surface imaging method presented in this work uses organometallic-organic bilayers. In these systems, thin films of radiation sensitive organometallic precursors are used as an imaging layer in conjunction with thick organic etch barrier layers. Upon exposure, the organometallic precursor film is selectively converted to metal oxide. After exposure, the unexposed regions of the film can be developed away. Subsequent dry pattern transfer in an oxygen plasma can be used to transfer the pattern defined in the thin oxide layer through the organic etch barrier layer. Organometallic precursor films with sensitivities on the order of 70 μC/cm2 are demonstrated which result in oxide films that possess an etch selectivity of 100:1 with respect to novolac in oxygen plasmas. 500 nm line-space patterns are demonstrated as a first lithographic imaging proof-of-concept.
A novel process employing photosensitive metallorganic precursor materials is used to pattern thin-film mixed-metal oxide structures. In this process a photosensitive metallorganic precursor is coated onto a silicon substrate and exposed to ultraviolet light through a mask to form patterned oxide structures or baked at low temperatures to produce blanket metal oxide thin films. In the case of direct photopatterning, a negative-tone process occurs in which the unexposed areas can be washed away using a developer solvent. The photochemical conversion of the precursor films was monitored using transmission Fourier transform infrared ͑FTIR͒ spectroscopy, and lithographic contrast experiments were conducted to estimate the dose required to pattern mixed oxide films of barium, strontium, and titanium. It was determined that the minimum dose required to print an image with the set of precursors investigated in this work was approximately 440 mJ/cm 2 for a precursor film thickness of 800 nm. Based on FTIR data, this dose corresponds to removal of approximately 20% of the organic material from the original precursor film. Dielectric properties were measured for photochemically converted oxide films via parallel-plate capacitance testing. The composition of the oxide films produced from a given precursor stoichiometry was determined by using X-ray photoelectron spectroscopy.
Metal-Insulator-Semiconductor (MIS) Schottky diodes were fabricated to study Fermi level unpinning by use of a thin TiO x insulator. For Ti-TiO x -n-Si junctions, the Schottky barrier height (SBH) was pinned due to O diffusion from TiO x into Ti during thermal anneals, as observed from XPS depth profiles. A thin AlO x barrier inserted between the Ti and the TiO x prevented O diffusion from TiO x into Ti, allowing SBH unpinning to be maintained after 450 °C anneals. IntroductionAs device dimensions shrink in CMOS technology, transistor performance is increasingly dominated by the external resistance (R ext ). Contact resistance at the metal-semiconductor interface is a primary contributor to this external resistance. The barrier height of the system is difficult to modulate since the Fermi level (FL) is pinned at this interface. Several studies have shown that a thin insulator can be inserted between the metal and silicon to create a metal-insulator-semiconductor (MIS) contact to unpin the FL, hence allowing for reduction in the Schottky barrier height (SBH) and R ext [1] [2] [3]. To be a viable process option for future nodes, this SBH unpinning at the MIS contact needs to survive the thermal budget of processes after contact formation. In this work using a thin TiO x insulator, we study the SBH unpinning of various metals on n-Si, and in particular the effects of anneals on the SBH at the Ti-TiO x -n-Si junction.
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.