Steven R. Young

A novel low-temperature method to fabricate MEMS resonators using PMGI as a sacrificial layer

A method to fabricate microelectromechanical systems (MEMS) clamped?clamped resonators using polymethylglutarimide (PMGI) as a sacrificial release layer has been developed. Control of the critical air-gap dimension between the resonator beam and drive electrode was maintained by varying the sacrificial PMGI thickness, allowing fabrication of devices with resonator-to-electrode gaps as small as 100 nm. The resonator beam was constructed by depositing a low stress, low temperature bi-layer alpha-TaN/SiON (50/2000 nm) film over the PMGI layer, followed by a multi-step etch process. Physical characterization of devices with varying beam lengths was performed via focused ion beam and scanning electron microscopy analyses to verify complete release of the resonator structures. Electrical testing showed a resonant frequency of 11.3 MHz, which agreed well with simulated results. The measured RF characteristics are fitted with a lumped element model that used Youngs modulus and the device quality factor as adjustable parameters. Youngs modulus of the individual components of the TaN/SiON bi-layer was measured and found to be in good agreement with the values used to fit the measured resonance.

63.2: High Brightness, High Voltage Color Field Emission Display Technology

We have designed nanotube-based field emission displays to operate above 6500 V. As a result, we have improved the white-screen luminance of HDTV resolution (0.726 mm pixel) field emission displays beyond 700 cd/m2. We have maintained good color purity without employing separate focusing electrodes. In addition, we demonstrate spacers operating beyond 10,000 volts on the anode without any charging that would distort the image.

Characterization of low-temperature Ultrananocrystalline/spl trade/ Diamond RF MEMS resonators

For the first time working MEMS resonators have been produced using low-temperature deposited (550/spl deg/ C) Ultrananocrystalline/spl trade/ Diamond (UNCD/spl trade/) films. Using a lumped-element model to fit experimental data, UNCD materials properties such as a Youngs modulus of 710 GPa and an acoustic velocity of 14,243 m/s have been deduced. This is the highest acoustic velocity measured to date for a diamond MEMS structural layer deposited at low temperatures. A 10 MHz resonator shows a DC-tunability of the resonance frequency of 15% between 15 and 25 V and the breakdown voltage behavior shows electrostatic breakdown rather than electro-mechanical pull-down for higher frequency devices. Good resonant frequency reproducibility is observed when cycling the resonators over bias voltages from 15 to 25 V and over RF power levels of -10 to 10 dBm.

Sub-80-nm contact hole patterning using Step and Flash Imprint Lithography

Recently, the International Roadmap for Semiconductors (ITRS) has included imprint lithography on its roadmap, to be ready for production use in 2013 at the 32 nm node. Step and Flash Imprint Lithography (S-FILTM) is one of the promising new methods of imprint lithography being actively developed. Since S-FIL is a 1X printing technique, fabrication of templates is especially critical. S-FIL has previously demonstrated the ability to reliably print high resolution line/space and contact hole features into a silicon-rich etch barrier material. Beyond printing with S-FIL however, there is the requirement to develop low or zero bias, high selectivity dry etch processes needed to transfer printed images into the substrate. In this study, the feasibility and methodology of imprinting sub-80 nm contacts, and pattern transferring this image into an underlying oxide layer is demonstrated. Critical parameters such as e-beam dose and etch biases associated with template pillar fabrication, and biases associated with pattern transfer processes for sub-80 nm 1:1 and 1:2 pitch contacts are discussed. Wafer imprinting was done on 200 mm wafers using Molecular Imprints Inc., Imprio 100TM system.

Electron beam directed repair of fused silica imprint templates

Imprint lithography has been shown to be an effective method for replication of nanometer-scale structures from a template mold. Step-and-Flash Imprint Lithography (S-FILTM) employs a UV-photocurable imprint liquid, which enables imprint processing at ambient temperature and pressure. The use of a transparent fused silica template facilitates precise overlay. With this combination of capabilities, NIL is a multi-node technique that is suitable for advanced prototyping of processes and devices to meet the anticipated needs of the semiconductor industry. However, since the technology is 1X, it is critical to address the infrastructure associated with the fabrication of templates. An essential part of this infrastructure is the capability to identify and repair template defects. Fused silica imprint templates are typically produced from photomask substrates, and it is straightforward to make use of the tools and processes that have been developed to repair commercial photomasks. However, the optical properties of the repaired region are of secondary importance because S-FIL patterning is based on direct transfer of topography (rather than indirect transfer of an optical image). As in conventional photolithography, both additive and subtractive repairs are required to correct a variety of defect types. Repair techniques that are based on electron-beam induced chemical reactions have demonstrated the capability to perform both additive (deposition) and subtractive (etching) processes at high resolution. This work is a demonstration that electron-beam directed additive repair is capable of repairing fused silica template structures with sub-100 nm resolution.

Evaluation of FIB and e-beam repairs for implementation on step and flash imprint lithography templates

In order for Step and Flash Imprint Lithography S-FIL or any other imprint lithography to become truly viable for manufacturing, certain elements of the infrastructure must be present. In particular, these elements include; fast and precise Electron Beam (E-beam) pattern writing, ability to inspect, and a methodology to repair. The focus of this paper will be to investigate repair of clear and opaque defects on S-FIL templates using Focused Ion Beam (FIB) and Electron beam technologies. During this study, FEIs Accura XT FIB mask repair system was used to selectively mill opaque line edge defects as small as 45 nm in the Cr-based and 30 nm in the quartz-based patterns. Repairs to the Cr pattern achieved a placement offset of 8.8 nm with a one sigma value of 11.4 nm. Additionally, a series of trench cuts were made perpendicular through line segments to determine the minimum cut resolution. In an effort to repair clear defects within chrome patterns, studies were performed to deposit carbon or a proprietary metallization using either FEIs FIB platform or E-beam mask repair research tool. This paper will discuss the repair strategy used and include characterization of repairs through Scanning Electronic Microscopy (SEM) and Atomic Force Microscopy (AFM) imaging. Furthermore, repair efficiency was determined by assessing the ability of the repair to hold up through the remainder of the template fabrication process and ultimately pattern transfer of imprinted features.