Performance of a Dual Side Substrate Metrology System for Micromachining Lithography

Advances in micromachining (MEMS) applications such as optical components, inertial and pressure sensors, fluidic pumps and radio frequency (RF) devices are driving lithographic requirements for tighter registration, improved pattern resolution and improved process control on both sides of the substrate. Consequently, there is a similar increase in demand for advanced metrology tools capable of measuring the Dual Side Alignment (DSA) performance of the lithography systems. There are a number of requirements for an advanced DSA metrology tool. First, the system should be capable of measuring points over the entire area of the wafer rather than a narrow area near the lithography alignment targets. Secondly, the system should be capable of measuring a variety of different substrate types and thicknesses. Finally, it should be able to measure substrates containing opaque deposited films such as metals. In this paper, the operation and performance of a new DSA metrology tool is discussed. The UltraMet 100 offers DSA registration measurement at greater than 90% of a wafer’s surface area, providing a true picture of a lithography tool’s alignment performance and registration yield across the wafer. The system architecture is discussed including the use of top and bottom cameras and the pattern recognition system. Experimental data is shown for tool performance in terms of repeatability and reproducibility over time. The requirements for tool accuracy and methods to establish accuracy to a NIST traceable standard are also discussed.

Nanomechanical Biosensor Using Polymer Membranes

In recent years several surface stress sensors based on microcantilevers have been developed for biosensing [1–4]. Since these sensors are made using standard microfabrication processes, they can be easily made in an array format, making them suitable for high-throughput multiplexed analysis. Specific reactions occurring on one surface (enabled by selective modification of the surface a priori) of the sensor element change the surface stress, which in turn causes the sensor to deflect. The magnitude and the rate of deflection are then used to study the reaction. The microcantilevers in these sensors are usually fabricated using material like silicon and its oxides or nitrides. The high elasticity modulus of these materials places limitations on the sensitivity and sensor geometry. Alternately polymers, which have a much lower elastic modulus when compared to silicon or its derivatives, offers greater design flexibility, i.e. allow the exploration of innovative sensor configurations that can have higher sensitivity and at the same time are suitable for integration with microfluidics and electrical detection systems.

Large-Scale Assembly of Carbon Nanotubes

The scale decomposition of a multi-scale system into small-scale order domains will reduce the complexity of the system and will subsequently ensure a success in nanomanufacturing. A novel method of assembling individual carbon nanotube has been developed based on the concept of scale decomposition. Current technologies for organized growth of carbon nanotubes are limited to very small-scale order. The nanopelleting concept is to overcome this limitation by embedding carbon nanotubes into micro-scale pellets that enable large-scale assembly as required. Manufacturing processes have been developed to produce nanopellets, which are then transplanted to locations where the functionalization of carbon nanotubes are required.

Is There a Critical Size in Nano Grained Metals for Ductile to Brittle Transition?

Nanoscale metal films and electrodes are extensively used in today’s micro and nano electronics as well as nano mechanical systems. These metal structures are usually polycrystalline in nature with nano scale grains connected to each other by grain boundaries. The small size offers large grain boundary to volume ratio that is likely to affect the metal properties significantly. Here, we discuss the role of grain size and boundaries in determining the mechanical behavior of metals, such as elasticity and yielding.

Self-Assembled Silicon Microdevices Driven by Muscle

Over the last two decades, a variety of micro-robotic systems have been developed including electrothermal, electrostatic, electrochemical, piezoelectric, and electromagnetic actuators based on MEMS technology. The development of these micro-actuators promises a revolution in biological and medical research and applications analogous to that brought about by the miniaturization of electrical devices in information technology. For example, controllable manipulation of these tiny actuators may enable precise temporal and spatial delivery of chemicals, micro-optics or microelectronics to specific targeted sites.

Simulation of Thermal Transport in Nanowire Composites for Macro-Electronics Applications

Thermal transport in thin film transistors (TFTs) composed of nanowires embedded in plastic substrates is considered. Random ensembles of intersecting and contacting wires embedded in a substrate are analyzed using Fourier theory. Heat generation due to self-heating is included. A finite volume scheme is used to obtain the temperature solutions in the wires and substrate. Temperature profiles in the ensemble are investigated as a function of wire number density, wire-contact Biot number as well as the Biot number for heat transfer to the substrate.

Nanoscale Heat Conduction in the SOI, Strained-Si and Tri-Gate Transistors

There have been many attempts in the recent years to improve the device performance by enhancing carrier mobility by using the strained-induced changes in silicon electronic bands [1–4] or reducing the junction capacitance in silicon-on-insulator (SOI) technology. Strained silicon on insulator (SSOI) is another promising technology, which is expected to show even higher performance, in terms of speed and power consumption, comparing to the regular strained-Si transistors. In this technology, the strained silicon is incorporated in the silicon on insulator (SOI) technology such that the strained-Si introduces high mobility for electrons and holes and the insulator layer (usually SiO2) exhibits low junction capacitance due to its small dielectric constant [5, 6]. In these devices a layer of SiGe may exist between the strined-Si layer and insulator (strained Si-on-SiGe-on-insulator, SGOI) [6] or the strained-Si layer can be directly on top of the insulator [7]. Latter is advantageous for eliminating some of the key problems associated with the fabrication of SGOI.

Nanoscale Heat Conduction in Data Storage Technology

The magnetic data storage industry has followed a similar density (and data rate) improvement curve as the semiconductor technology (Moore’s Law) for the past decade. However, whether the storage densities will continue to increase at this rate and be able to keep up with the improvements in processor technology is under a near term threat resulting from the fundamental physics up on which the hard disk drives are based. It is expected that novel, more unconventional technological solutions become necessary to overcome limitations, however, many of these technologies rely heavily on heating and energy transport at extremely short time and length scales. It is widely believed that further advances in high-technology data storage systems will be difficult, if not impossible, without rigorous treatment of the nano-scale energy transport. The nano-scale heat transfer research effort at Data Storage System Center (DSSC) has been focused on three interwoven areas of thermal design, failure analysis, and metrology of micro/nano-devices and structures relevant to data storage technologies. In this presentation, underlying physics and fundamentals of heat transport at nanoscale will be discussed. In addition, applications of the nanoscale heat transfer to the thermal analyses of the magnetic and phase change optical data storage technologies will be presented.

Simulation of Thermionic Emission from Quantum Wires

In the late 19th century, Edison observed electrical current flowing between hot and cold electrodes [1]. Since this discovery of thermionic emission, research has occurred with varying intensity in order to harness the simplicity and utility of the thermionic effect in power generation devices. Hatsopoulos and Gyftopoulos [2,3] provide details of the development of thermionic theory and practice. In general, thermionic power generation has not found widespread use, despite many inherent advantages over alternative power generation methods, because of material limitations that have precluded an attractive combination of power generation efficiency and capacity. This paper presents semiclassical and quantum models for the thermionic behavior of a newly developed class of materials, quantum wires, that may offer some promise in alleviating historic materials limitations of thermionic devices.

Nanoturf Surfaces for Reduction of Liquid Flow Drag in Microchannels

We report nano-engineered surfaces (NanoTurf), designed to make various micro- and nano-fluidic devices and systems less frictional for liquid flows, and describe microchannels made with such a surface. While our group has reported a dramatic (> 95%) drag reduction of discrete droplets flowing in a space between two parallel-plates covered with “random” nano-posts created by the “black silicon method” [1], this paper describes various nanofabrication techniques, including those capable of “designing” nanostructures with not only a good control of pattern sizes and periods but also practical manufacturability to be embedded in various micro- and nano-fluidic devices and systems. Microchannels are developed using the designed nanostructure surfaces and used for continuous flow tests.