Browsing by Subject "Microtechnology"
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Item Laser micro/nano scale processing of glass and silicon(2006) Theppakuttai Komaraswamy, Senthil Prakash; Chen, ShaochenItem Laser micro/nano scale processing of glass and silicon(2006-05) Theppakuttai Komaraswamy, Senthil Prakash, 1977-; Chen, ShaochenThe revolutionary progress in semiconductor, communication, and information industries based on electronic and photonic technologies demands for the development and enhancement of new laser processes to support micro and nanotechnologies. This dissertation is aimed at exploring the use of lasers for micro and nano scale processing of glass and silicon, the most commonly used materials in the IC industry. The objective of the dissertation is two fold: a) use lasers for locally micro bonding glass and silicon wafers, and b) use lasers for nanopatterning glass and silicon substrates by circumventing the diffraction limit of light. In the first part of the thesis, glass and silicon wafers are bonded locally in microscale by a pulsed Nd:YAG laser. Glass is transparent to the wavelength used and hence the laser beam passes through the glass wafer and is absorbed by silicon. As a result, silicon is melted and upon resolidification bonding is realized between the two substrates. The transient melting and resolidification of the substrates is studied experimentally and compared to the simulation results of a finite element numerical model. The bonded areas are studied in detail using a scanning electron microscope and a chemical analysis is done to understand the bonding mechanism. In the second part of the thesis, nanopatterns are created on glass and silicon substrates by circumventing the diffraction limit of light. The nanofeatures are created by irradiating silica and gold nanospheres deposited on a substrate. In case of silica spheres, features approximately half the diameter of the sphere were obtained by utilizing the optical field enhancement around the spheres. In case of gold spheres, features as small as 40 nm were realized by the excitation of coherent resonant electron plasma oscillations. The effect of sphere size, laser wavelength, polarization, incident angle, and energy were studied experimentally. Finally, these experimental results are compared with the numerical results from a multidimensional, heat transfer model.Item Micro/nano fabrication of polymeric materials by DMD-based micro-stereolithography and photothermal imprinting(2006) Lu, Yi; Chen, ShaochenItem Nano-scale large area gap control for high throughput electrically induced micro-patterning(2007-12) Raines, Allen Lee, 1973-; Sreenivasan, S. V.Micro- and nano-scale patterning is essential to the fabrication of various kinds of devices including electronic circuits, optical devices, optoelectronic devices, thin film heads for magnetic storage, displays, etc. There are several current and emerging applications that specifically require regular arrays of repeating patterns such as gratings, posts, and holes. At the nano-scale, for replication using lithography techniques such as optical lithography and imprint lithography, the cost of making the master can be a significant portion of the fabrication cost, particularly if small batches of customized parts are required. High resolution patterning using electric fields allows the creation of micro- and nano-scale structures using low resolution masters. Most of the literature to date has focused on using high glass transition temperature polymers that need to be heated to induce the patterning process. While this allows the ability to use a wide variety of materials, it leads to poor throughput as it can take several minutes to complete the patterning of one device region. The patterning speed can be increased by using photocurable, low viscosity monomers instead of high glass transition temperature polymers. Process control requires a tool that can control the parallelism of the gap between a conductive wafer and template to the nanometer level over large areas. The tool must have high resolution orientation and position control and high apparent stiffness to prevent the electric field from pulling the template and wafer together. In this research, high stiffness mechanism designs were investigated first. Such designs proved impractical, with travel, stiffness, and maximum side load requirements difficult or extremely expensive to meet. Therefore, a novel precision machine concept was explored. A parallel mechanism that is simultaneously actuated by piezo actuators and by voice coils was studied. Feedforward compensation of the applied electric force using voice coils was used to reduce the need for a stiff mechanism. The result was the Hybrid Active Gap Tool (HAGT), a 3-RPS parallel mechanism which has the ability to significantly enhance the quality of electrically induced patterning. Performance of the Hybrid Active Gap Tool was validated using a set of gap control experiments. The new design and control system resulted in very high precision orientation alignment needed for gap control. Without voice coil compensation, the tool has a stiffness of less than 3N/µm . With voice coil compensation, the apparent stiffness of the tool varies from a minvi imum of 30N/µm up to nearly infinite stiffness and into negative stiffness if overcompensation is intentionally used. Voice coil compensation allows the tool to meet the stringent performance requirements of the patterning process without the need for a high stiffness mechanism. Gaps as small as 400nm were maintained with the electric field applied and the gap changed by less than 5nm from the nominal 400nm during the process. Smaller gaps can be achieved with improvements in template mesa height calibration and better understanding of piezo actuated mechanism designs.