Maskless Projection Lithography

Photolithography is a key element of the modem integrated circuit process. It is photolithography, combined with metal deposition, that allows a three dimensional circuit to be built up on a two dimensional surface. Since it is such an important part of the semiconductor manufacturing industry, a massive base of research in this area already exists. The problem with this pre-existing research is that it is geared solely toward industrial purposes, as opposed to more academic research areas. The goal of my research is to move this industrial process into the academic setting of Pomom College

Chalcogenide Glass-on-Graphene Photonics

Two-dimensional (2-D) materials are of tremendous interest to integrated photonics given their singular optical characteristics spanning light emission, modulation, saturable absorption, and nonlinear optics. To harness their optical properties, these atomically thin materials are usually attached onto prefabricated devices via a transfer process. In this paper, we present a new route for 2-D material integration with planar photonics. Central to this approach is the use of chalcogenide glass, a multifunctional material which can be directly deposited and patterned on a wide variety of 2-D materials and can simultaneously function as the light guiding medium, a gate dielectric, and a passivation layer for 2-D materials. Besides claiming improved fabrication yield and throughput compared to the traditional transfer process, our technique also enables unconventional multilayer device geometries optimally designed for enhancing light-matter interactions in the 2-D layers. Capitalizing on this facile integration method, we demonstrate a series of high-performance glass-on-graphene devices including ultra-broadband on-chip polarizers, energy-efficient thermo-optic switches, as well as graphene-based mid-infrared (mid-IR) waveguide-integrated photodetectors and modulators

Mid-infrared materials and devices on a Si platform for optical sensing

In this article, we review our recent work on mid-infrared (mid-IR) photonic materials and devices fabricated on silicon for on-chip sensing applications. Pedestal waveguides based on silicon are demonstrated as broadband mid-IR sensors. Our low-loss mid-IR directional couplers demonstrated in SiNx waveguides are useful in differential sensing applications. Photonic crystal cavities and microdisk resonators based on chalcogenide glasses for high sensitivity are also demonstrated as effective mid-IR sensors. Polymer-based functionalization layers, to enhance the sensitivity and selectivity of our sensor devices, are also presented. We discuss the design of mid-IR chalcogenide waveguides integrated with polycrystalline PbTe detectors on a monolithic silicon platform for optical sensing, wherein the use of a low-index spacer layer enables the evanescent coupling of mid-IR light from the waveguides to the detector. Finally, we show the successful fabrication processing of our first prototype mid-IR waveguide-integrated detectors

Characterization Of Structural Relaxation In As2Se3 For Analysis Of Lens Shape Change In Glass Press Mold Cooling And Post-Process Annealing

This study explores the structural relaxation behavior of As 2Se3 by thermo mechanical analysis in order to characterize and eventually predict volume change in As2Se 3 upon relaxation during cooling after precision glass molding (PGM) and annealing. A vertical beam of As2Se3 was placed in a thermo mechanical analyzer (TMA) and fully relaxed at a given temperature. The temperature was then quickly changed a given amount and the 1-D relaxation of the beam was measured until it reached equilibrium at the new temperature. The resultant curve was then fit with a Prony series which captured the relaxation data. The mathematical representation of the relaxation is then analyzed as a function of time, temperature, and quench rate and can be used to predict one dimensional (1-D) length change upon relaxation. A maximum of three terms is needed to describe the relaxation behavior and that number declines with an increase in temperature. This decay of the number of Prony terms needed to describe relaxation points to a structure that relaxes with less complexity as it approaches Tg. These trends can be converted to 3-D due to the amorphous and therefore typically isotropic nature of As2Se3 glass. This volume change information as a function of vital processing parameters can then be used to predict the change in shape of a work piece during cooling or post process annealing within a precision molding cycle. The mathematical representation of volume relaxation can then be applied to finite element models (FEM) of As2Se3 lenses or other optical elements. © 2013 SPIE

A Maskless Photolithographic Prototyping System Using a Low-cost Consumer Projector and a Microscope

Lithographic processing has been the key technology responsible for the rapid advances in microelectronics, but is typically not accessible to undergraduates. We have developed a maskless photolithographic system that can be assembled from a consumer projector and a trinocular microscope. This system allows students to design and print custom patterns into photoresist in less than 30 min, without using a clean room, a mask facility, or a chrome-etch bath. Students can create and evaluate patterns, make changes to their design, or add additional layers of aligned patterns in a single laboratory session. The rapid turnaround time and low cost of ownership is useful for low-resolution (∼10 μm) prototyping. Photoresist is spun in a modified food processor and baked on a standard hot plate. Mating pieces were machined from aluminum. Only the digital light processing projector and food processor are modified, so the microscope, camera, and computer need not be dedicated to the system. The entire system can be assembled for less than $5000