Todd Bailey

Bio: Todd Bailey is an academic researcher from GlobalFoundries. The author has contributed to research in topics: Lithography & Resist. The author has an hindex of 29, co-authored 82 publications receiving 3900 citations. Previous affiliations of Todd Bailey include University of Texas System & IBM.

Step and flash imprint lithography: a new approach to high-resolution patterning

Abstract: An alternative approach to lithography is being developed based on a dual-layer imprint scheme. This process has the potential to become a high-throughput means of producing high aspect ratio, high-resolution patterns without projection optics. In this process, a template is created on a standard mask blank by using the patterned chromium as an etch mask to produce high-resolution relief images in the quartz. The etched template and a substrate that has been coated with an organic planarization layer are brought into close proximity. A low-viscosity, photopolymerizable formulation containing organosilicon precursors is introduced into the gap between the two surfaces. The template is then brought into contact with the substrate. The solution that is trapped in the relief structures of the template is photopolymerized by exposure through the backside of the quartz template. The template is separated from the substrate, leaving a UV-curved replica of the relief structure on the planarization layer. Features smaller than 60 nm in size have been reliably produced using this imprinting process. The resolution silicon polymer images are transferred through the planarization layer by anisotropic oxygen reactive ion etching. This paper provides a progress report on our efforts to evaluate the potential of this process.

Step and flash imprint lithography: Template surface treatment and defect analysis

Abstract: We have finished the construction of an automated tool for step and flash imprint lithography. The tool was constructed to allow defect studies by making multiple imprints on a 200 mm wafer. The imprint templates for this study were treated with a low surface energy, self-assembled monolayer to ensure selective release at the template-etch barrier interface. This surface treatment is very durable and survives repeated imprints and multiple aggressive physical and chemical cleanings. The imprint and release forces were measured for a number of successive imprints, and did not change significantly. The process appears to be “self-cleaning.” Contamination on the template is entrained in the polymerizing liquid, and the number of defects is reduced with repeated imprints.

Template for room temperature, low pressure micro- and nano-imprint lithography

Abstract: Described are imprint lithography templates, methods of forming and using the templates, and a template holder device. An imprint lithography template may include a body with a plurality of recesses on a surface of the body. The body may be of a material that is substantially transparent to activating light. At least a portion of the plurality of recesses may define features having a feature size less than about 250 nm. A template may be formed by obtaining a material that is substantially transparent to activating light and forming a plurality or recesses on a surface of the template. In some embodiments, a template may further include at least one alignment mark. In some embodiments, a template may further include a gap sensing area. An imprint lithography template may be used to form an imprinted layer in a light curable liquid disposed on a substrate. During use, the template may be disposed within a template holder. The template holder may include a body with an opening configured to receive the template, a support plate, and at least one piezo actuator coupled to the body. The piezo actuator may be configured to alter a physical dimension of the template during use.

Patterning curved surfaces: Template generation by ion beam proximity lithography and relief transfer by step and flash imprint lithography

Abstract: Submicron patterning of 1 in. diameter curved surfaces with a 46 mm radius of curvature has been demonstrated with step and flash imprint lithography (SFIL) using templates patterned by ion beam proximity printing (IBP). Concave and convex spherical quartz templates were coated with 700-nm-thick poly(methylmethacrylate) (PMMA) and patterned by step-and-repeat IBP. The developed resist features were etched into the quartz template and the remaining PMMA stripped. During SFIL, a low viscosity, photopolymerizable formulation containing organosilicon precursors was introduced into the gap between the etched template and a substrate coated with an organic transfer layer and exposed to ultraviolet illumination. The smallest features on the templates were faithfully replicated in the silylated layer.

Step and flash imprint lithography: Defect analysis

Abstract: Step and flash imprint lithography (SFIL) is a promising, low cost alternative to projection printing. This technique has demonstrated very high resolution and overlay alignment capabilities, but it is a contact printing technique so there is concern about defect generation and propagation. A series of experiments has been carried out with the goal of quantifying the effect of defect propagation. To that end, each unit process in SFIL was studied independently. The number of particles added during handling and transportation and due to SFIL machinery was deemed acceptable, and the added particles should not complicate the inspection of process defects. The concept of a “self-cleaning” process in which the imprint template becomes cleaner by imprinting was revisited. Inspection of an imprint template before and after imprinting revealed that the template actually becomes cleaner with imprinting. Visual inspection of multiple imprints did not reveal any systematic generation or propagation of defects. The inspection area used in this study was limited, however, since the inspection was both manual and visual. Imprinting for this defect study was performed at the University of Texas in a Class 10 cleanroom, and inspection was performed at International SEMATECH.

X-Ray Diffraction

Abstract: Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

Nanoimprint Lithography: Methods and Material Requirements**

Abstract: Nanoimprint lithography (NIL) is a nonconventional lithographic technique for high-throughput patterning of polymer nanostructures at great precision and at low costs. Unlike traditional lithographic approaches, which achieve pattern definition through the use of photons or electrons to modify the chemical and physical properties of the resist, NIL relies on direct mechanical deformation of the resist material and can therefore achieve resolutions beyond the limitations set by light diffraction or beam scattering that are encountered in conventional techniques. This Review covers the basic principles of nanoimprinting, with an emphasis on the requirements on materials for the imprinting mold, surface properties, and resist materials for successful and reliable nanostructure replication.

Patterning with block copolymer thin films

Abstract: The nanometer-scale architectures in thin films of self-assembling block copolymers have inspired a variety of new applications. For example, the uniformly sized and shaped nanodomains formed in the films have been used for nanolithography, nanoparticle synthesis, and high-density information storage media. Imperative to all of these applications, however, is a high degree of control over orientation of the nanodomains relative to the surface of the film as well as control over order in the plane of the film. Induced fields including electric, shear, and surface fields have been demonstrated to influence orientation. Both heteroepitaxy and graphoepitaxy can induce positional order on the nanodomains in the plane of the film. This article will briefly review a variety of mechanisms for gaining control over block copolymer order as well as many of the applications of these materials. Particular attention is paid to the potential of perfecting long-range two-dimensional order over a broader range of length scales and the extension of these concepts to functional materials and more complex architectures.