The design, fabrication, and implications of a solvothermal vapor annealing chamber

Abstract

This thesis documents the design, fabrication, use, and benefits of a prototype aluminum solvothermal vapor annealing chamber which facilitates the self-assembly of block copolymers (BCPs) on silicon wafers which are then used to generate nanoscale patterns through the use of additive lithography. The chamber aids in the low-waste production of research and development silicon wafers possessing unparalleled surface resolution and feature density, by way of nanoscale lithography. The concept of this chamber came out of a need by the MIT Department of Materials Science and Engineering for a faster and more controlled lithographic production process. The chamber's design lends to a more simplistic, more durable, safer, and environmentally cleaner process than traditional custom-made laboratory instruments. The prototype has the potential to become the standard apparatus for improving the process of solvothermal vapor annealing as a custom-built single solution. The chamber's design is intended to enable a safer, cleaner testing environment, and provide increased control to the researcher by decoupling the temperature control of the solvent, chamber, and sample holder. As a result, the chamber has the potential to allow for a decrease in time for the production of annealed silicon wafers with more dense features than current commercial processes enable. The chamber not only meets the required specifications of the solvothermal vapor annealing process, it also exceeds those expectations by allowing the researcher to reduce overall solvent usage. It supports an internal gage pressure of at least one atm psi and temperatures much greater than 100 degrees Celsius, both necessary conditions for the annealing process. These benefits are the direct result of five unique design characteristics. The following unique characteristics of the solvent chamber design are: a) A tightly toleranced sliding rod; b) A precisely machined sample-specific sized holder; c) A modular mount for the optical film measurement device; d) A set of digitally controlled heaters; e) A set of bolted and press-fitted pieces of aluminum, PTFE, quartz, and copper serve to contain the highly flammable gases, toluene and heptane, normally present in this process, safeguarding the researcher. Although the chamber has not been fully tested in an end-to-end solvothermal vapor annealing process, it demonstrates in self-testing to be a viable alternative and promising solution for Kevin Gotrik, Ph.D. Candidate in the Materials Science and Engineering. There is potential for modifications based on user feedback and implementation. Later prototypes could explore modifying the chamber geometry, wall thickness, and sealing properties to achieve higher operating pressures and temperatures.