Applications of atomic layer deposition for next-generation nanoscale devices
- Martin Michael Winterkorn.
- [Stanford, California] : [Stanford University], 2019.
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- Winterkorn, Martin Michael, author.
- Prinz, F. B., degree supervisor.
- Howe, Roger Thomas, degree committee member.
- Kenny, Thomas William, degree committee member.
- Stanford University. Department of Mechanical Engineering.
- Atomic Layer Deposition (ALD) is a thin film deposition technique that has gained prominence in recent years due to its ability to synthesize highly conformal and uniform films, with precise thickness control and for a wide range of materials. This work explores how the unique properties of ALD films can be leveraged through novel nanofabrication processes to enable higher performance devices. First, a comprehensive characterization of the etch rates of 9 oxide ALD films in 20 wet chemicals and vapor etchants is presented, as knowing the films' etch rates and their compatibility with commonly used processing chemicals is crucially important when integrating them into nanofabrication processes. Second, a new process is described that, by taking advantage of ALD films' excellent properties as etch stop layers for vapor releases, allows the simultaneous release of suspended structures of varying sizes and arbitrary shapes with high accuracy. This so-called "sandbox" process can be incorporated into the fabrication of many kinds of devices, and has been successfully employed for aluminum nitride piezoelectric resonators, resulting in a record high figure of merit. Finally, the development of thermal accelerometers featuring ultrathin suspended platinum thermistors with thicknesses down to 8 nm is presented. Using plasma-enhanced ALD of platinum for the first time in a thermal accelerometer enables a 100x reduction in beam cross-section compared to previous work. Plasma treatments and nucleation layer dependencies of ALD platinum are investigated to further enhance material properties. Novel fabrication processes allow large cavity sizes of up to 500 μm depth and 4000 μm length, resulting in unprecedentedly high aspect ratios exceeding 100,000:1, which confer many benefits such as increased heating efficiency and decreased thermal time constants.
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- Submitted to the Department of Mechanical Engineering.
- Thesis Ph.D. Stanford University 2019.