| dc.contributor |
Kingon, Angus, Committee Chair |
|
| dc.contributor |
Sitar, Zlatko, Committee Member |
|
| dc.contributor |
Osburn, Carlton, Committee Member |
|
| dc.contributor |
Maria, Jon-Paul, Committee Member |
|
| dc.creator |
Parker, Charles Bernard |
|
| dc.date |
2010-04-02T18:37:53Z |
|
| dc.date |
2010-04-02T18:37:53Z |
|
| dc.date |
2002-11-22 |
|
| dc.date.accessioned |
2023-02-28T17:08:03Z |
|
| dc.date.available |
2023-02-28T17:08:03Z |
|
| dc.identifier |
etd-10172002-004140 |
|
| dc.identifier |
http://www.lib.ncsu.edu/resolver/1840.16/3835 |
|
| dc.identifier.uri |
http://localhost:8080/xmlui/handle/CUHPOERS/265624 |
|
| dc.description |
Thin films of (Ba,Sr)TiO3 (BST) deposited by Liquid Source MOCVD were investigated. BST is a candidate dielectric for future-generation DRAM and as a tunable dielectric. Two areas of both scientific and commercial interest were investigated. The first area is the effect of decreasing dimension on ferroelectric properties. Several theories of size effects in ferroelectrics were evaluated. The dielectric response of a set of BST films of thicknesses from 15 to 580 nm was measured from 85 to 580 K. These films were extensively characterized and the boundary conditions that often influence size effects measurements were considered, including strain, finite screening length in the electrode, depolarization fields in the ferroelectric, atmospheric effects, control of stochiometry, and others. The data set was compared to the theoretical predictions and it was determined that Finite Size Scaling provided the best fit to the data. Using this theory, the predicted dielectric response was compared to the requirements of future generations of DRAM and was found to be sufficient, if film strain can be controlled. The second area is reliability. The types of lifetime-limiting electrical failure observed in BST are resistance degradation, time dependant dielectric breakdown (tddb), and noisy breakdown. Previous work on BST reliability has largely focused on resistance degradation at high temperature. This condition is only a small subset of experimental space. This work extends the understanding of BST failure into the low temperature regime and evaluates the effects of both DC and AC stress. It was found that tddb is the dominant failure mode at low temperature and resistance degradation is the dominant failure modes at high temperature. Synthesizing this work with previous work on resistance degradation allowed a failure framework to be developed. Rigorous extrapolation of resistance degradation and tddb lifetimes was compared to the requirements of future generations of DRAM and was found that while resistance degradation will not limit device lifetimes, tddb will. Refinement of BST processing will be necessary to reduce the defect causing tddb failure. |
|
| dc.rights |
I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
|
| dc.subject |
finite size scaling |
|
| dc.subject |
DRAM dielectric |
|
| dc.subject |
perovskite |
|
| dc.subject |
ferroelectric thin film |
|
| dc.subject |
barium strontium titanate |
|
| dc.title |
Size Effects and Reliability of (Ba,Sr)TiO3 Thin Films |
|