Lithium niobate reactive ion etching
Scientific Publication
- Report Number:
- DSTO-TN-0291
- Authors:
- Winnall, S.; Winderbaum, S.
- Issue Date:
- 2000-07
- AR Number:
- AR-011-490
- Classification:
- UNCLASSIFIED
- Report Type:
- Technical Note
- Division:
- Electronic Warfare Division (EWD)
- Release Authority:
- Chief, Electronic Warfare Division
- Task Sponsor:
- DST
- Task Number:
- DST 99/177
- File Number:
- 9505/19/21
- Pages:
- 24
- References:
- 1
- URI:
- http://hdl.handle.net/1947/3614
Abstract
Reactive ion etching (RIE) of lithium niobate substrates has been performed using CF4:O2 chemistry. A maximum etch rate of 38 A/min was obtained, and a deepest etch of 1.2 micro-m was achieved. The x-cut crystal orientation of the lithium niobate crystal etched more slowly than the z-cut orientation, at a ratio of 8:15. Sidewall roughness was minimsed at the expense of etch rate by increasing the oxygen flow rate for fixed CF4 flow rate. The achieved etch rate is suitable for low refractive index contrast devices such as integrated optical grating or lenses. However the low etch rate is impractical for low drive voltage etched modulators.
Executive Summary
Lithium Niobate is a useful synthetic material for integrated optical devices such as wideband electro-optical modulators. Etching the Lithium Niobate can reduce the drive voltage and improve efficiency. This work was undertaken under task DST99/177. Reactive ion etching (RIE) of lithium niobate substrates has been performed using CF4:O2 chemistry. A maximum etch rate of 38 Å/min was obtained, and a deepest etch of 1.2 μm was achieved. The x-cut crystal orientation of the lithium niobate crystal etched more slowly than the z-cut orientation, at a ratio of 8:15. Sidewall roughness was minimised at the expense of etch rate by increasing the oxygen flow rate for fixed CF4 flow rate. The achieved etch rate is suitable for low refractive index contrast devices such as integrated optical gratings or lenses. However the low etch rate is impractical for low drive voltage etched modulators.