铌酸锂刻蚀技术.doc

Wet Etching of Proton-exchanged Lithium Niobate - A Novel
Processing Technique
Abst rac t - A new and simple met hod to etch lit hium nioba te is repor ted. We have found that proton exchanged areas on the c+-face of the crystai can be etched away using a mixture of HF:HNO3 while the un-exchanged regions are left untouched・ The method can be used as a tool for studies of the proton exchange process, as well as form three-dimensional struetures.
Introduction
Wet etching is a frequently used processing step but is seldom applied to lithium nioba te because of the mat erial' s st rong etch resis tance which resu Its in low etch rates and some ti mes non-uniform et ching. In t his paper we prese nt a new met hod to etch lithium niobate.
Introduction of struetural defects speeds up the etching considerably, therefore combinations of ion bombardment and subsequent wet etching have been demons trated as a useful met hod for et ching lit hium nioba te. Laser enhanced et ching has been tried, as well as excimer laser ablation. Reactive ion etching (RIE) and reactive ion beam etching (RIBE) have given etch rates of a few tens of manometers per minute. These techniques are reviewed in [1].
One of the main applications of wet etching of lithium niobate is the use of HF/HNO3 for determination of domain polarity and defect topology [2] - [4]. This mixture attacks the negative c -face of the crystai while the positive is left essentially untouched. However, if the c*-face has regions of stress these will be etched. Such stress can for example originate from crystai dislocations or it can have been induced during surface polishing. The former is observed as single etch pits while the latter normally is seen as etch lines or traces of etch pits. Commercially available crystals intended for integrated optics applications are normally polished to a quality where no sign of the polishing is seen after etching・
Proton exchanged (PE) and annealed proton exchange (APE), using benzo