Fabrication method of multiple band surface acoustic wave devices

A method of fabricating a Surface Acoustic Wave (SAW) device having first and second SAW filters, which have different electrode thicknesses and are formed on a single piezoelectric ceramic substrate, the method comprising the steps of:

• forming a first conductive layer, an etch-stop layer made of conductive material and a second conductive layer one atop another in the recited order on the piezoelectric ceramic substrate;
• forming a mask on a first portion of the second conductive layer corresponding to a first SAW filter region;
• selectively removing a second portion of the second conductive layer corresponding to a second SAW filter region by using the mask;
• removing the mask and providing a photoresist pattern for forming electrodes of the first and second SAW filters, wherein the photoresist pattern is provided on the first portion of the second conductive layer corresponding to the first SAW filter region and on a portion of the etch-stop layer corresponding to the second SAW filter region;
• selectively removing the first and second conductive layers and the etch-stop layer by using the photoresist pattern as a mask;
• and
• removing the photoresist pattern;
• wherein
• the step of selectively removing the first and second conductive layers and the etch-stop layer comprises physically removing the etch-stop layer by using Ar gas in a high bias power range;
• and
• the step of physically removing the etch-stop layer comprises lowering the bias power, which is used for removing the etch-stop layer, before the first conductive layer is completely removed and after the etch-stop layer has been removed.