| 摘要 |
PURPOSE: To prevent electrode corrosion when the Al and Al alloy electrode of an elastic surface wave device is to be etched by chlorine gas plasma by performing etching by initially using Cl2 and BCl3 mixed gas and using only Cl2 gas at the end. CONSTITUTION: After forming a 0.15μm thick Al-0.5wt.% Cu alloy electrode layer 22 on a piezoelectric single crystal substrate 21, the resist pattern 23 of a surface elastic wave filter is formed by photolithography. Then, in the mixed gas generated by mixing Cl2 and BCl3 by 1:1, 30W plasma etching is performed under a pressure of 0.65Pa, and when the 50-60% of the whole etching time elapses, etching is performed by changing the atmosphere to the atmosphere that contains only Cl2 gas. The rate of etching on a metal 22 is increased by changing the atmosphere to the atmosphere that contains only Cl2 gas, however, sputtering to resist 23 is reduced. Thus, adhesion of the resist residual containing Cl and O, which induce electrode corrosion, is prevented and electrode pattern reliability is increased.
|
