Hello Myung Kwon I agree with a previous post that using xenon difluoride to etch your Mo would be an interesting alternative. Note it will etch at about 1/6th the rate of silicon so you would need to make sure there was no exposed silicon. Which raises the question, what is under your Mo? If it is silicon the XeF2 will continue to etch the Si after it is finished with the Mo. If it is just about anything other than Si it will stop. If you think you would like to try this we would be willing to run a sample for you to see how it works. XACTIX is the world wide leader in etching equipment using xenon difluoride with several models to meet diverse budgets. You can contact me directly or you can contact our local agent for support. Best Regards David Springer XACTIX, Inc. davids@xactix.com www.xactix.com