Yes SPR220 is also a good photoresist to use. I've heard many people it's pretty similar to AZ4562 in terms of performance. Not sure about the cost though! Alexandre Boé wrote: > Hi, > > I have used AZ4562 (8 ?m) to etch via holes trough 200 ?m of Si > without any problem. More recently, I have used SPR220 (5 ?m-thick) to > etch 150 ?m of Si. > > Regards, > > Alex > -- Dr. James Paul Grant Postdoctoral Research Associate Microsystems Technology Group 76 Oakfield Avenue Room 3 University of Glasgow Glasgow Scotland G12 8LS Telephone: +44(0)141 330 3374