Hi All I was wondering does anybody have any idea of the minium thickness of a silicon membrane that can be machined using an STS ICP Bosch etcher (or any toher bosch etcher).The system uses helium backside cooling which might 'pop' the membrane below a certain thickness. The trench width is 90um. I was hoping to get down below 20um, maybe to 10um. I've seen some papers in which they describe using a mounting wafer but it would be preferable not to do this for our application. Any help would be greatly appreciated. Thanks Rob Robert.Fahey@tyndall.ie