Recently I read some papers about MEMS part assembly.
But I couldn't understand one small thing.
If I etch the sacrificial layer using developer, how the MEMS parts are attached to silicon wafer?
As I think, the whole parts will be washed away with developer.
How the small parts are attached to wafer? and How can I get the parts after develop?
I attached similar fabrication process. please see the step (e)
I'm waiting for your help
Nickel is ferromagnetic. You can collect your nickel parts and move them around with an electromagnet. Depending on the parts' size and your dexterity, you may also be able to do it with a permanent magnet.
Perhaps I have not clearly understood your problem... but I think you want to produce micro-parts which should (of course) be anchored to the substrate in some rgion, and free to float in other regions, for example a cantilever.
If this is your task, you must think in 3D. Consider a top view of your wafer, and a PR coating the those areas of the structure where the sacrificial layer should not be etched off. This implies a masking step before the copper etch, at least in the simple case you have sketched
Giuseppe Curro
Sorry, My explanations was bad.
What I want to do is making micro parts which is totally free from the surface.
After that I'll assembly those parts.
But during etching process, there is chance to be flushed away with developer.
That's what I wanted to say.
but your answer is also helpful to my knowledge. Thanks :)
also, if you want to avoid photoresist etching with liquid which may carry away your parts (or stitch them to the substrate), you can try with oxygen plasma etching, or even a combination of the two. You can read this work as an example:
Article Gold-based thin multilayers for ohmic contacts in RF-MEMS switches
cheers
You may also want to look using lift-off photoresist where you can deposit metals that will submerged directly to your substrate after removing the resist. In doing so, you may also need to redesign your process to pattern your structures.
I think the problem is that one has to know which MEMS device one would like to construct. When this is known one can see how one fabricate its parts and how one assemble them together.
But your fab steps which you showed points out that you produce nickel parts which can be moved freely.
In order to leave them fixed to the substrate one has to leave part of copper layer not etched.
Best wishes
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