Handling a 8x8mm piece of a Si wafer with an array of Si3N4 membranes on it can be quite tricky -- especially during the so called "lift off" process.
Figure: Schematic of a smaller piece of wafer with SiN membrane.
During such operations the worst case scenario is pocking out the membrane. And according to Murphy's Law I have experimentally proven the following conclusions of Murphy's Law.
- If one looses grip on the piece of the wafer, the piece will rotate and fall down in such a way that,
- if it falls to the floor, it will fall on the fllow with the surface of the wafer with the membranes facing towards the floor.
- if one gets to catch it, the surface with the sensitive membranes will face towards the tweezers.
- If the first conclusion does not apply, the tweezers will slip off and scratch the membrane.
Figure: Experimental prove -- Scratched SiN membrane.