RSS

Applying Murphy's Law on SiN Membranes

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.

Conclusions

  1. If one looses grip on the piece of the wafer, the piece will rotate and fall down in such a way that,
    1. 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.
    2. if one gets to catch it, the surface with the sensitive membranes will face towards the tweezers.
  2. If the first conclusion does not apply, the tweezers will slip off and scratch the membrane.


Figure: Experimental prove -- Scratched SiN membrane.