This approach is described as a "passive" system because once initial conditions are set inside the flask, a continuing presence of helium and good insulation is all that is required to maintain those conditions.
Ms. TRAIL ZEA: The roof is down to the plywood and it caved in--the roof is caved in on the baby's room, so the baby's crib is all full of roof and insulation.
Only when all the masking and etching is complete is the sacrificial gate layer dissolved away, allowing the gates (and the insulation layers between the gate and channel of each transistor) to be filled in.