Since July 8, when coming out of the shutdown, there has been significant effort around temperature/humidity and duct smoke detectors. Across over 24 work orders that facilities opened, various issues were documented and resolved. A rough list of control and hardware problems that were addressed includes:
- The electrical distribution was shut down to install the new chiller feed and, when everything was powered back up, there were several issues with the building management system not being accurate;
- There was effort around getting the amount of glycol in the system correct;
- One of the cooling coils had an issue and needed repair;
- Air handler and two fans were intermittent at times;
- An actuator diaphragm had failed;
- At times, the heating coils were coming on;
- Some exhaust fans were tripping on overcurrent;
- The old chiller system was shutting down during the extreme weather;
- Water sprayers were temporarily installed on the condenser to lower head pressure;
- One of the mixing valves will need replacement. It’s currently operating in manual mode and is open (thanks to zipties). The repair will be done once it’s colder outside, to avoid flooding the labs with humidity during the 1-2 hours of repair.
Starting the end of last week (July 27), the system began to stabilize and condensation on equipment went away. By mid-week, MIT.nano staff was comfortable turning on some tools again (like asher and ebeamAu). Some tools, however, are still down. We are cautiously optimistic about the humidity having been stabilized. The plot below shows Bldg. 39 BMS data (it only has a 1 week rolling history, so we can’t look back to early July, unfortunately). The data suggests that, after a few tweaks (marker A in plot), the dew point in the fab is stable and nearly independent of outside conditions.
Some of the controls are still being optimized to reduce the jitter (you can see the dew point fluctuating a little at marker “B” in plot). There is now a lot of attention from many different people across facilities on the T/Rh/Td conditions in Fab-39. There can still be hot and humid days where the weather simply exceeds the designed capacity of the system. However, July is now over, and with the increased attention any problems can be addressed more quickly.
For now, the MIT.nano team will post daily T/Rh/Td data from the TRL photo room as a comment on the TRL coater, so that users can know the situation before coming into the lab.