16 Apr We have a new tool requiring WF6 (Tungsten Hexafluoride). Can I use a 3 stick valve manifold box in the line to feed the 3 chambers?
Delivering Tungsten Hexafluoride to a process tool can be tricky. We’ve seen a few gas delivery system installations that have taken some effort and attention to detail to set up correctly. Here are my suggestions:
- Keep the gas cabinet within 50 feet of the tool
- Chill the gas cylinder to 17ºC to stabilize the vapor pressure, and then heat the lines to the tool
- Set the delivery pressure at -1.5 psia at static in the gas cabinet
- The cylinder pressure should be 3 to 4 psia
- To avoid sucking liquid into the lines, don’t go above -1.5 psia at static
- Use 3/8″ tubing and components after the gas cabinet to point of connection with the process tool
- Don’t put regulators in the valve manifold box (VMB)
- Shouldn’t need to heat trace inside the VMB, BUT do so from the gas cabinet to the VMB, and the VMB to the tool. 72 – 75º from Cabinet to VMB; 80 – 85º from VMB to the tool
- With a new gas bottle, there isn’t sufficient head to run 3 chambers, and you need to be careful not to suck liquid into the gas lines. Chilling helps here.
- Initially run all 3 chambers when you get a new bottle installed to verify gas flows on initial start up. This will also verify the -1.5 psia at static setting on the standby regulator
Would be happy to talk through this a little further. Call me (Tom Britton) at 208.890.1417