Microsystems Technology Laboratories

The Lindberg 6” Tube Furnace is a 4" maximum substrate size, 1100 C maximum temperature furnace which is plumbed for N2, O2, steam oxidation, and forming gas, located within the EML.

It has selectable tubes, each with dedicated labware, allowing for EITHER TRL “Green” processing, if a process flow is approved by ptc@mtl.mit.edu, or EML “staff approved” processing.

Organics or contaminated items will NEVER be allowed

The user must verify the correct tube is installed, as any processing of TRL wafers with the EML tube will result in those wafers being disqualified from further TRL processing, and processing of EML wafers within the TRL tube will require user replacement of the quartz tube and labware. YOU must schedule with staff, in advance, to have the correct tube installed.

(A) Emergency Shut-off Procedure

In case of an emergency, such as overheating or breaking, do the following:

Shut off the EMO circuit breaker on the temperature control unit.

Shut off Oxygen and Forming gas valves, open Nitrogen.

Find MTL Staff.

(B) Warnings about this system

This is a manually controlled machine, so YOU must be careful not to choose a destructive sequence and be aware of the machine status at each step. This is a high temperature high current research tool and YOU must check for fire or burn hazards.

• Never use a temperature over 1100C!
• Never run O2 in the same run as forming gas!
• Never open the chamber when the tube temperature is over 500C, as the quartz tube could be damaged.
• Do not run at high temperature overnight.  Staff approval is required for overnight usage.
• Maximum gas flow is 5 SLM, which is 25% of the N2 “20 SLM” MFC
• Make sure the insulation is correctly installed on the right side of the tube, or the box will overheat and melt.  This will be done by staff when changing tubes, but be aware of the assembly.
• Look for flammables and remove them from a 1 meter radius around the tool.  This includes fabwipes or paper products, plastics, and especially solvent bottles.
• The end cap, cassettes, and wafers, will be hot after a run.  Don’t melt your gloves, plastic wafer boxes, or your hand, but instead let cool for 10 min. to be safe.

Following are instructions for correct operation of the Lindberg 6” Tube Furnace.

Preparation

Make machine reservations in CORAL.  Allow enough time to let your tube cool enough for unloading as part of your reservation time. 

If requiring a tube change, YOU must communicate with lab staff on these details and we will dedicate a portion of the week for that tube usage.  We will require the tube to be cool before changing, most easily accomplished by turning it off the night beforehand.

If doing a TRL process, be prepared to discuss the sequence with lab staff, and consider forwarding the approved sequence before the meeting, including the details of where and when the Piranha/HF dip is scheduled.

If doing an EML process, again your process must be approved in detail, at least by comprehensive verbal description.

Identify the correct quartz cassette and confirm the correct quartz tube is installed, after having previously scheduled with Lab Staff.  You MUST confirm this has been completed or you may not proceed!

Verify with Lab Staff that your substrates are allowed. Low melting temperature / high vapor pressure materials are not allowed even in the EML Tube.  If it ruins the tube, you will need to replace it.

Preclean your substrate immediately before the furnace run, as contamination occurs during storage.

Clean the tweezers you will use and the table with alcohol and a fabwipe.

Verify the Proper Starting and Ending Parameters

Idle temperature is 300C.

End cap is on, but not too tightly.

Gas flow is N2 at 10%, of 20 SLM, or 2 SLM  

Quartz cassettes are stored in their dedicated holders and are not left in the tube or on the loading tray.

Loading

Choose the quartz cassette which matches the process and tube you had approved or you will be buying new ones.  If you don’t know, ask staff!

IMMEDIATELY before removing the quartz boat from the protective storage, put on NEW gloves over the gloves you are wearing.  Once these gloves touch your uniform, glasses, or the keyboard, they are instantly decertified for quartz ware handling.

The quartz boats are stored in their dedicated holders, or may sit in the quartz loading tray or on the clean metal counter, but may never, ever, leave the tube or loading area.

Increase N2 flow to 20% (4 SLM), which is the normal run time flow rate as well, before removing the end cap.

Only handle the end cap by the HANDLE.  If you touch the interior of the tube or end cap, they will be ruined.  Put the end cap face down on the cleaned metal surface.

Hold the quartz loading tray snug to the tube end, and using the short quartz rod on top of the furnace, push the quartz wafer cassette about 6” into the tube. 

Put the short quartz rod back into the quartz sheath, and pull out the long quartz rod.  Never touch the long rod past the loading mark!  Push the quartz boat into the tube until the loading mark is flush with the swing door face, so the wafers are in the middle of zone 1.  Put the long rod away.

Immediately put the end cap back on the tube, but not tightly, or it will fuse closed.

Running

Start ramping up the temperature, in increments no more than 300C, allowing temperature stabilization, or the gas source end of the furnace, Zone 3, will be lagging too far behind the center, Zone 2, and an error will occur.

When at the correct run temperature, switch to the correct gas and flow rate for the calculated time.  At completion, return to N2 at 20%, and return the temperature to 300C.

Ending

After the temperature has dropped to the targeted temperature, always less than 500C, remove the end cap, holding only the handle, and place on the freshly re-cleaned metal surface.

Use the long, then short rods, never touching the front of the rod, to remove the quartz cassette onto the quartz loading tray.

Let the wafers cool before touching them even with metal tweezers!!! 

Do NOT touch quartz boats unless you have new gloves on top and the boat is cool.

Return furnace to the correct Starting / Ending Parameters, item #4 above