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Fga2, contaminated

Fga2 is a totally manual furnace which requires a lot of quartzware handling by the labmember. The furnace can accommodate 6 inch wafers as well as pieces.

Picture and Location

 

Background

 

Description of the Furnace:

 

  • Fga2 is a contaminated furnace used for the annealing of non- standard materials. 
  • Gases plumbed to the furnace are; N2, Ar and 4%H2 in N2 (forming gas).
  • The boat is manually pushed and pulled in/out of the furnace with the use of pull rods.
  • An ‘elephant’ (a short quartz semi-tube) holds the boat for loading and unloading.  It attaches to the furnace via the ground joint.
  • The temperature of the furnace is set be the user by adjusting the center position of the master/slave system.  Temperature range is 350-600C.  Temperature is verified by turning the multi-tube temp dial to fga2.
  • Idle (stand-by) condition one liter of N2 flowing.  The user must set the furnace back to idle manually.
  • Enable the furnace (gaas23).  Forming gas will not flow if the furnace is not enabled.

 

Process Capabilities

Cleanliness Standard

 Fga2 is contaminated.

Performance of the Tool

What the Tool CAN do

  • Forming gas, argon and nitrogen low temp anneals.

 

What the Tool CANNOT do

  • High temp H2 anneals.  Pure H2 is not plumbed to the tool and the temp controller has a maximum temp of about 600C.
  • Low temp oxidations.  O2 is not plumbed to the tool.

 

Process Monitoring

 

Contact List and How to Become a User

Contact List

The following people make up the Tool Quality Circle:

  • Process Staff: Nancy Latta, back-up Maurice Stevens.
  • Maintenance: Ray Seymour and Ted Berg.
  • Super-Users:

 

Training to Become a Tool User

Contact the Process Staff person assigned to the furnace.  Training is very quick, about 15 mins.

 

 

Operating Procedures

 

Cleaning procedures:

Samples must have an organic clean before going into fga2.  Acceptable cleans are;

Matrix O2 plasma clean

PRX127, 10 min at 40C at a contaminated wetbench (wbgen, wbgen2 or wbgaas)

Solvent clean, Acetone, Methanol, Isopropanol at a solvent wetbench

Please note; materials going into the tube should not vaporize when at temp.

 

Setting Up to Operate the Furnace:

  1. Open the side doors in the back of the furnace to expose the gas flow meters.  There will be one flow meter for each of the gases.  Adjust the float to the 5L line mark on the N2 flow meter.  This increases the flow of gas from one liter/min (idle) to five liter/min for operation.
  2. There are two buttons labeled AUTO and MANUAL.  The MANUAL button should be on in the idle mode.  When in AUTO the sequencer is controlling the time and which gas flows through the tube.
  3. You may switch on the other gases to verify they are set to the correct flows.  Make sure the MANUAL switch is on.  The gas buttons are marked as follows; F1 = Argon, F2 = Forming Gas and F3 = Nitrogen.  Please note; Forming Gas will flow only when both the Ar and FGA buttons are pushed.  Make sure to turn down the Ar flow to 0.5.     
  4. Set the furnace to the desired temperature.  Use the little dial to increase or decrease the idle temp (400C).  The values on the dial are about 30 units off from the actual temps, for example, a reading of 376 equals 400C.

 

Description of the Sequencer:

(NOTE: most users do not use the sequencer.  See Manual Operation.)

 The sequencer allows you to change gases and time events.  At the completion of the program an alarm will sound.  At this point you will need to remove your wafers using the long pull rod.

The sequencer has the following buttons and switches associated with it:

  • PROCESS- this is the program number.
  • TIME- this is where time is programmed for a process step.  The format is nnn.n minutes.
  • Readout shows both the Process Step and Time Remaining.
  • ALARM- three lights that indicate if there are any malfunctions or problems.  ALARM 1 will light up and sound because of user input, i.e., the end of the program.
  • ALARM RESET- stops the audible alarm and turns off the light.
  • N2- when lit Nitrogen is flowing.
  • N2/H2- when lit Forming Gas is flowing.
  • AR- when lit Argon is flowing.
  • PROGRAM OUT (END)- this switch is used to end a program.  ALARM 1 will sound.

 

There are five function buttons:

  • RUN- starts the sequencer program.
  • STOP- freezes the sequencer in the step that this button was pushed.  The timer stops, but all the programmed gases remain on.  An alarm will sound when this button is pushed.
  • RESET- this is the way that the program is reset.  When all the gas switches are in the off position, the end switch is deactivated and the timer is set to 0000 a program step is cleared when Reset is pushed.
  • STEP- advances from one program step to the next.  There are a total of 15 program steps.
  • STORE- saves the user set parameters in a program step.

 

 

Programming the Sequencer:

 Make sure the system is in AUTO.

 

    1. To program the sequencer turn the key to PROG.
    2. Select a number (0-3) at the PROCESS switch.  This will be your program number.
    3. Push RESET to begin at Step 00.
    4. Position all gas toggle switches to off (not lit) and End to the center position.
    5. Change the time switches to the time desired for Step 01 (nnn.n minutes).
    6. Press STORE.  This will advance to Step 01.
    7. Toggle on (lit) the gas and or END switches desired for Step 01.  Please note; Ar must be selected for Forming Gas to flow.  Make sure the flow meter is set to 0 (zero) on Ar.
    8. Enter the time for Step 02.
    9. Press STORE to program the parameters for Step 01 and advance to Step 02.
    10. Continue to program all steps.  Make sure that the last step has END chosen.  This will sound an alarm at the end of the program.
    11. Review the program you just created by pressing RESET to return to Step00.  Press STEP repeatedly to advance to the next steps.
    12. Turn the key back to RUN.

 Please note; the sequencer may be a bit baffling to set up, so most labmembers chose not to use it and instead change the gases manually using their own timers.

 

Manual Operation:

 

  1. Set the desired temperature.
  2. Increase the N2 flow from 1lpm to 5lpm and wait about 5 minutes.
  3. Load wafers.
  4. Wait for temperature to stabilize at the desired temp.
  5. Switch to desired gas.  For Ar anneals push N2 to off and Ar to on.  To run Forming Gas push N2 off and push both Ar and FGA on.  Make sure that the Ar flow is at zero and FGA flow is at 5lpm.
  6. Start timing.
  7. At the end of the anneal time turn Ar and FGA off and N2 on.
  8. Unload wafers.
  9. Turn N2 down to 1lpm, the stand-by condition.

 

 

Loading the Wafers into the Furnace

Just inside the mouth of the tube there is a boat with a four-inch cassette and a six-inch cassette.

  1. Enable the furnace.
  2. Remove the end cap.
  3. Attach the elephant to the end of the tube.  Be careful as the ground joint may stick together.
  4. Use the pull rod to slide the boat into the elephant.
  5. Let the boat cool for a few minutes and load wafers.
  6. Use the pull rod to push the boat back into the tube.
  7. Remove the elephant.
  8. Use push rod to slide the boat into the hot zone of the furnace.  The push rod is marked.
  9. Replace both the push rod and the end cap.
  10. Push the run button on the sequencer.

 

When the Program has Completed

  1. Push ALARM RESET to silence the alarm.
  2. Remove the end cap.
  3. Use the push rod to slide the boat to the mouth of the tube.
  4. Attach the elephant to the end of the tube.  Be careful as the ground joint may stick together.
  5. Use the pull rod to slide the boat into the elephant.
  6. Let the boat cool for a few minutes and unload wafers.
  7. Use the pull rod to push the boat back into the tube.
  8. Remove the elephant.
  9. Replace the end cap.
  10. Turn the gas flow meters at the back of the furnace down to the 1 liter/min mark.
  11. Disable the furnace.

Process Monitoring and Machine Qualification

Tool Qualification Run

 

Frequency

 

Procedure

 

Responsibility

 

 

Recommendation to users with critical processes

 

Machine Status States

Red:

Yellow:

Green:

 

Process Monitoring Results

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