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Silicon dioxide (SiO2) is deposited at between 300 and 450C (depending on needs... ie metals 300C), low pressure (~350 mtorr), from silane and oxygen with or without phosphine doping. Doped LTO is also called PSG, or phosphosilicate glass). The refractive index of the film depends on the phosphorous content, lower deposition rate. The refractive index is also influenced by the temperature of the deposition. Six inch. Gold group

Process Capabilities



Performance of the Tool

What the Tool CAN do

  • Deposit doped and undoped LTO.


What the Tool CANNOT do

  • Deposition thicker than 4 microns in a single deposition.


Process Monitoring


Contact List and How to Become a User

Contact List

The following people make up the Tool Quality Circle:

  • Process Staff: Maurice
  • Maintenance: Ted
  • Super-Users: J Provine


Training to Become a Tool User


Contact Process Staff



Operating Procedures (Quicksheet)


A.                 Check tube status

1.      Press Do key until Main Menu is reached.

2.      Use arrow keys to highlight Status Menu then press Return.

3.      Use arrows keys to highlight Tube Status then press Return.

4.      Type in Tube ID (4 for ThermcoLTO), then press Return.

5.      System should be running STBYLTO;  in prochold; temperature 350c


B.                  Vent tube

1.      Press START (STBYLTO recipe ends when boat is out)

2.      Load your wafers.


C.                 Load Recipe

1.      Enable Tube.

2.      Press STOP button until tube is in standby.

3.      Press Do key until Main Menu is reached.

4.      Use arrow keys to highlight Recipe Menu then press Return.

5.      Use arrows keys to highlight Compile Recipe then press Return.

6.      Type in Recipe Name (LTO300,LTO400...), then press Return.

7.      For Recipe Name #2, press Return.

8.      For Parameter Table, press Return.

9.      Use arrow keys to highlight Download Only then press Return.

10.   Type in Tube ID (4 for ThermcoLTO), then press Return.

11.   Recipe parameters are time and PH3 sccm.

12.   Type  Delay Time (in the HH:MM:SS format) then press Return.

       (Thermco will flash "Recipe Compile Succeeded" once recipe is loaded.)

D.                 Run Program

1.      Press START to initiate recipe, after 10 seconds press START a second time to initiate the tube close.

2.      Monitor and log the lowest base pressure (base step), the highest leak back pressure (leak step) and the pressure during deposition (dep step).

3.      Wait for tube to process wafers. After deposition, the tube will ramp down to 350c and hold until you press START.  The tube will vent and open (~17 min).

4.      Unload your wafers after they have cooled several minutes.

5.      Press STOP button until tube is in standby.

6.      Compile the STBYLTO recipe.

7.      Press START to initiate tube close.

8.      STBYLTO will leakcheck tube and the stop in the process hold step.

9.      Disable tube.

10.   Mute tube.

 E.                 If Leak Check Fails

1.      Put tube in standby.

2.      Compile LTOOUT recipe.

3.      Press START.  The recipe will reset temperature, backfill and then boat out.


Boat Calibration Procedure


                         With tube in Standby, vented and free to move in and out

1.      While pressing "enable" key, toggle "recipe" key until recipe 6 is displayed.

2.      Check tube status to confirm "boat cal" recipe is loaded.

3.   Press "Start" key.

      Boat loader will open to limit, close completely, and then open to load position.

      If boat calibration was successful tube status will go to "Complete"

4.     Press "Stop" key to put system in "Standby".

5.      While pressing "enable" key, toggle "recipe" key until recipe 1 is displayed.

6.     Check tube status to confirm desired recipe is loaded.


Process Monitoring and Machine Qualification

Process Monitoring Results

Tool Qualification Run



  1. Use six new 'L' test wafers; <100>, P-type (boron), 10-20 ohm-cm.

  2. Clean at wbclean-1/2 in the following sequence; 5:1:1 H2O:H2O2:NH4OH ten minutes, rinse, 5:1:1 DI;HCl:H2O2 ten minutes, rinse, 50:1 DI:HF 30 sec, rinse, spin dry.

  3. Load program LTO400 into Thermcolto. Time variable is 00:20:00.

  4. The boats must be loaded with dummies (13 wafers in each, loaded every other slot) at all times to ensure uniform wafer to wafer deposition.

  5. Using very clean tweezers or vacuum wand replace the dummy wafers with a cleaned test wafers the following positions with flats up:

1st boat (Front) in the 5th slot.

1st boat in the 13th.

1st boat in the 21st slot.

2nd boat (Back) in the 5th slot.

2nd boat in the 13th.

2nd boat in the 21st slot.




Use Woollam to measure silicon dioxide thickness across each wafer in nine locations with floating index of refraction using Silicon Oxide (100 - 10,000 Ang).  Record the average thickness, standard deviation, and index of refraction at 633nm. Test sites should be no more than about 15mm from the edge of the wafer.



Record results on badger. Update the trend chart on the wiki site.  If test values are not within 10% of plotted test average, contact the Diffusion Process/Maintenance team.

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