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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.


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

Please contact the Process Staff.


Operating Procedure

Basic Operation Instructions

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


    Vent Tube

    1. Press START (STBYLTO recipe ends when boat is out)
    2. Load your wafers.


      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.)


        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.

          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.
          4. 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"
          5. Press "Stop" key to put system in "Standby".
          6. While pressing "enable" key, toggle "recipe" key until recipe 1 is displayed.
          7. Check tube status to confirm desired recipe is loaded.


          Process Monitoring and Machine Qualification

           Each month, tool qualification runs are performed on most tools in the SNF to monitor variations in each tool’s performance. The purpose of the ThermcoLTO qual is to monitor thickness and uniformity both wafer-to-wafer and within a wafer. The qual is performed by SUMO members, but users may perform the specified qual process before tool use if more recent qual data is desired for reference.


          Qual Process Overview

          The ThermcoLTO qual runs three new "L" test wafers through the LTO400 for 20 minutes to be coated with 1,000A SiO2. After the deposition, the wafers are analyzed via Woollam using the nine point Silicon Oxide (100 - 10,000 Ang) analysis.


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

          2. Scribe wafer numbers, and clean in piranha at wbclean_res-piranha.
          3. 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.

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

          5. Ensure that all boats are loaded with dummies (13 wafers in each, loaded every other slot) at all times to ensure uniform wafer to wafer deposition.

          6. Using very clean tweezers or vacuum wand replace the dummy wafers with cleaned test wafers in the following positions in the center boat, making sure that the flats of the wafers are pointed upwards.

                • in the 5th slot.
                • in the 13th.
                • in the 21st slot.

          Post-Deposition Measurements

          1. Measure the thickness and index of refraction at 9 points across the wafer using Woollam program Silicon Oxide (100 - 10,000 Ang).
          2. Report the average thickness, standard deviation, and n at 633 nm for the wafer. Test sites should be no more than about 15mm from the edge of the wafer.


          Reported Data

          Qual data may also be found on the Badger comment log. The following data is reported for the ThermcoLTO qual.

          • average deposition thickness
          • one standard deviation
          • index of refraction

          If test values are not within 10% of plotted test average, contact the Diffusion Process/Maintenance team. Save wafers in a box with the date, furnace number, program name and growth time.  They may be re-tested at some time in the future.


          Qualification Results

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