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Oven 90°C

This oven is the 90°C prebake oven. It is used to bake wafers after resist coating.

Picture and Location

 Oven 90

The tool is located at FG2 on the Lab Map.


Process Capabilities

Cleanliness Standard

The 90ºC Oven appears in all three equipment groups (clean, semiclean, and gold) as part of the litho & analytical tools set.


Performance of the Tool

This oven is the 90°C postbake oven. It is used to bake wafers after resist coating.


How to Become a User

  1. "All Litho" is required before training on any of the lithography tools. Contact the trainers for the class schedule and training materials (which must be reviewed before the class).
  2. Read all material on the SNF website concerning this tool,including Background, Process Capabilities, Operating Procedures and Process Monitoring.
  3. Contact SNF training contact on the Equipment Summary page.


Operating Procedures


This oven is the 90°C postbake oven. It is used to bake wafers after coating.

  • 1 minute on a hotplate at 90°C is equal to 25 minutes bake time at 90°C in the prebake oven.
  • It can be used instead of the svgcoat hotplate, if you have resist on both sides of the wafers or if you are processing wafers on the Headway and want to do a batch bake instead of one at a time on the hotplate.
  • This oven has a platform with an exhaust hood (especially useful when putting wafers with thick resist in and out of the oven -- bring them to the platform boxed.
  • Don’t change the temperature, it should be 90ºC.
  • The power stays on all the time, don't turn it off.
  • Check for maintenance signs. 
  • No reservation is necessary.


Usage Notes:

  • Use only the Teflon cassettes with one brown button! (Never use the plastic storage cassettes!)
  • There are 3“ and 4” Teflon cassettes in blue boxes on top of the wbmiscres.
  • Don't place the blue boxes in the oven.
    • Open the box and pull out the Teflon cassette near the back of the platform to prevent fumes from getting into the room air. Place the Teflon cassette in the oven and close the door.
  • Make sure the door is closed properly!
    • Leave wafers in the oven for 25 minutes, use your own timer, don't use the timer at the oven.
    • Remove the Teflon cassette using a heat resistant glove!
      • The Teflon cassette expands a little bit, it will not fit into the blue box right away. Place the cassette carefully in the box; the cassette will shrink within 2 to 3 minutes.
    • Close the oven door properly!


    Additional Process Info

    Hotplate vs. Oven:

    On a hotplate, the substrate heats up first and then the portion of the resist closest to the wafer heats up next and begins to evaporate residual solvents and, finally, the topmost surface of the resist gets hot and evaporates the solvents within it.  As a result, there is a smooth evaporation of the solvents from the resist film.

    In an oven, the outermost portion of the resists tends to heat first.  This tends to form a "skin" on the top surface of the resist that makes it more difficult for the solvent evaporating from the layers closer to the wafer from fully evaporating. 

    In general, however, etch resistance and resist adhesion will be better with a longer, higher temperature post-development bake.

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