Lift-Off Metal Patterning

Lift-off is a technique that allows you to patten a metal layer without any etchant chemicals. Photoresist is spun on, exposed, and developed then the metal is sputtered or evaporated on top of the resist. The photoresist is then striped and any metal on top of it is peeled off. This leaves metal in only the areas in which the resist was not present after developing.

Typically, negative photoresist is preferred for lift-off for a number of reasons but I did not want to change my existing process so I attempted it with positive AZ4210 resist yielding decent results.

Photoresist can be removed in acetone or developer solution (assuming it is exposed by ambient light during processing) but a lower vapor-pressure solvent is preferred. An ultrasonic bath can also improve lift-off.

If lift-off is difficult, a thicker resist film or thinner metal coating can help. Also, substrate heating during deposition leads to resist softening and side wall coating, making lift-off impossible. I used a Peltier cooler in my chamber to prevent this.

4 thoughts on “Lift-Off Metal Patterning”

  1. Very informative article thank you for sharing this with us, I was searching to know more about lift-off metal patterning and here you provided all the details with the minor aspect. Keep sharing such things.

  2. How much will it cost to make cmos 7556 timer in 5000 .
    quantity.
    Speed around 500khz , supply current 10uA to 35uA , 2v to 6v operation.

    1. Use chinese rates for raw material price.
      How much is the raw material price, will it cost to make cmos 7556 timer in 5000 quantity.
      Speed around 500khz , supply current 10uA to 35uA , 2v to 6v operation.
      Don’t add labor cost nor shipping cost for raw materials .
      Time to make 5000 pieces

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