Cleaning is based upon what you want to remove from the sample, and in what order those things are layered. Generally speaking, it is best to work from “top-down.” This means that you clear off the most exposed layer, followed by the next layer, etc. Notable exceptions to this rule are deposited metals that are entirely on top of photo-resists (since removing the resist layer will remove the metal) and layers of different resists (since most resists are removed simultaneously).

Aluminum Removal:

1. Place sample into 50° C Al Etch (found on the acid bench)
   NOTE: Currently the normal containers of Al etch aren't functioning and Jim has set up a large container of heated Al etch next to the usual location
2. Once the aluminum is removed, rinse the sample in water to remove any excess acid
   NOTE: It is important to check the etch rate of the Al etch if only some aluminum should be removed
3. Rinse the sample in Acetone
4. Rinse the sample in IPA
5. Use compressed air to dry the sample

Chrome Removal:

1. Dip the sample into room temperature Cr etch (Cyantek CR-7)

Resist Removal:
NOTE: Resist refers to PMMA, LOR, and any of the AZ resists

1. Place sample into an Acetone bath
2. Sonicate the sample for 10-30 seconds
3. Rinse the sample with IPA
4. Use compressed air to dry the sample
   
   NOTE: If the sample isn't clean from this process, or if the resist is baked onto the sample, then follow these additional steps.
   
   
5. Place the sample into Nano-strip (also known as Piranha)
   1. If the sample appears to turn red, then alternate dipping it into Nano-strip and water until the red is gone
6. Once the sample is clear, rinse it in water to remove excess acid
7. Rinse the sample in Acetone
8. Rinse the sample in IPA
9. Use compressed air to dry the sample

NOTE: The sample shouldn't be taken straight to Nano-strip, since it takes far longer to get it clean. It is best to use the Acetone and sonicate method to get the majority off, then use Nano-strip to spot check.