etch passivation

# Etch Passivation (PASS)

Passivation can mean protection during etching or a post-etch treatment that reduces corrosion or reactivity.

## Place the step in context

Identify the incoming surface, the intended transformation and the surface delivered to the next module. A local abbreviation does not define chemistry, exposure time or acceptance limits.

## Integration context

Sidewall passivation is used in many non-aluminum etches, so PASS is not an Al-only concept. In chlorine-based Al etching, post-etch dechlorination or related treatment helps control corrosion before atmospheric exposure. Reported tool-specific treatments do not establish a universal H2O/CF4 or O2 process.

## What to verify

Distinguish sidewall protection from post-Al corrosion control; verify residues and corrosion after realistic queue time.

Before selecting removal conditions, identify all exposed neighboring materials and the amount of loss each can tolerate. Verify the result using the measurements appropriate to the structure, then check that the surface is suitable for the next deposition, contact or clean step.

## Related terminology

etch passivation, PASS, Al corrosion passivation. Short abbreviations are local process vocabulary and can have other meanings; use the full module name when searching.

## Source and scope

[Aluminum etch and corrosion control](https://www.nanofab.ualberta.ca/avoiding-corrosion-when-dry-etching-aluminum/). The diagram is an original teaching schematic. Layer choices and process families describe an example rather than a universal manufacturing recipe.