etch breakthrough

# Breakthrough (BT)

Breakthrough removes a surface barrier before the main target etch.

## 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

Examples include native oxide on polysilicon or an intentionally deposited cap in a metal stack. Opening a TiN cap and removing native oxide are different targets; neither always uses the same chemistry. The BT label names a job, not a fixed gas mixture.

## What to verify

Confirm the actual surface layer clears without consuming too much mask or underlying material.

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 breakthrough, breakthrough etch, BT. Short abbreviations are local process vocabulary and can have other meanings; use the full module name when searching.

## Source and scope

[Etch process resources](https://www.cleanroom.byu.edu/processes). The diagram is an original teaching schematic. Layer choices and process families describe an example rather than a universal manufacturing recipe.