etch process flow

# Etch Process Flow

An etch process flow is the sequence of preparation, pattern transfer, clearing and verification around an etch step. It describes decisions and dependencies, rather than only a list of gas settings.

## Before removal

Confirm the incoming filmstack, patterned opening and surface condition. Upstream thickness or mask variation changes the amount of removal needed; an unchanged recipe can produce a different result.

## Main etch and landing

The main step transfers the feature. The landing and overetch window must clear remaining target material without unacceptable loss beneath it. Endpoint signals need qualification against physical measurements; a signal change alone does not prove every feature has cleared.

## After removal

Choose cleans and strip steps that preserve exposed device materials. Inspect profile and residues, then compare the result with the next process step's needs. A shape that looks clean can still have poor electrical behavior.

## Release criterion

Accept a window that covers wafer position, feature geometry and incoming variation. Record the metrology, limits and disposition for an out-of-window wafer.

## Further reading

[Manufacturer technical overview](https://www.appliedmaterials.com/us/en/semiconductor/products/shape.html). The illustration is original and schematic; dimensions, layer counts and materials are illustrative rather than a vendor recipe.