Post-Etch Residue Cleaning System

Post-etch residue cleaning and post-implant resist stripping handle the wet-chemistry half of a job that plasma ashing starts but often can't finish alone: removing hardened, chemically modified residue that's left stuck to the wafer after a plasma etch or ion implant step, rather than fresh, unmodified photoresist. Etch byproducts and implant-crusted resist both bond to the surface in ways plain solvent strip wasn't designed for, which is why these steps run their own dedicated wet chemistries.

Wafer after plasma etch or implant
Residue bonded to surface, often already plasma-ashed in bulk
Wet residue removal
Post-etch residue clean
Removes polymer/metal-oxide byproducts from etch sidewalls and bottom
Post-implant resist strip
Dissolves carbonized crust that plasma ash alone leaves behind
Residue-free surface
Ready for next deposition, clean enough for contact/via fill

Etch byproduct residue is often metal-containing, which is exactly why it needs different chemistry than a simple resist strip. A metal or metal-oxide etch leaves behind sidewall and via-bottom residue incorporating atoms from the etched film itself — titanium, tungsten, or aluminum compounds mixed into the polymer byproduct — and these metal-bearing residues resist standard organic solvent strip chemistry. Post-etch residue cleaners use specialized formulations designed to dissolve that specific metal-organic combination without attacking the metal lines or contacts the etch just defined.

Post-Etch and Post-Implant Residue Removal residue chemistry here is fundamentally different from bulk resist strip Post-etch via — metal-bearing residue residue on via sidewalls contains etched-metal atoms Post-implant resist — carbonized crust crust survives plasma ash alone wet strip finishes what ashing couldn't fully remove both steps are tuned to attack a specific, chemically modified residue — not generic photoresist

These wet steps usually follow plasma ashing rather than replace it, because dry and wet residue removal attack the problem from different angles. Plasma ash handles the bulk, unmodified resist volume efficiently through gas-phase oxidation; the wet step that follows targets the thin, chemically stubborn residue layer — implant-hardened crust or metal-contaminated etch byproduct — that the plasma step's chemistry alone doesn't fully dissolve. Running both in sequence catches what either method alone would leave behind.

Post-etch residue cleaning and post-implant resist stripping exist because "the bulk of the resist is gone" and "the surface is actually clean enough for the next step" are two different standards, and the gap between them is exactly the chemically modified residue these wet steps are built to remove.

Take post-etch residue cleaning system further

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