APM / SC-1 Cleaning Chemistry (Standard Clean 1) Storage & Tank Compatibility

Storing APM / SC-1 Cleaning Chemistry (Standard Clean 1)? Start Here

APM / SC-1 ("Standard Clean 1," also called the ammonia/peroxide mixture) is the alkaline step of the classic RCA wet-clean used to strip organic residues and particles from silicon wafers. It is a formulation, not a single compound: a high-dilution blend of deionized water, ammonium hydroxide, and hydrogen peroxide, classically mixed near 5:1:1 (H₂O : H₂O₂ : NH₄OH) and run at roughly 70-75°C. The ammonia lifts particles by mild oxide etching while the peroxide re-passivates the surface. Because it pairs a base with an oxidizer at elevated temperature, materials of construction matter: storage and bath vessels must resist alkali and dilute peroxide without catalyzing peroxide breakdown. The chemistry is benign toward polyethylene, polypropylene, and fluoropolymers, but aggressive toward copper, aluminum, and carbon steel, which both corrode and trigger rapid, gassy peroxide decomposition. Always work from the blended-bath SDS rather than the concentrate component sheets.

Polyethylene (HDPE / XLPE) Compatibility with APM / SC-1

Verdict: Suitable (S) for storage and ambient handling of dilute SC-1 components. Published polyethylene resistance data rate 30% hydrogen peroxide as little-to-no attack at 20-50°C and rate ammonium hydroxide as broadly resistant, so HDPE and XLPE are chemically appropriate for makeup-water, dilute-ammonia, and dilute-peroxide storage as well as mixed SC-1 holding at ambient temperature. The real constraint is heat, not chemistry: an active SC-1 bath runs at 70-75°C, at or above polyethylene's recommended continuous-service temperature, so the hot recirculating bath itself is normally polypropylene or fluoropolymer (PVDF/PTFE). For poly tanks, specify heavy-wall / high-density resin, keep stored solutions cool, vent for any oxygen evolved by slow peroxide decomposition, and avoid concentrated (>50%) peroxide, which does degrade PE over time. Do not use copper, brass, aluminum, or carbon steel anywhere in the wetted path.

Material compatibility at a glance

A dilute aqueous bath whose dominant compatibility drivers are mild alkalinity (ammonium hydroxide) plus a dilute oxidizer (hydrogen peroxide) at elevated temperature. HDPE/XLPE, polypropylene, and fluoropolymers handle the chemistry well; the practical limit is heat, not chemical attack. Avoid copper, brass, aluminum, and carbon steel — they corrode and catalytically decompose the peroxide.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Corrosive / severe burns: the ammonium hydroxide makes SC-1 caustic — causes severe skin and eye damage; wear chemical goggles, face shield, and alkali-resistant gloves.
• Oxidizer: the hydrogen peroxide component may intensify fire and reacts with reducing agents and many metals; keep away from organics, fuels, and combustibles.
• Gas / pressure generation: peroxide decomposes (faster when hot or metal-contaminated), releasing oxygen — never store in sealed/unvented containers; provide pressure relief and venting.
• Respiratory irritant: ammonia vapor irritates eyes, nose, and lungs; handle with local exhaust or in a fume hood / ventilated wet bench.
• Heat hazard: working baths run near 70-75°C — burn risk and accelerated off-gassing; do not exceed bath temperature limits.
• Environmental: ammonia is very toxic to aquatic life — neutralize and treat spent bath; do not discharge untreated.

Common questions

Can I store SC-1 / APM cleaning chemistry in a polyethylene tank?

Yes for storage and ambient handling of the dilute solution and its dilute components — HDPE/XLPE resist 30% hydrogen peroxide and ammonium hydroxide. Use heavy-wall / high-density poly, keep it cool, and vent it for oxygen off-gassing. The hot active bath (70-75°C) is normally run in polypropylene or fluoropolymer instead, because heat, not chemistry, is the limit.

Why can't I use a metal tank for SC-1?

Copper, brass, aluminum, and carbon steel both corrode and act as catalysts that rapidly decompose the hydrogen peroxide, producing heat and oxygen gas. 316 stainless is borderline and needs passivation and review. Non-metallic vessels (poly, polypropylene, fluoropolymer) are the safe default.

Is SC-1 flammable?

No — it is a water-based solution with no flash point. However, the hydrogen peroxide makes it an oxidizer that can intensify a fire involving other materials, so keep it away from fuels, solvents, and other combustibles.

Do I need to vent an SC-1 storage tank?

Yes. Hydrogen peroxide slowly decomposes to water and oxygen — faster when warm or contaminated with metals — so any closed vessel can build pressure. Provide adequate venting or pressure relief and never seal it gas-tight.