Cleaning chemical mixing and concentration calculator
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KEY POINTS
SC1 (NH₄OH : H₂O₂ : H₂O = 1:1:5) contains about 3.7 wt% ammonia and about 4.8 wt% hydrogen peroxide and removes particles and organics. Concentration is the mass of each active ingredient, from stock concentration and density, divided by the total mass. Dilute SC1 such as 1:2:50 is now common to cut chemical use and surface roughening.
Inputs (volume ratio)
Volumes are approximated as simply additive. Mixing sulfuric acid and hydrogen peroxide (SPM) releases a lot of heat and can exceed 100 °C, so always add the sulfuric acid slowly to the hydrogen peroxide. Stock concentrations are typical electronic-grade values.
Common cleaning and etching solutions
| Solution | Composition (volume ratio) | Typical temperature | Main purpose |
|---|---|---|---|
| SC1 (APM) | NH₄OH : H₂O₂ : H₂O = 1:1:5 to 1:2:50 | 25 to 80 °C | Particle and organic removal |
| SC2 (HPM) | HCl : H₂O₂ : H₂O = 1:1:6 | 25 to 80 °C | Metal contamination removal |
| SPM | H₂SO₄ : H₂O₂ = 4:1 | 120 to 150 °C | Resist and organic removal |
| DHF | HF : H₂O = 1:50 to 1:1000 | Room temperature | Native oxide removal |
| BHF (BOE) | HF : NH₄F = 1:6 to 1:10 | Room temperature | Oxide etching (stabilized rate) |
How RCA cleaning is put together
RCA cleaning is a wafer cleaning sequence published by RCA in 1970, and half a century later it is still the basic recipe. SC1 uses the alkalinity of ammonia to etch the silicon surface slightly while hydrogen peroxide oxidizes it, lifting particles off along with the surface. SC2 uses acidic hydrochloric acid to dissolve metal ions. A typical flow inserts a DHF step between them to strip the native oxide.
Today SC1 is commonly diluted heavily, for example 1:2:50, and run at lower temperature to cut chemical use and surface roughening. Combined with ozonated water, functional water and single-wafer spin cleaning, the best chemistry and concentration is chosen for each step.
FAQ
What is the concentration of SC1 1:1:5?
With 29% ammonium hydroxide and 30% hydrogen peroxide, about 3.7 wt% NH₃ and 4.8 wt% H₂O₂.
In what order should SPM be mixed?
Add the sulfuric acid slowly to the hydrogen peroxide. The mixture releases a lot of heat and can exceed 100 °C.
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Last updated: October 23, 2026