RCA clean
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The RCA clean is a standard set of wafer cleaning steps which needs to be performed before high temp processing steps (oxidation, diffusion, CVD) of silicon wafers in semiconductor manufacturing. Werner Kern developed the basic procedure in 1965 while working for RCA, the Radio Corporation of America [1] It involves the following :
- Removal of the organic contaminants (Organic Clean)
- Removal of thin oxide layer (Oxide Strip)
- Removal of ionic contamination (Ionic Clean)
The first step (called SC-1, where SC stands for Standard Clean) is performed with a 1:1:5 solution of NH4OH + H2O2 + H2O at 75 or 80 degrees (Celsius)[1]. This treatments results in the formation of a thin silicon dioxide layer (about 10 Angstrom) on the silicon surface, along with a certain degree of metallic contamination (notably Iron) that shall be removed in subsequent steps.
The second step is a short immersion in a 1:50 solution of HF + H2O at 25 degrees Celsius, in order to remove the thin oxide layer and some fraction of ionic contaminants[1].
The third and last step (called SC-2) is performed with a 1:1:6 solution of HCl + H2O2 + H2O at 75 or 80 degrees Celsius. This treatment effectively removes the remaining traces of metallic (ionic) contaminants[1].
