RCA clean

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 [http://www.mines.edu/fs_home/cwolden/chen435/clean.htm "RCA Clean", materials at Colorado School of Mines] ] 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). 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.

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.

Additions

In his book, "Handbook of Semiconductor Wafer Cleaning Technology" [William Andrew Publishers, Applied Science Technology] , Werner Kern writes that the first step in the ex situ cleaning process is ultrasonically degrease in trichloroethylene, acetone and methanol.

RCA cleaning (also known as SC1/SC2 etching) submits silicon wafers to oxidation by NH₃:H₂O₂:H₂O mixtures, oxide removal in diluted HF, further oxidation by HCl:H₂O₂:H₂O mixtures, and final etching in diluted HF.

Notes and references

External links

* [http://www.ece.gatech.edu/research/labs/vc/processes/rcaClean.html "RCA Clean", School of Electrical and Computer Engineering,Georgia Institute of Technology]

ee also

*Silicon
*Wafer (electronics)
*Silicon on Insulator
*Chemical-Mechanical Polishing