RCA-2 Si wafer cleaning

Source: His_Master's_Voice

INRF application note

Process Name:



Mark Bachman, Spring 2002.  Adapted for AMPEL ANF by M. Beaudoin, April 2014.


The famous RCA-2 clean (sometimes called “standard clean-2”, SC-2), developed by Werner Kern at RCA laboratories in the late 1960’s, is a procedure for removing metal ions from silicon wafers. The decontamination works based on sequential oxidative desorption and complexing with H2O2-HCl-H2O (RCA-2). Typically this is preceded by an RCA-1 clean (SC-1, H2O2-NH4OH-H2O) to remove organic residues. In the process, it oxidizes the silicon and leaves a thin oxide on the surface of the wafer.

This is a dangerous wetbench process and requires qualification for dangerous wetbench processes.  The use of dangerous chemicals requires that the user may not perform the process alone.

Time Needed:

This process takes 30 minutes to complete in total.

Materials Needed:
  • Hydrogen chloride (HCl)
  • Hydrogen peroxide
  • Pyrex bath containers
  • Hot plate

Setup time for this process is about 5 minutes. This process takes about 20 minutes to complete. The general recipe is for RCA-2 cleanser is: 6 parts water (H2O), 1 part 27% hydrogen chloride (HCl). 1 part 30% hydrogen peroxide (H2O2).
300 ml DI water
50 ml HCl
50 ml H2O2 (30%)


Put 300 ml DI water in a Pyrex beaker, carefully add 50 ml HCl and then heat to 70±5° C on hot plate. Remove from hot plate and add 50 ml H2O2 (30%). Solution will bubble vigorously after 1–2 minutes, indicating that it is ready for use. Soak the silicon wafer in the solution for 10 minutes. When finished, remove the wafer and rinse with clean DI water.


To dispose of the RCA-2 solution, follow the procedure outlined in the wetbench SOP.  For quantities less than 100 ml, slowly pour the solution into the sink under running DI water.  For quantities larger than 100 ml, fill a glass beaker about 1/3 full of DI water, then pour up to 100 ml of RCA-2 solution in that beaker; slowly pour this into the sink under running DI water.

Safety & Emergency:

All ANF safety and procedural regulations must be followed.  Use of RCA requires at least one other person in the clean room (buddy system). RCA clean should be performed in a laminar flow bench, using apron, acid gloves and eye protection including full face shield.

Hydrogen peroxide is an explosive chemical. Never leave the RCA process unattended. Do not store the hydrogen peroxide near the hotplate or any other source of heat. Any small spills should be wiped up immediately with wipes. Rinse the wipes with DI water and dispose of in the waste can.

In case of exposure to skin or eyes, flush immediately with water for 15 minutes. Remove all clothing that are exposed and flush with water. Report to ANF staff or report to UBC Risk Management.  Seek medical attention to ensure that the burns are minimal. In case of large spill, follow the ANF Standard Operating Procedure for chemical spills.

  • Prudent Practices in the Laboratory, National Research Council, 1995.
  • W. Kern and J. Vossen, Eds., Thin Film Processes, Academic Press: New York, 1978, Ch V-1.
  • W. Kern, Ed., Handbook of Semiconductor Cleaning Technology, Noyes Publishing: Park Ridge, NJ, 1993, Ch 1.