Gold Etch Using Potassium Iodide Solution

Source: goldingots

INRF application note

Process Name:



Mark Bachman and Liang (Lily) Wu, Spring 2002.  Adapted for AMPEL ANF, M. Beaudoin, April 2014.


This process etches gold by using Potassium Iodide (KI) solution.

Time Needed:

The time of this process depends on the thickness of the film. The etching rate of the KI solution is 0.5 – 1 μm/min at room temperature.

Materials Needed:
  • Potassium Iodide
  • Iodine
  • DI water
  • Glass container

Setup time for this process is about 5 minutes. The general recipe is for KI solution is shown below:

  • 4 g KI (solid)
  • 1 g I2 (solid)
  • 40 ml DI water

Prepare etchant soultion in the following manner. Use a digital balance to measure 4 g of KI and 1 g of I2 in a glass container. Pour 40 ml DI water in the container, and dissolve the solid by agitation. Put the solution in a bottle (glass or poly) and label “KI gold etchant 1:4:40 I2/KI/H2O”. Add your name and the date.

To perform gold etch, soak the substrate into the solution with mild agitation. Near the expected etch time, check the substrate by DI rinse every 30 seconds until the gold color is gone. After a thorough DI rinse, blow dry the substrate.

The etchant may be re-used if clean. Put recycled etchant back in proper location (in assigned location under wetbench).


If the etchant should be discarded (old or dirty), dispose the waste gold etchant into rink under lots of running DI water. Rinse all containers three times in clean water.

Safety & Emergency:

All ANF safety and procedural regulations must be followed. Review the ANF standard operating procedures for fire, chemical spill, and chemical exposure. Perform all work in the fume hood with nitrile gloves and eye protection.

Iodine is toxic–may be fatal if swallowed or inhaled. It is corrosive, causes burns and harmful by inhalation and through skin absorption. It is readily absorbed through skin, very destructive of mucous membranes and upper respiratory tract, eyes and skin, a severe irritant. It sublimes at room temperature to yield dangerous levels of vapor.

Inhalation of KI dust may irritate respiratory tract. It may also act as a skin or eye irritant. May cause sensitization or allergic reaction. 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 riskmanagement. Seek medical attention to ensure that the burns are minimal. In case of large spill, follow the ANF Standard Operating Procedure for chemical spills.

  • MSDS documents for iodine and potassium iodide.
  • 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.