Clean+the+Silicon+and+Mica

Working with the AFM and doing DNA tiling in relation to manipulating the APTES solution requires a relatively large procedure. One must clean both silicon and mica. In order to be adept at using the AFM and DNA tiling one must know the procedure thoroughly.

1.)The first step in the method of cleaning silicon is to cut the large silicon wafers into 1 cm.x1 cm squares. Then attach scotch tape to both sides of the silicon squares and then take them off to remove debris. Place the chips and a toluene solution into a beaker and let it boil for 30 minutes under the fume hood. Put a watch glass on top. This part removes the grease from the silicon wafers. Rinse the wafers with 18 ohm water after the wafers have cooled, then dry it off with N2 gas.

2.) Secondly, add 20 ml of concentrated H2SO4 to six to seven ml of (30%) H2O2 (piranha acid) in a 50 ml beaker. This will destroy any organic molecules and reduce contamination. Boil the dry wafers in the piranha acid for 15 to 30 minutes at 90° C. Cover the beaker with a lid. Remove wafers using plastic or metal tweezers. Rinse them thoroughly with distilled H2O. Dry them with N2 gas and dispose of the piranha acid into the acid waste bottle.

3.) Now comes another major part in the procedure. First put on protective gear such as latex gloves, an apron, and goggles. Move the wafers to the MOS bench in the clean room. Turn on the RCA1 and RCA2 baths which are located on a counter with two sinks on it. Put the silicon chips in the HF bath in order to get rid of all the excess particles that may have accumulated on your silicon.

4.) Place wafers into the RCA 1 bath for ten minutes. Turn on the bubbles. Rinse wafers and tweezers for two cycles in distilled water. Place wafers and tweezers into RCA 2 (HCL and H2O) and bathe for ten minutes, and also turn on the bubbles. Then also rinse the silicon wafers for two cycles in H2O. What this process does is removes the natural uneven SiO2 layer and grows a new one nm thick layer on the wafers. When this is complete, dry the wafers with N2 gas and store the newly cleaned silicon wafers in a clean container. Finally, turn off the bubblers and heaters, clean up the bench for any spilled chemicals, and take off protective gear.

To clean mica, you must put double-sided scotch tape on the surface of the mica, and then peel it off. You are done. You will be using mica only to look at examples of what DNA looks like under the AFM.

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