I am using 50ml: 24ml:2ml::HNO3:H20:buffered hf to etch silicon. 500A of chromium is used as mask layer. After etching, I use chrome etchant (purchased from sigma aldrich) to remove the mask layer. But in the optical microscope, I still see the traces of chrome on my pattern. Can anyone help me?
Have you tried the chromium etch by Microchemicals? It was a good choice for our fabrication on silicon wafer using 50A of Chromium with 500A of gold.
I have had this before. You can not remove chromium traces fully from silicon surface by simple wet etching, because chromium and silicon inter-diffuse into each other during chromium deposition, forming chromium silicides. You can refer to our XPS/AFM research done about initial chromium deposition stages. Thin Solid Films 01/2008; 516(10):2943-2947
I recommend hot, concentrated Phosphoric acid - CAREFULLY DANGER - as long as the substrate allows this. Silicon will be fine with Phosphoric acid.
@armondo i tried that. it did not [email protected] try to buy from microchemicals....
@Darius thanks for the explanation......@Alexander thanks for the suggestion....i try and see.
I had this problem before and i tried by buffered HF. Unfortunately it didn't work. By which process you deposit chromium layer on Si substrate?
usually for e beam evaporation the temperature of process is around 180 C and in this temp it is not possible to form chromium silicides. i had this problem with Cr that i evaporated with E Beam. i etched my sample by RIE ( sf6 gas with 130 in flow and 130 in voltage) and i saw a strange structure on si substrate.
i repeated my method again and this time i kept my sample in developer longer than before and it worked. If you want to do this, you notice that you must allocate a longer time for post baking.If you want more detail let me i know.
Emad, what do you mean by developing for longer? Do you mean putting the sample in the Cr etchant for longer? What kind of structures did you see on the si substrate?