Dear guys
I have a question; what kind of developer or remover can disslove Al2O3?
I plan to use Al2O3 as capping layer top of the other materials.
I heard it by in chance that Al2O3 could be dissolved when the sample deep into developer for photoresist developling.
thank you in advanced.
Best
Dear Gyuhyeon Park,
I have also understood that developer can etch Al2O3 slowly, but have not used it myself for that purpose and do not know the rate. An RCA-2 solution could also work, but I have no experience using it for that purpose.
I have used piranha acid (H2SO4 and H2O2 ratio 3:1 at 95 degrees C for 15 minutes) to etch a thin hardmask layer (~10 nm) of Al2O3, which in my case worked very well. Note that I do not know the exact etching rate.
I noticed 1%HF also etches Al2O3, submersion of 10 minutes also seemed to remove 10nm of Al2O3.
Act very careful with either one of the solutions!!
- Piranha is very acidic and a strong oxidizer which attacks organic materials strongly accompanied by gas formation, heat build up and possible explosion. Preparation of the solution is accompanied by an exothermic reaction, so be very careful and add the peroxide to the acid slowly (and do not add them vice versa). Note the solution loses its properties over time so prepare a fresh solution just before etching.
- HF is corrosive but poisonous as well (attacks nervous system).
Take appropriate precautions (gloves, fume hood, etc.)!
Regards,
Bernhard
KOH and TMAH can remove Aluminum based Oxides and Nitrides. Most of the Photoresist developers are TMAH based, that is why they attack and remove Al2O3 layer. If you go directly to TMAH Instead of developer, your thin layer will be etched lot quicker depending on the concentration of TMAH solution of course. For KOH, usually the etch rate is about 1um/min for evaporated Al2O3 layers. Similar rate is possible for TMAH but I don't know for sure.
Developer solution doesn't harms the base materials (i.e substrate). But, if it does the then you can dilute your develoer solution.
Eg. : For the development of AZ (positive photoresist) we can use the develoer solution in (Developer : DI water ) 1:3 ratio.
Regards,
Varun
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