Hello everyone!
I'd like to try the electrochemical etching of a silicon wafer, but I need to work with a two-electrode configuration (a strip of aluminum foil as a back-contact and a platinum coil as the counter electrode), applying a current density constant (250 mA/cm2), for 30 seconds. Is there a technique already integrated in the software that allows you to do this?
is it possible to work with two electrodes with this tool?
Thank you!
Tiziano
Dear Sir
u can use any source meter so as to fix the current during etching process ( over wise the current will change due to the changing resistance of the Si during the process)
for the current 250 mA/ cm2 is too much start with 10mA/cm2 and time more than 30 mint
for 30 sec its not enough to remove the native oxide layer
good luck
In principle you can use two electrode cell where the silicon must be as an anode to oxidize and etch it by fluoride media HF.
For the details of the process please see the paper: http://jes.ecsdl.org/content/145/1/332.short
When oxide is formed with sufficient thickness it impedes the flow of the current.
Best wishes
Thanks everyone for the answers. I will use youe advices for my tests. What I didn't understand is if there is a way to do this (electrochemical etching) with a palmsens (potentiostat / galvanostat).
Best wishes
Dear Tiziano Di Giulio,
as was mentioned above, you can use any power source meter in potentiostatic or galvanostatic mode to perform an electrochemical etching of semiconductor wafer. Usually, the specially designed pentiostats for etching are designed to work with three electrodes: working electrode (the semiconductor sample), counter electrode (a Pt wire) and a reference electrode (Ag/AgCl). It is not clear what is your objective? Ordered pores or just porosification of Si? In any cases you can try anodizaton with just two electrodes (without reference electrode). If your potentiostat is designed to work with reference electrode, then just connect it (reference electrode) together with counter electrode.
Regarding to the required current density: it strongly depends from the number of free carrier concentration in the crystal and electrolyte concentration.
Regards,
Eduard
Dear Eduard, thank you for your answer.
What I would like to do Is a nanoporous layer starting from a wafer silicon (P++ doped). Is that possibile for you to make it with a palmsense potentiostat (It has 3 electrods)?
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