Cr-Au binary metallization system works well only on oxidised susbtrates.

Therefore try to use oxidised silicon substrates, instead of straight ssilicon.

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However if you are trying to metallize silicon with gold for ohmic contacts, for make some electronic devices on silicon.  This is known as beack metallisation.

You must sputter clean your silicon substrates first, then deposit/evaporate gold in good clean vacuum at some substrate temperature. Probably Au-silicon metallisation needs some alloying treatment in vacuum. Check the literature.

Also consult the Handbook of thin film technology, which has a beautiful chapter on metallization and discussed in detail how you do the metallization for n-type and p-type silicon substrates.

 K. Sreenivas

the above answer by K.Sreenivas is appropriate.

Also some times vacuum chamber is not so clean at it appears,that adds to the problem. Do bring vacuum to 10E-6 torr first keep it for an hour then start the process. If DP is used, be sure oil vapours are not escaping into the chamber.

Dear Sir,

               Thankyou so much for giving reply , but one thing i forgot say is i have used silicon dioxide only . i have used 20 nm of cromium and 80 nm of gold , then i have done tape text .gold is simply coming out ,but chromium is still there .even if you wipe it also gold is going .so please suggest me the proper recipe , i am using sputtering as deposition technique.

I never faced any problem in preparing S/SiO2/Cr/Au, even with 4-5 nm Cr and 20 nm Au. I would suggest you to check the base pressure (keep it

Trying doing a chromium and gold blend and finish with gold. 

So you are depositing Cr on SiO2, and then putting a Au layer , and it is coming off.

whether you use SiO2 surface on silicon, or a plain simple glass both surface are oxide surface.

for initial testing you can tray simple well cleaned glass pieces.

I hope this is problem you are facing.

Please note: Cr-Au should be deposited without breaking the vacuum one after the another.  Cr layer should be thin, not more than 100 to 200 angstroms.  If it becomes thick, you will face adhesion problems. If possible, you should try to have some substrate temperature (150 to 200 deg C) while depositing gold. Please note you must have a good level of vacuum.  while you are making such bilayer metallisations by evaporation, and thermal evaporation is the best way out.

K. Sreenivas

The Cr thickness must be less than 5 nm and if the Cr was deposited by thermal deposition, the adhesion layer of gold on Cr is very good.