You may deposit a SnO2 thin film by reactive sputtering technique. Sputter Sn on oxygen environment but process parameters need to be standardized.

Alternately, make suspension of commercial SnO2 nanopowder in organic solvent and spin coat on the substrate followed by annealing.

I agree with opinion of Mr. A. Kumar.  

The main problem depositing SnO2 is that it needs about 500oC and high oxygen fluxes to get stoichiometric oxide. Otherwise you always get sn2+ and sn4+ mixture. Also think about sncl2 reaction with the ITO substrate, dissolution, sn diffusion into in2o3 could occur...

you can use ethylene glycol as solvent for spray pyrolysis....then heat at 150C.....

What is your target thickness? Any requirement about the crystallite size? Does the film crystals need to be oriented in a controlled way?

With reactive sputtering, you can get stoichiometric SnO2 films at room temperature without much trouble.

Thank you all for the responses. Well I don't have the leisure of using other facilities. I myself have designed a spray pyrolysis system. The solvent which i would use is methanol or ethanol (Prefer ethanol coz of its less toxic effects). I have to study the impedance properties. I am concentrating on thickness right now. But would like to get a even film. I am designing a hot plate. But using a normal heating element I am not getting a temperature above 360C. Will it suffice? 

Request all above for your valuable suggestions.

try to use glass wool to insulate all the heating surface except the part where you subtrate is, tempereture will increase up to 500oC. SnO2 usually requires that temp to be stoichiomeyric and crystalline

For the deposition of tin oxide, you may try with SnCl4 5 H20 which is readily soluble water. 

As for as heater is concerned, you may try with a thicker spiral coil (used in kitchen) with alternative base. This U can reach even upto 550 degree C in closed environment.

Someone has idea for chemical treatment of ITO/PET surface except the UVO3.

We want to print the SnO2 (alfa sear) solution on ITO/PET substrate

Thank you for your help

If use spray pyrolysis, to get a good adhesive film on Ito substrate take care for the cleaning procedure , use SnCl2. 5H2O dissolve in same quantity of methanol and deionised water substrate kept at 400 oc during deposition to obtain homogeneous films