You can use electrodeposition method and get a thickness of your choice

HI!!! For very thin film you can do analog sweep voltametry for desired time.... the longer the time thicker your film.

R. F. plasma polymerization of aniline is also a good technique for thin film deposition of   polyaniline.

Sir, I have already synthesized the polymer, I wanted to coat that on glass layer.

dip coating. 

in dip coat technique, the glass did not hold the material from the solution, while in spin coat the material got thrown of the glass plate.

if isn't,t holding on substrate use some wetting agent 

You can use dip-dry dip-dry technique

I am trying on solgel method but the material is not depositing as a layer. How could I over come this problem? Please suggest