Reza, you have two main sources of the EMI - firstly you processor and secondly the phase control circuit. You can determine if it is the phase control circuit as the interference gets worse as phase angle gets towards 90degrees. As I mentioned before, you need an inductor. What size inductor? start at 100uH - how to make the inductor? See www.amidon.com. You'll need a powdered iron core. Normally i'd use a yellow/white mix (see the data sheets!). You'll have to calculate the size of the core and number of turns, size of conductor to suit your application. If in doubt, make an educated guess and see how it works. Remember, the more inductance the better!

If your processor is generating the EMI, then you will have to take steps to either shield the processor or use a double-sided pcb at a minumum.