Hello Sourav,
Let me that this is a media mischief .There is no FULL FEE WAIVER FOR ALL SC/ST students as it is made out.Here is the actual news"The HRD Ministry has also decided to give a total fee waiver for the differently-abled, students from SC and ST community and those belonging to families with annual income less than Rs 1 lakh, officials in the Ministry said".These days even sweepers will earn 9000 pm which make their children ineligible for this concession. One more thing, it's  irrespective of branches.

For SC and disabled students there is a complete fee waiver in IITs. It's not only branch specific. It is for all the branches. The decision was taken in 2016 and is still applicable. So if you're getting an IIT with your JEE score then it's really good. 

All the very best