From diploma to B.tech you have to give entrance exam for B.tech.
If you stop your diploma then you have to give entrance exams for B.tech in robotics

The eligibility criteria for B.tech is you have to pass 10+2 with 60% marks if you are general student you have to work more hard you have to maintain your percentage near 70% up.

For top colleges of b.tech robotics engineering you can visit here . There is cutoff, and name of entrance exam also

https://engineering.careers360.com/colleges/list-of-be-btech-in-automation-and-robotics-colleges-in-india

Thank you. I hope this answers helps you.