Hello there,
For doing M.Tech in Robotics, you need to complete your B.Tech first. Here are some branches which you can choose for your B.Tech :

1. Robotics Engineering
2. Electronics and Communication Engineering
3. Electrical Engineering
4. Mechanical Engineering
5. Computer Science Engineering
6. Industrial and Production Engineering
7. Aeronautical Engineering
With these branches, you can apply for MTech in Robotics.

Hope this answer helps you.
Good luck!!