Hello student each degree is best to do PhD As any Master student after completing their Masters course can apply for PhD. But if you want to do it after B.tech it's even more good. As after B.tech lots of student take admission in MS OR PHD. PhD is not just important course but its very valuable and worthwhile also. After completing PhD after B.tech the placement rate is very high and good.

Feel free to comment if you have any doubt

Good luck