The good thing about science is that it is so diverse and yet so interrelated.
Take any field of science and with some or the other way, you will find them related.
Same is the case with BSc and B.tech. The latter is nothing but same as the former,only with a little practical professional experience. I know a Chemical Engineer working as a Scientist in a top Biology research institute. So its all about choice and the steps you take for it.
So first thing you need to decide is which aspect of engineering or which domain interests you the most and then start working for it. Like research papers, some short courses or prefrebly some internship.
Once you have enough to prove yourself and your choice, then go for it. Nobody can stop you.
All the best.