Yes you can become a scientist adter doing yout Btech. and Mtech..For this you have to do Phd in your area of interest and further you should continue your research

There are many opportunities to become scientist after completing B.TECH CSE in india.

1.Prepare your core subjects thoroughly and appear for Exams like ISRO,DRDO and BARC.Questions are generally from previous year gate questions. Just practice them carefully.

2. As you are searching for a post like scientist then you must have the qualities like curiosity to know logical reasons behind every concepts.

3.After qualifying written paper ,next comes interview round. Prepare well for interview round and show confidence while answering the questions asked in the interview.