B.tech and b.sc both are the degree qualifications and both are good.
You can do anything as your wish but remember every year only few members about 100 candidates will be selected as IAS officers and if you are really work hard for that strongly determined to become IAS .the you can go with degree (b.sc) for better time preparing
With b.tech you can also prepare and also you can have advantage of getting in some other fields also
Choice is yours
All the best