Since you're from Mexico you can't participate in Erasmus program because it's for European Union citizens but I guess there are similar programs in South-America as well.
You could go to your home-university international relations department and ask for help from them. I'm sure they'll know something to recommend you Being abroad for a semester or a year is easiest if you participate in a program and be an exchange student. Or if you know the university you'd like to study in Finland and the subject then you could also write to their international relations department to ask for recommendations about grands and scholarships.
Scholarships are more often offered for people who are already graduated (like you also mentioned, CIMO) or to the ones who are staying longer and doing the whole study abroad (though there are also other kind of scholarships for the ones staying for a year).
Anyway, all the best in finding a suitable one for you