Could the phalcon 3 work under php 7 ?
Yes. phalcon 3.0.1.
I am not seeing the build for PHP 7.0 for v3.0.1.
https://static.phalcon.io/www/files/phalcon_x64_vc14_php7.0.0_3.0.0_nts.zip is the only valid download for PHP 7, but this is for Phalcon 3.0.0.