how to achive this kind of effect on the voice ?

Sugar Bytes Effectrix or illformed glitch can do this. Or you could do it by hand by chopping the audio up.
 
Yeah, chop it manually.

Say you have this word you want to chop. Figure our where you want it to start, then chop one 8th or 16th (or whatever works) note worth of audio, copy+paste to taste. Then at the end you obviously just put the end part of that audio.

But be careful, this effect is so used that it kind of starts to be out of fashion today. That being said, i like it in moderation and if it really fits the song.
 
Or say you have a vocal phrase that you chop up into sixteen 16th notes and load them onto a sampler. Each key/pad has a different 16th note sound on it. Use midi to trigger the samples.
 
Thanks a lot for your help !
I Will try this as soon as possible.

Well its not a problem if this effect has been overused

I like it on those 2 particular songs, and wanted to know how it's done.

I am only a noob in mix and mastering :)