After some research I fall on the linux screw FAQ: How to disable/remap a keyboard key in Linux? but it wasn't clear enough so here is what you should do.
- run the keycode command xev in your prompt
- press on the key that has a bad mapping
- identify the keycode in the xev prompt: state 0x10, keycode 86 (keysym 0x63, c), ....
- change the keycode mapping : xmodmap -e 'keycode 86=c C'
- add (4) cmd in your .bachrc otherwise you will need to redo it in every terminal