Share your experience!
As @Phy said, the problem it's not the phone nor the sensor, the problem it's the protective glass.
I think you might want to change this statement
@Seriner wrote:
i love sony i love z3 but only one problem is that sensor i can recommend this.
You should change it to the protective glass, as it's causing this problem, you should contact them (protective glass brand) so they can make the modifications on future products.
There's no way to do so, not only with Sony phones but androids, you might be able to do so if you root your phone and maybe there's an app that allow you to do that, check the XDA forum.
Even if the glass has a hole for the proximity sensor, if the glass it's too thick it might still be partially blocking the proximity sensor.