I'm working on a 4-layer pcb project. Nothing is really high-speed on it (except for USB). I'm planning to have a ground plane on the top inner layer, and to ground fill the top layer.

In this case, is it good idea to connect the pins of decoupling capacitors of an IC (a STM32L4) directly to the ground fill? I'm afraid to catch some noise from the ground fill.
The alternative would be to put a gap between these pads and the ground fill, and to connect directly decoupling capacitors to the inner ground plane with a via. Or maybe to create a local GND fill around the IC, which would be connected only to the inner ground plane with some vias.

I read some references about good grounding and EMC (EMC engineering from Henry W. Ott e.g.) but I didin't find any clear answer or argument to choose between these solutions.

Thanks!