Is sketching an ideation method?

I was creating my case studies and while I was explaining my design process(design thinking in that case), I fell into this dilemma.

Where should I include SKETCHING, ideation or prototype phase?

In one perspective, we're ideating solutions through sketches, so it can be an ideation method. In another perspective, sketches can be treated as prototype like paper-prototypes. Anyone felt the same thing? How did you manage to fix this?