NPN with smaller emitter width has better NFmin, why?

"The transistors with minimum emitter width have better NFmin performance due to lower base resistance"

Why? Can anyone explain more detail?

The vertical transistor is built with emitter on top, base in the middle, and collector deep inside.

The contact for the emitter is right above it. To contact the base, you have to contact it beside the emitter. If the emitter is wide, then the base is wide as well. Since you contact the base at its edges, the current has to travel far to reach the mdidle, hence you get a larger base resistance.

Greg