Want a scrollabe list inside content but scrolling list should not scroll entire content

Hi guys, I tried using ion-scroll first as following,

    some conent

  <ion-scroll scrollY="true">
      <ion-item *ngFor=...></ion-item>

but ion-scroll not worked, I guessed it failed to work because the list was dynamically created, so the ion-scroll height was 0 at the beginning.

The list height always expands content, how could I make the list only scroll itself? thanks