  We propose a braneworld scenario in a modified symmetric teleparallel
gravitational theory, where the dynamics for the gravitational field is encoded
in the nonmetricity tensor rather than in the curvature. Assuming a single real
scalar field with a sine-Gordon self-interaction, the generalized quadratic
nonmetricity invariant $\mathbb{Q}$ controls the brane width while keeping the
shape of the energy density. By considering power corrections of the invariant
$\mathbb{Q}$ in the gravitational Lagrangian, the sine-Gordon potential is
modified exhibiting new barriers and false vacuum. As a result, the domain wall
brane obtains an inner structure, and it undergoes a splitting process. In
addition, we also propose a non-minimal coupling between a bulk fermion field
and the nonmetricity invariant $\mathbb{Q}$. Such geometric coupling leads to a
massless chiral fermion bound to the 3-brane and a stable tower of
non-localized massive states.
