Normal quantum tunneling says that because of quantum superposition, there is a slight chance that a particle can just pass through a potential energy barrier. I realized that the reverse could happen too. Imagine that a particle, say an electron is shot through a single slit. Because of quantum superposition, there is a small chance that the particle could be blocked by the slit even though it appears as it is going straight through it. Is this possible?

(For quantum tunneling)

https://en.wikipedia.org/wiki/Quantum_tunnelling

Tunneling is not an issue of superposition, and yes, reflection is possible even though the particle classically has enough energy to overcome the barrier.

https://en.m.wikipedia.org/wiki/Rectangular_potential_barrier#E_>_V0