The whole point of the double slit experiment is that you get the interference patterns you'd expect from double slits, even when there is no more than one photon in the chamber at a time. One photon enters, one photon hits the detector, it's probability distribution suggests it's being interfered with.
The one-two punch of the photoelectric effect and the double slit experiment (the classic first two labs of QM) force you to accept that photons behave both like waves, and like particles.
The one-two punch of the photoelectric effect and the double slit experiment (the classic first two labs of QM) force you to accept that photons behave both like waves, and like particles.