We present two-dimensional fully kinetic collisional particle-in-cell (PIC) simulations of the interaction of an ultra-intense laser with a solid density target. We find that the angular spread of the electrons is mostly due to the curved geometry of the electron acceleration region. Electron scattering off the magnetic fields caused by Weibel-like instabilities plays a smaller role. The angular spread can be counteracted by structuring the target into regions of different resistivity and we present a novel elliptical geometry of the high-Z core which can keep the electrons collimated for larger distances behind the target compared with cylindrical geometry.