The generation of counter-propagating photon pairs via out-of-plane pumping is demonstrated in InGaP waveguides molecularly bonded to wet thermal oxide. A generation rate of (5.1 ± 1.2) 102 pairs/s is measured with 2.6 mW of pump power inside a 1 mm long and 250 nm thick InGaP waveguide. The pump configuration allows compensation of the momentum mismatch between orthogonally polarized photons propagating in opposite direction. Degenerated counter-propagating spontaneous photon pair generation is demonstrated in a 2 mm long and 235 nm thick InGaP waveguide within the 1400-1600 nm window via photon-correlation measurements. A red(blue)-shift of 190(160) nm in the counter-propagating TE(TM)-like modes is measured when tilting the pump 19.5ºto achieve degenerated generation of photon pairs at 1600 nm. An increase of the pair generation rate to (1.7 ± 0.4) 103 pairs/s at 1550 nm, attributed to a larger overlap between the interacting fields has been observed when tilting the pump 18.9º. The fabrication process including heterogeneous integration of 200-250 nm thick and 1-2 mm long doubly inverse tapered waveguides on SiO2 and thermally oxidized Silicon substrates via native oxide molecular bonding is presented.