The solid phase reactions of Ni thin films with refractory wide bandgap semiconductor BP(100) were investigated both in the thermal process and the ion beam induced process with RBS, AES, XRD and XPS. In the thermal reaction process, reactions of Ni thin films with BP started around 350°C. Transient metastable phases were observed between 400°C and 450°C. The formation of the fully reacted crystalline phase with the mixture of NiB and Ni3P was observed at 450°C. At elevated temperatures above 600°C, mixture of phases with less Ni content was found to be formed. For the ion beam induced process inhomogeneous reaction was observed at LN2 and the reaction at RT showed an amorphous phase with the same composition as the first thermal phase. The reaction at 200°C induced the same crystalline phase as the first thermal phase. The reacted layer thickness as a function of the ion beam fluence between RT and 300°C increased linearly with the fluence by showing the thermal dependence with an activation energy of Ea=O.31±O, O6eV above 100°C.