Using a density functional method, the adhesion characteristics of a photoresist polymer/ TAO interface with and without impurities are investigated. A slab model is employed to study the importance of different TaO crystal faces. The results indicated that TaO (110) was the most important crystal face. Through geometry optimisation of the polymer on TaO (110), the effects of impurities including C, O, Si, NaOH and H2O are analysed. It was found that majority of the impurities were harmful for the adhesion, especially Si, H2O and OH, which should be removed during wafer fabrication process.