Research Of Corrosion Electrochemical Property And Chemical Mechanical Polishing Of Gallium Nitride Material

With the rapid development of semiconductor technology,the third generation of semiconductor materials have drawn great attention.Gallium nitride,as one of the representative materials of the third generation of semiconductors,has been widely applied in the fields of short wavelength emitters and high power transistors because of its excellent performance.At present,GaN usually grow on the heterogeneous sapphire,which has a large number of lattice defects and roughness on its surface,and then affect the performance of devices.Chemical mechanical polishing is the only step to obtain global planarization and smooth GaN surface on atomic level,and performance of GaN-based devices will be improved accordingly.The effect of UV irradiation,oxidants?H₂O₂,NaClO and KMnO₄?and pH of solutions on the corrosion/passivation on GaN surface were researched by electrochemical experiments in this paper.Moreover,sodium dodecyl sulfate was added into potassium permanganate solutions to investigate its mechanism of action on GaN surface.According to the electrochemical results,the polisher was used to polish GaN wafers,and then the consistency of GaN material removal rate and electrochemical experiments was studied.The atomic force microscope?AFM?was used to test the surface morphology of GaN.The resuls show that UV irradiation could effectively promote the corrosion of GaN surface in H₂O₂ and NaClO solution.At the same time,the most corrosive effect happened when GaN was in 1 vol.%H₂O₂ acidic solution and 2 vol.%NaClO alkalescent solution.Combined with the results of CMP,the Ra roughness of GaN was only 0.06 nm after polishing with H₂O₂-based slurry.The highest removal rate?404.6 nm/h?of GaN was obtained when GaN was polished with NaClO-based slurry,the Ra roughness of GaN after polishing was 1.61nm.Based on these results,two step polish of 2 vol.%NaClO and 1 vol.%H₂O₂-based slurry was put forward to GaN polish,which can obtain good surface quality after polishing with high removal rate.GaN surface would passivated by KMnO₄ oxidizer,and 0.3 M highly acidic KMnO₄ solution showed the best passivative effect on GaN,and the removal rate of GaN under this condition was 129.5 nm/h.On this basis,0.05 M SDS was added to promote the passivation and then improve the removal rate to 242.8 nm/h significantly,the Ra roughness of GaN after polishing was 0.47 nm.From the researches mentioned above,the corrosion and passivation characteristics of GaN surface studied by electrochemical method have guiding function for CMP to some extent,and the removal rate of GaN in CMP can be further analyzed and explained by the results of electrochemical experiments.