Research And Application Of O₃ In Gate Oxidation Clean

During the manufacturing process of the integrated circuit,wafer clean process have great significance to the yield,quality and reliability.According to statistics,during the production of integrated circuit,over 50%of production scrap is caused by micro-pollutants.As the miniaturization of electronic devices and the development of the high level of integration,the semiconductor industry have more and more requirements on silicon surface cleanliness.Wafer clean process got continued to develop and meet more challenge.In advanced CMOS process,gate oxygen is the heart of the whole process,which has a direct effect on the reliability of CMOS devices,so the gate oxidation process has higher requirements on the silicon surface.Gate oxidation process is generally divided into two steps,WET clean process is used to remove natural oxidation layer on the surface,also remove trace metals and surface impurities to provide a clean wafer surface.Then next step the furnace tube grow a high quality of oxide layer.In the process of gate oxygen cleaning,the wet chemical is directly exposed to the silicon surface,and the cleanliness of the surface and the damage to the silicon surface directly affect the performance of the product.The traditional lattice oxygen clean process combined HF or BOE SPM,SC1 and HCl together to provide a clean surface.In the paper,it introduces a new chemical O₃ to develop a new lattice oxygen cleaning process.With the optimized process,it provides a high quality GATE OXIDE and meet CMOS product performance requirements.By analyzing the basic mechanism and principle of the failure of gate oxide layer,this paper finds out the root cause of the failure of gate oxygen,and determines the research direction from improving the quality of gate oxide layer.Due to the limitations of lattice oxygen cleaned,O3 will be introduced into the new GATE oxidation cleaning process,O3help to reduce the content of organic matter and heavy metals,can prevent the metal ions and the surface particle adsorption,and effectively prevent the generation of watermark and the natural oxide layer.Finally it greatly improve cleaning efficiency of GATE oxidation clean and the quality of the gate oxide.During study,the O₃ optimum concentration and the optimal supply time were determined by combining a large number of data analysis and experimental and engineering application data.Through studying the relationship between the oxide thickness of O3oxidation and the chemical and surface properties,the best process position with stable oxide thickness were obtained.Through the study of the effect of SC1 on the surface roughness of silicon and optimization SC1 process,the thickness variation of O3 oxidation was reduced to improve the quality of the gate oxide layer.By studying removal ability of O₃ treatment on metal ions,organic matter and impurity particles,further reduce the number of metal contaminants and defects on the surface of the silicon,thus effectively reduce the risk of oxide layer pinhole defect;By optimizing the flow rate and the O₃ supply structure,the O₃oxidation layer's uniformity is improved.The results show that the introduction of O₃ into the process of gate oxygen cleaning can significantly improve the surface pretreatment ability and improve the quality of gate oxide which has significant contribution in improving the yield and reliability of the device.