Mechanism Of Oxygen Enrichment In Micro Region Of Single Crystal Si C Substrate By Tribochemical Mechanical Polishing With Fixed Abrasive

As a new type of semiconductor material,Si C is widely used in the production of semiconductor devices as a substrate.Therefore,the surface quality of Si C is particularly important,which has also attracted the attention of many scholars and many scholars’research on ultra precision and low damage of Si C surface.In this paper,the common 6H-Si C is mainly selected as the research object,and the mechanism of action of Si C in the process of tribochemical mechanical polishing is studied,which means that Si C can be more efficient in the grinding and polishing process and obtain better surface quality after grinding and polishing has a certain meaning.（1）In this paper,a non-traditional tribochemical mechanical polishing method is used,that is,dry tribochemical mechanical polishing is used to polish 6H-Si C,which is more conducive to analyze the tribochemical reaction in the polishing process and avoid the influence of some other factors.Firstly,five solid-phase chemicals that can produce oxygen when heated are selected as oxidants in the polishing process,namely Na₂CO₃·1.5 H₂O₂,Na OH,KIO₃,KCl O₃ and KMn O₄.These five solid-phase oxidants are added to the dry tribochemical mechanical polishing process of Si C respectively.After the test and the inspection of the Si C surface after the test,it is found that the selected five solid-phase oxidants can produce oxygen after the surface of the Si C is polished,and the atomic percentage of oxygen elements are different.The oxygen atomic percentage of Si C after dry polishing with Na₂CO₃·1.5 H₂O₂ is the highest,and the oxygen atomic percentage of surface after dry polishing with KCl O₃ is the lowest.After detection,the generation of surface oxygen element is due to the formation of silicon oxide on the surface,and the main material is Si O₂.After polishing,it is calculated that the material removal rate of Si C and Na OH dry polishing is the highest,and that of Si C and KCl O₃ dry polishing is the lowest.（2）In order to further improve the polishing process rate,improve the material removal rate and obtain better surface quality,two solid-phase chemicals are selected as catalysts and added to the dry polishing process of solid-phase oxidant and Si C.The two solid-phase catalysts are glycine copper and Fe₂O₃respectively.After dry polishing,it was found that only Na₂CO₃·1.5 H₂O₂ and KMn O₄ increased the surface material removal rate and surface oxygen atomic percentage after adding the two selected catalysts,and the addition of glycine copper in KMn O₄ has little increase on the material removal rate and the percentage of surface oxygen atoms.According to the change of surface material removal rate and surface roughness after polishing,it is found that only when glycine copper is added to Na₂CO₃·1.5 H₂O₂ and Si C during polishing,and only Na₂CO₃·1.5 H₂O₂ and KMn O₄ and the addition of Fe₂O₃ in the polishing process of Si C will accelerate the tribochemical reaction rate in the polishing process.Other solid-phase oxidants mixed with solid-phase catalysts will not accelerate the oxygen production rate of solid-phase oxidants in the polishing process.After the test,the surface products were detected,and the surface was still silicon oxide dominated by Si O₂.（3）According to the selected solid-phase oxidants and solid-phase catalysts and the polishing test of Si C,a solid-phase oxidant Na₂CO₃·1.5 H₂O₂,which can make the surface quality and the material removal rate of Si C better after polishing,is selected in this paper.Abrasive particles with different particle sizes are added in the polishing process of only Na₂CO₃·1.5 H₂O₂ and Si C,the changes of surface roughness and surface material removal rate of Si C after adding abrasive with different sizes were tested.It was found that both of them increased with the increase of abrasive size.Because the simulation analysis can verify the test results and observe the microscopic changes,in order to further study the action mechanism of abrasive in the polishing process,the software is used to simulate and study the effects of different abrasive sizes and shapes on the surface morphology,material removal and residual stress of the oxide film on the polished Si C surface.The abrasive sizes are W1,W7,W14 and W28,the shapes of abrasive are set as regular hexagon,regular octagon,regular decagon and circular abrasive respectively.Through simulation,it can be found that with the increase of abrasive size,the greater the deformation of workpiece surface,the greater the depth of profile,and the grinding force also increases with the increase of abrasive size;according to the equivalent plastic strain figure,it is found that the larger the size of abrasive,the larger the area of the equivalent plastic strain figure,that is,the greater the amount of material removed;with the increase of the number of sides of regular polygon,the surface deformation of workpiece is smaller,the surface morphology is more and more gentle and stable,and the surface quality of workpiece is better and better;the more the number of sides of regular polygon abrasive,the less the tangential grinding force,indicating that the surface deformation is small and the machining effect is better;according to the equivalent plastic strain figure,it is found that the more sides of the regular polygon,the smaller the area of the equivalent plastic strain figure,that is,the smaller the amount of material removed.（4）In this paper,a solid-phase oxidant Na₂CO₃·1.5 H₂O₂ is selected,in the polishing process of solid-phase oxidant and Si C,different process parameters are combined to study the matching relationship and law between the residual oxygen content on the surface of Si C after polishing and the process parameters.Two level factors A humidity and four level factor B polishing pressure,C polishing time and D polishing pad speed are selected by orthogonal test for the polishing test of Si C.The test results show that the change of surface roughness of Si C is very small under different combinations of process parameters;after analysis,only factors A and D have a significant effect on the percentage of surface residual oxygen atoms,the order of significance of the four factors is F（A）>F（D）>F（B）>F（C）.