The Influence of Chemical Mechanical Polishing on Wafer Surface Haze
|School||Shanghai Jiaotong University|
|Keywords||Chemical mechanical polishing Planarization Haze Microroughness|
With the rapid development of IC manufacturing technology, IC size issmaller and smaller. Now45nm process has been widely applied. As we allknow, IC size is restricted by photolithography resolution. But the wafersurface planarization also has an effect on resolution. Currently higherstandards of silicon surface planarization technology have been set. Due tothe difference of wafer surface planarization requirement, manifoldplanarization technology has been used. As the only technology being ableto provide the global planarization, chemical mechanical polishing(CMP)is currently used more and more widely in semiconductor fields. CMP iscomposed of chemical etching and mechanical polishing.With the rapid development of IC manufacturing technology, wafersurface microroughness became more and more important. It is a mostimportant parameter of wafer surface quality. Wafer surface (or thin filmsurface) will bring bad effects to IC and next process with a badmicroroughness. So we hope that wafer surface (or thin film surface) has agood microroughness. The purpose of this dissertation is studying therelationship between CMP and wafer surface microroughness. Throughmodifying CMP process recipe, we want to improve wafer surfacemicroroughness. This paper also introduce particle defect on wafer surface.And improving wafer surface microroughness has effects on the measureof particle defect. All the paper is composed by three parts:1. First, the paper introduces the development of planarizationtechnology. And it also introduces the structure of CMP and its import toIC manufacturing. Then, it concretely introduces the mechanism of CMP. At last, the paper introduces the measurement of wafer surface quality. Itincludes a detailed introduction of wafer surface microroughness and itsmeasurement. SSIS (Scanning Surface Inspection Systems) is the mostpopular way to measure wafer surface microroughness. Within SSIS, hazeis a most important parameter to show the wafer surface microroughness.Through the relationship between haze and wafer surface microroughness,we find that Haze will become bigger when wafer surface become rougher.2. This part introduces the measurement of particle defect on wafersurface. Through studying particle defect, we find that the main cause ofparticle defect on wafer surface is wafer surface microroughness. Then wedo some experiment to confirm this inference.3. We modify CMP process parameter (for example: down forcepressure, related rotation, slurry flow rate and slurry ratio) to get some kindof wafer surface microroughness. And we get the haze of these wafers bySSIS. We find when chemical etching rate and mechanical polishing rateare balanceable, haze is least. Then we measure the particle defect of thesewafers. The result tells us: When wafer surface microroughness isimproved, the number of particle defect will reduce.Through studying, we concluded that the ratio between chemicaletching and mechanical polishing had effects on wafer surfacemicroroughness. When chemical etching and mechanical polishing are onbalance, the wafer surface microroughness can reach a minimum.