| As the chip process tends to be finer and integrated,chemical mechanical planarization(CMP)has become one of the indispensable processes for integrated circuit fabrication.CMP is the main process for achieving global planarization in integrated circuit manufacturing.However,the continuous reduction of feature sizes and the increasing integration have put forward higher requirements for CMP.From the current research^there are problems between the practical application and the theory research of CMP,and the fundamental research on CMP technology is not comprehensive enough.As the main planarization process used in experiments and tests in China,The 2 inch and 4 inch wafers CMP processes have not been comprehensively and thoroughly studied.Therefore,this paper will conduct research on this for providing guidance for the theoretical and practical research of CMP and posing the optimal parameter combination.Firstly,this paper choose silicon oxide as planarization material,and systematically analyzes the main parameters in the CMP process of 2 inch and 4 inch wafers.In the planarization process,the change of each parameter is related to CMP exert great influence on the material planarization rate(MRR)and its Nu(within wafer non-uniformity).Based on this,the main indexes of the two evaluation CMP processes such as material removal rate(MRR)and within wafer non-uniformity(Nu)are analyzed to optimize parameters and improve the CMP process and then find the main parameters affecting these two indexes.Secondly,the relationship between the contact stress distribution on the wafer and the down load exerted by the planarization head was studied.In the case where the planarization head is composed of the adsorption pad and the gas film,the relationship among the down load,the removal rate and the stress distribution is obtained through experimental analysis.When experiments were carried out using a gas-film structured planarization head,it was found that there is a region where the within wafer non-uniformity(Nu)is extremely low.As the down load increase,the proportion of this region gradually increase.But the Nu value of the whole wafer was not obvious Influenced.Both static and dynamic analysis have shown that the stress distribution of the planarization head has a great effect on the planarization rate and its within wafer non-uniformity.The parameters analysis of the consumables such as the flow rate and the drop point of the slurry and material of the planarization pad is an important part of the planarization parameters analysis.Based on the actual production and theoretical analysis,these parameters were analyzed and then found its influences on the 2 inch and 4 inch wafer CMP process.The experimental results have certain guiding significance for both actual production and theoretical experiments.Chemical mechanical planarization is a dynamic process.In this paper,the rotational speed of the planarization head and the planarization disc,the range of lateral movement of the planarization head and the conditioning head are analyzed and studied.The study found that when the rotational speed become overlarge,the planarization parameter especially the within wafer non-uniformity(Nu)are unstable.In addition,the swing range of the planarization head and the condition head have less influence on the planarization result,which is different from the actual production.Finally,the main influencing factors of planarization rate and its within wafer non-uniformity were analyzed by orthogonal test.The order of influences on the planarization experiment results is:pressure,planarization head rotation speed,slurry flow rate and drop point.And found the best combination of parameters for the 2 inch and 4 inch wafer silicon oxide CMP process.This experiment result was verified by repeated experiments.The results of the experimental analysis have great guiding significance for the subsequent experiments and actual production. |
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