0.11?0.18?m Integrated Circuit Foundry IMD Bubble Defect Principle And Solution

With the development of technology,miniaturization and multi-function have already become the development trend of electronic productions.IC(Integrated Circuit),the core of electronic productions,start to use smaller gate linewidth,more metal layers,shorter RC(Resistance and Capacitance)delay to realize these requirements.Smaller gate linewidth means IMD(Inter Metal Dielectric)structure need have strong gap-fill capacity to make sure the isolation between metal lines,and researchers also tried to adjust the oxide film materials for functions improvement.Under this background,HDP FSG(High Density Plasma Fluorine Silicon Glass),start to be used as one of the main IMD process in 0.11?0.18?m productions base on the strength of gap-fill capacity and short RC delay performance.The extensive use of HDP FSG process has led to the development of integrated circuit,but during the progress of mass production,we always found some IMD bubble defects which made the productions cannot meet the criteria of visual inspection,lead function and reliability failures,induced production scrape.IMD bubble defect have become one of main challenges in 200mm foundry 0.11?0.18?m mass production lines.This paper combined with production lines experience,suspect IMD bubble have some relationships with IMD structure of 0.11?0.18 ?m productions.According to the comparison result of defect happen ratio between 0.11?0.18?m,0.25?m and 0.35?m productions,we found IMD bubble is only exist on the productions which use HDP FSG as IMD structure.Base on this information,we suspect IMD bubble is induced by fluorine ion,exist in HDP FSG process,increased activity during high temperature process,escape and broke through the limitation of oxide layer,induced IMD bubble defect.This paper verified this failure mode through experiments,according to the IMD bubble failure rate and severity,we distinguished the major and minor factors of IMD bubble defect.This paper tries to find solutions from two sides:Reduce the defect source or enhance defense system,increase the defense capacity,make sure fluorine ion cannot break through the limitation of oxide layer,eliminate IMD bubble defect.Considering the actual situation of production,this paper provides the solution:Use FSG liner instead of SRO(Silicon Rich Oxide)film in IMD structure,enhance defense system,prevent fluorine ion break through oxide layers,eliminate IMD bubble defect.We also implemented this solution in mass production environment,got positive results.This paper verified the failure mode of IMD bubble defect,provide the solution.From foundry side,this solution can avoid at least 1200 pieces wafer scrap per year,improve 0.11?0.18 ?m production yield from 97.5%to 98.3%,increase customer satisfactory,can bring huge economic benefit to the whole company.