Research On The Defects And Solutions Caused By Tracker For The 55 Nm Process

Lithography is a key process in the fabrication process of integrated circuits.It is a process of transferring a pattern fabricated on a mask onto a silicon substrate using a photochemical reaction mechanism.Lithography determines the minimum process size of the chip,which occupies about45% of the chip manufacturing time.The quality of the lithography process directly affects the yield of the device,and the defect is the most important and direct cause of the low yield.In the factories which are at the 55 nm mass production stage,about 80% of the defects are due to equipment.Analysis on and summary of defects examples caused by lithography process equipment will help improve the yield of mass production and provide a reference for achieving higher integration.This paper mainly studies three typical defects caused by the tracker at the 55 nm process mass production stage: scratch defect,line shape defect,edge defect,and analyzes the main causes of these three defects by a series of experiments to get the solutions for equipment transformation and management improvement:(1)Scratch defect was caused by scratches between components due to deformation of deformable parts during work.The self-made gap measurement tool was used to ensure that the gap between the pre-installed oring and inner cup of the unit are maintained at about 1 mm,and the equipment was modified to increase the fixing devices of the components in the developing tank and to increase the number of monitoring stations from 4 to 6 to reduce the occurrence of scratch defect;(2)The line shape defect was confirmed through experiments as caused by particles falling through the BARC machine after subsequent rotation to form a film.For line shape defect,it was alleviated by improving the cleaning methods and frequency of arm,CPHP,and nozzle tip.At the same time,related modification such as expanding the exhaust pipe diameter is used to reduce defect;(3)Edge defect was caused by liquid falling on the surface of the silicon wafer during the developing process.For the edge defect,through a series of experimental studies,the nozzle suction height was optimized,at first the original liquid level was equal to the nozzle,then modifying a distance about 1～2 mm between the liquid surface and the nozzle tip,and adjust the displacement of the equipment,the amount was increased to 10 liters per minute.In conclusion,mean time between failure of equipment increased from the previous 84 hours to the current 168 hours;the equipment’s uptime increased from 92% to 93%;the annual production capacity target set during the mass production phase was achieved.The energy efficiency of the whole plant was improved.