内电介质层沉积中的等离子体损伤对栅氧完整性的影响研究

Investigation on effect of plasma damage for gate oxide integrity during internal dielectric layer deposition

随着半导体器件工艺尺寸不断缩小,栅氧化层的厚度已接近极限,实际生产中栅氧完整性(gate oxide integrity,GOI)问题越来越凸现.本文主要研究由于内电介质层(internal dielectric layer,ILD)沉积中的等离子体损伤导致栅氧化层工艺失效问题.采用不同沉积方式对ILD沉积,发现高密度等离子体(high density plasma,HDP)化学气相沉积过程中具有较重的等离子体,会降低器件的栅氧可靠性.HDP沉积过程中采用循环沉积-刻蚀-沉积来实现对所有填充结构轮廓的调整,实验结果发现降低沉积-刻蚀循环次数可以有效改善对栅氧等离子体损伤,但其填充效果会降低.采用高深宽比沉积工艺(high aspect ratio process,HARP)对栅氧等离子体损伤较小.由于受ILD轮廓问题影响,纯HARP填充工艺效果不佳.本文针对特殊的填充结构提出采用HDP与HARP结合的方式同时解决栅氧等离子体损伤及填充效果不佳的问题.

As the shrinking of semiconductor devices size,the thickness of gate oxide layer is approaching its limit.The gate oxide integrity(GOI)problem in actual production is becoming more and more serious.The gate oxide process failure caused by plasma damage during internal dielectric layer(ILD)deposition was mainly studied in this paper.Different deposition methods were used to deposit the IDL.It was found that there was heavier plasma during the high density plasma(HDP)chemical vapor deposition,which could affect,even reduce the gate oxide reliability of the device.The depositions-etchings-depositions cycle was used to adjust the profile of whole gap filling structures in HDP deposition.The experimental results showed that the reducing of depositions-etchings cycle number could effectively improve gate oxide plasma damage,but its gap filling effect would be reduced.HARP with high aspect ratio process had less damage plasma to the gate oxide than that of HDP.Due to the influence of the IDL profile,the pure HARP deposition method had poor gap filling ability.This paper presented a method that HDP combined with HARP could balance the problem of gate oxide plasma damage and poor gap filling effect for the special filling structure.