An effective haze monitoring method

Monitoring and controlling of haze defect is becoming important more than ever before [1]. Regular and frequent mask inspection is expected to reduce the risk of defect print on wafer [2]. However, such frequent inspection requires longer inspection time and additional cost, which should lead to worsening of productivity. It is known that haze defect grows from non-killer defect at its infant stage to killer defect as time advances. And such haze growth process is dependent on the haze size in its infant stage, location of haze generation and such. If the haze inspection procedure were customized in a most suited way to optimally monitor the growth characteristics of haze, the inspection throughput would become higher without sacrificing the performance and reliability of mask inspection itself. For such a purpose, we have studied an effective haze monitoring method that ensures both sensitivity and throughput high enough. We will show that a variable scan method using a DUV mask inspection tool is quite effective in cutting down inspection time and cost.