Challenges and experiences with mask inspection round robin

To prevent failures during wafer manufacturing caused by mask defects, mask manufacturers utilize high-resolution inspection tools. To detect printing mask defects for 40nm wafer technology critical layers or below, the inspection is typically performed with DUV light using Die-to-Database or Die-to-Die detection methods. Mask defect inspection tools are typically adjusted using a programmed defect mask with generic background patterns by each mask manufacturer individually, as a mask defect standard is not available. As the mask features and defect types used for the programmed defect masks as well as the sizing methods for the mask defects are also not standardized, each mask manufacturer inspects the masks with different defect sensitivities and therefore might not necessarily detect the same defects. As a result, the defect level of a delivered mask can vary between mask manufacturers. The Advanced Mask Technology Center (AMTC) as a joint venture of GlobalFoundries and Tekscend Photomask, is the captive mask shop for GlobalFoundries. To ensure that the defect level of masks delivered from AMTC and other suppliers are comparable a round robin test was launched.