An Ultralow Stress Ta4B Absorber for X-Ray Masks

Abstract

The stress controllability, stress uniformity, stress stability and dry etching characteristics of Ta₄B films deposited by an in-line type sputtering system were investigated in detail. Low average stress Ta₄B films within ±10 MPa have been fabricated on polished SiC films that demonstrate excellent reproducibility by step annealing. Stress uniformity of the film showed an approximate range of 7 MPa on a Si wafer in a 30 mm square area when the deposition conditions were modified. The Ta₄B film demonstrated long-term stress stability and excellent resistance to the acid and water used in the cleaning process. The Ta₄B film also ensures fine pattern formations below 0.2 µ m.