CD control of sub-200 nm x-ray masks using an e-beam writer

In this paper the use of a commercial electron beam lithography machine (Leica Cambridge EBMF 10 cs/120) is presented as an inspection tool for the control and the metrology of X-ray masks with absorber dimensions down to 100 nm. Isolated gold absorbers fabricated on silicon nitride membranes as well as highly dense patterns of 100 nm lines and 150 nm spaces, were successfully measured and controlled by making use of the standard machine electron collector (annular channel plate electron multiplier), and by means of a developed software. A statistical precision of about 2 nm on both isolated and interacting absorber structures was achieved by this method. The measured line-width uniformity of 1.5 nm over a structure range of 20 μm, demonstrates the excellent quality of sub-200 nm gold absorbers.