Improved X-Ray Mask Structure
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
An improved X-ray mask structure is described in which one or more windows 12 are used to form an X-ray exposure pattern, and separate windows 14 are used for alignment. The exposure-forming windows are covered with a thin X-ray transparent membrane 10 carrying an X-ray absorbing pattern 16. In the separate windows, used only for alignment, the X-ray transparent membrane has been removed, leaving one or more free-standing alignment bars 18 bridging the alignment windows. The free-standing bars form holes 20 in an alignment area. The holes provide means for detecting the alignment marks on the wafer (not shown) without any loss of the signal received from the marks on the wafer. The X-ray transparent area can be boron-doped silicon, BN or any other appropriate substrate. The alignment areas consist of a metallic film (i.e.