Patent ID: 11402744

Abstract:
A photomask blank has a first layer, a second layer, a third layer and a fourth layer. The first layer has a chromium content of 40 atomic % or less, an oxygen content of 38 atomic % or more, and a nitrogen content of 22 atomic % or less. The second layer has a chromium content of 38 atomic % or less, an oxygen content of 30 atomic % or more, a nitrogen content of 18 atomic % or less, and a carbon content of 14 atomic % or less. The third layer has a chromium content of 50 atomic % or less, an oxygen content of 30 atomic % or less, and a nitrogen content of 20 atomic % or more. The fourth layer has a chromium content of 44 atomic % or less, an oxygen content of 20 atomic % or more, a nitrogen content of 20 atomic % or less, and a carbon content of 16 atomic % or less.