Photomask blank, method of manufacturing photomask, and photomask

A transmissive photomask having a circuit pattern of a film made of a material containing silicon on a substrate,

• wherein a film made of a material containing chromium is formed to be in contact with the film made of the material containing the silicon in a portion located on an outer peripheral portion of the substrate which is a region where a circuit pattern of the film made of the material containing the silicon is not formed,
• the film made of the material containing chromium is a stacked film having a three-layer structure including a first layer, a second layer, and a third layer from a side apart from the substrate, and each of the first layer, the second layer and the third layer contains chromium, oxygen and nitrogen,
• the first layer has a chromium content of 40 atomic % or less, an oxygen content of 50 atomic % or more, a nitrogen content of 10 atomic % or less, and a thickness of 20 nm or more,
• the second layer has a chromium content of 50 atomic % or more, an oxygen content of 20 atomic % or less, and a nitrogen content of 30 atomic % or more,
• the third layer has a chromium content of 40 atomic % or less, an oxygen content of 50 atomic % or more, and a nitrogen content of 10 atomic % or less, and the photomask is a transmissive photomask.