US Patent 11292065 Cutting tool

A cutting tool comprises a substrate and an AlTiN layer, the AlTiN layer including a first major surface and a second major surface, the AlTiN layer including a first region having a distance of 0 nm or more and 30 nm or less from the first major surface and having a maximum oxygen content ratio of more than 0 atomic % and less than 5 atomic %, a second region having a distance of more than 30 nm and 100 nm or less from the first major surface and having a maximum oxygen content ratio of 5 atomic % or more and 30 atomic % or less, and a third region having a distance of more than 100 nm and 150 nm or less from the first major surface and having a maximum oxygen content ratio of more than 0 atomic % and less than 5 atomic %.