Reflective photomask blank and reflective photomask
A reflective photomask blank ( 10 ) of a first aspect includes a substrate ( 1 ); a reflective layer ( 2 ) formed on the substrate ( 1 ); and a light absorbing layer ( 4 ) formed on the reflective layer ( 2 ). The light absorbing layer ( 4 ) includes a tin oxide film with an atomic ratio (O/Sn) of oxygen (O) to tin (Sn) being more than 1.50 and equal to or less than 2.0, and with a film thickness of 25 nm or more and 45 nm or less. Consequently, the shadowing effect of a reflective photomask for pattern transfer using extreme ultraviolet light as a light source is suppressed or reduced to improve the performance of transfer to a semiconductor substrate, and further, the cleaning resistance of the light absorbing layer is improved.
1. A reflective photomask blank for producing a reflective photomask for pattern transfer using extreme ultraviolet light as a light source, the reflective photomask blank comprising:
a substrate;
a reflective layer including a multilayer film and formed on the substrate; and
a light absorbing layer formed on the reflective layer,
wherein the light absorbing layer includes a tin oxide film with an atomic ratio (O/Sn) of oxygen (O) to tin (Sn) being more than 1.50 and equal to or less than 2.0, and with a film thickness of 25 nm or more and 45 nm or less.
2. The reflective photomask blank according to claim 1 , wherein the film thickness of the tin oxide film is 32 nm or more and 45 nm or less.
3. The reflective photomask blank according to claim 1 , wherein a material forming the tin oxide film contains 80 at % or more of tin (Sn) and oxygen (O) in total.
4. The reflective photomask blank according to claim 1 , further comprising a capping layer formed between the light absorbing layer and the reflective layer.
5. A reflective photomask comprising:
a substrate;
a reflective layer formed on the substrate; and
a light absorbing pattern layer formed on the reflective layer and patterned, the light absorbing pattern layer including a tin oxide film with an atomic ratio (O/Sn) of oxygen (O) to tin (Sn) being more than 1.50 and equal to or less than 2.0, and with a film thickness of 25 nm or more and 45 nm or less.
6. The reflective photomask blank according to claim 2 , wherein a material forming the tin oxide film contains 80 at % or more of tin (Sn) and oxygen (O) in total.
7. The reflective photomask blank according to claim 2 , further comprising a capping layer formed between the light absorbing layer and the reflective layer.
8. The reflective photomask blank according to claim 3 , further comprising a capping layer formed between the light absorbing layer and the reflective layer.