Method of preparing laminate and laminate for optical use
The method of preparing a laminate includes: preparing a process target, which is a laminate before being processed, where a light-shielding film has been disposed; and preparing a cleaned laminate through a first cleaning including applying UV rays and carbonated water to the process target, wherein the light-shielding film includes a transition metal and an element selected from the group consisting of oxygen, nitrogen, and carbon.
1 . A laminate where a light-shielding film is disposed,
wherein the light-shielding film comprises a transition metal and an element selected from the group consisting of oxygen, nitrogen, and carbon, and
wherein a reflectance of the light-shielding film is 35% or less with respect to a light having a wavelength of 193 nm,
wherein the laminate comprises residual ions measured by ion chromatography, and wherein the residual ions comprise sulfur-based ions and nitric acid-based ions, and
wherein the residual ions comprise sodium ions, phosphoric acid ions, potassium ions, magnesium ions and calcium ions, and a sum of an amount of the sodium ions, an amount of the phosphoric acid ions, an amount of the potassium ions, an amount of the magnesium ions, and an amount of the calcium ions is equal to or more than 0 ng/cm 2 and less than or equal to 0.01 ng/cm 2 .
2 . The laminate of claim 1 , wherein an amount of the sulfur-based ions is more than 0 ng/cm 2 and less than or equal to 0.1 ng/cm 2 and an amount of the nitric acid-based ions is more than 0 ng/cm 2 and less than or equal to 0.1 ng/cm 2 .
3 . The laminate of claim 1 , wherein the residual ions comprise halogen ions, and wherein an amount of the halogen ions is more than 0 ng/cm 2 and less than or equal to 0.1 ng/cm 2 .
4 . The laminate of claim 3 , wherein the transition metal comprises chrome and the halogen ions comprise fluorine ions or chlorine ions.
5 . The laminate of claim 1 , wherein the residual ions comprise ammonia ions and an amount of the ammonia ions is more than 0 ng/cm 2 and less than or equal to 1.0 ng/cm 2 .
6 . The laminate of claim 1 , wherein the residual ions comprise ionic impurities including sulfur-based ions, nitric acid-based ions, halogen ions, and ammonia ions, and an amount of the ionic impurities is more than 0 ng/cm 2 and less than or equal to 1.5 ng/cm 2 .
7 . The laminate of claim 1 , wherein the laminate is a photomask blank or a photomask.