Process of depositing a coating onto a substrate by reactive sputtering

A process of depositing a coating onto a substrate by reactive sputtering, comprising the steps of:

• introducing a non-reactive gas and a reactive gas containing at least one element of said coating into a closed chamber;
• establishing a plasma of said non-reactive gas;
• directing said reactive gas towards said plasma and a target, said target having a surface layer directed towards said substrate;
• either a) reacting said reactive gas with atoms extracted from said target by sputtering, or b) forming free radicals by ionization/decomposition for depositing said surface layer onto said target and then ejecting atoms from said surface layer by action of ionized gas;
• depositing said coating onto said substrate as a substantially uniform and reproducible coating with good adhesion to a surface of said substrate;
• and
• controlling the thickness of said surface layer during sputtering by repeatedly adjusting the concentration of said non-reactive gas and said reactive gas in said closed chamber, whereby said target is sputtered substantially at the same rate as the rate at which said surface layer is formed so as to avoid consuming said target.

A process of depositing a coating onto a substrate by reactive sputtering in a closed chamber under vacuum, comprising the steps of:

• introducing a concentration of a non-reactive gas and a concentration of a reactive gas containing at least one element of said coating into said closed chamber at respective flow rates;
• subsequently establishing a plasma of said non-reactive gas and said reactive gas within said closed chamber;
• depositing free radicals formed from said reactive gas as a surface layer onto a target, said free radicals containing at least one element of said coating;
• ejecting said at least one element from said target surface layer by the sputtering action of ions striking said target surface layer with sufficient energy, said ejected at least one element being capable of reacting with said reactive gas;
• depositing said ejected at least one element onto said substrate as a substantially uniform and reproducible coating with good adhesion to a surface of said substrate;
• and
• controlling the thickness of said target surface layer during sputtering by adjusting said concentration of said non-reactive gas and said concentration of said reactive gas in said closed chamber to avoid consuming said target and thereby allow for reactive sputtering without the need for replacing said target.