Method for depositing multilayer coatings
The invention relates to a method and apparatus for the generation of multilayered coatings onto substrates. Typically the apparatus used is a closed field unbalanced magnetron configuration in conjunction with one or more cylindrical and rotatable shields and a substrate carrier on which the substrates to be coated are carried. The shields and substrate holder are provided for rotation about a common axis of rotation. The shields are provided with apertures to allow the selective positioning of the apertures to define a passage or passages along which material from the targets can pass onto the substrates. The targets can be cleaned prior to the coating stage by operation of the targets with the shields selectively positioned to prevent the deposited material from reaching the substrates.
1. A method for controlling the application of a multilayered coating onto at least one substrate in a coating chamber, said method comprising:
positioning a plurality of unbalanced magnetrons with targets of material to be deposited in the coating chamber to face towards a substrate holder in the chamber,
interposing between the substrate holder and the magnetrons, first and second shields, providing in said shields at least one aperture which, when selectively positioned with respect to a magnetron, allows material deposited from the magnetron target to pass therethrough and onto the substrates and characterised in that the shields are rotated during magnetron activation, with the movement of one or both of the shields being continuous at a selected speed which can be varied or fixed to suit particular coating requirements, so as to move and position the respective apertures to define a passage for selected periods of time to allow the passage of material deposited from a magnetron target and then to move the shields to repeat the same as required with respect to the first and second magnetrons as required to apply the multilayered coating onto the substrates, and
arranging the magnetrons in a closed field unbalanced magnetron (CFUBM) configuration with adjacent unbalanced magnetrons have outer magnetic assemblies of opposite polarity;
wherein the shields and substrates are provided at floating electrical potential during the coating application and the speed of rotation of the shields is independently controlled.
2. A method according to claim 1 characterised in that the magnetrons are continuously operated during the deposition process to deposit material from the respective target and when the apertures of the shields are not positioned to define a passage for the material the deposited material applies to the wall of the shield which faces the target.
3. A method according to claim 1 wherein when no passage is defined by the shield apertures at a particular magnetron at a particular time during the coating procedure that magnetron can be moved to a shut down or standby condition.
4. A method according to claim 1 wherein a reactive gas is introduced into the coating chamber during the coating procedure to allow the deposited material to form a compound material on the substrates.
5. A method according to claim 1 characterised in that the method includes the step of conditioning or preparing the material targets in each of the magnetrons prior to operation of the shields to form deposition passages, during which preparation stage material is deposited from the magnetron targets and the shields are positioned to prevent material from the targets reaching the substrates.
6. A method according to claim 1 characterised in that the relative positions of the shields when forming a passage for the deposited material from a magnetron target are selected to define the width of the passage defined by the apertures.
7. A method according to claim 6 wherein the apertures are positioned in line to define a full width passage.
8. A method according to claim 6 wherein the apertures are offset or of differing widths to define a passage of a width less than the width of the largest width aperture.
9. A method for the control of operation of apparatus for applying a coating onto at least one substrate, said coating comprising a series of layers and said apparatus including within a coating chamber at least two unbalanced magnetrons for the selective deposition of material from magnetron targets onto the substrates, and a plurality of cylindrical shields positioned between the targets and the substrate holder, said shields including apertures formed therein which can be selectively positioned to define a passage for deposited material from the targets onto the substrates and characterised in that the method comprises the steps of:
preparing the targets by operating the unbalanced magnetrons to deposit material from the targets in the coating chamber and positioning the shields to prevent the passage of deposited material onto the substrates;
applying a predetermined power level to the magnetrons and maintaining said power level during the application of the deposited material onto the substrates and continuously rotating the shields during such application, whereby the apertures in the shields are selectively positioned to allow the selective application of the material onto the substrates through passages defined by the apertures;
configuring the magnetrons in a closed field unbalanced magnetron (CFUBM) configuration with adjacent unbalanced magnetrons having outer magnetic assemblies of opposite polarity; and
selecting the speed of rotation of the shields;
wherein the substrates and shields are provided at floating electrical potential when applying the coating, and wherein either (i) the plurality of shields are continuously rotated in opposite directions during application of deposited material onto the substrates, or (ii) the plurality of shields are continuously rotated in a direction opposite to rotation of the substrate holder during application of deposited material onto the substrates.
10. A method according to claim 9 wherein the deposition of material is to be by reactive deposition and a reactive gas is introduced into the coating chamber to a defined level after the magnetron target preparation steps have been completed.
11. A method according to claim 10 wherein when the appropriate gas level is reached and maintained, the apertures in the shields are selectively positioned to allow the selective application of the material onto the substrates through passages defined by the apertures.
12. A method according to claim 10 wherein monitoring means are provided in the coating chamber and when the appropriate gas level is reached to match a predetermined value the same is monitored for a period of time to ensure the same is stable and if so the gas continues to flow at that same rate.
13. A method according to claim 12 wherein a gas control method is used including any of magnetron power supply voltage variation or mass spectrometer control of gas partial pressures.
14. A method according to claim 12 wherein Optical emission monitoring (OEM) is used to control the gas flow.
15. A method according to claim 14 wherein OEM is used to control the reactive gas flow at the required level for a stoichiometric coating to be applied to the substrates.
16. A method according to claim 10 wherein the power level applied to the magnetrons during the preparation stage is higher than that applied during the material deposition.
17. A method according to claim 10 wherein stable operating conditions are established prior to the deposition of the material onto the substrates by enabling the preparation and cleaning of the targets without contaminating the substrates by positioning the shields to prevent the passage of the material onto said substrates during the preparation stage.
18. The method according to claim 1 , wherein the first and second shields are continuously rotated in opposite directions during magnetron activation.
19. The method according to claim 1 , wherein the first and second shields are continuously rotated in a direction opposite to rotation of the substrate holder during magnetron activation.