Apparatus and a Method of Controlling Thickness Variation in a Material Layer Formed Using Physical Vapour Deposition

Abstract

A magnet assembly is disclosed for steering ions used in the formation of a material layer upon a substrate during a pulsed DC physical vapour deposition process. Apparatus and methods are also disclosed incorporating the assembly for controlling thickness variation in a material layer formed via pulsed DC physical vapour deposition. The magnet assembly comprises a magnetic field generating arrangement for generating a magnetic field proximate the substrate and means for rotating the ion steering magnetic field generating arrangement about an axis of rotation, relative to the substrate. The magnetic field generating arrangement comprises a plurality of magnets configured to an array which extends around the axis of rotation, wherein the array of magnets are configured to generate a varying magnetic field strength along a radial direction relative to the axis of rotation.

What is claimed is: 
     
         1 . An apparatus for controlling thickness variation in a material layer formed via pulsed DC physical vapour deposition, the apparatus comprising:
 a chamber for housing a target from which the material layer is formed, and a substrate upon which the material layer is formable, the chamber comprising an inlet for introducing a gas into the chamber;   a plasma generating arrangement for generating a plasma within the chamber; and,   a voltage source for applying an RF bias voltage to the substrate;   a plasma localising magnetic field generating arrangement configured to generate a plasma localising magnetic field proximate the target for localising the plasma adjacent the target; and,   a magnet assembly for steering ions that form of a material layer upon a substrate during a pulsed DC physical vapour deposition process, the magnet assembly comprising:
 a magnetic field generating arrangement for generating a magnetic field proximate the substrate; and 
 means for rotating the ion steering magnetic field generating arrangement about an axis of rotation, relative to the substrate; 
 wherein the magnetic field generating arrangement comprises a plurality of magnets configured in an array which extends around the axis of rotation, and wherein the array is configured to generate a varying magnetic field strength along a radial direction relative to the axis of rotation. 
   
     
     
         2 . The apparatus according to  claim 1 , wherein the magnetic field is substantially unaffected by the plasma localising magnetic field. 
     
     
         3 . The apparatus according to  claim 1 , wherein the magnetic field generating arrangement is disposed at a side of the substrate which is opposite a side of the substrate facing the plasma. 
     
     
         4 . The apparatus according to  claim 1 , wherein the array comprises a plurality of linear subarrays arranged in a parallel configuration. 
     
     
         5 . The apparatus according to  claim 1 , wherein the array comprises a spiral array centred on the axis of rotation. 
     
     
         6 . The apparatus according to  claim 1 , wherein the array comprises a plurality of concentric, substantially circular sub-arrays, centred on the axis of rotation. 
     
     
         7 . The apparatus according to  claim 1 , wherein at least two magnets of the array are arranged in a stacked configuration. 
     
     
         8 . The apparatus according to  claim 1 , wherein the plurality of magnets are disposed within a cassette having a plurality of recesses adapted to receive the plurality of magnets. 
     
     
         9 . The apparatus according to  claim 8 , wherein the magnets within the recesses are configured to a first and second array, the second array being disposed above upon the first array. 
     
     
         10 . The apparatus according to  claim 8 , wherein the recesses comprise a first and second recess portion which extend along the radial direction relative to the axis of rotation, the first and second recess portions being angularly separated around the axis of rotation by substantially 180°. 
     
     
         11 . The apparatus according to  claim 8 , wherein the cassette comprises at least three of the recesses which extend along a radial direction relative to the axis of rotation, the at least three of the recesses being angularly separated around the axis of rotation. 
     
     
         12 . The apparatus according to  claim 8 , further comprising at least one non-magnetic spacer for spacing the magnets within at least one of the recesses. 
     
     
         13 . The apparatus according to  claim 8 , wherein the varying magnetic field strength is greater proximate a periphery of the recesses in the cassette than a centre of the cassette. 
     
     
         14 . The apparatus according to  claim 1 , wherein the array comprises a plurality of linear recesses arranged in a parallel configuration. 
     
     
         15 . The apparatus according to  claim 14 , wherein each of the linear recesses extends to a periphery of the cassette. 
     
     
         16 . The apparatus according to  claim 14 , further comprising at least one non-magnetic spacer for spacing the magnets within at least one of the linear recesses. 
     
     
         17 . The apparatus according to  claim 14 , wherein the varying magnetic field strength is greater proximate a periphery of the linear recesses in the cassette than a centre of the cassette. 
     
     
         18 . The apparatus according to  claim 1 , wherein the means for rotating the magnetic field comprises a spindle and a drive assembly for driving the spindle, the spindle being rotationally coupled at one end with the cassette and at the other end with the drive assembly.