Systems and Methods for Controlling Substrate Approach Toward a Target Horizontal Plane

Abstract

A determination is made of a real-time azimuthal position of a notch alignment feature located on a support surface of a substrate holder relative to a fixed reference ray extending perpendicularly away from a rotational axis of the substrate holder as the substrate holder rotates about the rotational axis. A determination is made of an approach initiation azimuthal position of the notch alignment feature relative to the fixed reference ray at which vertical movement of the substrate holder should initiate in order to have the notch alignment feature located at a prescribed azimuthal position relative to the fixed reference ray when the substrate holder reaches a prescribed vertical position. A determination is made of a time delay required to have the notch alignment feature located at the approach initiation azimuthal position. Vertical movement of the substrate holder is initiated in accordance with the determined time delay.

What is claimed is: 
     
         1 . An apparatus for holding a substrate, comprising:
 a substrate holder having a lower surface configured to contact a backside of a substrate, the substrate holder configured to hold the backside of the substrate against the substrate holder;   a rotation mechanism connected to the substrate holder, the rotation mechanism providing rotational control of the substrate holder about a rotational axis that extends perpendicular to the lower surface of the substrate holder at a rotational center location on the lower surface of the substrate holder;   a lift mechanism connected to the substrate holder, the lift mechanism providing vertical position control of the rotational center location along a direction perpendicular to a target horizontal plane;   a tilt mechanism connected to the substrate holder, the tilt mechanism providing for control of an angle of the lower surface of the substrate holder as measured about the rotational center location between the rotational axis and the direction perpendicular to the target horizontal plane; and   a controller connected to direct synchronized operation of the rotation mechanism, the lift mechanism, and the tilt mechanism, such that a specified location on a perimeter of the lower surface of the substrate holder is at a first prescribed distance above the target horizontal plane when the rotational center location is at a second prescribed distance above the target horizontal plane as the rotational center location is moved perpendicularly toward the target horizontal plane.   
     
     
         2 . The apparatus for holding the substrate as recited in  claim 1 , wherein the controller is configured to direct execution of a lift mechanism control command with a delay of less than one microsecond, and wherein the controller is configured to direct execution of a rotational mechanism control command with a delay of less than one microsecond. 
     
     
         3 . The apparatus for holding the substrate as recited in  claim 1 , wherein the controller is programmable to enable operation of the rotation mechanism, the lift mechanism, and the tilt mechanism in accordance with a prescribed recipe. 
     
     
         4 . The apparatus for holding the substrate as recited in  claim 1 , wherein the target horizontal plane is a surface of a bath of electroplating solution. 
     
     
         5 . The apparatus for holding the substrate as recited in  claim 1 , wherein the specified location on the perimeter of the lower surface of the substrate holder is a notch alignment feature to which a notch of the substrate is substantially aligned when the substrate is positioned on the substrate holder. 
     
     
         6 . The apparatus for holding the substrate as recited in  claim 5 , wherein the controller includes a notch alignment feature location module configured to determine a real-time azimuthal position of the notch alignment feature about the rotational axis. 
     
     
         7 . The apparatus for holding the substrate as recited in  claim 6 , wherein the notch alignment feature location module is implemented as a combination of hardware and firmware. 
     
     
         8 . The apparatus for holding the substrate as recited in  claim 5 , wherein the controller includes an approach initiation control module configured to determine an approach initiation azimuthal position of the notch alignment feature about the rotational axis when the lift mechanism initiates movement of the substrate holder toward the target horizontal plane for a given combination of rotational speed of the substrate holder about the rotational axis and vertical movement speed temporal profile for the substrate holder toward the target horizontal plane. 
     
     
         9 . The apparatus for holding the substrate as recited in  claim 8 , wherein the vertical movement speed temporal profile for the substrate holder includes a vertical acceleration temporal profile for the substrate holder and a vertical velocity temporal profile for the substrate holder. 
     
     
         10 . The apparatus for holding the substrate as recited in  claim 5 , wherein the controller includes a contact verification module configured to record an azimuthal position of the notch alignment feature about the rotational axis when the rotational center location is at the second prescribed distance above the target horizontal plane. 
     
     
         11 . A method for holding a substrate, comprising:
 disposing a substrate on a substrate holder so that a bottom surface of the substrate is positioned against a lower surface of the substrate holder and so that a top surface of the substrate is facing downward and away from the substrate holder;   operating a rotation mechanism to provide rotational control of the substrate holder about a rotational axis that extends perpendicular to the lower surface of the substrate holder at a rotational center location on the lower surface of the substrate holder;   operating a lift mechanism to provide vertical position control of the rotational center location along a direction perpendicular to a target horizontal plane located vertically below the substrate holder;   operating a tilt mechanism to provide control of an angle of the lower surface of the substrate holder as measured about the rotational center location between the rotational axis and the direction perpendicular to the target horizontal plane; and   synchronously controlling operation of the rotation mechanism, the lift mechanism, and the tilt mechanism so that a specified location on a perimeter of the lower surface of the substrate holder is at a first prescribed distance above the target horizontal plane when the rotational center location is at a second prescribed distance above the target horizontal plane while moving the rotational center location perpendicularly toward the target horizontal plane.   
     
     
         12 . The method as recited in  claim 11 , wherein the lift mechanism executes a substrate holder vertical movement command with a delay of less than one microsecond, and wherein the rotation mechanism executes a substrate holder rotation command with a delay of less than one microsecond. 
     
     
         13 . The method as recited in  claim 11 , wherein the rotation mechanism, the lift mechanism, and the tilt mechanism collectively operate in accordance with a prescribed recipe. 
     
     
         14 . The method as recited in  claim 11 , wherein the target horizontal plane is a surface of a bath of electroplating solution. 
     
     
         15 . The method as recited in  claim 11 , wherein the specified location on the perimeter of the lower surface of the substrate holder is a notch alignment feature to which a notch of the substrate is substantially aligned when the substrate is disposed on the substrate holder. 
     
     
         16 . The method as recited in  claim 15 , further comprising:
 determining a real-time azimuthal position of the notch alignment feature about the rotational axis.   
     
     
         17 . The method as recited in  claim 16 , wherein the real-time azimuthal position of the notch alignment feature about the rotational axis is determined through a combination of hardware and firmware. 
     
     
         18 . The method as recited in  claim 15 , further comprising:
 determining an approach initiation azimuthal position of the notch alignment feature about the rotational axis when the lift mechanism initiates movement of the substrate holder toward the target horizontal plane for a given combination of rotational speed of the substrate holder about the rotational axis and vertical movement speed temporal profile for the substrate holder toward the target horizontal plane.   
     
     
         19 . The method as recited in  claim 18 , wherein the vertical movement speed temporal profile for the substrate holder includes a vertical acceleration temporal profile for the substrate holder and a vertical velocity temporal profile for the substrate holder. 
     
     
         20 . The method as recited in  claim 15 , further comprising:
 recording an azimuthal position of the notch alignment feature about the rotational axis when the rotational center location is at the second prescribed distance above the target horizontal plane.