Spindle assembly for force controlled polishing
AssigneeLam Research Corporation
InventorMiguel A. Saldana
Life of this patent
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Abstract
A spindle assembly for force controlled operation in applications such as the chemical mechanical planarization of semiconductor wafers includes an axially and rotatably movable spindle driven by a force producing device. The force producing device is controlled by a position feedback loop in a first mode of operation and a spindle force control feedback loop in a second mode of operation so that the same force producing device controls spindle movement in the first mode of operation and maintains a constant pressure on a workpiece based on the detected applied pressure in the second mode of operation.
Claims23
A spindle assembly for force controlled processing of a workpiece, the force controlled spindle assembly comprising:
- a holding device for holding the workpiece;
- an axially movable spindle, the holding device connected to one end of the axially movable spindle;
- a load cell mounted on the holding device, the load cell positioned to sense a pressure applied to the workpiece and produce a load sense signal representative of the pressure applied;
- a force producing device operatively coupled to the axially movable spindle, the force producing device configured to impart a force along a longitudinal axis of the spindle;
- a positional transducer operatively connected to the spindle, the positional transducer positioned to sense an axial position of the spindle and produce a position signal representative of the axial position of the spindle;
- and
- a servo controller in communication with the positional transducer via a first feedback loop for receiving the position signal, in communication with the load cell via a second feedback loop for receiving the load sense signal, and in communication with the force producing device, wherein the servo controller controls the force producing device based on one of the position signal and the load sense signal.
A method for force controlled processing of a semiconductor wafer mounted on an end of an axially movable spindle operatively coupled to a force producing device, the force producing device controllable by a first feedback loop and a second feedback loop, the method comprising:
- moving the spindle along a longitudinal axis;
- monitoring a position of an axially movable spindle via the first feedback loop;
- disengaging the first feedback loop when the spindle reaches a first position;
- engaging the second feedback loop, the second feedback loop monitoring pressure applied at the semiconductor wafer;
- and
- maintaining a substantially constant force at the semiconductor wafer on the end of the spindle by adjusting the position of the spindle in accordance with the monitored pressure, wherein the position of the spindle and the pressure applied at the semiconductor wafer are controlled using the force producing device.
A force controlled spindle assembly for applying a constant pressure to a workpiece, the force controlled spindle assembly comprising:
- a rotatable, axially movable spindle, a holding device connected to one end of the rotatable, axially movable spindle;
- an electromagnetic force producing device operatively coupled to the spindle, the electromagnetic force producing device configured to impart a force along a longitudinal axis of the spindle;
- a servo controller in communication with the electromagnetic force producing device and providing a control signal to the electromagnetic device;
- a first feedback loop for communicating a position signal representative of a position of the spindle to the servo controller from a position transducer;
- and
- a second feedback loop for communicating a load sense signal representative of a pressure applied to a workpiece by the spindle to the servo controller from a load sensor, the load sensor positioned adjacent the workpiece.
A spindle assembly for force controlled chemical mechanical planarization processing of a workpiece, the force controlled spindle assembly comprising:
- a holding device for holding the workpiece;
- an axially movable spindle, the holding device connected to one end of the axially movable spindle;
- a load cell mounted on the holding device, the load cell positioned to sense a pressure applied to the workpiece and produce a load sense signal representative of the pressure applied;
- a positional transducer operatively connected to the spindle, the positional transducer positioned to sense an axial position of the spindle and produce a position signal representative of the axial position of the spindle;
- a force producing device operatively coupled to the axially movable spindle, the force producing device configured to impart a force along a longitudinal axis of the spindle;
- and
- a servo controller in communication with the force producing device, the load cell and the positional transducer, the servo controller having a first mode of operation wherein the servo controller controls a position of the spindle using the force producing device based on the position signal, and the servo controller having a second mode of operation wherein the servo controller controls a force applied by the force producing device to the workpiece based on the load sense signal.
Dependencies are inferred from the claim text.