Single wafer megasonic cleaner method, system, and apparatus
First Claim
1. A method for removing contaminants from the surface of a workpiece comprising the steps of:
- rotating the workpiece about an axis, at a low angular velocity;
directing a stream of cleaning fluid, having megasonic energy, at a surface of the workpiece, such that said stream of cleaning fluid delivers substantially uniform megasonic energy to all points on the surface of the workpiece, and then rotating the workpiece at a high angular velocity until the surface of the workpiece is dry of cleaning fluids.
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Abstract
The present invention is directed to a method, system, and apparatus for applying megasonic energy to the surface of a workpiece for the removal of contaminants. A nozzle dispenses a stream of deionized water or other cleaning fluid at a radial position on the surface. A stepping motor moves the arm over the surface, in a step-wise manner, allowing megasonic energy to be applied in a uniform manner. The workpiece is rotated at low speeds to provide a more uniform application. Chemical solutions may optionally be added to dissolve contaminants or change the Zeta potential of the contaminants to make particles easier to detach and suspend. A high-RPM dry spin cycle further removes cleaning fluid and suspended contaminants, preventing them from reattaching. The present invention is compatible with numerous types of workpieces including 12″ semiconductor wafers.
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Citations
24 Claims
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1. A method for removing contaminants from the surface of a workpiece comprising the steps of:
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rotating the workpiece about an axis, at a low angular velocity;
directing a stream of cleaning fluid, having megasonic energy, at a surface of the workpiece, such that said stream of cleaning fluid delivers substantially uniform megasonic energy to all points on the surface of the workpiece, and then rotating the workpiece at a high angular velocity until the surface of the workpiece is dry of cleaning fluids. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for removing contaminants from the surface of a workpiece comprising the steps of:
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rotating the workpiece about an axis, at a low angular velocity;
directing a stream of cleaning fluid, wherein the stream of cleaning fluid comprises megasonic energy, through a nozzle at a surface of the workpiece, while moving the nozzle over the workpiece such that said stream of cleaning fluid delivers substantially uniform megasonic energy to all points on the surface of the workpiece; and
then rotating the workpiece at a high angular velocity until the surface of the workpiece is dry of cleaning fluids. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method for removing contaminants from a workpiece having a top surface and a bottom surface, comprising the steps of:
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rotating the workpiece at a low angular velocity;
directing a first stream of cleaning fluid, wherein the first stream of cleaning fluid comprises megasonic energy, through a first nozzle at the top surface of the workpiece, while moving the first nozzle transversely over said top surface such that said first stream of cleaning fluid delivers substantially uniform megasonic energy to all points on the top surface, wherein at least a portion of the megasonic energy delivered to the top surface propagates to the bottom surface;
directing a second stream of cleaning fluid at the bottom surface of the workpiece; and
then rotating the workpiece at a high angular velocity until the workpiece is dry of cleaning fluids. - View Dependent Claims (20)
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21. A method for cleaning contaminants from the surface of a workpiece, comprising the steps of:
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providing a megasonic cleaning stream by applying megasonic energy to at least one stream of cleaning fluid;
directing at an optimal angle said at least one megasonic cleaning stream to the surface of the workpiece;
rotating the workpiece at a low angular velocity sufficient to maintain a uniform laminar flow profile of the megasonic cleaning stream on the surface of the workpiece; and
moving said megasonic cleaning stream over the workpiece such that a substantially uniform amount of megasonic energy is delivered to each point on the workpiece. - View Dependent Claims (22)
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23. A method for cleaning contaminants from the surface of a workpiece, comprising the steps of:
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providing a megasonic cleaning stream by applying megasonic energy to at least one stream of cleaning fluid;
directing at an angle between 60 and 70 degrees said at least one megasonic cleaning stream to the surface of the workpiece;
rotating the workpiece at a low angular velocity sufficient to maintain a uniform laminar flow profile of the megasonic cleaning stream on the surface of the workpiece; and
moving said megasonic cleaning stream over the workpiece such that a substantially uniform amount of megasonic energy is delivered to each point on the workpiece.
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24. A method for cleaning contaminants from the surface of a workpiece, comprising the steps of:
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providing a megasonic cleaning stream by applying megasonic energy to at least one stream of cleaning fluid;
rotating the workpiece at a low angular velocity sufficient to maintain a uniform laminar flow profile of the megasonic cleaning stream on the surface of the workpiece; and
moving said megasonic cleaning stream over the workpiece such that a substantially uniform amount of megasonic energy is delivered to each point on the workpiece, wherein said moving includes directing said stream at each, in turn, of a selected plurality of radii of said workpiece for a selected period of time, each period of time being selected in order to achieve substantially uniform distribution of megasonic energy to each point on the workpiece.
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Specification