Pad condition and polishing rate monitor using fluorescence
First Claim
1. A method for determining the polishing rate during abrasive polishing of the surface of a semi-conductor wafer in which a slurry including a liquid having a suspension of abrasive particles is sprayed upon a surface of a rotating polishing pad and a rotating semi-conductor wafer is brought into contact with the surface of the polishing pad, a portion of the surface of the pad exposed during contact, the method comprising:
- directing electromagnetic radiation onto the exposed surface of the pad;
detecting the intensity of the electromagnetic radiation produced due to the electromagnetic radiation being directed upon the pad; and
converting the detected intensity into a polishing rate of removal of the surface of the wafer by utilizing a predetermined functional relationship between the intensity and the polishing rate.
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Accused Products
Abstract
The invention is directed to a method for detecting the chemical mechanical polishing rate of a surface of a semi-conductor wafer. In chemical mechanical polishing, a slurry made of abrasive particles suspended in a chemically abrasive liquid is dispensed on the surface of a rotating polishing pad. The wafer to be polished is rotated and lowered into contact with the rotating polishing pad. The method includes directing an X-ray beam at an exposed surface area of the polishing pad, and detecting the intensity of the X-ray fluorescence which results from the beam illuminating the pad. Since both the CMP rate of removal of a wafer surface and the intensity of the X-ray fluorescence are functions of the density of the abrasive particles in the slurry, the CMP rate of removal can be expressed as a function of the density. Accordingly, the detected intensity of the X-ray fluorescence can be converted directly into the CMP rate, without interfering with the CMP process.
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Citations
23 Claims
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1. A method for determining the polishing rate during abrasive polishing of the surface of a semi-conductor wafer in which a slurry including a liquid having a suspension of abrasive particles is sprayed upon a surface of a rotating polishing pad and a rotating semi-conductor wafer is brought into contact with the surface of the polishing pad, a portion of the surface of the pad exposed during contact, the method comprising:
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directing electromagnetic radiation onto the exposed surface of the pad; detecting the intensity of the electromagnetic radiation produced due to the electromagnetic radiation being directed upon the pad; and converting the detected intensity into a polishing rate of removal of the surface of the wafer by utilizing a predetermined functional relationship between the intensity and the polishing rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for performing abrasive polishing comprising:
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rotating a polishing pad and spraying a slurry including a liquid having a suspension of abrasive particles onto a surface of the pad; rotating a semi-conductor wafer and bringing the rotating wafer into contact with the surface of the pad with an area of the surface of the pad exposed during contact; directing electromagnetic radiation at the exposed surface area of the pad; detecting the intensity of the electromagnetic radiation produced due to the electromagnetic radiation being directed upon the pad; and converting the detected intensity into a polishing rate of removal of the surface of the wafer by utilizing a predetermined functional relationship between the intensity and the polishing rate. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An apparatus for determining the polishing rate during abrasive polishing of the surface of a semi-conductor wafer in which a slurry including a liquid having a suspension of abrasive particles is sprayed upon a surface of a rotating polishing pad and a rotating semi-conductor wafer is brought into contact with the surface of the polishing pad with a portion of the surface of the pad exposed during contact, the apparatus comprising:
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means for directing electromagnetic radiation at the exposed surface of the pad; means for detecting the intensity of the electromagnetic radiation produced due to the electromagnetic radiation being directed upon the pad; and means for converting the detected intensity into a polishing rate of removal of the surface of the wafer. - View Dependent Claims (18, 19, 20, 21)
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22. A semi-conductor workpiece processing machine comprising:
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a rotatable workpiece carrier, the rotating motion of the carrier being imparted to a workpiece carried thereon; a rotatable polishing pad having an upper surface, said carrier and pad relatively movable to allow the workpiece to be brought into contact with said pad, said pad having a larger surface area than the workpiece so as to leave a surface of the pad exposed when the workpiece is in contact with said pad; a slurry dispenser disposed to dispense slurry upon the upper surface of said pad; an X-ray tube disposed to direct an X-ray beam at the exposed surface area of the pad; an X-ray spectrometer, said spectrometer receiving the fluorescence reflected from the pad and determining the intensity thereof; and means for converting the intensity of the reflected beam into a polishing rate of removal of the surface of the wafer and for providing a readout of the rate.
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23. A method for performing abrasive polishing comprising:
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rotating a polishing pad and spraying a slurry including a liquid having a suspension of abrasive particles onto a surface of the pad rotating a semi-conductor wafer and bringing the rotating wafer into contact with the surface of the pad with an area of the surface of the pad exposed during contact; directing electromagnetic radiation at the exposed surface area of the pad; detecting the intensity of the electromagnetic radiation produced due to the electromagnetic radiation being directed upon the pad; and terminating polishing when, after the detected intensity has first reached a substantially steady level, the intensity undergoes a reduction to a level which is less than a predetermined level.
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Specification