Slurry polisher using ultrasonic agitation
AssigneeAT&T Bell Laboratories
InventorsGabriel L. Miller, Eric R. Wagner
Life of this patent
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Abstract
Slurry in a slurry polisher is ultrasonically agitated during polishing to dislodge embedded debris and grit from the polishing pad and thereby improve the uniformity of material removal, lengthen the life of the pad and avoid scratches and defects on the surface being polished. The method is particularly useful for applications in which slurry polishing is used for planarizing deposited layers on semiconductor wafers where non-uniformities caused by such embedded material can affect process yields. Apparatus is disclosed for applying ultrasonic energy to the slurry so that such energy is focussed on the pad.
Claims6
An improved method of polishing a planar workpiece comprising:
- applying said workpiece to a rotating pad at a first location so that the motion of the pad with respect to the workpiece defines a circular path on said pad, said pad being covered with a polishing slurry;
- and
- agitating said slurry ultrasonically at a second location adjacent to said path but separated from said workpiece to dislodge embedded grit from said pad, thereby enhancing the polishing action of the slurry on said workpiece.
A method of planarizing a deposited layer on a semiconductor wafer comprising:
- applying the deposited layer on said wafer to a rotating pad at a first location so that the motion of the pad with respect to the wafer defines a circular path on said pad, said pad being covered with a polishing slurry;
- and
- agitating said slurry ultrasonically at a second location adjacent to said path but separated from said wafer to dislodge embedded grit from said pad, thereby enhancing the polishing action of the slurry on said deposited layer.
Improved apparatus for polishing a planar workpiece, which comprises:
- a rotating horizontal pad carrying a quantity of polishing slurry;
- means situated at a first location for applying said workpiece to said pad so that the motion of said pad with respect to said workpiece defines a circular path on said pad;
- and
- means situated at a second location adjacent to said path for ultrasonically agitating said slurry to dislodge embedded grit from said pad, thereby enhancing the polishing action of the slurry on said workpiece.
Improved apparatus for planarizing a deposited layer on a semiconductor wafer, which comprises:
- a rotating horizontal pad carrying a quantity of polishing slurry;
- means situated at a first location for applying the deposited layer on said wafer to said pad so that the motion of said pad with respect to said workpiece defines a circular path on said pad;
- and
- means situated at a second location adjacent to said path for ultrasonically agitating said slurry to dislodge embedded grit from said pad, thereby enhancing the polishing action of the slurry on said deposited layer.
Dependencies are inferred from the claim text.