ENDPOINT CONTROL OF MULTIPLE SUBSTRATES OF VARYING THICKNESS ON THE SAME PLATEN IN CHEMICAL MECHANICAL POLISHING
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Abstract
A difference between a first expected required polish time for a first substrate and a second expected required polish time for a second substrate is determined using a first pre-polish thickness and a second pre-polish thickness measured at an in-line metrology station. A duration of an initial period is determined based on the difference between the first expected required polish time and the second expected required polish time. For the initial period at a beginning of a polishing operation, no pressure is applied to whichever of the first substrate and the second substrate has a lesser expected required polish time while simultaneously pressure is applied to whichever of the first substrate and the second substrate has a greater expected required polish time. After the initial period, pressure is applied to both the first substrate and the second substrate.
8 Citations
26 Claims
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1-13. -13. (canceled)
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14. A computer-implemented method of polishing, comprising:
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measuring a first pre-polish thickness of a layer of a first substrate at an in-line metrology station; measuring a second pre-polish thickness of a layer of a second substrate at the in-line metrology station; simultaneously contacting the first substrate and the second substrate to the same polishing pad, wherein pressures applied to the first substrate and the second substrate are independently controllable; determining a difference between a first expected required polish time for the first substrate and a second expected required polish time for the second substrate based on the first pre-polish thickness and the second pre-polish thickness; determining a pressure ratio to apply between the first substrate and the second substrate using the difference between the first expected required polish time and the second expected required polish time such that the first substrate and the second substrate have closer to the same thickness at an intermediate time before a projected endpoint time than without such a pressure difference; and at least until the intermediate time, applying pressures to the first substrate and the second substrate at the pressure ratio. - View Dependent Claims (15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26)
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20. The method of claim 20, wherein the layer of the first substrate and the layer of the second substrate are metal.
Specification