Method of copper electroplating
First Claim
1. A method of forming copper interconnect, comprising:
- forming trenches in a dielectric layer disposed on a wafer;
forming a barrier layer over the trenches and dielectric layer immersing the wafer, under bias, in a plating solution;
performing a first plating operation at a forward current density between 10 and 30 mA/cm2 and for a duration between 2 and 60 seconds;
performing a second plating operation at a reverse current density between 15 and 60 mA/cm2; and
performing a bulk fill plating operation at a forward current density between 30 and 80 mA/cm2.
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Abstract
An electroplating process for filling damascene structures on substrates, such as wafers having partially fabricated integrated circuits thereon, includes immersing a substrate, under bias, into a copper plating solution to eliminate thin seed layer dissolution and reduce copper oxide, an initiation step to repair discontinuities in a copper seed layer, superfill plating to fill the smallest features, reverse plating to remove the adsorbed plating additives and their by-products from the substrate, a second superfill plating to fill intermediate size features, a second reverse plating to remove adsorbed plating additives and their by-products from the substrate, and a bulk fill plating with high current density to fill large features. The superfill and reverse plating operations may be repeated more than twice prior to bulk filling in order to provide the desired surface morphology.
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Citations
31 Claims
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1. A method of forming copper interconnect, comprising:
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forming trenches in a dielectric layer disposed on a wafer;
forming a barrier layer over the trenches and dielectric layer immersing the wafer, under bias, in a plating solution;
performing a first plating operation at a forward current density between 10 and 30 mA/cm2 and for a duration between 2 and 60 seconds;
performing a second plating operation at a reverse current density between 15 and 60 mA/cm2; and
performing a bulk fill plating operation at a forward current density between 30 and 80 mA/cm2. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of electroplating copper, comprising:
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immersing a wafer into a plating bath having a electrode therein;
applying a first voltage between the electrode and the wafer to produce a first forward current;
applying a second voltage between the electrode and the wafer to produce a second forward current;
applying a third voltage between the electrode and the wafer to produce a third forward current;
applying a fourth voltage between the electrode and the wafer to produce a first reverse current;
applying a fifth voltage between the electrode and the wafer to produce a fourth forward current;
applying a sixth voltage between the electrode and the wafer to produce a second reverse current; and
applying a seventh voltage between the electrode and the wafer to produce a fifth forward current. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
subsequent to applying the third voltage and prior to applying the fourth voltage, removing the voltage between the electrode and the wafer;
subsequent to applying the fourth voltage and prior to applying the fifth voltage, removing the voltage between the electrode and the wafer;
subsequent to applying the fifth voltage and prior to applying the sixth voltage, removing the voltage between the electrode and the wafer; and
subsequent to applying the sixth voltage and prior to applying the seventh voltage, removing the voltage between the electrode and the wafer.
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17. The method of claim 16, wherein the first, second, third, and fourth forward currents have a current density of between 10 and 30 mA/cm2.
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18. The method of claim 17, wherein the first and second reverse currents have a current density of between 15 and 60 mA/cm2.
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19. The method of claim 17, wherein a final forward current has a current density of between 30 and 80 mA/cm2.
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20. The method of claim 19, wherein the final forward current results from applying the seventh voltage.
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21. A method of electroplating a metal layer over a seed layer on a wafer, comprising:
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placing the wafer in a plating solution having at least one electrode disposed therein;
performing a plurality of low current plating and low current de-plating operations, followed by a higher current bulk fill operation;
wherein the low current plating operations comprise forcing a forward current density of between 10 and 30 mA/cm2, the low current de-plating operations comprise forcing a reverse current density of between 15 and 60 mA/cm2, and the bulk fill operation comprises forcing a forward current density of between 30 and 80 mA/cm2. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification