Enhancement of electrolyte hydrodynamics for efficient mass transfer during electroplating

Patent metadata

Field	Value
Publication number	US-10662545-B2
Application number	US-201715799903-A
Country	US
Kind code	B2
Filing date	Oct 31, 2017
Priority date	Dec 12, 2012
Publication date	May 26, 2020
Grant date	May 26, 2020

Abstract

Methods and apparatus for electroplating material onto a substrate are provided. In many cases the material is metal and the substrate is a semiconductor wafer, though the embodiments are no so limited. Typically, the embodiments herein utilize a porous ionically resistive plate positioned near the substrate, the plate having a plurality of interconnecting 3D channels and creating a cross flow manifold defined on the bottom by the plate, on the top by the substrate, and on the sides by a cross flow confinement ring. During plating, fluid enters the cross flow manifold both upward through channels in the plate, and laterally through a cross flow side inlet positioned on one side of the cross flow confinement ring. The flow paths combine in the cross flow manifold and exit at the cross flow exit, which is positioned opposite the cross flow inlet. These combined flow paths result in improved plating uniformity.

First claim

What is claimed is:

1. An electroplating apparatus comprising:
(a) an electroplating chamber configured to contain an electrolyte and an anode while electroplating metal onto a planar substrate;
(b) a substrate holder configured to hold the planar substrate such that a plating face of the substrate is separated from the anode during electroplating;
(c) an ionically resistive element comprising:
(i) a porous material that provides a plurality of interconnecting 3D channels through the ionically resistive element, wherein the plurality of interconnecting 3D channels are adapted to provide ionic transport through the ionically resistive element during electroplating;
(ii) a substrate-facing side that is parallel to the plating face of the substrate and separated from the plating face of the substrate by a gap; and
(iii) either (1) a plurality of protuberances positioned on the substrate-facing side of the ionically resistive element, or (2) a step positioned on the substrate-facing side of the ionically resistive element, wherein the step has a height and a diameter, wherein the diameter of the step is coextensive with the plating face of the substrate, and wherein the height and diameter of the step are sufficiently small to allow electrolyte to flow under the substrate holder, over the step and into the gap during plating;

(d) an inlet to the gap for introducing cross flowing electrolyte to the gap; and
(e) an outlet to the gap for receiving cross flowing electrolyte flowing in the gap,

wherein the inlet and outlet are positioned proximate azimuthally opposing perimeter locations on the plating face of the substrate during electroplating.

2. The electroplating apparatus of claim 1 , wherein the ionically resistive element comprises the step.

3. The electroplating apparatus of claim 1 , wherein the gap between the substrate-facing side of the ionically resistive element and the plating face of the substrate is less than about 15 mm, as measured between the plating face of the substrate and an ionically resistive element plane.

4. The electroplating apparatus of claim 1 , wherein the ionically resistive element comprises the plurality of protuberances, and wherein a distance between the plating face of the substrate and an uppermost height of the protuberances is between about 0.5-4 mm.

5. The electroplating apparatus of claim 1 , wherein the ionically resistive element comprises the plurality of protuberances, and wherein the protuberances are oriented, on average, perpendicular to a direction of cross flowing electrolyte.

6. The electroplating apparatus of claim 1 , wherein the ionically resistive element comprises the plurality of protuberances, and wherein at least some of the protuberances have a length to width aspect ratio of at least about 3:1.

7. The electroplating apparatus of claim 1 , wherein the ionically resistive element comprises the plurality of protuberances, and wherein at least two different shapes and/or sizes of protuberances are present on the ionically resistive element.

8. The electroplating apparatus of claim 1 , wherein the ionically resistive element comprises the plurality of protuberances, and further comprising one or more cutout portions on at least some of the protuberances, through which electrolyte may flow during electroplating.

9. The electroplating apparatus of claim 1 , wherein the ionically resistive element comprises the plurality of protuberances, and wherein at least some of the protuberances comprise a face that is normal to an ionically resistive element plane.

10. The electroplating apparatus of claim 1 , further comprising a cross flow injection manifold fluidically coupled to the inlet.

11. The electroplating apparatus of claim 10 , wherein the cross flow injection manifold is at least partially defined by a cavity in the ionically resistive element.

12. The electroplating apparatus of claim 1 , further comprising a flow confinement ring positioned over a peripheral portion of the ionically resistive element.

13. The electroplating apparatus of claim 1 , wherein the inlet spans an arc between about 90-180° proximate the perimeter of the plating face of the substrate.

14. The electroplating apparatus of claim 1 , further comprising a plurality of azimuthally distinct segments in the inlet, a plurality of electrolyte feed inlets configured to deliver electrolyte to the plurality of azimuthally distinct inlet segments, and one or more flow control elements configured to independently control a plurality of volumetric flow rates of electrolyte in the plurality of electrolyte feed inlets during electroplating.

15. An ionically resistive plate for use in an electroplating apparatus to plate material on a semiconductor wafer of standard diameter, comprising:
a plate that is coextensive with a plating face of the semiconductor wafer, wherein the plate comprises a porous material and has a thickness between about 2-25 mm;
a plurality of interconnecting 3D channels formed in the porous material of the plate, wherein the plurality of interconnecting 3D channels are adapted to provide ionic transport through the plate during electroplating; and
either (1) a plurality of protuberances positioned on one side of the plate, or (2) both (a) a step comprising a raised portion of the plate in a central region of the plate, and (b) a non-raised portion of the plate positioned at a periphery of the plate.

16. The ionically resistive plate of claim 15 , wherein the ionically resistive plate comprises the plurality of protuberances.

17. The ionically resistive plate of claim 15 , wherein the ionically resistive plate comprises the step and the non-raised portion of the plate.

18. A method for electroplating a substrate comprising:
(a) receiving a planar substrate in a substrate holder, wherein a plating face of the substrate is exposed, and wherein the substrate holder is configured to hold the substrate such that the plating face of the substrate is separated from an anode during electroplating;
(b) immersing the substrate in electrolyte, wherein a gap is formed between the plating face of the substrate and an ionically resistive element plane,
wherein the ionically resistive element is at least about coextensive with the plating face of the substrate,
wherein the ionically resistive element comprises a porous material having a plurality of interconnecting 3D channels, wherein the plurality of interconnecting 3D channels are adapted to provide ionic transport through the ionically resistive element during electroplating, and
wherein the ionically resistive element comprises either (1) a plurality of protuberances on a substrate-facing side of the ionically resistive element, the protuberances being coextensive with the plating face of the substrate, or (2) a step on a substrate-facing side of the ionically resistive element, the step positioned in a central region of the ionically resistive element and surrounded by a non-raised portion of the ionically resistive element;

(c) flowing electrolyte in contact with the substrate in the substrate holder (i) from a side inlet, into the gap, and out a side outlet, and (ii) from below the ionically resistive element, through the ionically resistive element, into the gap, and out the side outlet, wherein the side inlet and side outlet are designed or configured to generate cross flowing electrolyte in the gap during electroplating;
(d) rotating the substrate holder; and
(e) electroplating material onto the plating face of the substrate while flowing the electrolyte as in (c)

Assignees

• Novellus Systems Inc

Inventors

• Mayer Steven T
• Buckalew Bryan L
• Fu Haiying
• Ponnuswamy Thomas
• Diaz Camilo Hilton
• Rash Robert
• Porter David W

Classifications

• C25D21/12 Primary

  Process control or regulation (controlling or regulating in general G05) · CPC title

• C25D17/002

  Cell separation, e.g. membranes, diaphragms · CPC title

• C25D17/001

  Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells · CPC title

• C25D5/08

  Electroplating with moving electrolyte e.g. jet electroplating {(using locally applied jets of electrolyte C25D5/026)} · CPC title

• C25D7/12

  Semiconductors · CPC title