Enhancement of electrolyte hydrodynamics for efficient mass transfer during electroplating

Patent metadata

Field	Value
Publication number	US-9834852-B2
Application number	US-201615291543-A
Country	US
Kind code	B2
Filing date	Oct 12, 2016
Priority date	Dec 12, 2012
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

The embodiments herein relate to methods and apparatus for electroplating one or more materials onto a substrate. In many cases the material is a metal and the substrate is a semiconductor wafer, though the embodiments are no so limited. Typically, the embodiments herein utilize a channeled plate positioned near the substrate, creating a cross flow manifold defined on the bottom by the channeled 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 the channels in the channeled 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 substrate, the substrate being substantially planar;
(b) a substrate holder configured to hold the substrate such that a plating face of the substrate is separated from the anode during electroplating;
(c) an ionically resistive element comprising:
(i) a plurality of channels extending through the ionically resistive element and adapted to provide ionic transport through the ionically resistive element during electroplating;
(ii) a substrate-facing side that is substantially parallel to the plating face of the substrate and separated from the plating face of the substrate by a gap, the gap forming a cross flow manifold between the ionically resistive element and the substrate; and
(iii) 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 substantially coextensive with the plating face of the wafer, 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 cross flow manifold during plating;

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

wherein the inlet and outlet are adapted to generate cross flowing electrolyte in the cross flow manifold to create or maintain a shearing force on the plating face of the substrate during electroplating.

2. The electroplating apparatus of claim 1 , wherein the height of the step is between about 2-5 mm.

3. The electroplating apparatus of claim 2 , wherein a height of the cross flow manifold is between about 1-4 mm.

4. The electroplating apparatus of claim 1 , wherein a periphery of the step comprises a transition region where the step is rounded.

5. The electroplating apparatus of claim 4 , wherein the transition region has a width of about 2-4 mm.

6. The electroplating apparatus of claim 1 , wherein the diameter of the step is between about 2-10 mm smaller than an inner diameter of the substrate holder.

7. The electroplating apparatus of claim 1 , further comprising a cross flow injection manifold region fluidically coupled to the inlet, wherein during electroplating, electrolyte flows for a distance between about 10-15 mm after leaving the cross flow injection manifold region before reaching the plating face of the substrate.

8. The electroplating apparatus of claim 1 , wherein the cross flow manifold has a height of about 15 mm or less.

9. The electroplating apparatus of claim 1 , further comprising a lower manifold region positioned below a lower face of the ionically resistive element, wherein the lower face faces away from the substrate holder.

10. The electroplating apparatus of claim 1 , further comprising a cross flow injection manifold fluidically coupled to the inlet, wherein the cross flow injection manifold is at least partially defined by a cavity in the ionically resistive element.

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

12. A channeled ionically resistive plate for use in an electroplating apparatus to plate material on a semiconductor wafer of standard diameter, comprising:
a plate that is approximately coextensive with a plating face of the semiconductor wafer, wherein the plate has a thickness between about 2-25 mm;
at least about 1000 non-communicating through-holes extending through the thickness of the plate, wherein the through-holes are adapted to provide ionic transport through the plate during electroplating; and
a step comprising a raised portion of the plate in a central region of the plate;
a non-raised portion of the plate positioned at the periphery of the plate.

13. The channeled ionically resistive plate of claim 12 , wherein a height of the step is between about 2-5 mm.

14. The channeled ionically resistive plate of claim 12 , further comprising a transition region proximate a periphery of the step, wherein the step is rounded over a width of the transition region.

15. The channeled ionically resistive plate of claim 14 , wherein the width of the transition region is between about 2-4 mm.

16. A method for electroplating a substrate comprising:
(a) receiving a substantially 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 the anode during electroplating;
(b) immersing the substrate in electrolyte, wherein a cross flow manifold is formed between the plating face of the substrate and an ionically resistive element,
wherein the ionically resistive element is at least about coextensive with the plating face of the substrate,
wherein the ionically resistive element is adapted to provide ionic transport through the ionically resistive element during electroplating, and
wherein the ionically resistive element comprises 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, over the step, into the cross flow manifold, over the step again, and out a side outlet, and (ii) from below the ionically resistive element, through the ionically resistive element, into the cross flow manifold, over the step, and out the side outlet, wherein the side inlet and side outlet are designed or configured to generate cross flowing electrolyte in the cross flow manifold 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).

17. The method of claim 16 , wherein the step has a height between about 2-5 mm, and wherein a height of the cross flow manifold is between about 1-4 mm.

18. The method of claim 16 , wherein a periphery of the step comprises a transition region where the step is rounded.

19. The method of claim 16 , wherein electrolyte flows for a distance between about 10-15 mm after leaving a cross flow injection manifold before reaching the plating face of the substrate, wherein the cross flow injection manifold is fluidically coupled to the side inlet.

20. The method of claim 16 , wherein partitions are provided in the cross flow manifold, the partitions being configured to divide flowing electrolyte into adjacent streams within the cross flow manifold, the adjacent streams having substantially linear flow paths.

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

• C25D17/001

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

• C25D17/002

  Cell separation, e.g. membranes, diaphragms · 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