US20060137989A1

US20060137989A1 - Electrochemical plating apparatus and method

Info

Publication number: US20060137989A1
Application number: US11/317,715
Authority: US
Inventors: Ji Hong
Original assignee: Dongbu Electronics Co Ltd
Current assignee: DB HiTek Co Ltd
Priority date: 2004-12-23
Filing date: 2005-12-22
Publication date: 2006-06-29
Also published as: KR20060072497A; KR100698063B1

Abstract

An apparatus and a method for electrochemical plating form a metallic layer on a substrate having a seed layer. The apparatus includes an electrochemical cell containing an electrolyte solution; a plurality of bodies arranged in the electrochemical solution to form an anode; a substrate having a seed layer thereon, the substrate disposed in the electrochemical cell opposite the anode, such that the anode and the seed layer are separated by an ion travel distance; and a distance controller for independently driving at least one of the plurality of bodies to control the ion travel distance, thereby enabling uniformity control of the metallic layer formed on the substrate by independently adjusting distances between the substrate and respective bodies constituting the anode. The method is applicable to the formation of a metallic layer on a large-scale wafer, so that uniformity of an electrochemical metal layer for semiconductor devices having a small feature size can be advantageously controlled.

Description

This application claims the benefit of Korean Patent Application No. 10-2004-0111156, filed on Dec. 23, 2004, which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to electrochemical plating, and more particularly to an electrochemical plating apparatus and method, which can improve uniformity of a metallic layer formed on a substrate using an anode made up of a plurality of metal bodies.
2. Discussion of the Related Art
Electrochemical plating may be performed, for example, to fill a via or contact hole, or other a feature formed in a substrate (wafer), when forming a line of circuitry in an integrated circuit. Chemical vapor deposition or physical vapor deposition is typically used to deposit a barrier diffusion layer on the feature and to deposit a conductive metal seed layer on the barrier diffusion layer. Electrochemical plating uses an electrochemical plating apparatus to deposit on the seed layer a conductive metallic layer of, for example, copper, thereby filling the feature and covering the associated structure. Finally, a conductive wire is defined by planarizing the deposited metallic layer by, for example, chemical-mechanical polishing.
During the electrochemical plating, the deposition of the metallic layer on the seed layer is accomplished by electrically biasing the seed layer of the substrate with respect to an anode, and the seed layer and the anode are both submerged in an electrolyte solution of an electrolyte cell. That is, a voltage is applied to the seed layer and referenced to the anode, such that the electrified seed layer attracts metal ions during deposition.
Referring to FIG. 1, a contemporary electrochemical plating apparatus comprises an electrochemical cell 12 in which an anode 30 and a substrate 20 having a seed layer 40 thereon are submerged in an electrolyte solution 14 filling a process bath 10. The anode 30 is a conductive metal (e.g., copper) body, which is typically disposed at the lower end of the electrochemical cell 12, that is, in the bottom of the process bath 10. The substrate 20 is disposed in the electrochemical cell 12 opposite the anode 30 and is positioned so that the seed layer 40 faces the anode. A bias voltage (V) is applied across the anode 30 and the seed layer 40 to generate, within the electrolyte solution 14, an electrical field between the anode and seed layer, which is maintained during deposition. That is, the seed layer 40 is electrified for the deposition of the metallic layer, such that the electrolyte solution 14 in the electrochemical cell 12 acts as a medium to deliver metal ions that are supplied from the anode 30 to the seed layer 40 on the substrate 20, whereby the chemical reaction between the anode and electrolyte solution is augmented by applying the electrical charge. The electrical field is set to promote an enhanced deposition of the metallic layer on the seed layer 40 according to the lines of flux generated within the electrolyte solution 14, which extend to the substrate 20 from a point below the anode 30, thus passing through the anode.
The formation of a uniform (e.g., even thickness) metallic layer on the seed layer 40 may depend on optimization of several factors, including an ion travel distance D (distance between the anode 30 and the substrate 20); a bath resistance R_b(resistance of the electrolyte solution 14), which depends on the ion travel distance; and a seed resistance R_s(resistance of the seed layer 40), which depends on the thickness and uniformity of the seed layer. Here, the bath resistance R_bshould be high and the seed resistance R_sshould be low (namely, by forming a thick seed layer having a high degree of uniformity). Also significantly influencing metallic layer formation is the configuration of the anode 30, which may constitute a continuous (planar) disc-shaped body having a flat upper surface (FIG. 2) or by one having an upper surface formed of a plurality of concentrically arranged, V-shaped grooves 32 (FIG. 3). Neither of these configurations, however, consider the ion travel distance D, which, when varied, changes the bath resistance and thus the current density between the anode 30 and the substrate 20, thereby affecting the uniformity of the metallic layer formed on the seed layer 40.
For example, for an optimal bath resistance, the ion travel distance may be set to provide the substrate 20 with a metallic layer 42 having a uniform thickness as shown in FIG. 4A. Meanwhile, as shown in FIG. 4B, if the ion travel distance is increased to a first distance D₁, the bath resistance may be maximized, but the increased resistance results in the formation of a metallic layer 42′ exhibiting excessive thickness near the perimeter of the substrate 20 and thinner formations at its central portions. On the other hand, as shown in FIG. 4C, if the ion travel distance is decreased to a second distance D₂, thereby lowering the bath resistance, the resulting formation is a metallic layer 42″ exhibiting excessive thickness near the center of the substrate 20 and thinner formations toward its perimeter.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus and a method for electrochemical plating that substantially obviate one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an apparatus and a method for electrochemical plating, which enhances uniformity of a metallic layer formed on a substrate.
Another object of the present invention is to provide an electrochemical plating apparatus and method for forming a metallic layer on a substrate, which enables the distance between an anode body and the substrate to be independently controlled.
Another object of the present invention is to provide an apparatus and a method for electrochemical plating for forming a metallic layer on a substrate, which enables an optimal bath resistance to be maintained across a wafer.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided an electrochemical plating apparatus comprising an electrochemical cell containing an electrolyte solution; a plurality of bodies arranged in the electrochemical solution to form an anode; a substrate having a seed layer thereon, disposed in the electrochemical cell opposite the anode, such that the anode and the seed layer are separated by an ion travel distance; and a distance controller for independently driving at least one of the plurality of bodies to control the ion travel distance.
In another aspect of the present invention, there is provided a method for forming a metallic layer on a substrate having a seed layer, the method comprising arranging, in an electrolyte solution, a plurality of bodies as an anode so that the seed layer faces the anode; setting a distance between the seed layer and a corresponding body of the anode by independently driving at least one of the plurality of bodies; and generating an electrical field between the seed layer and the anode according to the set ion travel distance.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
FIG. 1 is a schematic view of a contemporary electrochemical plating apparatus;
FIGS. 2 and 3 are each a combined plan view and cross-sectional view of the anode of FIG. 1, respectively showing different anode body configurations;
FIGS. 4A-4C are each cross-sectional views of views of the electrochemical plating apparatus of FIG. 1, respectively illustrating formations of a metallic layer on a substrate according to an ion travel distance;
FIG. 5 is a schematic view of an electrochemical plating apparatus in accordance with an exemplary embodiment of the present invention; and
FIGS. 6A and 6B are each a combined plan view and cross-sectional view of the anode of FIG. 5, respectively showing different anode body configurations.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, like reference designations will be used throughout the drawings to refer to the same or similar parts.
Referring to FIG. 5, the electrochemical plating apparatus according to the present invention comprises an electrochemical cell 112 in which an anode 130 and a substrate 120 having a seed layer 140 thereon are submerged in an electrolyte solution 114 filling a process bath 110. The anode may be disposed at the lower end of the electrochemical cell (that is, in the bottom of the process bath). Thus, the substrate 120 is generally disposed in the electrochemical cell 112 opposite the anode 130 and positioned so that the seed layer 140 faces the anode. The apparatus generally includes a power source for applying a bias voltage (V) across the anode 130 and the seed layer 140 to generate, within the electrolyte solution 114, an electrical field between the anode and seed layer, which is maintained during deposition. The anode 130 generally supplies metal ions to the seed layer 140 according to the generation of the electrical field and a chemical reaction between the anode and the electrolyte solution 114.
According to the present invention, the anode 130 includes first and second bodies 132 and 134 that typically comprise a conductive metal (e.g., copper). Also, the electrochemical plating apparatus according to the present invention comprises a distance controller 150 for controlling (and/or adjusting) the distance between the seed layer 140 and the anode 130 by independently driving at least one of the first and second bodies 132 and 134, to control, adjust or maintain an ion travel distance separating the seed layer from the respective bodies of the anode. Thus, a plurality of bodies (e.g., the first body 132 and the second body 134) is arranged in the electrochemical solution to form the anode 130. The first body 132 may have an annular configuration, including a circular and/or centrally disposed opening. The second body 134 may have a disc configuration corresponding or complementary to the annular configuration of the first body 132, and is generally movable, under control of the distance controller 150, with respect to the annular configuration of the first body and/or the substrate 120/seed layer 140. That is, regardless of its actual shape (which may also be square, hexagonal, octagonal, etc.), the second body 134 is configured to be received by (or fit within and preferably match the shape and [substantially] the dimensions of) the opening of the first body 132.
The first body 132 is positioned in the process bath 110 to be separated by a fixed distance D₁′ from the seed layer 140 on the substrate 120. Alternatively, the first body 132 may be held in a fixed position and/or location relative to the seed layer 140 and/or the substrate 120, and the position of the substrate 120 may be variable with respect to the first body 132. The first body 132 serves to supply the metal ions to the seed layer 140 by virtue of the applied voltage and the chemical reaction between the anode 130 and the electrolyte solution 114. The second body 134 is inserted into and passes through at least part of the (circular) opening of the first body 132 by the operation (driving) of the distance controller 150. Generally, the second body 134 is set an adjustable distance D₂′ from the seed layer 140 and/or the substrate 120. The second body 134 also serves to supply metal ions to the seed layer 140 by virtue of the applied voltage and the chemical reaction between the anode 130 and the electrolyte solution 114. The ion travel distance between the seed layer 140 and the second body 134 (namely, the adjustable distance D₂′) is adjusted by the distance controller 150, which vertically moves the second body according to a control signal generated before and/or during a manufacturing process for making the metallic layer on the substrate (e.g., a wafer), thereby enabling uniform formation of the metallic layer on the substrate 120. Naturally, the anode 130 may comprise 3 or more generally concentric bodies, each positioned a different distance from the substrate 120 and/or seed layer 140.
In the exemplary embodiment of the present invention, the distance between the seed layer 140 and each body of the anode 130 (i.e., the ion travel distance) may be set by passing the second body 134 through the central opening of the first body 132 according to a driving operation of the distance controller 150 In addition to or in place of the anode body driver, the distance controller 150 may include independent current supplies to each anode body, to generate separate and/or different electrical fields for transferring the metal ions of each anode body 132 and 134 through the electrolyte solution 114 and thereby form the metallic layer on the substrate 120. Therefore, the electrolytic cell 112 may separately generate lines of flux in the electrolyte solution 114 to deliver metal ions to the seed layer 140 from each of the first and second bodies 132 and 134 in accordance with the bath resistances established by the respective ion travel distances. That is, metal ions from the first body 132 are delivered by virtue of a first bath resistance R_b1according to the fixed distance D₁′, while metal ions from the second body 134 are delivered by virtue of a second bath resistance R_b2according to the adjusted distance D₂′. Possible adjustments (relative positions) of the respective bodies of the anode 130 according to the present invention are shown in FIGS. 6A and 6B.
In the electroplating apparatus and method according to the present invention, the distance between the seed layer 140 and a corresponding body of the anode 130 may be set by independently driving at least one of the plurality of bodies (for example, the second body 134), whereby one of the plurality of bodies (for example, the first body 134) may be positioned a first distance from the seed layer and another of the plurality of bodies (for example, the second body 134) may be moved to a second (generally shorter) distance from the seed layer. Thus, the distance controller 150 may be operated (e.g., controlled by a control signal) to optimize the distance between the anode 130 and the seed layer 140 by setting the distance between the second body 134 and the anode 130 to a distance different from the fixed position of the first body 132 (for example, by moving the second body through an opening in the first body). As a result, the respective bath resistances R_b1and R_b2can be optimized by controlling the distance between the seed layer 140 and the respective bodies of the anode 130 (e.g., the first and second bodies 132 and 134), thereby enabling the metallic layer 142 to be formed relatively uniformly on the substrate 120.
Alternatively or additionally, the controller 150 may provide a different amount of current to each of the anode bodies in the anode 130 to generate different electric fields between each anode body and the substrate and/or seed layer. This embodiment may be particularly advantageous when the anode 130 comprises 3 or more anode bodies.
As apparent from the above description, the apparatus and the method for electrochemical plating according to the invention can control uniformity of the metallic layer formed on a substrate provided with a seed layer, by independently adjusting distances between the substrate and respective bodies constituting the anode. As a result, when forming a metallic layer on a large-scale substrate (wafer), uniformity of an electrochemical metal layer for semiconductor devices having a small feature size is advantageously controlled.
It will be apparent to those skilled in the art that various modifications can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers such modifications provided they come within the scope of the appended claims and their equivalents.

Claims

1. An electrochemical plating apparatus, comprising:

an electrochemical cell containing an electrolyte solution;

a plurality of bodies in the electrochemical solution forming an anode;

a substrate having a seed layer thereon, in said electrochemical cell opposite the anode, such that the anode and the seed layer are separated by an ion travel distance; and

a distance controller for independently driving at least one of said plurality of bodies to control the ion travel distance.

2. The apparatus according to claim 1, said plurality of bodies comprising:

a first body having an annular configuration; and

a second body having a disc configuration corresponding or complementary to the annular configuration of the first body.

3. The apparatus according to claim 2, wherein the annular configuration of said first body has a central opening for receiving the disc configuration of said second body.

4. The apparatus according to claim 2, wherein said distance controller controls the ion travel distance by moving one of said first body and said second body.

5. An electrochemical plating apparatus, comprising:

an electrochemical cell containing an electrolyte solution;

a plurality of bodies in the electrochemical solution forming an anode;

a substrate having a seed layer thereon, in said electrochemical cell opposite the anode, such that each body of the anode is separated from the seed layer by an ion travel distance; and

a distance controller for independently controlling the ion travel distance of at least one of said plurality of bodies.

6. A method for forming a metallic layer on a substrate having a seed layer, the method comprising:

arranging, in an electrolyte solution, an anode comprising a plurality of anode bodies so that the seed layer faces the anode;

setting a distance between the seed layer and a corresponding body of the anode by independently driving at least one of the plurality of bodies; and

generating an electrical field between the seed layer and the anode according to the distance.

7. The method according to claim 6, wherein the plurality of bodies includes a first body and a second body, the second body being movable with respect to the first body.

8. The method according to claim 6, wherein a first body of the plurality of bodies and the seed layer are positioned a first distance from each other; and said distance setting comprises:

moving a second body of the plurality of bodies to a second distance from the seed layer.

9. The method according to claim 6, wherein the plurality of bodies includes first and second bodies, the first body having an annular configuration and the second body having a disc configuration corresponding to the annular configuration of the first body, and wherein the annular configuration of the first body has an opening for receiving the disc configuration of the second body.

10. The method according to claim 6, wherein the metallic layer comprises copper.

11. An electrochemical plating apparatus, comprising:

an electrochemical cell containing an electrolyte solution;

an anode in the electrolyte solution, comprising a plurality of bodies; and

a distance controller adapted to (i) position at least one of said plurality of bodies a predetermined ion travel distance from a substrate having a seed layer thereon in said electrochemical cell opposite the anode, and/or (ii) provide an independent amount of current to each of said plurality of bodies.

12. The apparatus according to claim 11, said plurality of bodies comprising:

a first body having an annular configuration; and

13. The apparatus according to claim 12, wherein the annular configuration of said first body has a central opening adapted to receive the disc configuration of said second body.

14. The apparatus according to claim 12, wherein said distance controller is adapted to control an ion travel distance between said substrate and said anode by moving at least one of said first body and said second body.

15. The apparatus according to claim 12, wherein said distance controller is adapted to control an ion travel distance between said second body and said substrate by moving said second body.

16. The apparatus according to claim 11, wherein said distance controller is positioned under at least one of said plurality of bodies.

17. A method for forming a metallic layer on a substrate having a seed layer, the method comprising:

setting a distance between the seed layer and/or substrate and one or more bodies of an anode comprising a plurality of bodies, the seed layer facing the anode in an electrolyte solution; and

generating an electrical field between the seed layer and the anode according to the set distance.

18. The method according to claim 17, said distance setting comprising:

positioning a first body of the plurality of bodies and the seed layer and/or substrate a first distance from each other; and

moving a second body of the plurality of bodies to a second distance from the seed layer and/or substrate.

19. The method according to claim 18, wherein the second body is moved through an opening in the first body.

20. The method according to claim 17, wherein the metallic layer comprises copper.