Patent Application
20200131662
A metal plating process is performed for electroplating metal onto a semiconductor wafer, such as within trenches, via structures, or other portions of the semiconductor wafer. In an example, a seed layer, such as a copper layer, is formed over a surface of the semiconductor wafer. The seed layer carries electrical plating current from a wafer edge of the semiconductor wafer across the surface of the semiconductor wafer. The electrical plating current is supplied by a power source that is connected to an anode and is connected to the wafer edge as a cathode. The electrical plating current provides electrons that convert metal ions to metal atoms that accumulate on the surface of the semiconductor wafer. The seed layer has a resistance from the wafer edge to a center region of the semiconductor wafer, which results in a voltage drop causing a terminal effect where the electrical plating current is higher at the wafer edge than the center region. The higher electrical plating current results in a greater accumulation of metal atoms at the wafer edge than the center region, thus resulting in non-uniformity issues across the wafer.
The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are generally used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide an understanding of the claimed subject matter. It is evident, however, that the claimed subject matter can be practiced without these specific details. In other instances, structures and devices are illustrated in block diagram form in order to facilitate describing the claimed subject matter.
One or more systems and methods for promoting metal plating profile uniformity are provided herein. A magnetic structure, such as a permanent magnet or an electromagnet, is used to modify electrical plating current so that the electrical plating current is substantially uniform across a surface of a semiconductor wafer during a metal plating process. Controlling the electrical plating current compensates for a resistance across the surface of the semiconductor wafer that would otherwise result in a relatively larger edge plating current than a center plating current, at times referred to as a terminal effect. The terminal effect results in more metal atom accumulating on a wafer edge of the semiconductor wafer than a center portion of the semiconductor wafer. In this way, maintaining a similar electrical plating current for the semiconductor wafer mitigates the terminal effect, and thus promotes uniform metal plating across the surface of the semiconductor wafer.
A method 100 of promoting metal plating profile uniformity is illustrated in
At 102, the magnet structure is positioned at a first position with respect to the semiconductor wafer. In an embodiment, the magnet structure is positioned outside the plating cell (e.g.,
At 104, the magnetic structure is used to apply a force to the electrical plating current. In an embodiment, the force is applied to metal ions to move the metal ions away from the wafer edge of the semiconductor wafer. Moving the metal ions away from the wafer edge decreases an edge plating current associated with the wafer edge. In this way, the edge plating current is modified to a current value similar to a current value of the center plating current. In an embodiment, the force is applied to metal ions to move the metal ions towards the center portion of the semiconductor wafer. Moving the metal ions towards the center portion increases a center plating current associated with the center portion. In this way, the center plating current is modified to a current value similar to a current value of the edge plating current. Because the center plating current and the edge plating current have similar current values, metal atoms accumulate on the surface of the semiconductor wafer in a uniform or conformal manner so that the wafer edge and the center portion have similar thicknesses. It is appreciated that an embodiment of a center plating current 454 and an edge plating current 452 is illustrated in
In an embodiment, the magnetic structure is rotated with respect to the semiconductor wafer. A rotational speed of the magnetic structure is modifiable during the metal plating process. In an embodiment, a position of the magnetic structure is modified from the first position to a second position with respect to the semiconductor wafer. The difference in the first position and the second position corresponds to a change in horizontal distance between the magnetic structure and the center portion of the semiconductor wafer or corresponds to a vertical distance between the magnetic structure and the surface of the semiconductor wafer. The magnetic structure is moved in a horizontal, vertical direction, or any other direction during the metal plating process. In an embodiment, a magnetic strength of the magnet structure is modified during the metal plating process, such as by adding or removing a number of permanent magnets or by changing a power setting of an electromagnet. The magnetic strength is changed to adjust a metal plating profile resulting from the metal plating process. In this way, the magnetic structure is used to control electrical plating current in a manner that promotes metal plating profile uniformity or any other desired metal plating profile.
Accordingly, the magnetic structure 204 is used during the metal plating process to modify the electrical plating current 210. The magnetic structure 204, at the first position above the semiconductor wafer 206, creates a magnetic field 212 proximate the center portion of the semiconductor wafer 206. In an embodiment, the magnetic field 212 applies a force, such as an attractive force, to metal ions so that that metal ions are moved 214 toward the center portion of the semiconductor wafer 206. In an embodiment, the magnetic structure increase increases a center plating current associated with the center portion of the semiconductor wafer 206. In this way, the center plating current has a current value similar to an edge plating current value such that the effect of the wafer resistance 218 is generally negated. The similarity between the center plating current and the edge plating current promotes metal plating uniformity. It is appreciated that an embodiment of a center plating current 454 and an edge plating current 452 is illustrated in
The system 250 comprises magnet movement component 254. In an embodiment, the magnet movement component 254 is configured to rotate 256 the magnetic structure 204 with respect to the semiconductor wafer 206. The magnet movement component 254 is configured to modify a rotational speed of the magnetic structure 204. In an embodiment, the magnet movement component 254 is configured to modify a position of the magnetic structure 204 in a vertical direction 260 with respect to the surface of the semiconductor wafer 206. In an embodiment, the magnet movement component 254 is configured to modify a position of the magnetic structure 204 in a horizontal direction 258 with respect to a center of the semiconductor wafer 206. Modifying at least one of the magnetic strength of the magnetic field 262 or the position of the magnetic structure 204 relative to the semiconductor wafer 206 allows control to be exercised over plating current to promote a desired metal plating profile across the semiconductor wafer 206.
According to an aspect of the instant disclosure, a system for promoting metal plating profile uniformity is provided. The system comprises a magnetic structure that is positioned at a first position with respect to a semiconductor wafer that is to be electroplated with metal during a metal plating process. The magnetic structure is configured to modify at least one of an edge plating current or a center plating current associated with the metal plating process.
According to an aspect of the instant disclosure, a method for promoting metal plating profile uniformity is provided. The method comprises positioning a magnetic structure at a first position with respect to a semiconductor wafer that is to be electroplated with metal during a metal plating process. A force is applied using the magnetic structure. In an embodiment, the force decreases an edge plating current associated with the metal plating process. In another embodiment, the force increases a center plating current associated with the metal plating process.
According to an aspect of the instant disclosure, a system for promoting metal plating profile uniformity is provided. The system comprises a plating cell configured to perform a metal plating process upon a semiconductor wafer. The system comprises a magnetic structure configured to apply a force with respect to a metal plating current associated with the metal plating process. In an embodiment, the force decreases an edge plating current associated with the metal plating process. In another embodiment, the force increases a center plating current associated with the metal plating process.
Although the subject matter has been described in language specific to structural features or methodological acts, it is to be understood that the subject matter of the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as embodiment forms of implementing at least some of the claims.
Various operations of embodiments are provided herein. The order in which some or all of the operations are described should not be construed to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated given the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. Also, it will be understood that not all operations are necessary in some embodiments.
It will be appreciated that layers, features, elements, etc. depicted herein are illustrated with particular dimensions relative to one another, such as structural dimensions or orientations, for example, for purposes of simplicity and ease of understanding and that actual dimensions of the same differ substantially from that illustrated herein, in some embodiments.
Further, unless specified otherwise, “first,” “second,” or the like are not intended to imply a temporal aspect, a spatial aspect, an ordering, etc. Rather, such terms are merely used as identifiers, names, etc. for features, elements, items, etc. For example, a first channel and a second channel generally correspond to channel A and channel B or two different or two identical channels or the same channel.
Moreover, “exemplary” is used herein to mean serving as an example, instance, illustration, etc., and not necessarily as advantageous. As used in this application, “or” is intended to mean an inclusive “or” rather than an exclusive “or”. In addition, “a” and “an” as used in this application are generally to be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Also, at least one of A and B or the like generally means A or B or both A and B. Furthermore, to the extent that “includes”, “having”, “has”, “with”, or variants thereof are used, such terms are intended to be inclusive in a manner similar to “comprising”.
Also, although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The disclosure includes all such modifications and alterations and is limited only by the scope of the following claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure. In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.
This application is a divisional of and claims priority to U.S. patent application Ser. No. 13/971,881, titled “MAGNETIC STRUCTURE FOR METAL PLATING CONTROL” and filed on Aug. 21, 2013, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13971881 | Aug 2013 | US |
| Child | 16731169 | US |
