Patent Application
20120315754
Various embodiments described herein relate to apparatus, systems, and methods associated with interconnects, such as contacts and interconnection lines.
Ruthenium has been investigated as a barrier and/or seed material. Using ruthenium in place of other barrier metals such as tantalum can lower contact resistance, improve adhesion of subsequent conductors, and improve gap filling capability due to its seed enhancement at small dimensions.
Ruthenium is a rare transition metal of the platinum group of the periodic table and chemically resistant to most other chemicals. Compared to ruthenium, copper is a more reactive metal. Copper is more easily corroded under either acidic and alkali conditions. When ruthenium is used as barrier for copper interconnects, processing operations such as slurry polishing and post chemical mechanical processing (CMP) chemistry clean accelerates copper chemical dissolution much faster than ruthenium, resulting in preferential material removal, such as dishing, voiding and corrosion of copper structures, while ruthenium is removed much slower.
It is desirable to improve processes using ruthenium in interconnects.
In the following detailed description of the invention, reference is made to the accompanying drawings that form a part hereof and in which are shown, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made.
The term “horizontal” as used in this application is defined as a plane parallel to the conventional plane or surface of a substrate, such as a wafer or die, regardless of the orientation of the substrate. The term “vertical” refers to a direction perpendicular to the horizontal as defined above. Prepositions, such as “on”, “side” (as in “sidewall”), “higher”, “lower”, “over” and “under” are defined with respect to the conventional plane or surface being on the top surface of the substrate, regardless of the orientation of the substrate. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
Examples of electrical contacts 112 can include tungsten or tungsten alloy contacts. Although the contact 112 of
In one example, the material 120 containing ruthenium is deposited using chemical vapor deposition. Other deposition methods include, but are not limited to, atomic layer deposition (ALD) and physical vapor deposition.
The protective material 130, 132 provides chemical and mechanical protection of the material 120 containing ruthenium. The protective material chosen is substantially non-reactive with the material 120 containing ruthenium, and is easily removed at a later stage of processing using methods such as etching, washing, buffing, etc.
One example of a suitable protective material includes silicon nitride (Si3N4). Another example of a suitable protective material includes resist carbon. Other materials with selective reactivity or selective removability with respect to ruthenium can be used in various embodiments.
In one example, the removal includes a planarization operation of the top surface 114 of the substrate 100. In one example, the planarization includes a chemical-mechanical polishing (CMP) operation. The slurry in a CMP operation can be selected to be particularly aggressive when removing ruthenium, due to ruthenium's relatively inert properties to chemical removal, and due to ruthenium's mechanical hardness and strength. In the examples shown, the protective material 132 is a sacrificial material that protects a bottom 121 and sides 122 of the material 120 containing ruthenium during the harsh CMP process. Because the protective material 132 is sacrificial, damage to the protective material 132 during a CMP operation does not matter, provided the bottom 121 and sides 122 of the material 120 containing ruthenium remain protected. The CMP process on top surface 114 can shorten trenches with minimal oxide recess, thus potentially resulting in an easier aspect ratio to fill.
After removal of the upper portions of the material 120 and the protective material 132, the remainder of the protective material 132 is removed, as illustrated in
Because the relatively non-reactive and mechanically strong material 120 containing ruthenium has already been removed from the top surface 114, the subsequent removal of the upper portion of the conductor 140 is relatively straight forward. Differences in removal rate and reactivity between the conductor 140 and the material 120 containing ruthenium are mitigated by removing the respective materials in different operations. Integrity of the material 120 containing ruthenium is preserved during the removal process by the use of the sacrificial protective material.
An embodiment of an information handling system such as a computer is included in
In this example, information handling system 800 comprises a data processing system that includes a system bus 802 to couple the various components of the system. System bus 802 provides communications links among the various components of the information handling system 800 and may be implemented as a single bus, as a combination of busses, or in any other suitable manner.
Chip assembly 804 is coupled to the system bus 802. Chip assembly 804 may include any circuit or operably compatible combination of circuits. In one embodiment, chip assembly 804 includes a processor 806 that can be of any type. As used herein, “processor” means any type of computational circuit such as, but not limited to, a microprocessor, a microcontroller, a graphics processor, a digital signal processor (DSP), or any other type of processor or processing circuit or cores thereof. Multiple processors such as “multi-core” devices are also within the scope of the invention.
In one embodiment, a memory device 807, is included in the chip assembly 804. Those skilled in the art will recognize that a wide variety of memory device configurations may be used in the chip assembly 804. Acceptable types of memory chips include, but are not limited to, Dynamic Random Access Memory (DRAMs) such as SDRAMs, SLDRAMs, RDRAMs and other DRAMs. Memory chip 807 can also include non-volatile memory such as NAND memory or NOR memory.
In one embodiment, additional logic chips 808 other than processor chips are included in the chip assembly 804. An example of a logic chip 808 other than a processor includes an analog to digital converter. Other circuits on logic chips 808 such as custom circuits, an application-specific integrated circuit (ASIC), etc. are also included in one embodiment of the invention.
Information handling system 800 may also include an external memory 811, which can include one or more memory elements, such as one or more hard drives 812, and/or one or more drives that handle removable media 813 such as floppy diskettes, compact disks (CDs), digital video disks (DVDs), and the like.
Information handling system 800 may also include a display device 809 such as a monitor, additional peripheral components 810, such as speakers, etc. and a keyboard and/or controller 814, which can include a mouse, or any other device that permits a system user to input data into and receive data from the information handling system 800.
While a number of embodiments of the invention are described, the above lists are not intended to be exhaustive. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of embodiments of the present invention. It is to be understood that the above description is intended to be illustrative and not restrictive. Combinations of the above embodiments, and other embodiments, will be apparent to those of skill in the art upon studying the above description.
