Copper-based chips

Copper-based chips are semiconductor integrated circuits, usually microprocessors, which use copper for interconnections. Since copper is a better conductor than aluminium, chips using this technology can have smaller metal components, and use less energy to pass electricity through them. Together, these effects lead to higher-performance processors.

The transition from aluminium to copper required significant developments in fabrication techniques, including radically different methods for patterning the metal as well as the introduction of barrier metal layers to isolate the silicon from potentially damaging copper atoms.


Because of the lack of volatile copper compounds, copper could not be patterned by the previous techniques of photoresist masking and plasma etching that had been used with great success with aluminium. The inability to plasma etch copper called for a drastic rethinking of the metal patterning process and the result of this rethinking was a process referred to as an "additive patterning" or a "Damascene" or "dual-Damascene" process.

In this process, the underlying silicon oxide insulating layer is patterned with open trenches where the conductor should be. A thick coating of copper that significantly overfills the trenches is deposited on the insulator, and chemical-mechanical planarization (CMP; also called chemical-mechanical polishing) is used to remove the copper to the level of the top of the insulating layer. Copper sunken within the trenches of the insulating layer is not removed and becomes the patterned conductor. Damascene processes generally form and fill a single feature with copper per Damascene stage. Dual-Damascene processes generally form and fill two features with copper at once, e.g., a trench overlying a via may both be filled with a single copper deposition using dual-Damascene.

With successive layers of insulator and copper, a multilayer (5-10 metal layers or more) interconnection structure is created. Without the ability of CMP to remove the copper coating in a planar and uniform fashion, and without the ability of the CMP process to stop repeatably at the copper-insulator interface, this technology would not be realizable.

Barrier metal

A barrier metal layer must completely surround all copper interconnections, since diffusion of copper into surrounding materials would degrade their properties. For instance, silicon forms deep-level traps when doped with copper. As the name implies, a barrier metal must limit copper diffusivity sufficiently to chemically isolate the copper conductor from the silicon below, yet have high electrical conductivity in order to maintain a good electronic contact.

The thickness of the barrier film is also quite important; with too thin a layer, the copper contacts poison the very devices that they connect to; with too thick a layer, the stack of two barrier metal films and a copper conductor have a greater total resistance than an aluminium interconnection would have, eliminating that benefit of the technology.

The improvement in conductivity in going from earlier aluminium to copper based conductors was modest, and not as good as to be expected by a simple comparison of bulk conductivities of aluminium and copper. The addition of barrier metals on all four sides of the copper conductor significantly reduces the cross-sectional area of the conductor that is composed of pure, low resistance, copper. Aluminium, while requiring a thin barrier metal to promote low ohmic resistance when making a contact directly to silicon or aluminum layers, did not require barrier metals on the sides of the metal lines to isolate aluminium from the surrounding silicon oxide insulators.


Resistance to electromigration, the process by which a metal conductor changes shape under the influence of an electric current flowing through it and which eventually leads to the breaking of the conductor, is significantly better with copper than with aluminium. This improvement in electromigration resistance allows higher currents to flow through a given size copper conductor compared to aluminium. The combination of a modest increase in conductivity along with this improvement in electromigration resistance was to prove highly attractive. The overall benefits derived from these performance improvements were ultimately enough to drive full-scale investment in copper-based technologies and fabrication methods for high performance semiconductor devices, and copper-based processes continue to be the state of the art for the semiconductor industry today.

ee also


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Copper interconnect — Copper based chips are semiconductor integrated circuits, usually microprocessors, which use copper for interconnections. Since copper is a better conductor than aluminium, chips using this technology can have smaller metal components, and use… …   Wikipedia

  • Copper silicide — Identifiers CAS number 12159 07 8 Properties Molecular formula Cu5Si …   Wikipedia

  • Copper Fox Distillery — is a distillery that produces American whiskey in Sperryville, Virginia. The owner and operator of Copper Fox Distillery is Rick Wasmund. Contents 1 History 2 Process 3 Products 4 Awards …   Wikipedia

  • Thermal copper pillar bump — The Thermal Copper Pillar Bump, also known as the thermal bump , is a thermoelectric device made from thin film thermoelectric material embedded in flip chip interconnects (in particular copper pillar solder bumps) for use in electronics and… …   Wikipedia

  • Chemical-mechanical planarization — Chemical Mechanical Polishing/Planarization is a process of smoothing surfaces with the combination of chemical and mechanical forces. It can be thought of as a hybrid of chemical etching and free abrasive polishing. Contents 1 Description 2… …   Wikipedia

  • Barrier metal — A barrier metal is a material used in integrated circuits to chemically isolate semiconductors from soft metal interconnects, while maintaining an electrical connection between them. For instance, a layer of barrier metal must surround every… …   Wikipedia

  • Технологический процесс в электронной промышленности — Кристаллический кремний …   Википедия

  • Titanium nitride — (titaniumnitrogen) (sometimes known as Tinite or TiNite) is an extremely hard ceramic material, often used as a coating on titanium alloy, steel, carbide, and aluminium components to improve the substrate s surface properties. Applied as a thin… …   Wikipedia

  • Paul Horn (computer scientist) — Dr. Paul M. Horn, IBM research director, has been developing pervasive computing and deep computing, and was also instrumental in developments such as the first copper based chips. External links * [… …   Wikipedia

  • Business and Industry Review — ▪ 1999 Introduction Overview        Annual Average Rates of Growth of Manufacturing Output, 1980 97, Table Pattern of Output, 1994 97, Table Index Numbers of Production, Employment, and Productivity in Manufacturing Industries, Table (For Annual… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.