Posts Tagged ‘semiconductors’
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January 29th, 2010
Concerns over shift from gold to copper bonding wire
There has been a lot of media coverage (see here and here for examples) of this week’s announcement of the results of a survey, conducted by SEMI, the global semiconductor industry association, which shows the semiconductor industry has serious reservations about the reliability and yield of copper bonding wire.
This global survey does show that an increasing number of companies are considering using copper for some new products – but the results of this survey show that there are still serious reservations in the industry over the use of copper wire in packaging technology. It is clear that gold has proven reliability and a track record – industry professionals still recognise this. We plan to undertake further research to discover the extent of the difference in reliability of gold versus copper over the coming months……
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October 1st, 2009
Better outlook for electronics demand
More than one electronics industry analyst is suggesting the outlook for the semiconductor industry is better than it has been for some time. IC Insights, iSuppli and SEMI have all made positive comments on this topic in the last couple of weeks. When this will feed through into increased gold bonding wire demand is not yet clear…. -
September 21st, 2009
The use of gold for fabrication of nanowire structures
A few weeks ago I mentioned IBM were growing silicon nanowires using gold nanoparticles. An excellent review of why gold is by far the most widely used seed particle material for growth of semiconductor nanowires has just been published by a team from Lund University (Maria E Messing, Karla Hillerich, Jonas Johansson, Knut Deppert and Kimberly A Dick) in Gold Bulletin.
The review explains that although a couple of other materials have been reported to successfully initiate growth of nanowires, gold is the most universal particle material, capable of seeding a variety of different types of nanowires at a wide range of growth conditions. In the review the group identified and described the production and deposition methods of different types of gold particles used for nanowire growth including:
gold particles made from thin films
aerosol-generated gold particles
gold particles made by lithographic methods
and colloidal gold particles.
They also discussed the different advantages and disadvantages of each particle type if the nanowires are to be used for large scale production of semiconductor devices and perhaps most importantly, the fundamental reason for gold being superior to other materials for initiating growth of nanowires. Their conclusion? The ability of gold to easily form alloys with the growth precursors, its inertness to oxygen and the high diffusivities through gold are all important and added together are what make gold such a suitable material for nanowire seed particles.
Schematic demonstrating particle-assisted nanowire growth. (a) The seed particles are formed/deposited on the substrate and (b) by heating the substrate to a desired temperature and introducing growth materials an alloy is formed. (c) When a supersaturation of the alloy particle with growth material is achieved, nucleation occurs at the particle-substrate interface. (d) Nanowire growth occurs at the particle-wire interface as long as growth material is provided. (e) By switching to growth conditions favoring planar growth radial heterostructures, known as core-shell nanowires, can be grown. (f) Nanowires containing axial heterostructures with very sharp interfaces can be formed by switching between different growth materials. (g) If a second generation of gold particles is deposited onto the as-grown nanowires and (h) the growth process is repeated, branched nanowires for formation of nanowire networks can be grown.Copyright: Gold Bulletin
Richard Holliday
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