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Katherine Derbyshire, Thin Film Manufacturing's founder, is a respected industry commentator and a contributing editor of Semiconductor Magazine. Here's a sample of recent publications:
2001 2002 2003
After years of hard work by SEMI and other organizations, the 300 mm fab automation standards are essentially complete. These documents define everything from the mechanism for opening a FOUP (front-opening unified pod) to software messages, providing essential guidelines for fully automated fabs and their suppliers. Still, Asyst Technologies director of marketing Michael Brain explained, a standard is not a specification. Though standards give fabs and equipment suppliers a common language, designers still must connect the components to form a working production line.
Observers are beginning to worry that the technical limits of optical lithography may not matter. Moore's Law, the observation that transistor density doubles every 18-24 months at constant cost, may run aground on the rock of economics, not technology. The next three device generations appear to be technically feasible, but few companies can afford them. As the IC industry struggles through the worst downturn in its history, rising manufacturing costs and weak consumer demand are squeezing profit margins and development budgets. Some companies are beginning to wonder if the benefits of keeping up justify the costs.
Ever since 1990, when researchers at Cambridge University demonstrated electroluminescence in poly(para-phenylene vinylene) (PPV), organic semiconductors have attracted research dollars, venture investments, and even Nobel prizes. They have not, however, achieved significant product sales until very recently. In the last year or two, organic semiconductors have begun to appear in commercial products. The technology appears poised for rapid growth.
How much is a photomask worth? The question is becoming more important as resolution
enhancements increase the complexity and cost of mask manufacturing. Chip manufacturers
complain that the mask's share of the total process cost is climbing rapidly,
while mask manufacturers explain that money to improve their infrastructure
has to come from somewhere.
As feature sizes shrink, the differences between idealized transistors in textbooks
and real integrated circuits become more pronounced. Dielectrics allow leakage
current. Junction edges blur. Contacts consume the underlying silicon. Thermal
processes help define the interfaces between regions and layers. They supply
essential energy for oxidation, dopant activation, and other steps, but can
also drive diffusion and defect formation. Process engineers face a constant
tradeoff between minimizing unwanted atomic movement and supplying enough energy
to make the process work.
Failure analysis was once limited to chips for military and aerospace applications, which often have extensive testing and certification requirements. As general purpose chips become more valuable and the cost of field returns increases, more chip and system manufacturers are turning to failure analysis as the last line of defense against poor performance. A properly conducted failure analysis can save hundreds of thousands of dollars in field returns, lost production, and customer good will.
The purpose of a cleanroom is simple: to protect process wafers from all forms
of contamination. Actually achieving that goal is not so simple. Humans, automation
equipment and even the process itself introduce a steady stream of particles
and chemical contaminants.
Yield experts whove been in the semiconductor industry for more than a few years may remember a Golden Age, roughly between the half-micron and quarter-micron generations. The industry had eradicated its most serious yield killers with protocols for clean manufacturing, purity standards for source chemicals, and tight specifications for incoming wafers. Mature process steps resulted in stable process flows. Particles from a few known sources caused most yield excursions. Like most Golden Ages, this one looks better in retrospect than it did at the time. Semiconductor manufacturing has never been easy. Still, managing yield is more difficult now than it has ever been.
Photoresist gives the aerial image tangible reality. Where photons strike the resist, it becomes soluble in developer. The reaction is simple in concept, but fraught with complications. A production-worthy photoresist is a balance between optical, physical and chemical properties. Each new device generation changes the balance; each new wavelength may force chemists to start over again.
Integrated circuit designers and manufacturers need each other. Without designs, the fab sits idle. Without manufacturing, the design is merely a theoretical construct. Both must work together to deliver functioning circuits in a timely manner.
When it first appeared on the scene, process engineers greeted chemical mechanical planarization (CMP) with shock and derision. Mechanical grinding with a particle-laden slurry, mere microns away from the wafer's exquisitely polished surface, was nothing short of heresy. Fab managers who had religiously shunned every possible particle source now had to tolerate unimaginable levels of filth. Just a few short years later, CMP now contributes to every layer, from transistor fabrication to final metallization.
A new fab represents an enormous investment of time, money and corporate resources. The success or failure of an entire company can depend on that fab's return on the investment. Maximizing ROI requires a careful balance of many different factors, from the initial fab design to the production ramp phase.
From the status indicators on an automotive dashboard to the photorealistic
rendering offered by high-end laptops, flat panel displays (FPDs) are an essential
component of portable electronic systems. As portable systems proliferated in
1999 and 2000, active matrix liquid crystal display (AM-LCD) sales, the largest
segment of the display market, surged. According to iSuppli's Joseph Castellano,
sales jumped from around US$10 billion in 1998 to almost US$17 billion in 2000,
before falling back below the US$15 billion level in 2001.
In 1977, Hideki Shirakawa, Alan Heeger, Alan MacDiarmid and co-workers launched
enormous new interest in conducting polymers when they demonstrated that halogen-doped
polyacetylene had conductivity 109 times greater than the undoped
material. Since that discovery, which earned the three scientists the 2000 Nobel
Prize in Chemistry, conducting polymers have found applications ranging from
color-changing coatings for windows to antistatic packaging for electronic components.
The largest optoelectronic fabs now process volumes comparable to mid-size silicon fabs. Optoelectronic devices, once purchased primarily by cost-insensitive customers like the military, are making their way into the extremely cost-sensitive consumer electronics space. Device manufacturers are shifting away from research and development-oriented emphasis on device physics to focus on yield, cost and process stability.
The steady march of Moore's Law owes a great deal to a happy accident of device physics: smaller transistors run faster, consume less power and are less expensive to manufacture. In sub-100 nm transistors, however, higher speed and lower power consumption no longer go hand in hand. Improvements in one may threaten the other, and power consumption is proving especially difficult to scale.
Optical lithography has defied predictions of its demise for more than two decades. Silicon dioxide dielectrics haven't yet achieved such Rasputin-like resiliency, but they haven't been replaced yet, either. The 2001 International Technology Roadmap for Semiconductors (ITRS), released in late November, pushes the need for effective dielectric constants (k) below 3.0 back to the 90 nm technology node. The 1997 Roadmap predicted that such low-k materials would be needed for the 180 nm node.
Metrology-enabled processes like copper interconnects and sub-resolution lithography require unprecedented dependence on automated control systems. As feature sizes shrink and fabs push new and existing equipment to its limits, managers are finding that they have no choice but to make the investment.
A conversation about trends in lithography with interviewer Tom Adams. The magazine, based in Hong Kong, includes both English and Chinese versions, but neither appears to be online.
AMD's ambitious copper program has delivered dramatic microprocessor performance
gains and allowed the company to take significant market share away from archrival
Intel, but few other companies have achieved similar successes. As technology
continues to advance, more and more manufacturers will confront copper manufacturing
Quantum computing offers potential solutions to problems that are intractable for conventional computers. Actually realizing a quantum computer, however, is fiendishly difficult. While no immediate breakthroughs are apparent, quantum computers may be part of later steps on various roadmaps to achieve ever-higher computational throughput in smaller spaces.
The end of optical lithography has been predicted before. As one observer at this year's SPIE Microlithography Conference noted, "the end" has been about seven years away for the last 20 years. Still, the industry consensus seems to be that this time the end really is in sight.
Discussions of tool connectivity often resemble alphabet soup: SECS, GEM, XML, OBEM, E87 and on and on. The underlying issues are often lost in arguments about definitions and confusion about terminology. This article attempts to explain why tool connectivity is important, why it's difficult, and what fabs and their suppliers can do about it.
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