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Unformatted text preview: cility7 . For example, the lithograph
equipment needed for an eight-inch fab8 is valued at 8-9 million dollars and lithograph
equipment for a twelve-inch fab is valued at 20 million dollars. Because every new generation of
DRAM needs new lithograph equipment, this cost is huge.
Wafer size is an important factor that can enhance productivity in the same generation of
product and the same process. Thousands of chips are designed from one wafer9 . After circuit is
plated, a wafer is split into thousands of chips and packaged through the assembly process.
Therefore wafer size can determine the productivity among the same product generation since a
larger wafer can make more chips. More chips with the same process can reduce the cost of
production. From this point of view, productivity is a very critical factor to overcome the rising
cost of equipment and fabrication for a larger wafer and is one of the key factors for cost
reduction. At this point, DRAM providers have competed to invest and build fabs which can be
capable of producing chips with larger wafers. But, the cost of building a leading edge fab has
increased as well as shown in table 3-2. "Chip makers gripe bitterly, but litho costs keep soaring", EETIMES, September 1999
fab means normally a factory in the semiconductor industry.
9 The number of chips is depending on product generation and wafer size.
7 8A Table 3-2 Rising cost of building a leading-edge fab, 1983 to 2003 Year 1983 -1990 1997 2001 2007 Wafer (inches in diameter) 4 6 8 12 12 Linewidth (microns) 1.200 0.800 0.250 0.130 0.065 Cost (US $ millions) $200 $400 $1,250 $3,000 $5,000 Source: Adapted from Hurtarte et al., Readapted from Clair Brown and Greg Linden, Chips and
Change, 2009,table 2-1
As the costs of fab increase, DRAM providers have invested in new generation
technology which shrinks the line width in the chip for profitability. But, the cost of new
generation technology has also dramatically increased. The cost of $1.5 billion dollars for
developing 65 nm increased to $2.4 billion dollars for 45nm'".
As shown in figure 3-5, these kinds of R&D costs have continuously increased and
reduced the revenues gaps. Annual growth rate of revenues will stay at 6.5% but annual growth
rate of RD&E" will be 12.2% between 2004 and 2020 per the following by forecast of VLSI
research'. 10 G. Dan Hutcheson , The R&D crisis, VLSI Research INC, 2005 " Research,~development and extension
12 G. Dan Hutcheson , The R&D crisis, VLSI Research INC, 2005, page4
28 Chip Making R&D Versus Revenues(Worldwide in $M) 1E +05 .... .................................................... 1E+06 Revenues - ----------------------------- ... .... - .....
-- " ...-----------.......---------------- -------.....--------..---..------..-- ..--.-----..- 1957 198 19- 2007 200 l 2020 2020 Figure 3-5 Chip Making R&D Versus Revenues (Source: G. Dan Hutcheson, The R&D crisis,
VLSI Research INC, 2005, page 4)
The increasing cost of fabrication is a critical issue as discussed but the DRAM providers
don't have other options such as foundry services since design and process engineers should
work together due to the DRAM process characteristics. In other words, manufacturing process
is the competitive point among DRAM providers. It is a critical bottleneck for the industry
profitability. 3-3-2 Limitation of technology
As already discussed, the DRAM industry has grown by doubling the density with the
same size of chip following Moore's law. The core technology for the new generation of DRAM
is the photolithography. Photolithography equipment occupies a huge portion of total DRAM fabrication costs, i.e., 20% of total fixed cost. The reason why the price of lithography equipment
is high is that it is very difficult to enhance its function. Optical lithography is currently used for photolithograph equipment. This technology is
still evolving despite the fact that many experts expect that lithograph technology cannot follow
Moore's law due to physical limitations. The micron light beam using wavelengths of 0.436micron has been used for 20 years and blue-light technology using wavelengths of 0.365-micron
was applied to the lithograph equipment. Then the technology using wavelengths of 0.248micron appeared in 1990s. In 1999 lithograph equipment using 0.193-micron wavelength was
shown and is still used for 35-nano meter fabrication process. But, experts insist that more
enhancement technology is uncertain. Also, a partnership for technology development among
semiconductor providers can be the debatable issue due to the issues of patent and technology
Physical limitation of the technology can be explained by S-curve of semiconductor
technology shown in figure 3-6. Semiconductor Performance: Minimum Line Width over Time
Year 1960 1965 1970 1985 1980 1975 1990 2000 1995 20 2- e
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- Fall '07