1996 Electronics Industry Environmental Roadmap - Civil and ...

Emerging Technologies
should take ownership of the “Grand Challenges,” mobilizing resources for a concerted
public/private partnership. This chapter proposes seven such Grand Challenges:
6.4.1 “Dry” Wafers
The predominance of wet processing in wafer fabrication was referred to earlier in this chapter.
Various industry efforts at SEMATECH, the Semiconductor Research Corporation, and
elsewhere have started to address the substitution of dry processes in wafer fabrication.
For example, the use of laser direct-write as a patterning technology to replace masks holds a
great deal of promise for the elimination of a substantial quantity of hazardous substances.
Laser-direct write, however, will require a great deal of additional research and development
before it reaches a point of acceptance in the industry. The dry wafer challenge could also
address alternative technologies for contamination prevention and cleaning.
6.4.2 The Packageless Chip
Emerging packaging and interconnect technology is increasingly moving to the use of bare die
and direct-chip attach, in which unpackaged chips are attached to substrates via advanced
interconnect technologies such as array bonding and flip chip. Further improvements in chip
performance have the potential of creating a “printed wiring board on a chip,” in which case the
highly integrated microprocessor may be directly attached onto a functioning physical component
of a system, such as the glass for a display. The possibility for increased miniaturization by,
essentially, making the display the mother board presents an intriguing possibility for future
products.
In these cases, the materials used for bonding, materials used for underfill, and the processes used
for minimizing (or eliminating) and removing excess materials will require great focus in
research and development. A primary issue, from an environmental standpoint, will be the
nature of the materials used—lead-free solders, anisotropic adhesives, and other of material
combinations yet to be finalized. For example, a variety of lead-free solder alloys are currently
being examined in laboratories, generally focusing on component materials such as indium, zinc,
and tin. A collaborative effort at development and characterization of these materials and their
application in environmentally conscious processes, could substantially benefit an industry
seeking acceptable alternatives for increased system performance.
6.4.3 Zero Emissions Processes
Beginning with the development and implementation of robust mass balance tools, a focused
effort to design, prototype, and implement closed loop processes in electronics manufacturing
could yield significant benefits. Closed loop processes are already in use in some Japanese
industry fabs, and more advanced U.S. fabs are beginning to experiment with closed loop
modules within the manufacturing environment. These closed loops processes would depend
heavily on improved in situ monitoring and feedback systems, providing reliable data on the
application of materials, chemicals, and gases throughout the production process. Furthermore, a
true zero emissions environment would incorporate effective recapture/recycling components in
order to minimize, and eventually eliminate, emissions or additions to the waste stream.
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