CHM 585/490

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CHM 585/490

• Chapter 19
• Semiconductors

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Semiconductors

• The market for imaging chemicals photoresists,
  developers, strippers, and etchants for the
  combined semiconductor and printed wiring board
  applications is in excess of 3 billion

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Moores Law
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Moores Law

• Its not a Law of Nature, but it comes close. In
  1965, Intel co-founder Gordon Moore made the
  observation that has become known as Moores Law
  the number of devices on a single chip (and the
  chips potential performance) doubles every year
  or so.

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• Integrated circuits millions of transistors
  layered on fingernail-sized chips of silicon.
• After 30 years of operation under Moores Law,
  manufacturers have reduced circuit patterns to
  incredibly thin line widths pushing 0.18
  microns, less than 1/160 the width of a human
  hair.

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Lithography

• Photosensitive polymer film is exposed to light
  to alter the solubility.
• If the exposed area of the resist film becomes
  insoluble after light exposure, then the resist
  is termed negative
• If the exposed area becomes more soluble
  positive photoresist

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Photoresists

• In certain applications, the film becomes a
  permanent, functional component of the device
  being constructed, typically serving as an
  electrical insulator or protective encapsulant
• Most commonly, the resist is removed or
  stripped after the image has been transferred
  to the substrate.

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Essential Attributes of Lithographic Resists

• Must form uniform defect-free films on the
  substrate
• Coated film must display adequate adhesion to the
  substrate
• Must have suitable radiation sensitivity.
  Exposure tools are so costly that throughput is a
  key measure of performance.

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Diazonapthoquinone inhibits solubility of Novolac
resin in base
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Wavelength

• In any optical imaging system, the size of the
  smallest element that can be accurately resolved
  is related to the wavelength of exposing light.
• The smaller the wavelength, the finer the feature
  that can be resolved

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Need Lower Wavelengths

• New resists are designed for imaging with light
  of 193 nanometer wavelength
• Aromatic materials are opaque in this region
• Many newer resists based upon acrylate copolymers

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MMA for organic solubility, low shrinkage,
adhesion and mechanical properties TBMA for acid
catalyzed deprotection MAA for aqueous base
solubility and increased Tg
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Acid photochemically generated.
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Many other uses for polymers in microelectronic
applications

• Adhesives
• Conductive adhesives
• Interlayer dielectrics
• Glob Top

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Some microelectronic polymers

• Polyimides
• Epoxies
• BCBs
• Parylenes

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Polyimides
Kapton
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Polyimides
Kapton
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Epoxies

• Epoxy resins are high-performance thermosetting
  resins. High performance coatings continue to be
  the primary application worldwide
  electrical-electronic laminates, adhesives,
  flooring and paving applications, composites, and
  tooling and molding products are the other major
  end uses. Industrialized nations are by far the
  largest producers and consumers of epoxy resins

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• In 1999, the estimated epoxy resin production
  value for the United States, Western Europe and
  Japan was over 2 billion.
• In 1999, almost 650 thousand metric tons of epoxy
  resins were consumed in the United States,
  Western Europe and Japan combined. Between 1999
  and 2004, overall growth in epoxy resin demand is
  expected to average about 3.2 per year in the
  United States

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• The three leading producers of epoxy resins are
  Resolution (formerly Shell's Epoxy Resins and
  Versatics business), Dow and Vantico. Together
  they account for approximately 75 of the world's
  capacity.

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Dow BCB Resins
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Diels Alder Reactions
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BCBs
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Parylenes

• Used for conformal coatings

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Parylene Polymerization