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SDK Develops New Grade of Charge Dissipating Agent for EB Lithography

April 12, 2005

Showa Denko K.K. (SDK) has developed Espacer 300F, a new grade of charge dissipating agent that substantially enhances the efficiency of electron-beam lithography process in the production of integrated circuits. The new product will be announced, jointly with a major photomask producer that cooperated in the development, at the Photomask Japan 2005 international symposium starting tomorrow in Yokohama.

Charge dissipating agents are used in the EB lithography process to ensure pattern accuracy by preventing positional errors due to electrostatic charge. As further integration of ICs will require semiconductor processing at narrower line widths, there is a growing need for highly efficient charge dissipating agent.

SDK developed a highly conductive, water-soluble polymer (polyisothianaphthenesulfonate) based on the guidance by Professor Alan J. Heeger of the University of California, Santa Barbara, for about 10 years from 1983. (Professor Heeger was awarded the Nobel Prize in Chemistry in 2000 for his discovery and development of a conductive polymer.)

Since 1992, SDK has been selling Espacer, containing the conductive polymer with high purity, as charge dissipation agent. Espacer is stable at high temperatures for EB lithography process and can readily be removed with water washing after the resist bake process.

In addition, the new grade, Espacer 300F, has the following advantages:

  • 1.No erosion of positive-tone chemical amplified resist. This is a problem with existing charge dissipating agents.
  • 2.Enables efficient coating on resist
  • 3.Substantially simplifies the process as it can be removed by water washing after the post exposure bake process (not after the resist bake process)

These advantages have been demonstrated at production lines of a major photomask manufacturer.

According to a report from the International Technology Roadmap for Semiconductors, the line width for semiconductor processing, which is 90 nm or less in 2004, is expected to become 65 nm or less in 2007. Espacer will meet that need by effectively preventing positional errors.

SDK is allocating its resources to the semiconductor processing materials business under its medium-term consolidated business plan, the Sprout Project. In addition to the charge dissipation application, Espacer will be used in nano-scale processing for advanced medical treatment and optical materials. Thus, SDK is planning to increase sales of Espacer to ¥5 billion in 2010.

For further information, contact:
Planning Dept., Electronics Sector. (Phone: 81-3-5470-3277)

[Terminology]

  • 1.Effect of electrostatic charge
    When electron beam is radiated on materials with low conductivity, electron beam is bent due to the effect of electrostatic charge, damaging pattern accuracy.
  • 2. EB lithography
    A process for transferring IC pattern on a photomask to a wafer of semiconductor.
  • 3.Positional errors (Distortion of patterns after electron beam radiation)

(With Espacer)

(Without Espacer)

(These photographs are provided by JEOL Ltd.)
  • 4.Resist bake process
    A heating process for drying solvent contained in resist.
  • 5.Positive-tone chemical amplified resist
    A resist in which acids generated by electron beam radiation act as catalyst in a reaction that removes electron-beam-radiated pattern. Used in high-sensitivity LB process.
  • 6.Post exposure bake process
    A heating process after writing by electron beam radiation.