Bilayer Photoresist handles sub-65nm lithography.

Press Release Summary:

Bilayer photoresist uses silicon polymer in imaging layer to optimize etch selectivity for addressing demands of sub-65nm lithography. Level of silicon content also eliminates need for separate hardmask layer and accompanying process steps. Photoresist exhibits no detectable levels of outgassing during lithography process, and etch selectivity lends to successful transfer of smaller circuit patterns onto target wafer.

Original Press Release:

Dow Corning and Tokyo Ohka Kogyo Develop Silicon-Infused Bilayer Photoresist, Achieving Higher Etch Selectivity and Simplifying Sub-65nm Lithography

Outgassing Problems Resolved With New Bilayer Photoresist

MIDLAND, Mich., Dec. 7 -- Dow Corning Corp. and Tokyo Ohka Kogyo Co., Ltd. (TOK) announced today that they have developed and launched a commercially available bilayer photoresist that uses a silicon polymer in the imaging layer, thereby improving etch selectivity to address the demands of 65nm lithography and beyond. The new photoresist's high silicon content also eliminates the need for a separate hardmask layer, simplifying sub-65nm processing.

The breakthrough material marks a critical step forward for the semiconductor industry, both in terms of photoresist technology and the extension of 193nm lithography. Incorporating Dow Corning's innovative silicon polymer into TOK's photosensitive material enables TOK to introduce a new class of photoresist. By eliminating the hardmask layer and accompanying process steps, the new material provides a cost-effective solution for sub-65nm lithography.

As the semiconductor industry looks to extend 193nm lithography beyond the 45nm node, thin imaging layers are needed to achieve the necessary resolution and desired process windows. Increased etch selectivity is also required to successfully transfer smaller circuit patterns onto the target wafer. Current photoresists based on organic chemistries typically don't have the required etch selectivity, so they are often used in conjunction with several other layers, including a hardmask layer that provides the necessary etch resistance.

The new photoresist, now available from TOK, also exhibits no detectable levels of outgassing during the lithography process. Outgassing, the slow release of chemicals during exposure, has proved problematic for previous photoresist materials containing silicon, as the silicon released through outgassing can contaminate the optics in an exposure tool.

"Our joint development with TOK has accomplished something that no one has been able to do before: incorporate a silicon polymer in a photosensitive material and avoid problems with outgassing, which have prevented the use of silicon in photoresists in the past," said Tomonobu Noguchi, Electronics & Advanced Technologies marketing director with Dow Corning. "With next-generation lithography technologies still years away from commercialization, Dow Corning and TOK are working together to ensure that optical lithography will be extended beyond the 65nm node."

The jointly developed photoresist has proved applicable to dry lithography as well as immersion lithography, an advanced imaging technology that is gaining market acceptance for the 45nm node and beyond. TOK has successfully achieved a 35nm line/space pattern using the photoresist under immersion lithography conditions.

Dow Corning and TOK have had a joint development agreement since 2002 to develop advanced photolithography materials based on silicon. The collaboration takes advantage of TOK's sophisticated microprocess technologies and application expertise in photolithography, with Dow Corning's innovation and manufacturing capability for silicon-based materials. The lithography development work is being conducted at TOK's R&D facilities in Kanagawa, Japan.

About Dow Corning

Dow Corning Corporation ( is a globally integrated provider of materials, application technology and services, and is focused on providing innovative technology for all segments of the electronics industry. Dow Corning has development and applications centers strategically located throughout Asia, Europe and the United States. The centers offer advanced resources for electronics materials and services, and are staffed with experienced professionals who can provide technical support to customers locally. Dow Corning Corporation is equally owned by The Dow Chemical Company (NYSE:DOW) and Corning Incorporated (NYSE:GLW). More than half of Dow Corning Corporation's sales are outside the United States.

About Tokyo Ohka Kogyo (TOK)

Tokyo Ohka Kogyo Co., Ltd. ( supplies an assortment of manufacturing materials centered around photoresist used in fabricating semiconductors, flat panel displays, printed wiring boards and semiconductor packaging, as well as photolithography-related chemicals. The company also furnishes equipment that is indispensable for fabricating leading-edge semiconductors, liquid-crystal-display panels and semiconductor packaging. In addition, TOK offers photopolymer plates and pre-sensitized plates, which are in widespread use in the printing field, as well as high-purity chemicals for use by the chemistry, electronics, pharmaceuticals, food products, and textile industries.

CONTACT: Don Piering of Dow Corning, +1-989-496-8972,; Bruce Hokanson of Loomis Group, +1-360-574-4000,, for Dow Corning; TOK: Junichi Onodera, +81-467-75-9667,, or Hiroshi Akama, ++81-44-435-3000,

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