300mm Prime vs. 450mm: not an either/or choice

06/01/2011

Paul Lindner, EV
Group, St. Florian,
Austria

There is much debate today on whether the industry should focus its energies on transitioning to 450mm wafers or maximizing 300mm production efficiency (300mm Prime). Yet, 300mm Prime vs. 450mm is not an either/or choice. Both are essential, and both must be developed in parallel. Continually falling chip prices demand an interim solution to enhance productivity on existing 300mm capacity while 450mm development is underway.

Industry organizations like SEMI and SEMATECH are actively engaged with equipment suppliers and chipmakers to identify ways to increase 300mm productivity. For example, implementing material buffer zones on process equipment (a concept formulated through SEMATECH's ISMI Initiative) can eliminate wait times due to first-wafer effects as well as overhead hosting transport (OHT) delivery time. By implementing this, EV Group demonstrated a 26% improvement in throughput on its wafer bonding systems. Additional concepts include transitioning from the cluster-tool concept with complex configurations and many process stations to a more modular fashion—with each module having fewer process stations and a smaller footprint. This approach provides chipmakers with lower incremental investments as volumes ramp at a much greater degree of manufacturing flexibility and efficiency.

The fact remains that even with 300mm Prime, the semiconductor industry will only delay the inevitable need for a longer-term solution to enable continued cost reductions. The industry can ill afford to wait until all productivity enhancements are squeezed out of 300mm before development in 450mm infrastructure begins. By then it will be too late, and both chipmakers and equipment suppliers will lose.

Some may argue that investing in both 300mm Prime and 450mm is too cost-prohibitive. Yet, many of the investments and subsequent lessons learned in implementing 300mm Prime guidelines can be transferred to 450mm development. In addition, 300mm Prime guidelines can be beneficial long-term in enabling manufacturing improvements in adjacent markets. Perhaps the biggest barrier to 450mm implementation is process integration. While several leading equipment suppliers are testing processes individually at the alpha stage, no process development line currently exists that provides a complete picture of the interaction of their process with upstream and downstream processes. Industry consortia can play a key role by providing a test fab environment for 450mm equipment, while chipmakers can contribute to the investment costs for 450mm process equipment and help evaluate them in the test fab environment.

Transitioning to larger wafers also places greater demand on process uniformity. Wafer bonding is a case in point, where many variables—including temperature and pressure—must be applied uniformly with a high degree of precision. Addressing wafer bond uniformity will be particularly critical with 450mm because the design nodes at which 450mm will be implemented will also see a much wider adoption of SOI substrates, which require high-precision wafer bonding.

EV Group is actively committed to both 300mm Prime and 450mm and is taking a multi-track approach to them in parallel: 1) internal development programs; 2) joint tool evaluation work with leading substrate and IC manufacturers; and 3) government and industry consortia-driven efforts. One example of the latter is the ENIAC JU project EEMI450 (http://www.eemi450.net/), which involves a network of research institutes such as imec, Fraunhofer and CEA-Leti, equipment and materials suppliers such as Soitec and Siltronic, as well as Intel, to help build the infrastructure needed for 450mm.

The economic and process challenges the industry faces as it turns toward 300mm Prime and 450mm are not insignificant, but they are not insurmountable. What they require is that companies across the semiconductor value chain be willing to step forward, accept some risk and work together.

Paul Lindner is Executive Technology Director at EV Group, DI Erich Thallner Straße 1, 4782 St. Florian am Inn, Austria; ph.: +43 7712 5311-0; email [email protected].

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