Standards Task Force Established on 450 mm Wafer Handling


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Standards Task Force Established on 450 mm Wafer Handling

In March 2007, the Silicon Wafer Committee approved a Task Force to explore technical requirements--and possibly develop an industry-wide standard--for 450 mm test wafers. A Standards New Activity Request Form (SNARF) was developed, outlining the scope of the activity. Several meetings have been held on the topic, most recently at SEMICON West 2007 in San Francisco with approximately 40 representatives from all quarters of the industry attending.

The question of whether a new silicon wafer size specification is needed, and when a transition could cost-effectively be implemented, has become one of the most controversial issues facing the semiconductor industry today. According to Semiconductor International, “…there have been few instances where our industry has found itself as sharply polarized about a technology transition as it is over the perceived need to migrate from a 300 mm wafer to a 450 mm wafer.” It has been estimated that the cost of the 300 mm wafer transition was $12 billion and has yet to show a return. Concerning 450 mm, the cost could exceed $20 billion and the transition could take as long as eight years to bring to market. Such a financial impact could lead to further industry consolidation in the industry, resulting in a reduction in the number of both device makers and equipment suppliers.

The scope of the SNARF is limited to the mechanical characteristics of 450mm silicon handling test wafers, including diameter, thickness, notch, edge polish, and surface polish. Edge profile is expected to be investigated in another task force.  While a clear industry strategy or timing on wafer size is not yet identified, R&D activities by some device makers and suppliers has created a need to provide a standard specification for a 450mm wafer handling to support early designs, feasibility studies, and design of experiments, according to standards proponents. The Task Force effort is not intended to drive development or timing, but is intended to serve an immediate need for research and early design investigation, including 450mm wafers, carriers, load ports, AMHS, and metrology.

The Task Force is chaired by Mike Goldstein, representing Intel and co-chaired by Masaharu Watanabe of NuFlare Technology. In addition to Intel, semiconductor manufacturers represented in the July 18 meeting were Renesas Technology, TSMC, Fujitsu, and Samsung.

Among the highlights of the Task Force meeting was Mike Goldstein’s review of the key challenges to the industry and results of simulations at Intel. A discussion of wafer carrier considerations was provided by Gary Gallagher of Entegris. Tetsuo Fukuda from Fujitsu provided a summary and explanation of current edge profile standardization efforts in Japan, including the results from a JEITA study on edge profile. Additional JEITA studies will look at the film thinning process in device fabrication.

Dinesh Gupta provided an historical perspective on wafer standards, noting that determining wafer specifications will require technical data and input by many companies, including silicon and equipment suppliers that are currently not members of the Task Force. He recommended that to avoid multiple changes to the specification after its development a consensus on key parameters and their values, based on serious study, must be reached prior to the finalization of the Standard. Werner Bergholz from Jacobs University provided a provocative case for consideration of thinner wafers referring to the PV industry example of ‘floppy’ wafer handling and sawing experience.

For the complete meeting minutes and background information on the Task Force, click here.

Industry experiences with the 200 mm to 300 mm wafer transition are being applied to the 450 mm question. Surveying 300mm software/hardware, metrics and safety standards over the past 12 years, many standards quickly stabilized providing the industry immediate and long-term benefit, but many others generated ongoing re-balloting and revision challenges. During the 200mm to 300mm wafer transition, device manufacturers and suppliers have acknowledged that dialog on user requirements, definitions of tasks and supplier feedback occurred too late, resulting in costly ongoing revisions.

The establishment of the Manufacturing Technology Forum (MTF) was designed to address these issues, while providing an added economic review and analysis of new standards initiatives. SEMI established the Manufacturing Technology Forum (MTF) to provide additional oversight and coordination with semiconductor device makers into the industry standards process. The new advisory body will improve the SEMI standards process by providing a forum for collective and early understanding and collaboration of user requirements before and during the standards development process. The MTF fills an important process gap that became apparent during the 200-300mm transition when oftentimes Standards had to be revised several times or completion was delayed, because there was no early understanding or consensus of need, urgency and economic impact.

At this time, the establishment of the Task Force on such a controversial topic demonstrates the effectiveness of SEMI International Standards in bringing together diverse industry interests to achieve a common good. The MTF recommendation to the Task Force, based on the assessment of MTF’s Productivity Engineering Assessment Working Group, will also demonstrate the ability of MTF to provide prompt review of a proposed standard’s economic impact prior to Task Force and Standards Committee consideration.

Currently, the Silicon Wafer Committee is evaluating test wafer standards requirements to support R&D efforts on 450 mm. The MTF will also evaluate the establishment of a Task Force on this subject. While debate continues over the economic justification and timing of proposed wafer size transition issues, SEMI International Standards is working effectively to bring together various stakeholders together on the topic and provide a forum for a comprehensive review and thorough analysis of the technical requirements needed for industry progress.