SEMI Standards – Enabling the 450 mm Transition
By James Amano, Senior Director, SEMI International Standards
Since the submission of the first SNARF (standards proposal) in 2007, 450 mm standardization efforts at SEMI have rapidly grown, and as of May 2013, 15 450 mm-related SEMI Standards have been published. These specifications, covering wafers, carriers, loadports, and tape frames, have enabled the industry to continue the development of equipment, materials, interfaces, and processes, but further standardization will be necessary for a successful transition to manufacturing on 450 mm wafers. Directed by customer requirements, SEMI Standards task forces are now at work on 13 other proposals, and new proposals are expected to be generated this summer during SEMICON West.
The first critical milestone was the publication of SEMI M74 - Specification for 450 mm Diameter Mechanical Handling Polished Wafers in 2008, developed by the Silicon Wafer Committee. The specification includes dimensional requirements for 450 mm wafers such as diameter, thickness, notch, edge profile, and surface finish. The selected value for the wafer thickness specification, 925μm, was a compromise between the need for a wafer thick enough to enable good surface topography and minimize wafer breakage, the need to limit the gravitational bow, and the need to maximize the crystal yield. Although industry 450 mm timing was not yet identified, device makers and suppliers required a standard specification for a 450 mm handling wafer to support early designs, feasibility studies, and design of experiments, and to provide a common reference for comparison. This effort met an immediate need for research and early design investigation, including 450 mm wafers, carriers, load ports, AMHS, metrology, and selected equipment already in development.
Once dimensional specifications were established in SEMI M74, the Physical Interfaces & Carriers Committee was able to standardize key parameters for moving and handling 450 mm wafers, including wafer carriers, load ports and transport systems. SEMI E154 - Mechanical Interface Specification for 450 mm Load Port came first, and included the interfaces between:
- Load Port and Carrier Delivery System (equivalent to 300 mm SEMI E15.1 and E64);
- Port and Carrier Door (equivalent to 300 mm SEMI E62); and
- Load Port and Semiconductor Manufacturing Process Equipment (equivalent to 300 mm SEMI E63).
SEMI E158 - Mechanical Specification for Fab Wafer Carrier Used to Transport and Store 450 mm Wafers (450 FOUP) and Kinematic Coupling rapidly followed, with parameters such as reference planes, kinematic coupling pin shapes and locations, conveyor rail locations and dimensions, areas reserved for purge ports, automation handling flange, wafer support features, and distance between adjacent wafer slots (wafer pitch).
Twelve other 450 mm SEMI Standards have since followed, including two back-end documents focused on tape frames from the Assembly and Packaging Committee, and a new standard addressing cluster tool and process module interfaces will be published later this month. (A complete listing of published 450 mm Standards is at http://www.semi.org/node/42416)
As mentioned above, though, there is more work to be done to enable a successful transition to 450 mm wafers. Additional standardization needs will be introduced and discussed at SEMICON West at the Silicon Wafers – Future Standardization to Enable the Transition program, which will be held Wednesday, July 10, 2013, from 2:30 PM to 5:30 PM at the San Francisco Marriott Marquis. Speakers from Intel, G450C, and others will introduce some of these new concepts during this seminar, which will be considered for standardization by the SEMI Standards Advanced Wafer Geometry Task Force under the Silicon Wafer Committee. Among the topics will be proposals and justification for a notchless wafer, a more stringent wafer edge exclusion area, as well as a broad discussion of standards opportunities and challenges related to facilities, as mere scaling will not be an option.
Pre-competitive collaboration is challenging and involves hard work, but creates significant benefits for the industry as a whole as well as for companies that actively participate. If your company is not yet involved in these efforts to shape the future, learn more about SEMI Standards by visiting www.semi.org/en/Standards. Note that participation in the SEMI Standards Program is free, but requires registration. To learn more, contact your local SEMI Standards staff or register at: www.semi.org/standardsmembership.
SEMI, Standards Watch - May 2013