Rudolph technologies, sematech collaborate on 300-mm system

02/01/1997

Rudolph Technologies, SEMATECH collaborate on 300-mm system

Randy Goodall, I300I, Austin, Texas and Rob Loiterman, Rudolph Technologies Inc., Flanders, New Jersey

A new 300-mm wafer metrology system from Rudolph Technologies Inc. (RTI) is now in service, providing 300-mm developers with access to film thickness measurements at the International 300mm Initiative (I300I) support center. SEMATECH funding was instrumental in bringing the tool to market at least a year ahead of RTI`s internal timetable.

In 1994, the semiconductor industry made the decision to move toward manufacturing devices on 300-mm wafers, with the first pilot line targeted for 1997 and early production planned for 1998. To achieve this aggressive timeline, SEMATECH saw the need for concurrent engineering in a large number of production tools. Metrology tools in particular were required early in the program for process tool development, cleaning tool development, and 300-mm wafer development. Also critical were tools with the ability to measure the larger wafer dimensions (thickness, lithographic flatness, and warp), unpatterned particle detection, and thin-film thickness. One of SEMATECH`s key objectives was to make these measurement capabilities available by the end of 1996. In 1996, SEMATECH transferred its 300-mm activities to I300I, a newly formed international consortium, to manage this project through to completion.

Whereas the transition to 200-mm wafers was driven by independent device manufacturers, these companies did not have the billions of dollars necessary to fund the development of new tools for the move to 300 mm. Industry consortia such as SEMATECH (and later I300I and SELETE) recognized the need for IC companies and suppliers to work together. SEMATECH decided to solicit joint projects as an incentive to make critical tools available for development of 300-mm processes as soon as possible. Since metrology tools were key to this rapid development process, SEMATECH decided to provide assistance to this vendor group through partial (20%) funding of joint SEMATECH-supplier development projects. Requests for quotations outlining specifications for 300-mm tools capable of measuring wafer flatness, particles on unpatterned wafers, and film thickness were distributed in February 1995 to US measurement tool suppliers.

RTI`s proposal called for the development of a new 300-mm tool platform rather than a reworking of an existing 200-mm tool. By combining its measurement technologies with the latest wafer handling and factory automation features, RTI set out to exceed SEMATECH`s specifications by creating a production-worthy tool rather than an R&D prototype, since ultimately a production worthy tool is what the industry requires.

When the project began, very little was defined or standardized in terms of 300-mm tool design, automation, or processes. SEMATECH guided RTI toward other industry members who were spearheading developments in these areas. RTI contacted a device manufacturer who then was most advanced in 300-mm development and listened closely to the company`s input. RTI also participated in committees formed by leading semiconductor equipment manufacturers, as well as participated in SEMI standards meetings to keep current with the standards being suggested.

These efforts provided feedback and helped answer such questions as: Is a minienvironment required? Will larger tools have an impact on cleanroom space? Will open cassettes or pods be used? What particulate performance is required? Tool guidelines were eventually set through discussions with other member companies and participation on SEMI standards committees.

RTI partnered with Meissner & Wurst in the development of a totally integrated minienvironment with a specially designed directed airflow system to improve wafer cleanliness. To deal with the expanded machine footprint (required to handle larger wafers) impinging on valuable cleanroom space, RTI decided to create a through-wall mounted system-a configuration not previously available for its 200-mm measurement tools. Due to the uncertainty over wafer carriers and other factory requirements, engineers took a modular approach to system design that was flexible enough to meet a variety of future fab requirements.

RTI decided to develop its 300-mm tool in phases that were timed to match key industry decisions. Phase One involved creating an open cassette tool capable of measuring 300-mm wafers from an "open" newly designed cassette. Phase Two involved a system capable of removing wafers from one of two pods, which could be either side or bottom opening and could be placed on all of the pod loaders currently produced in the industry. RTI also developed the open cassette tool to handle wafer sizes from 5 in. to 300 mm, important in early 300-mm development when alternate size wafers will need to be measured.

The finished Caliber 300 now available, incorporates a minienvironment that meets new cleanliness requirements of Class 0.01 at 0.1 ?m in the area of the wafer. It has automated wafer handling, and the ability to accept open cassettes or side-opening pods from a choice of factory automation vendors.

A system is currently available at RTI`s California Applications Lab as part of the SEMATECH shared measurement resource service program for qualifying and testing new equipment. Another system is installed at I300I`s Process Support and Metrology Center in Austin, TX, for use by I300I consortia members. The center is able to produce basic process wafers and measure subsequently processed wafers on-site, and will be putting down films for 300-mm equipment demonstrations.

The initial investment and risks taken by both SEMATECH and RTI have paid off with the development of a commercially available, production-ready 300-mm film thickness measurement tool. Due to SEMATECH`s program, RTI moved in the 300-mm direction in 1996 rather than in 1997 as originally planned. The project has met both SEMATECH`s and I300I`s goals by providing the industry with a metrology tool and a shared resource.

Other SEMATECH-funded programs have included KLA Instruments` development of an advanced deep UV reticle inspection tool. The effort was designed to ensure that the photomask industry has the inspection technology it needs to move forward to mask line sizes of 0.5 to 0.6 micron. The achievements of these and other cooperative industry projects will continue to facilitate the development of process tools.

Randy Goodall is associate director of support technology at I300I; ph. 512/356-7622, fax 512/356-3305. Robert Loiterman is VP of engineering and manager of R&D at Rudolph Technologies Inc.; ph 201/691-1300, fax 201/691-5480.