KLA-Tencor unveils ‘Precice’

March 7, 2001–San Jose, California–KLA-Tencor Corp. has introduced Precice, a production-worthy in-situ film thickness and end-point control system for copper CMP.

As a key component on the latest-generation of CMP systems, Precice enables chipmakers to achieve greater repeatability and accuracy in their copper CMP processes by automatically compensating for incoming variations on a wafer-to-wafer basis. By reducing the risk of process errors due to non-uniform polishing, Precice helps to speed the ramp of new copper processes and maximize copper yields.

Metal film thickness and uniformity can vary significantly from wafer to wafer following copper deposition. Chipmakers are faced with the challenge of compensating for these variances in order to achieve the desired polishing results for each wafer during CMP. Before the development of in-situ metrology, where a sensor is embedded into the CMP tool to take film thickness and uniformity measurements, wafers had to be taken to an off-line metrology tool to detect film variances in order to adjust the CMP process accordingly. Current in-situ “optical only” methods provide limited information that CMP engineers need in order to optimize their copper CMP processes. The major disadvantages of “optical only” systems are unreliable end pointing due to previous level pattern noise when polishing upper metal levels, and the inability to provide “real time” CMP removal rate and uniformity information.

“Precice incorporates several unique features to provide real-time, accurate film thickness measurements during CMP, and enables the CMP tool to dynamically adjust for film variations to ensure proper control of the CMP process at all times,” says Pete Nunan, vice president of technology development at KLA-Tencor. “This solution minimizes the yield-limiting defects that occur from over- or under-polishing wafers such as dishing, erosion, and metal residuals. Precice is sensitive enough to provide real-time measurements on a broad range of patterned wafers without recalibration. This is a critical requirement for foundries and semiconductor manufacturers that are fabricating many different IC designs as part of their business model.”

KLA-Tencor’s Precice system uses a combination of optical and eddy-current technologies that allow customers to run multiple steps within the CMP process with a high degree of repeatability. Unlike competing eddy-current technologies that only monitor relative changes in film thickness, Precice’s eddy-current probe provides accurate thickness measurements in real time–enabling customers to more rapidly polish the bulk thickness of copper first without fear of eroding the underlying layer. It also automatically compensates for temperature and pad-wear effects that occur during CMP, without which false measurements would occur.

Precice’s optical system is designed for high reliability in the harsh CMP environment. It uses a single-wavelength, multi-angle reflectometer, which provides more comprehensive data than competing single-angle laser reflectance systems. The reflectometer also eliminates false end-point reporting–a fatal error in volume production.

“We successfully developed Precice to address one of the most critical technology hurdles to bringing copper into full production,” says Nunan. “The fact that we have recently shipped a multi-million dollar order of Precice to a major CMP tool manufacturer is indicative of the system’s unique capabilities.”

Precice is the latest addition to KLA-Tencor’s process module control solution for copper (CuPMC ), and further rounds out the company’s advanced inspection and metrology capabilities.


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