Nanometrics’ laser profiler for copper CMP

Nov. 6, 2002 – Milpitas, CA – Nanometrics Inc., which supplies the semiconductor industry with integrated and standalone metrology tools, has announced the introduction of its newest metrology system, designed to control the copper CMP process.

The Nano CLP-9010 copper laser profiler non-destructively monitors the metal loss between an isolated copper feature and the surrounding dielectric region. The small footprint measurement module is a high-throughput, small-spot-size laser profiler that can be easily integrated within a metal CMP system. Unlike reflectance-only methods, the laser profiling technology is immune to previous level patterning noise that can cause unreliable end-pointing of the polishing process.

Integration of the Nano CLP-9010 gives users control over the copper CMP process because it ensures that the process can be continuously monitored, improving both the wafer yield and cost efficiency. Specifically, the module’s laser profiler provides IC manufacturers with a substantially more stable copper process because it performs monitoring of every wafer at all metal layers. In contrast, chipmakers have traditionally used standalone, offline metrology tools that are slower and have an increased risk of wafer damage and contamination.

The non-contact laser profiler performs quick, precise and direct measurements across the surface of the wafer to determine the amount of copper loss. The laser profiling technology improves the stability of the copper process by monitoring metal loss on the wafer, allowing the process engineer to minimize the degradation of global planarity on the wafer.

Measuring planarity is particularly important to control of the copper CMP process because the metal polishes faster than the dielectric. Excessive metal loss from over-polishing can ultimately result in a reduction in the depth of field of the lithographic process, while under-polishing can increase the probability of shorts in the metal layers.

In addition, Nanometrics’ laser profiler technology can predict the minimum copper thickness on the largest copper features and allow direct calculation of copper thickness. The laser profiling technology underwent beta testing with a leading DRAM manufacturer in 2001. The testing demonstrated the capability of the new technology to meet the production monitoring requirements of copper CMP processes.


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