Nanometrics unveils photoluminescence mapping system

Nanometrics, a supplier of integrated and stand-alone metrology equipment for the semiconductor industry, has introduced the VerteX rapid photoluminescence (PL) mapping system, which is used for compound semiconductor production control during volume manufacturing of optoelectronic devices such as LEDs.

The company claims the tool marks the first automated PL mapping system that accurately predicts emission wavelengths for green LEDs at the wafer level. The VerteX PL represents Nanometrics’ initial product launch since completing its acquisition earlier this year of Accent Optical Technologies, a supplier of overlay and thin-film metrology and process-control systems.

VerteX’s control of laser-excitation conditions allows for accurate matching of PL data to electroluminescence (EL) test information, resulting in faster run-to-run epitaxial layer growth feedback to enable the predictive metrics required for volume production of LEDs, particularly green LEDs. With most systems, the exact emission wavelength of a green LED can only be measured by an electrical test after the wafer has been fully processed. VerteX, however, can forecast diode performance before the wafer is fully processed, providing the data needed to actively adjust process controls for optimal epitaxial layer growth—the yield-limiting step in LED production.

Nanometrics says that the tool also can be used during the manufacture of a range of optoelectronic materials, including ultraviolet (UV) diode lasers for high-definition DVD and Blu-Ray optical disc appliances.

“As production volumes increase and tolerances tighten for epitaxial layers, customers demand a metrology tool that not only provides accurate measurements, but that can provide the processing data required to accelerate time to yield,” said Tom Ryan, Nanometrics’ product manager for compound semiconductors.

Ryan added, “In the case of LED processing, VerteX makes possible accurate predictive processing metrics of green, blue, and UV LED emission wavelengths at the wafer level...This system also demonstrates Nanometrics’ commitment to the emerging markets for LEDs, such as backlighting for LCD TV displays, automotive headlights, and solid-state lighting.”

The new VerteX product complements Nanometrics’ portfolio of wafer-inspection systems, including the RPM2000 desktop PL mapping system, and it adds another component to the company’s closed-loop advanced process control (APC) capabilities, enabling Nanometrics to provide a predictive metrics strategy for its customers. www.nanometrics.com