NEXIV applies 3-D measuring to semiconductor packages

JULY 13--Nikon Instruments Inc. (Melville, NY; www.nikonusa.com), a developer of advanced optical technology for microscopy, has announced an addition to its NEXIV line of advanced metrology products. The confocal NEXIV VMR-K3040ZC addresses the metrology needs of complex IC packages resulting from the demand for reliable semiconductor products. Measurement of multilayer chips, and the position and height of the wire and microbumps connecting multiple layers, is critical to semiconductor manufacturing. The fusion of these technologies requires accurate, high-speed precision measurement for 3-D structures, including materials composed of vastly different reflectivity rates.

"As the development of wafer-level chip size package manufacturing accelerates, new challenges in height measurements comes to bear on existing inspection and measurement processes," said Mike Metzger, Nikon general manager, Industrial Department, Nikon Instruments. "Nikon's confocal NEXIV solution applies confocal optics and 3-D measurement capability to solve problems before production is impacted."

Widely used in bioscience research, confocal microscopy offers several advantages over conventional optical microscopy, including controllable depth of field, the elimination of image degrading out-of-focus information, and the ability to collect serial optical sections from material samples. The key to the confocal approach is the use of spatial filtering to eliminate flare in material sample images. The Nikon Confocal NEXIV uses a Nipkow disk, which features multiple, symmetrically placed spirals of pinhole apertures through which light is passed and split into "mini-beams." As the disk rotates, each beam scans across a portion of the sample field and generates a 3-D image. The image is projected into a digital CCD camera using optical sectioning technology. The result is a 3-D image captured in one scan delivering highly accurate and reliable height measurement data.

For applications in the semiconductor industry, a high degree of accuracy for height measurement is demanded. The Confocal NEXIV features a new optical measuring head using confocal capabilities to solve the problem of Z-series measurement. This head supports a micron-level measuring capability, and has been optimized for semiconductor measuring by stressing low distortion to optimize the entire field of view. The optical head assures the accuracy of both measurement and magnification.

The Confocal NEXIV separates the functions of brightfield and laser autofocus. Each optical system is switchable by users employing an easy-to-use GUI interface. The brightfield optical system is user-selectable and the laser autofocus is handled by autofocus power emissions. The objective lens is common for brightfield and laser autofocus applications.