Z-axis measurement | Z-axis measurement

Key Words: confocal, focus, 3-D imaging, depth of focus, non-contact measuring, vision / video measuring

Definition:Measurement down (perpendicular to the horizontal) into a sample

TECHNOLOGY:

Z-axis measurement provides operators with the opportunity of obtaining a 3-D understanding of a sample. This can be achieved by contact measurement (generally for larger pieces with holes, fissures, indents etc) and also with non-contact optical /laser techniques. Microscope-based optical methods are particularly useful for small scale measurement or for samples sensitive to touch for example wafer chip manufacture. Because a microscope objective focuses at a plane at a know distance from the objective, focus level can in itself be used as a metrology tool. Accurate focusing, and hence more accurate metrology, is aided by motorized / laser auto focus technologies. Confocal imaging, a technique widely used in biological environments, may also be applied to industrial metrology. It provides micron and submicron accuracy for metrology applications. Offering several advantages over conventional optical microscopy, confocal imaging provides controllable microscope depth of field, the elimination of out-of-focus information, and the ability to collect serial optical sections from samples. With appropriate microscope software, these serial images can be reconstructed to provide a 3-D representation of the area captured.

APPLICATIONS:

Z-axis measurement is useful in quality control, reverse engineering and research environments. Confocal imaging, in particular, is ideal for measuring micro-dimensional 2D and 3D samples with high accuracy. Examples include bump heights on advanced IC packages, MEMS, probe card, micro lens, contact lenses, photo spacers for color FPD panel, molds and others.

MICROSCOPE CONFIGURATION:

Nikon provides a number of solutions for Z-axis measurement:

1. MM400 and MM800 series measuring microscopes. LM model stands for these microscopes incorporate a motorized vertical movement mechanism with a 10mm/sec speed. Up/down control is accurately provided with a dedicated controller. A newly developed split-prism Focusing Aid (FA), in addition, enables accurate focusing during Z-axis measurements to minimize error resulting from differences in the depth of focus of different objectives.
2. NIS-Elements software, for use on a wide range of microscopes including the MM400 and MM800 series, provides motorized Z-focus control and supports two methods of Z-axis capture: ‘absolute’ and ‘relative’ positioning.
3. Vision measuring systems:
   • The iNEXIV VMA-2520 has been specifically designed for three-dimensional samples. It provides a long 200mm Z-axis stroke and a 73.5mm working distance, enabling easy Z-axis measurement. This system has multi sensor capability (touch probe ready) to offer greater flexibility in Z-axis measurement.
    
   • Nikon's Confocal NEXIV VMR-K3040ZC addresses the metrology needs of complex IC packages. The confocal head supports micron-level measuring capability, and has been optimized for semiconductor measuring by stressing low distortion to optimize the entire field of view.

RECOMMENDED SYSTEM:

 Please consult your local Nikon representative for advice suited to your specific needs.