Nano-Level 3-D Measurement Using Combination of Laser Lights Phase Shifts

To improve the productivity of very large scale of LSls and large LCD panels, the technologies to inspect the LSls are required. To remove the less than one-micrometer contaminants on the LSls, it is required to extract their 3-D shape and position, precisely. To meet with these requirements, a nano-level 3-D shape extraction method has been developed. Here, the basic idea of the method and the experimental result are described. To extract a nano-level 3-D shape, the method using some interference images is effective. Interference image is generated between reflected light on LSI surface and reference light. At this time, if the position of the mirror of a reference light is changed at regular intervals, the brightness change of same position on interference images shapes a sine wave. When heights of LSI differ between coordinates, the brightness of interference image differs. And the phases of brightness changes differ according to height of a viewing pixel. To meet with the requirement to measure longer than one wave-length, the combination method of multiple wavelength lasers has been introduced