Lasertec now announces commercialization of a new product “WASAVI Series TSV300S” that measures etching depth and bottom shape of Via in the Through Silicon Via formation process.
* WASAVI: Wafer Surface Analyzing and Visualizing System
Currently, in the aim to implement higher density, higher operating speed and lower power consumption of semiconductor devices, practical realization of the 3D integration device that consists of vertically stacked circuits is impelled. Through Silicon Via plays a very important role of vertically connecting the upper layer circuits and the lower layer circuits in the 3D integration. TSV is formed by the etching process. In addition to depth control in this etching process, measurement of bottom surface shape is becoming a very important item recently because the bottom surface shape determines the product yield. TSV300S developed here by Lasertec measures the bottom surface shape and the opening size of Via with high speed and accuracy in addition to depth measurement of high aspect ratio Via, which has been very difficult to perform,.
TSV300S consists of a measurement system based on a combination of the shearing interferometer which is used in the Lasertec phase shift/transmittance measurement system that is a de fact standard in the industry, and a uniquely developed IR optics. When a Via with high aspect ratio is measured from the patterned surface using visible light, it has been difficult to measure depths of the Via over the whole bottom surface because intensity of the reflected light from the Via bottom is weak and the visible light reaches only to the center and its vicinity of the Via bottom. TSV300S has realized high accuracy etching depth measurement and also Via bottom surface shape and opening size measurement that has been difficult by the conventional measurement systems.
Because the measurement by TSV300S is based on optics principle, inspection can be performed by a non-destructive way. Also, all automatic measurement of depth, etched opening (surface, bottom) and bottom aspect shape of the etched bottom has been realized, making complicated operation procedures required by the other measuring methods unnecessary. By these advantageous performances of TSV300S, very stable inspection of TSV processes from development stage to mass production stage can be performed.
Inspection system for depth, bottom surface shape and CD in TSV forming process