Patterned sapphire substrates (PSS) have a dense pattern of bumps that need to be inspected for uniformity of height and shape
- PSS reduce threading dislocation density and also improve the optical emission efficiency by internal reflection. However, small dimensions and steep sidewalls of the PSS create a challenging situation for conventional optical profilers such as interferometer and laser confocal systems.- Stylus and AFM measurements take too long (>10 minutes) and do not provide enough statistical information on the wafer.
The Zeta-20 is an ideal solution in this application. A 94µmX70µm scan is accomplished in about a minute. As shown in the images, the PSS bumps are resolved with high clarity, enabling quantitative results over a much larger area as compared to an AFM or a stylus profiler.
The Zeta-20 3D software allows the user to draw one or multiple cross sections. Measurement cursors can be automatically positioned to calculate feature height and width. Additional features include roughness measurements, box or circle cursors for 2D feature dimensions, ability to save the data file in a format compatible with spreadsheets and databases.
