industry metrology
Inspecting and reviewing wide bandgap semiconductors
The SICA inspection tool can identify many forms of defect, including: (a) a pit in the centre of a big bump (b) a V-shaped pit (c) a bump (d) a hole (e) cracks around the wafer edge
In addition to its tools dedicated to the inspection of SiC substrates and epiwafers, Lasertec offers an inspection and review system for transparent wafers called “TROIS series”. Designed to detect and analyse defects on wide bandgap semiconductors, the TROIS series features the same optics as the SICA tools, and allows the user to carry out inspections without interference from the hetero-epitaxial film. One of the strengths of the TROIS series is that the wavelength of its light source can be varied, ensuring optimal performance for various wafers. To meet requirements for production of large-size wafers, the latest model of the series, TROIS33, is capable of inspecting wafers up to 8 inches in diameter. Maximum throughput is six wafers per hour (for 6-inch wafers).
film grown close to it.
Specifically, the alignment trace function is capable of performing three insightful tasks: Identifying what types of defect have a large impact on electrical characteristics of a device, and how many of them are acceptable; determining what types of defects can be the root cause of yield-killing defects; and enabling the formation of a grading structure for detecting and describing defects in substrates, epiwafers and devices.
The unique capabilities of our tool are already creating something of a stir within the SiC industry. Device manufacturers are starting to consider using our tool for incoming inspections, and the SICA series is already playing a role in the SiC supply chain. Its deployment is sure to rise over the coming decade, enabling it to play a key role in improving the bang-per-buck of SiC power electronics.
The author thanks Hirokazu Seki, Takeshi Higuchi and Genichiro Kamiyama for their help in compiling this article.
© 2012 Angel Business Communications. Permission required.
OptiCentric Max UP ®
The Ultimate Solution for Alignment, Assembly and Final Inspection of Microlithography Optics
• Ultra-accurate measurement of centration error (lens center thickness and air spacing optional)
• All granite, all air-bearing construction providing exceptional rigidity and thermal stability, smooth motion and unrivaled accuracy
• Additional alignment unit equipped with heavy duty piezoelectric actuators provid- ing automated alignment with submicron accuracy
OptiCentric Max 300 UP
• Specifically designed for precision optics with a diameter up to 300 mm, 1000 mm height and 500 kg weight
OptiCentric Max 600 UP
• Specifically designed for microlithogra- phy and space optics with a diameter up to 800 mm, 2.000 mm height and 1.500 kg weight
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www.compoundsemiconductor.net October 2012
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