Sonoscan has announced its AW322 200 fully automated system for ultrasonic inspection of MEMS wafers. Based on Sonoscan’s C-SAM technology, the system images and identifies internal gap-type defects down to 5 microns in size. It is especially useful for finding non-bonds, voids and other defects in the seals surrounding the MEMS wafer cavities.
AW322 200 system features include:
- Two loadports, two stages and multiple transducers, enabling it to image two 8-inch MEMS wafers simultaneously. Other models in the AW series are available to accommodate wafer sizes from 100-300mm.
- The SECS/GEM-enabled Robotic Handling Station includes alignment and drying operations.
- Waterfall technology to minimize water exposure during scanning.
- Sonoscan’s advanced analysis software for accurate application of the user’s accept/reject criteria.
In operation, the Robotic Handling Station counts and unloads wafers from the carriers, aligns wafers for scanning and positions wafers on the stage. The transducers travel over 1 m/s while pulsing ultrasound at frequencies up to 230 MHz and receiving thousands of return echoes per second. Both the transducers and the 500 MHz bandwidth pulser/receiver were designed and manufactured by Sonoscan.
The key defects imaged in MEMS wafers are non-bonds of the seal to a wafer, voids within the seal material and other gap-type defects that can compromise the hermeticity of the cavity.
After scanning, both the acoustic wafer image and the wafer data can be used for accept/reject determination. Criteria are defined by the user with respect to acceptable defect counts and sizes.