Measuring silicon bricks optically

The side lengths, phase lengths, angles and diagonal lengths of the silicon blanks, the so-called bricks, are inspected using the new system. In particular, a banana shape of the bricks resulted in frequent problems during manual inspection. If deviating areas of the wafer are sawn in the next stage, they can detach from the carrier and result in lengthy downtime of the saw.

Micro-Epsilon uses its scanCONTROL 2800 laser scanner for automatic inspection of silicon bricks. Four sensors are installed opposite each other, which measure the complete surface area. Depending on the machining state of the brick, the surface alternates between reflective and matt. In the normal case, the exposure time at the sensor regulates itself automatically for each profile depending on the reflection factor of the surface. However, if the surface changes within one laser line, many conventional scanners cannot cope. A high precision solution has therefore been developed due to the knowledge and expertise of Micro-Epsilon engineers.