Three-dimensional (3D) scanners are becoming increasingly common in many industries. However most of these
scanning technologies have drawbacks for practical use due to size, weight, accessibility, and ease-of-use. Depending on
the application, speed, flexibility and portability can often be deemed more important than accuracy. We have developed
a solution to address this market requirement and overcome the aforementioned limitations. To counteract shortcomings
such as heavy weight and large size, an optical sensor is used that consists of a laser projector, a camera system, and a
Structured laser light is projected onto the measured object with a newly designed laser projector employing a single
Micro Electro Mechanical Systems (MEMS) mirror. The optical system is optimized for the combination of a Laser
Diode (LD), the MEMS mirror and the size of measurement area to secure the ideal contrast of structured light. Also,
we developed a new calibration algorithm for this sensor with MEMS laser projector that uses an optical camera model
for point cloud calculation.
These technical advancements make the sensor compact, save power consumption, and reduce heat generation yet still
allows for rapid calculation. Due to the principle of the measurement, structured light triangulation utilizing phase-shifting
technology, resolution is improved. To meet requirements for practical applications, the optics, electronics,
image processing, display and data management capabilities have been integrated into a single compact unit.
With the refined lithography techniques that exist today, it is critical for overlay measurement tools to perform with great measurement precision. Tool induced shift, TIS, is one of the key factors taken into consideration when evaluating the performance of an overlay measurement tool. TIS can be observed as a numerical value, and the measurement value is corrected by the TIS value. However, in an overlay measurement tool with TIS, the measured values could be shifted due to an interaction between TIS and a film stack structure of wafer. Therefore, it is essential to minimize the TIS values. We extend our study on the lens surface aspheric error, which is known to be one of the root causes of TIS. As this point of view, we constructed our overlay measurement tool, NRM-3100, and were able to decrease TIS values.