06/27/2017

Measuring inaccessible parameters – FRT has the right solution: hybrid metrology

Semiconductor, MST / MEMS / Nano, Sapphire / LED, Photovoltaic, Automotive, Mechanical Engineering, Medical Technology, Optics, Packaging … – the application area for 3D surface measuring tools is diverse and constantly growing with new requirements and applications. Components and measurement tasks are becoming more complex, so certain measurements cannot be solved with one sensor alone as the desired parameters are not directly accessible. Even a multi-sensor arrangement alone does not help here. But FRT also offers the right solution for this: hybrid metrology.

With the multi-sensor concept, the 3D surface measuring tools of the well proven MicroProf® series can be equipped with topography point and area sensors as well as film thickness sensors. It is possible to solve a specific task by measuring with different sensors and then combining the different results to output the desired feature. The pivotal point is that the tool, respectively the used recipe, knows the complete measuring requirements and fully implements these. This means that not only the measurements with all necessary sensors are automated, but the software also records the different measurement results and calculates the desired parameters from these. An example of an application of hybrid metrology is presented here.

The layer stack is located on a wafer and is composed of an opaque silicon substrate, an overlying transparent oxide layer and an adjacent opaque copper layer. In order to determine the thickness of the copper layer  relative to the top of the oxide, the total copper thickness, including the transparent oxide layer is measured with a topography sensor. The thickness of the transparent oxide layer is then measured separately with a film thickness sensor. By subtracting the oxide thickness from the previously determined overall copper thickness, the desired step height of the copper layer is obtained.

We certainly have a solution for your specific application. Do not hesitate to contact us with any questions. Our experts will be glad to take care of your needs and work out individual solutions for you.