Components and measuring tasks in 3D surface metrology are becoming more and more complex. Certain measurement tasks can no longer be solved by a single sensor. In these cases hybrid metrology can shine.
As the word "hybrid" already implies in its origin, measured values from different measurements are "mixed" in order to obtain new information that cannot be measured directly in this way. Such complex applications are often found in wafer processing or complex coatings.
But how does hybrid metrology work now?
Modern 3D surface measuring tools can combine several measuring principles by different point, line, field of view and layer thickness sensors in one device. This makes it possible to solve a measuring task with different sensors by carrying out a measurement with each sensor. The different results are then combined with each other.
The measuring tool and the recipe used must know the complete measuring task and implement it completely. This means that not only the measurements with all the necessary sensors are carried out automatically, but the software also records the different measurement results and calculates the desired parameters from them. An example of an application of hybrid metrology is shown here.
Example: Determination of the opaque copper layer
The present layer system is located on a wafer and consists of an opaque silicon substrate, a transparent oxide layer on top and an opaque copper layer in a limited area on top. To determine the thickness of the copper layer, the topography sensor measures the thickness of the copper layer including the transparent oxide layer. Furthermore, the thickness of the transparent oxide layer is measured separately with a layer thickness sensor. By subtracting the oxide thickness from the previously determined total thickness, the desired step height of the copper layer is obtained.
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