Confovis, the optical metrology specialist from Jena, Germany, presents its fully automated measurement system for wafer inspection of different wafer types (MEMS, Standard, Thin, Taiko, Warped, Frame). The measurement system WAFERinspect combines confocal 3D-measurements, classical 2D-measurements and visual inspection, which allows the analysis of different process steps within the semiconductor production.
Increasing integration, new sensor concepts and other requirements boost the demands on the applied technologies and required measurement strategies for sensors. Confovis’ patented confocal measuring technique, based on the Structured Illumination Microscopy (SIM), allows the three-dimensional characterization of different material combinations, transparent layers (also Stacks of SiOx, SiNx, etc.), reflecting surfaces, photoresist and many other surfaces. Thus, process-critical quantities (e.g. CD-measurements of structures) that are not on the same focus plane can be solved/displayed in 3D (step height and width) in future. The wafer loading, the measurement and the transmission of measurement results is fully automated and adjusted to the customer’s specifications. Likewise, the communication via SECS/GEM is fully integrated as well as the communication between the wafer loader and the measurement system.
Understanding of processes with Confovis WAFERinspect
- Fully automated measurements and automated handling with a wafer loader (by Mechatronic Systemtechnik) possible
- Fully automatic measurements also on difficult wafer types (MEMS, Standard, Thin, Taiko, Warped, Frame)
- Three-dimensional characterization on different surfaces and material combinations possible
- Classical 2D structural measurements (Line/Space, Diameter, Overlay) also on different structures due to Cognex- and/or Halcon-interface
- Visual inspection and defect review (.kla-file)
- Roughness measurements traceable to standards
- Influences of new process technologies can be characterized and documented
- SECS/GEM-communication
Before completion, every wafer goes through hundreds of process stages in the semiconductor fab for several weeks. Correspondently it is necessary to efficiently secure critical process steps in order to avoid rejects. Especially the introduction of new sensor concepts and process technologies is a great challenge, as many of the new processes and appearing effects will not allow an automated defect detection and can be documented and monitored by the person responsible for the process only. With the WAFERinspect measurement system the user can, after loading of the wafer through the wafer loader, specifically record complete DIEs, insert markings on the pictures or save comments – with an easy navigation via mouse clicks.
A measurement system for multi-process-analysis
According to the requirements within the process step, the measuring method can be chosen in the measurement recipe. This allows the user to carry out a 2D analysis of e.g. Line/Space or Overlay measurements. Also demanding contrast transitions and complex structures can be taught and measured thanks to Cognex- and Halcon-interfaces. Additionally, due to increasing requirements of technologies and processes, there are more and more structures that cannot be covered by ‘standard solutions’ without any adaption. 3D measuring technique allows to capture structures in MEMS three-dimensionally, also underetchings or angles and step heights can be measured to the nanometer. Whereas white light interferometers measure wrong height information for different material combinations or cause an inverting of height information on edges of transparent materials, Confovis’ confocal measuring procedure is resistant towards such effects.
User-friendly and fast measuring by recipe
The increasing number of special measuring tasks requires a user-friendly control and recipe organization. The Confovis software WAFERinspect puts exactly these requirements into practice. Without programming, recipes can be created, copied and edited afterwards as well as transferred to other devices. Also, it is possible to create these recipes offline in order to reduce the expenditure of time with greatly increasing numbers of recipes (> 1,000). It is possible to put the recipes into different hierarchies so that a general overview is guaranteed.
