Depending on the requirements of the structure to be produced, wafers go through many different process steps and partially remain in the wafer fab for weeks until production is complete. Wafer inspection by defect inspection and dimensional measurements ensure that wafers with defects are eliminated from production. The wafer inspection with Confovis measurement systems helps to detect variations in processes, find the cause and adjust it.
With the WAFERinspect measurement and AOI systems and the patented confocal optical measuring method (Structured Illumination Microscopy, SIM), both defect detection and dimensional measurements are possible on one tool.
Measuring tasks - wafer inspection system
Confocal 3D measurements
- Independent of materials: silicon, epoxy, glass, chrome, resist, etc.
- Measurements of demanding surfaces without artifacts (no ‘bat wings’)
- High speed: 60 confocal frames per second (250 mil. measuring points/s)
- Film Thickness / Layer Stack
- Step Height
- Oblong holes
- Macro defects
- Micro defects
- Particle Inspection
- Golden Sample
- Artificial Intelligence
- Neuronal networks
- Operator mode (visual inspection)
- Color images
- Extended depth of focus images
- Documentation by commentary function
- Digital inking
- Visual inspection with fine alignment, KLARFF-files
Wafer inspection and wafer metrology with Confovis
MEMS often require the measurement of multi-dimensional structures that lie partly below the surface. With its unique accuracy and resolution, which come very close to those of an atomic force microscope (AFM), Confovis is in a position to measure angles, distances and various dimensions. With its partner Mechatronic Systemtechnik, Confovis cooperates with a specialist in the field of MEMS wafer handling, i.e. wafers which must be touched (gripped) mostly on the edges only.
2D measurements of wafers
The autofocus function of the Confovis WAFERinspect measurement system uses parts of the confocal beam path, so that the autofocus functions on all surfaces (i.e. on a mirror, too). The z-axis of the measuring unit which is there anyway makes it possible to measure top and bottom CD in one step. The measurement will be evaluated with Halcon or Cognex software. The interface between the Confovis software and the two market-leading products makes it possible to reliably measure absolute distances in a „die“, the „die-to-die shift“ or also line/space structures smaller than 1 µ. Redistribution layers (RDL) will also become measurable in connection with the positioning of „dies“ during the wafer inspection with Confovis.
During the defect scan the wafers are continuously moved and scanned by the measuring system. The defects thus detected are being cut out and saved during this process together with the associated wafer coordinates.
If macro defects (such as voids, scratches or breakouts) extend over more than one image field, the Confovis WAFERinspect software will automatically put them together. Subsequently, the defects will be classified to the trained classes by the neural network in the classificator of the Neurocheck software. This two-step procedure will ensure that also defects hitherto unknown and not trained yet can be detected. Defects without clear allocation will be saved in the class „unsafely classified defects“.
The results of all defects are presented in the Defect Map. In addition to that, they can be issued in KLARF format, so that the results are transmitted via SECS/GEM to the host in compressed form.
SECS/GEM and semi-standard
The Confovis WAFERinspect measurement system can, in combination with a wafer-handling system (equipment front end module, EFEM), measure and inspect various types of wafers. The partner for EFEM-systems is Mechatronic Systemtechnik. It is possible without modifying the hardware to check and inspect various wafer sizes and also 300 mm x 300 mm panels on one system, with the systems being available with one or two load ports.
Formulas are generated via the user interface of the Confovis Systems, which does not require any programming knowledge. Measurements once carried out during the wafer inspection can be saved as formula with one click. Evaluations will be carried out with any software, such as MATLAB, Python or by individual Confovis plug-ins. The navigation is done via GDS-II coordinates or via the Confovis software that can teach a wafer layout with three clicks. It is also possible to upload KLARFF-files.
The EFEM-interface is used for the communication with the host. The integration of a WAFERinspect automated optical inspection (AOI) and metrology tool follows the same standard as established AOI tools, but provides a larger function range.
Special edge grip end-effectors and chucks, on which the wafer merely rests on the edge, are a prerequisite for handling MEMS-wafers.
The system benefits of the confocal centerpiece of the Confovis WAFERinspect measurement system in connection with the Mechatronic wafer handling system (EFEM) come especially to the fore when measuring transparent wafers and wafers with warpages and bows.
MEMS, Micro LED, Mebran, Probe Marks, Bond Pads & Wires, RDL (Redistribution layer), UBM, Silicon, Prime Silicon, Glass, SOI, Sapphire, GaAs, SiC, GaN, InP, GaSb, Ge, LiTaO3, LiNBO3, epitaxial
E5 (Equipment Communication), E10 (RAM), E30 (GEM), E37.1 (HSMS), E39 (Object Services), E94 (Control Job Management), E40 (Process Job Management), E87 (Carrier Management), E90 (Substrate Tracking), E84 (Carrier Handoff Interface)