Wafer Inspection

confovisMeasurement TasksWafer inspection

Wafer inspection technology:
Defect inspection and dimensional measurement increase output

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 measurement ensure that wafers with defects are eliminated from production. Wafer inspection with Confovis measurement systems helps to detect variations in processes, find the cause and adjust it. Defect detection and dimensional measurements are possible with the WAFERinspect measurement systems and Confovis’ patented .

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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
  • Topography
  • Coplanarity
  • Bumps
  • Roughness
  • Step Height

2D measurements

Critical Dimensions

  • Line/Space
  • VIAs
  • Oblong holes
  • Overlay

Defect inspection

  • Macro defects
  • Micro defects
  • Particle Inspection
  • Golden Sample
  • Artificial Intelligence
  • Neuronal networks


Visual inspection​

  • Operator mode (visual inspection)
  • Color images
  • Extended depth of focus images
  • Stitching
  • Documentation by commentary function
  • Digital inking
  • Visual inspection with fine alignment, KLARFF-files

Wafer inspection and wafer metrology with Confovis

Confocal measurement of MEMS, 3D packaging (especially bumps), probe marks, LED, roughness, CIS (CMOS image sensor), … The reliability of the measurements and the measuring speed are crucial for these wafer inspection measuring tasks. Established optical surface measuring instruments do not achieve the 3D-accuracies in the lower one-digit nanometer range as requested by the further miniaturization. 3D-measurements will typically be made with SIM, the confocal measuring procedure patented by Confovis, within two seconds (120 measurement planes with a z-range of 20 µ and an accuracy of < 4 nm) and with a measurement result irrespective of the material of the surface to be measured. Even the most difficult combinations of passivation layers and copper can be measured without any problems and prior knowledge.

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“, thedie-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.

Multi sensor technology

Apart from the centerpiece of the Confovis WAFERinspect measurement system, the patented confocal sensor, Confovis pursues the „Best of Class“ strategy.

    • layer thickness sensors (Filmmetrics)
    • chromatically confocal and WLI sensors (Precitec)
    • triangulation sensors (LMI/Micro Epsilon)

The advanced software of the Confovis WAFERinspect measurement system makes it possible to integrate sensors of other manufacturers, thus making the Confovis measuring system upwardly compatible. The user can therefore retrofit his system in a cost-effective way, if new measuring jobs are required as part of the wafer inspection (such as another measuring range for the layer thickness).

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.

Wafer handling

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.

Wafer inspection with Confovis

The Confovis WAFERinspect measuring systems combine the advantages of defect detection and dimensional measurements. In this way, macro and micro-defects are detected and classified at high speeds, with dimensional measurements also being carried out at the same time. The use of a wafer loader that can load various types of wafers (e.g. MEMS, glass, warped, TAIKO, frame etc.) will facilitate the most demanding measurement tasks in the field of automated process control.

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