MEMS wafers, microfluidic wafers etc. need to be checked and inspected to detect imperfections (defect inspection) as well as measured in 2D and 3D (wafer inspection), in order to improve the control of production processes. The integration of defect detection into WAFERinspect, the high-resolution measurement system from Confovis, creates a process control instrument which can detect the defects and measure all structures in 2D and 3D.
Defect inspection with Confovis: Capturing smaller structures reliably
The requirements concerning the die placement in the fan-out process can be satisfied with the Confovis WAFERinspect measurement system. The same applies to the calculation of coordinates in various layers. Parts of the structure (e.g. bumps) can also be fully measured in 3D during the setup process, or on demand, within two seconds, so as to establish the reason of variations via the wafer or the panel.
Hairline cracks in the multi-layered processes are mainly created by stress in the surfaces. These hairline cracks are low-contrast and mostly so narrow, so that light optical methods reach their limits. The measurement capability of the confocal Confovis sensor with its nanometer precision can detect cracks on the basis of the changing surface topography, especially when they have been created by compressive stress. Processes can be optimized by preventive measurements of topographies at critical places, before stress cracks occur.
Probe marks make special demands on the defect inspection
The combination of the 2D defect inspection and the high-precision 3D-measurements facilitates a quantitative analysis of changes in the needle prints. This will allow an automated combination of defect inspection and the 3D measurement of the critical probe marks, in order to readjust the probing process as early as possible.