Automated wafer inspection of large samples

Automated wafer inspection of large samples

Although the trend in the semiconductor industry is clearly towards miniaturisation, there is also a lot going on at the other end of the scale. Wafers with a diameter of 400 mm, for example, are becoming larger and larger, and sample cards for testing are also increasing in size and complexity. For the automated inline wafer inspection of large and flat samples, Steinmeyer Mechatronik has therefore developed a high-precision XYZ positioning system that can accommodate substrates weighing up to 50 kg and measuring up to 650 x 650 mm.

Commercially available microscope systems often offer sophisticated operating environments and extensive measuring tools integrated in the software. However, the measurable object sizes are often severely limited due to the small stands supplied. Measuring larger objects thus quickly becomes a laborious task with several partial measurements. Steinmeyer Mechatronik closes this gap with the new XYZ positioning system for automated inline wafer inspection.

The inspection system was specially developed for applications in high-resolution quality control and microscopy and offers space even for heavy substrates or workpieces weighing up to 50 kg as well as large-area objects up to 650 x 650 mm. The Z-axis was also designed for heavyweights and can carry microscopes, measuring heads, sensors or camera systems weighing up to 20 kg. The height adjustment over the travel distance of 100 mm is carried out manually with a sliding thread or optionally motorised. In the case of motorised vertical adjustment, a ball screw drive in combination with a spindle brake guarantees the necessary optimum self-holding, so that the vertical position is held with sub-µm stability even when taking pictures with the highest resolution.

Precise measurement with repeatability down to 2 µm

The positioning system allows simultaneous movement of the specimen in X and the microscope system in Y for a resulting movement in the horizontal XY plane in a minimal installation space. This ensures a small footprint. For different applications, the specimen support is available in several versions: as a ground plate, as a plate with a drilling grid or as a chuck. Accessibility is provided from the top as well as from two sides, which offers easy loading and insertion of the inspection system into further process steps.

With repeat accuracies of less than 2 µm, the positioning solution from Steinmeyer Mechatronik meets the highest demands for precision. Thanks to the stiffness-optimised design and massive, heavy granite base plate with air dampers, excellent decoupling from floor vibrations is ensured - ideal for measurements with µm and sub-µm resolution even in real industrial environments. The motion axes can be controlled both in fully integrated operation in the existing microscope software as well as integration into the process-side control system. The low-emission positioning system is enclosed on all sides and thus ideally prepared for use under cleanroom conditions.

Ideal for inspection of multiple or large wafers or probe cards

As an expert in the development of customised special solutions, Steinmeyer Mechatronik offers a range of optional adaptations and extensions for automated inline wafer inspection, e.g. surface inspection or layer thickness measurement. These include, among others, various travels up to 1,000 mm, wipeable, smooth surfaces, clean room designs up to ISO class 1, individual solutions for cable routing and adapted vibration decoupling by means of damping rubber shims or pneumatic dampers.

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