Scanning InfraRed Depolarization

Stress measurement at the wafer level is an established technology for the optical, non-destructive, and contactless characterization of stresses within semiconductor materials. It utilizes the photo-elastic effect to make stresses visible, enabling close monitoring of semiconductor production process steps.

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Shear Stress Reveals Wafer Defects

As nodes become smaller and process steps more costly, detecting defects as early as possible is crucial. Wafer substrates and epitaxial layers can contain critical defects that may affect later device performance or even cause wafer breakage during subsequent processing. Our technologies provide contactless, non-destructive measurement of shear stress. Because each defect is associated with a characteristic stress field, measuring shear stress with our tool is a reliable way to detect and characterize defects early on. Our customers trust and rely on our solutions to monitor process steps in modern, fully automated fab environments.

Scientist in protective eyewear observes a stress measurement process in a clean room environment

Relevant industries

Semiconductor

The SIRD system provides fast, contactless, and non‑destructive stress and defect analysis for semiconductor wafers. Using the photoelastic effect, it identifies global stress fields and critical defects such as dislocations and cracks. It supports silicon, silicon carbide, gallium nitride, gallium arsenide, indium phosphide, aluminum nitride, and other compound semiconductor materials.

SIRD delivers essential insights for crystal growth optimization and reliable quality control, ensuring consistently high wafer performance.

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Why Measure Stress?

Residual stress states are “fingerprints” that provide insight into a wafer and the process steps it has undergone. Monitoring stress is essential for identifying defects by their characteristic stress fields on semiconductor substrates, epitaxial layers, and component structures. This capability is enabled by SIRD (Scanning InfraRed Depolarization) from PVA TePla.

The function

SIRD utilizes the photo-elastic effect to quantitatively measure stress. The photo-elastic effect induces a change in the polarization of the probing laser, which is proportional to the stress within the material. By measuring this change in polarization, the stress can be accurately calculated for various materials.

Key Capabilities

Intelligent software solutions empower the SIRD system to process the acquired maps by automatically detecting defects, classifying them, and binning them according to severity. Fully customizable functions offer flexibility in creating recipes for interpreting results and reporting in the form of output documents and numerical data.

With over 25 years of experience in semiconductor fab automation, SIRD provides fully operator-less, 24/7 production monitoring, including standard SECS/GEM interfaces in accordance with SEMI 300.

By using our technologies, you can closely monitor your production process and catch deviations early in the process chain, before they become costly problems.

Internal view of a PVA TePla SIRD system showing a wafer mounted on a rotating stage with precision inspection sensors and robotic components inside the stainless-steel chamber.

The systems at a glance

SIRD

SIRD Stress Measurement

The SIRD (Scanning InfraRed Depolarization) system is a transmission dark-field plane polariscope. A fixed-position, linearly polarized laser beam penetrates the wafer. If the crystal structure is perfect and stress-free, the polarization of the laser beam remains unchanged. However, if there are shear stresses or defects in the crystal, the laser beam undergoes depolarization caused by stress-induced birefringence. Using material-specific coefficients, the shear stress is calculated from this depolarization.

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SIRD SiC 200

Scanning InfraRed Depolarization - Optimized for Silicon Carbide

SIRD SiC 200 is a modified version of the standard SIRD technology, optimized for measuring silicon carbide substrates and epitaxial layers. Silicon carbide is an increasingly important material for power applications. Its high cost necessitates close monitoring of process steps, from growth to epitaxy to structuring. Using SIRD SiC 200 enables quantitative measurement of the internal stress state, revealing growth stresses and defects.

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