Faster simultaneous crystal orientation analysis for wafer-bonded structures

Wafer bonding has come to play an essential role in the production of advanced electronic and acoustic devices. But these cutting-edge applications come with a traditional challenge: measuring each wafer layer’s crystal orientation independently without errors, damage, or delays.

Read on to learn why simultaneous dual-layer analysis can now be faster, more benchtop-friendly, and more accessible than ever – and how this opens new possibilities for emerging radiofrequency applications.

How is wafer bonding used in electronic and acoustic devices?

Wafer bonding allows manufacturers to combine materials with complementary mechanical, thermal, and piezoelectric properties. In radiofrequency (RF) applications specifically, piezoelectric-on-insulator (POI) substrates enable the combination of thin piezoelectric films with silicon’s mechanical and thermal properties.

One common structure is a lithium tantalate (LTO) film on a silicon base, with an insulating silicon dioxide layer in between – also known as LTO-on-Si. This structure delivers the acoustic confinement, thermal stability, and tunable electromechanical coupling needed for surface acoustic wave (SAW) filters in 5G and emerging 6G technologies.

Why is characterizing crystal orientation essential in wafer-bonded structures?

Crystal orientation directly influences wave propagation, coupling efficiency, suppression of spurious modes, and thermal behavior in SAW devices. In LTO-on-Si structures, so does the relative rotational offset or “twist” between the LTO and silicon layers.

That means you need both out-of-plane and in-plane measurements for each layer. And it’s crucial to get them right: the smallest misalignment can degrade your device’s thermal stability, energy coupling, and acoustic wave speed.

What are the challenges of characterizing crystal orientation in wafer-bonded structures?

Traditionally, analyzing both layers independently has been difficult. Inverting your sample to measure each layer separately would slow your workflow, limit automation possibilities, and risk damage or critical repositioning errors.

Azimuthal scanning removes the need for sample inversion in thin POI structures, measuring both the out-of-plane tilt and in-plane rotation of each layer simultaneously from one surface. But it often requires large, floor-standing instruments and a specialized setup for wafer-bonded structures.

Simultaneous dual-layer analysis is faster with SDCOM

Malvern Panalytical’s SDCOM XRD analyzer does it differently. It makes azimuthal scanning for simultaneous dual-layer measurements fast, benchtop-friendly, and accessible in manufacturing and quality control settings. Dual-layer measurements are already integrated into its workflow, so there’s no additional setup.

Backed by results: SDCOM’s performance analyzing LTO-on-Si POI structures

We put the SDCOM to the test on 19 LTO-on-Si POI structures, bonded across a range of twist angles. The results demonstrated:

• Speed: Out-of-plane and in-plane rotation measurements for both layers in just 50 seconds.
• Precision: Standard deviations of just 0.001° for offcut and 0.01° for twist across 10 repeated measurements.
• Accuracy: Results that track target values.

In short: for semiconductor researchers and manufacturers exploring emerging RF applications from the bench, the SDCOM provides the robust, high-throughput characterization you need.

Download our application note for the full breakdown of SDCOM’s performance in characterizing crystal orientation in wafer-bonded LTO-on-Si POI structures.