Services
Microstructure Failure and Load Limit Prediction Service
- Having trouble with yield or field losses?
- Are parts breaking during processing?
- Need to match reliability to customer requirements?
- Upgrading an existing microstructure design?
A. M. Fitzgerald & Associates can help. We are pleased to announce new services in failure and load limit prediction for brittle microstructures:
Features
- Predict microstructure load limits before building final devices
- Find out where a structure is most likely to break and under what conditions
- Useful for MEMS, optoelectronics, photovoltaic cells and other crystalline microstructures
- Keeps IP secure – no need to reveal process details
Benefits
- Shorten design cycle time and save money by predicting structural limits before building final devices
- Improve yield by creating devices that are less likely to fail
- Increase confidence in performance specs
- Match device performance to market needs
A. M. Fitzgerald & Associates’ microstructure failure and load limit prediction services are based on a patent-pending, two part process:
Part 1
Test specimens are prepared using the same manufacturing process to be used on final device, and their surface strengths are measured according to ASTM standards C1239-07 and D6272-02.
Part 2
Finite-element numerical simulation is used to determine stresses in a device under operating loads. The results of the simulation are combined, using our proprietary algorithm, with surface strength information obtained in Part 1 to predict failure points and load limits.
Figure 1: Flow chart of a device design cycle that leverages our failure prediction methods. Reliability simulation prior to fabrication start is now possible.
How failure prediction works
Failures of crystalline microstructures initiate at surfaces. The surfaces are weaker than the bulk crystalline material due to microscopic imperfections that are caused by manufacturing processes. Details such as tool type and operating parameters are very important!
Figure 2: Surface properties of silicon etched by different processes vary greatly and have a significant effect on fracture strength.
We quantify the effect that a manufacturing process has on surface strength using test structures. This provides information that is specific to a particular process run on a particular tool. However, our protocol is designed so that we never need to know our customers’ proprietary process details.
Relying on more than ten years’ experience with finite-element numerical simulation, we model stresses in devices under load. Using ANSYS Multiphysics, we can model any type of load input, such as thermal, electrostatic, shock, or sinusoidal. Load limits and failure points are then predicted by combining stress simulations with knowledge of surface strength obtained from test structures.
Figure 3: Comparison between predicted failure force for a micro-mirror in tension and in torsion, and fracture force data from actual micro-mirrors (see inset photo above).
Further technical details are available here:
Fracture Prediction in Single Crystal Silicon MEMS (.pdf)
Getting started
Contact us to ask about failure and load limit prediction. We are currently engaging beta customers for this new suite of services.
