Simulating FBAR models in 3D allows designers to capture the filter's full performance. This model was created in softMEMS from a GDSII mask layout and process steps and these have been imported into OnScale's Designer mode.
The typical workflow for the design and development of MEMS devices is based on a mask layout design. It combines the 2D mask layout with the process flow to create 3D solid models of the MEMS devices. The layout-based discretized 3D models need to be converted into system models. Now, these high-fidelity MEMS 3D models can contain between 100,000 to 1,000,000 degrees of freedom to fully capture the effect of process flow on 3D geometry and its effect on device performance. FEA simulations of these models can take few days to run and sometimes it is not even possible to run these models. Given this a MEMS design engineer must rely on reduced-order or lumped model approximations, which do not truly capture the effect of etching, residual stresses and packaging effects. The makes the system design optimization of MEMS devices a big challenge to achieve the required performance.
At OnScale we have developed fast time-domain multiphysics 3D finite-element (FE) solvers and seamlessly integrated them with cloud high performance computer (HPC) capabilities that address these constraints. MEMS design engineer can now import full 3D high-fidelity models of MEMS devices created in Mentor Graphics / SoftMEMS and run FEA simulations in OnScale to accurately understand the performance of these devices in less than a few hours.
In this example we will show you how to run the model on the cloud and post-process the results using the OnScale Post Processor.
Film bulk acoustic resonators (FBARs) can often exhibit spurious modes across the pass band, which is one of the design challenges that an RF engineer faces. OnScale gives engineers the ability to quickly prototype a design to understand how effective it is in removing these modes. This structure consists of a piezoelectric active layer (Aluminum Nitride) with Molybdenum electrodes on a silicon substrate.
Download and Open the Model
OnScale input files have the file extension *.jfp. To open the downloaded file:
- Open OnScale.
- Select Designer mode.
- Click the menu button in the top-left of the application and select Open Project.
Preview Model is used to view both the geometry dimensions and material assignment of a model to ensure that the design is correct. To preview a model, click Preview Model in the Home tab of the application ribbon. To close the preview, click the red x in the top right-hand corner of the widget.
Run Model on Cloud
To run the model on the cloud, click Run on Cloud in the Home tab of the application and follow these steps:
- Click Estimate.
- Set CPUs to 2.
- Click Run.
- From the Home tab, click Storage.
- Click the refresh icon to refresh storage.
- Select the job name from the dropdown menu.
- Click Download and select Download All.
Choose a directory to download the results to. These results will be stored in the folder: fbar_noseedlayer...-YYYYMMDD-HHMMSS\1 where YYYYMMDD-HHMMSS is the current date and time.
Switch to Post Processor
Post Processor is a suite of tools used to visualise and analyse output data generated from OnScale simulations. To switch to Post Processor, click the button in the top-right:
What kind of analysis can I do in Post Processor? Find out here.
To plot the results in Post Processor, follow these steps:
- In File Explorer, navigate to the download directory and double-click the file fbar_noseeded...flxhst to load it
- In Results Manager, double-click pize load_1:Charge to plot the charge on the active electrode of the FBAR.
Have a play around with the model in Designer. Add a few more outputs and open them in the Post Processor once you have run the simulation. You can also calculate impedance/admittance on the electrodes by selecting the voltage or charge records from the Results Manager and clicking the impedance and admittance buttons found in the XY Tools section of the Home tab. Below is the Impedance of the FBAR.