RF Modules and MEMS

Mobile communications and miniaturization has led to an explosion in the quantity and complexity of the RF devices needed in this connected world. The advent of 5G technology will propel RF devices and modules to a new level. Likewise, MEMS have fueled innovation in industrial and consumer electronics, connecting the physical and digital worlds. These devices require complex manufacturing processes and require a unique approach to process control.

Mass Load Metrology

Ensuring filter performance and die yield

Mass loading is a technique used to tune the resonant frequency of RF filters. To successfully tune a filter with this technique, accurate metrology and frequency measurements are needed. The Echo acoustic metrology system accurately measures the mass load film which can be combined with frequency measurements from electrical test through Onto Innovation's Discover software to monitor and control the mass load process steps in filter manufacturing.

RF Filter Metrology

BAW filter process control

State-of-the-art smartphones continue to add more frequency bands and contain more than 60 RF filters. With the planned migration to 5G, the complexity of the filters is increasing several fold to enhance the user experience as well as to provide flexibility to mobile providers.

Frequency response of filters is determined by a combination of the thickness and acoustic properties of the piezoelectric layer layer. Thickness uniformity requirements for the films are beyond what process tools can offer at deposition and there are several options available to achieve such tight controls post-deposition. Metrology techniques employed for characterizing these properties must meet the sensitivity, accuracy and stringent repeatability requirements.

The Echo acoustic metrology system can simultaneously and accurately measure the piezo layer as well as the top and bottom electrode films on product wafers. Measurements from the technique are used to feed forward to the trimming process to adjust the center frequency and improve wafer to wafer variability. Also, when combined with frequency measurements through Onto Innovation's Discover software, value added SPC control is provided to improve yield.

SAW/BAW Filter Inspection

Identifying defect sources to improve yield

Filters have become critical to managing the number of frequency bands that current mobile devices use to ensure clear communication. Filters have also become a significant portion of the overall cost of goods within RF front end modules. Reducing defectivity is critical to achieving performance and yield. Onto Innovation's advanced inspection systems are used throughout the process to highlight, track, and classify yield-robbing defects.

Cavity Integrity

Look beyond the surface to ensure quality

The ability to detect defects that are not visible on the top surface of a device is critical for many MEMS devices. Multiple angles in multiple directions further complicate the ability to properly monitor device quality and integrity. Onto Innovation uses unique illumination techniques across multiple wavelengths to create the optimal inspection capability for each unique MEMS device.

Substrate Handling

Solutions for the most strict wafer handling requirements

Complex MEMS manufacturing processes not only require a variety of handling solutions, but also place stringent demands on wafer handling, including limiting wafer contact to the extreme edge of a wafer, or perhaps, limit contact with the wafer completely.

A variety of handling solutions are needed to support the variety of requirements, including the ability to offer no wafer contact while also delivering wafer inversion capability for combined frontside and backside substrate inspection. Customized handling solutions can be created to meet the most demanding handling requirements.

Consulting and Applications Services

Onto Innovation's process control consulting services allow busy manufacturers to focus on production while we examine how to improve the process.

The Onto Innovation applications teams have over twenty years of experience with hundreds of successful projects worldwide across multiple industries. Contact us today to discuss your application study needs.

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