Technology, Process and Cost

Qualcomm Thin-Film SAW Filter Technology in Diversity Module

By Yole SystemPlus — Feb 2022

A deep-dive analysis of Qualcomm’s QuSAW filter technologies, with novel wafer-level packaging enabling multiplexer on single die and engineered Piezo-on-Insulator substrate.

According to Yole’s estimate, the filter market was almost $7B in 2021 – accounting for roughly half of the overall RF front-end market. As a critical component in the RF front-end, there are many innovations in the filter field to reduce cost and size while improving performance. One such innovation is the TF-SAW (thin film surface acoustic wave) filter, which is built on Piezo-on-Insulator substrates. Yole expects a 23% CAGR growth from 2021 – 2026 for TF-SAW filters and POI substrates. When it first appeared in 2019 in the Apple iPhone series, Murata’s TF-SAW filter shifted Apple’s supply chain. In 2020, Qualcomm joined the race to supply high-performance SAW filters. With its QuSAW technology, Qualcomm reinforced its position as a leader in integrated duplexer modules with Samsung.

For the Fan-Edition of the Samsung Galaxy S20 in 2020, Qualcomm supplied Samsung with two diversity modules that feature several multiplexers for mid-band (MB) and high-band (HB) diversity paths. The modules integrate several dies, including a low-noise amplifier (LNA) using RFSOI substrate and two versions of Qualcomm’s TF-SAW filters.

This report focuses on these two versions of Qualcomm’s TF-SAW, which were first manufactured for Samsung. The components use an innovative lithium tantalate wafer bonded to a silicon substrate using an oxide layer with two kinds of wafer-level packaging. The first one uses the well-known thin film acoustic packaging (TFAP) technology employed for several years at Qualcomm for TC-SAW and FBAR BAW filters. Meanwhile, the newly-developed second device allows for integrating the filter without any air cavities and simplifying the integration at its maximum level. This TF-SAW technology allows Qualcomm to produce quadplexer devices on a single die.

This report contains a deep analysis of the filter die, with a complete cost analysis of the component. A comparison with Murata’s IHP-SAW and Qualcomm’s TC-SAW and SAW filter technology is also furnished.