Backside RF Filter Integration via TSV Conductors
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Solution Overview
Problem
Integrating radio frequency (RF) filters, such as SAW and BAW filters, at the wafer level during CMOS processing is challenging due to fabrication scale issues on monolithic devices.
Innovation Solution
Forming an RF filter on the backside of a semiconductor substrate with through-silicon-via (TSV) conductors extending from the front side to electrically couple the filter to devices, allowing for integration at the wafer level and space savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF filters are integrated at the wafer level during CMOS processing, then additional chips are eliminated and integration efficiency is improved, but fabrication complexity increases due to scale issues on monolithic devices
Solution Approach 1:
The substrate is divided into a front side for CMOS device fabrication and a back side for RF filter formation. This segmentation allows each side to be optimized independently for its specific function, avoiding the fabrication complexity of integrating both on a single monolithic structure while maintaining wafer-level integration benefits
Solution Approach 2:
The RF filter is moved from the traditional planar integration approach to a three-dimensional configuration by forming it on the back side of the substrate. This dimensional change enables simultaneous front-side CMOS processing and back-side filter formation without interference, resolving the fabrication complexity issue while maintaining high integration efficiency
2Device complexity
If RF filters are formed separately and attached using flip chip techniques, then fabrication complexity is reduced, but device area increases and integration is less efficient
Solution Approach 1:
The RF filter and CMOS devices are merged into a single integrated structure by forming the filter on the back side of the same substrate that holds the CMOS devices on the front side. This eliminates the need for separate filter chips and their attachment processes, reducing overall device area while maintaining fabrication simplicity
Solution Approach 2:
By utilizing the back side of the substrate as an additional dimension for filter placement, the design eliminates the need for lateral expansion that would occur with separate filter chips. This vertical integration approach reduces the footprint area while keeping the fabrication process straightforward
Data Source
AI summary
A design structure for an integrated radio frequency (RF) filter on a backside of a semiconductor substrate includes: a device on a first side of a substrate; a radio frequency (RF) filter on a backside of the substrate; and at least one substrate conductor extending from the front side of the substrate to the backside of the substrate and electrically coupling the RF filter to the device.