Common Silicon Substrate for Battery and IC Integration
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Solution Overview
Problem
The complexity and cost of fabricating body-mountable electronic devices are increased by the need for separate substrates for batteries and electronic components, and the expansion of lithium-based batteries during charging can cause stress and interference with device operation.
Innovation Solution
A silicon substrate is used as a common substrate for both lithium-based batteries and electronic components, with through-silicon vias (TSVs) providing electrical connections between the battery current collectors and electronic components, allowing the battery layers to be deposited on one surface and electronic component layers on the opposite surface, thereby reducing complexity and mitigating expansion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate substrates are used for batteries and electronic components, then each component can be independently fabricated, but device complexity and fabrication cost increase
Solution Approach 1:
The patent merges the battery substrate and electronic component substrate into a single common substrate. The battery is fabricated on the back surface of the substrate while electronic components are fabricated on the front surface, eliminating the need for separate substrates and reducing overall device complexity while maintaining independent fabrication capabilities
Solution Approach 2:
The common substrate serves multiple functions simultaneously: it acts as the structural base for the battery, the mounting platform for electronic components, and the mechanical support for the entire device. This multi-functional approach reduces the number of components needed and simplifies the overall device architecture
2Use of energy by moving object
If lithium-based batteries are integrated into body-mountable devices, then power supply capability is improved, but battery expansion during charging causes stress and interferes with device operation
Solution Approach 1:
The device is segmented into two distinct functional zones on opposite surfaces of the substrate: the battery occupies the back surface where expansion can occur without affecting electronics, while electronic components are placed on the front surface. This spatial segmentation isolates the expansion stress to a specific region that does not interfere with device operation
Solution Approach 2:
The common substrate acts as an intermediary between the battery and electronic components. It provides mechanical isolation, allowing the battery to expand during charging without transmitting stress to the sensitive electronic components on the other side of the substrate
3Reliability
If through-silicon vias are used to connect battery current collectors to electronic components, then electrical connection is achieved, but fabrication process complexity increases
Solution Approach 1:
The patent transitions from planar electrical connections to three-dimensional vertical connections through the substrate. Through-silicon vias provide electrical pathways in the vertical dimension, enabling direct connection between the battery current collectors on the back surface and electronic components on the front surface, thereby achieving reliable electrical connection while maintaining a compact form factor
Data Source
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AI summary
An example device includes a silicon substrate having a first substrate surface and a second substrate surface; a plurality of layers associated with one or more electronic components of an integrated circuit (IC), where the plurality of layers are deposited on the second substrate surface; a lithium-based battery having a plurality of battery layers deposited on the first substrate surface of the silicon substrate, where the lithium-based battery includes an anode current collector and a cathode current collector; a first through- silicon via (TSV) passing through the silicon substrate and providing an electrical connection between the anode current collector and the plurality of layers associated with the one or more electronic components of the IC; and a second TSV passing through the silicon substrate and providing an electrical connection between the cathode current collector and the plurality of layers associated with the one or more electronic components of the IC.