Nanowell Sensor Layout With Buried Bond Pads and TSV Routing
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Solution Overview
Problem
In sensor systems, such as biosensor systems, the need to increase data throughput requires reducing nanowell sizes and increasing their numbers, while maintaining compatibility with electronic components like bond pads, which are often damaged or corroded by fluid flow and wire bonding processes, limiting the size of the flow channel and nanowell array.
Innovation Solution
The bond pads are positioned under a passivation stack, allowing the flow channel to be enlarged over them, and through-silicon vias (TSVs) and redistribution layers (RDLs) are used to maintain electrical contact, protecting the bond pads from fluid damage and enabling a larger nanowell array within a fixed footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If bond pads are exposed on the surface for wire bonding, then electrical connection is enabled, but the flow channel area is restricted and bond pads are damaged or corroded by fluid flow
Solution Approach 1:
The bond pads are extracted from the flow channel area and positioned underneath the passivation stack, separating their function from the fluid flow path. This allows the flow channel to expand over the bond pads without exposing them to fluid damage, while TSVs provide alternative electrical connection paths.
Solution Approach 2:
The passivation stack serves as an intermediary layer that protects the bond pads from fluid exposure while allowing TSVs to penetrate through it for electrical connection. This mediator enables both fluid flow protection and electrical connectivity simultaneously.
2Productivity
If nanowell array size is increased to improve data throughput, then more analytes can be processed, but the sensor footprint must be enlarged
Solution Approach 1:
The design transitions from a two-dimensional surface layout to a three-dimensional structure by stacking components vertically. Bond pads are moved to a lower layer underneath the passivation stack, freeing up surface area for a larger nanowell array while maintaining electrical connections through vertical TSV pathways.
Solution Approach 2:
The bond pads are nested underneath the passivation stack, with TSVs providing vertical electrical connections through the stack. This nested arrangement allows the flow channel and nanowell array to occupy the same horizontal footprint without interference from bond pads, enabling higher density integration.
3Productivity
If flow channel is enlarged to accommodate more nanowells, then data throughput increases, but bond pads become more susceptible to fluid damage
Solution Approach 1:
The bond pads are extracted from the flow channel region and repositioned underneath the passivation stack, removing them from the harmful fluid environment. This extraction allows the flow channel to be enlarged for higher throughput without increasing fluid exposure to bond pads.
Solution Approach 2:
The passivation stack is placed beforehand as a protective barrier between the fluid flow and bond pads. This protective layer cushions the bond pads from fluid damage while allowing the flow channel to expand freely above it.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration increases the number of nanowells that can be accommodated without expanding the sensor system's footprint, enhancing data throughput while protecting electronic components from fluid exposure.
Implementation Method 1
the bond pads are protected by the passivation stack, the flow channel area of the sensor system is no longer restricted by the bond pads and may be enlarged such that it is disposed over the bond pads
Implementation Method 2
A through-silicon via (TSV) is in electrical contact with the bond pad. The TSV extends through the base substrate.
Implementation Method 3
analytes (such as clusters of DNA segments, nucleic-acid molecular chains, or the like) that are disposed in a nanowell array of an image sensor structure may be tagged with an identifiable label (such as a fluorescently labeled molecule) that is delivered to the analytes via fluid flow through the flow channel
Implementation Method 4
The analytes may then emit photons of an emissive light, which may be transmitted through the passivation stack and into light guides of the image sensor structure that are associated (e.g., located directly below) with each nanowell. The light guides direct the emissive light photons to light detectors
Data Source
AI summary
A system includes an image sensor structure and a flow cell. The image sensor structure includes an image layer disposed over a base substrate. A device stack is disposed over the image layer. A bond pad is disposed in the device stack. A passivation stack is disposed over the device stack and the bond pad. An array of nanowells is disposed in a top layer of the passivation stack. A through-silicon via (TSV) is in electrical contact with the bond pad. The TSV extends through the base substrate. A redistribution layer (RDL) is disposed on a bottom surface of the base substrate. The RDL is in electrical contact with the TSV. The flow cell is disposed upon the top layer of the passivation stack to form a flow channel therebetween. The flow channel is disposed over the array of nanowells and the bond pad.