Stitched Image Sensor Die Redundancy for Faulty Block Bypass
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Solution Overview
Problem
In image sensor integrated circuit dies formed by stitching multiple tiles, a faulty instantiation of circuitry blocks can render the entire image sensor inoperable due to hard-coded routing layouts that do not allow for easy substitution of functional instantiations, leading to inefficiencies and reduced yield.
Innovation Solution
Incorporating testing and selection circuitry to identify and utilize functional instantiations of circuitry blocks, using multiplexer circuitry to connect a selected instantiation to the necessary features and test circuitry, and storing indications of functional instantiations for later use, allowing for real-time replacement of faulty blocks during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hard-coded routing layouts are used to assign circuitry block instantiations, then the circuit design is simplified and manufacturing is easier, but the system loses adaptability and a single faulty instantiation renders the entire image sensor inoperable
Solution Approach 1:
The patent implements dynamic routing selection by replacing static hard-coded connections with multiplexer-based dynamic routing. The multiplexers allow the system to dynamically select which instantiation of a circuitry block to connect to the routing infrastructure, enabling runtime adaptation when faults are detected in any instantiation.
Solution Approach 2:
The system changes the routing parameter from fixed to variable by introducing selection logic that can change connection parameters based on instantiation functionality. Test circuitry detects functional status and changes routing parameters to bypass faulty instantiations, maintaining system operation with alternative instantiations.
2Productivity
If multiple instantiations of circuitry blocks are created through stitching, then yield potential is improved through redundancy, but device complexity increases due to additional testing and selection circuitry
Solution Approach 1:
The patent segments the circuitry block functionality into multiple independent instantiations, each capable of performing the same function. This segmentation allows individual testing and selective activation, where test circuitry evaluates each segment separately and routing logic activates only functional segments, thereby managing complexity through modular organization.
Solution Approach 2:
The patent introduces intermediary components (multiplexers and test circuitry) that mediate between multiple instantiations and the routing infrastructure. These intermediaries manage the complexity by providing standardized interfaces for testing and selection, shielding the core functional blocks from direct complex interconnections while enabling yield improvement through redundancy.
3Ease of manufacture
If a single faulty instantiation is present, then manufacturing cost is reduced by avoiding full redesign, but reliability drops to zero as the entire image sensor becomes inoperable
Solution Approach 1:
The patent implements beforehand cushioning by creating redundant instantiations of circuitry blocks before manufacturing completion. Test circuitry is integrated to detect faults in these redundant copies, and routing logic is pre-configured to automatically bypass faulty instantiations. This prior preparation ensures that if any instantiation fails, alternative functional instantiations are already available, cushioning against total failure.
Solution Approach 2:
The system implements discarding and recovering by identifying faulty instantiations through test circuitry, discarding (disconnecting) the defective copies via multiplexer selection, and recovering functionality by activating alternative instantiations. This process maintains reliability without requiring redesign, as the system recovers from faults by switching to pre-manufactured redundant copies.
Data Source
AI summary
An image sensor may be implemented using a stitched image sensor die. The stitched image sensor die may be formed from a step and repeat exposure process using a set of tiles in a reticle set. Multiple instantiations of a same circuitry block on a given tile may be patterned and formed on the image sensor die. The image sensor die may include circuitry configured to enable testing of one or more instantiations of the same circuitry block. The image sensor die may include memory circuitry for storing indications of a functional instantiation of the multiple instances and may use the functional instantiation for normal operation.