Photodiode Array Guard Structure Removal
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Solution Overview
Problem
Existing optical sensors experience tracking errors due to guard structures between adjacent photodiodes, which create optically dead areas and disrupt light sensitivity across the array.
Innovation Solution
The absence of guard structures between adjacent photodiodes in a shared epitaxial structure allows for improved light tracking by eliminating optical dead zones and enabling uniform light sensitivity, with downstream processing to account for electrical crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard structures are placed between adjacent photodiodes to provide electrical isolation, then electrical isolation is improved, but optical sensitivity is worsened due to creation of optically dead areas
Solution Approach 1:
The patent removes the guard structures (isolation structures) between adjacent photodiodes in the optical sensor array. By extracting these structures that caused optical dead zones, the patent eliminates the optically dead areas while maintaining electrical isolation through alternative means, thereby improving optical sensitivity without sacrificing electrical isolation reliability
Solution Approach 2:
The patent merges adjacent photodiodes by eliminating the isolation structures between them, allowing the photodiodes to be in direct contact within the same epitaxial structure. This merging removes the physical barriers that created optical dead zones, enabling continuous light sensitivity across the photodiode array while electrical isolation is maintained through other mechanisms
2Reliability
If guard structures are placed between adjacent photodiodes to prevent electrical interference, then electrical interference is reduced, but tracking accuracy is worsened due to disrupted light sensitivity
Solution Approach 1:
The patent extracts and removes the guard structures between photodiodes that were causing tracking errors. By taking out these isolation structures, the patent eliminates the optically dead areas that disrupted light sensitivity and caused tracking inaccuracies, thereby improving tracking accuracy while electrical isolation is maintained through alternative approaches
3Reliability
If isolation structures are used between photodiodes to ensure electrical separation, then electrical separation is improved, but light sensitivity uniformity is worsened due to optically dead zones
Solution Approach 1:
The patent removes the isolation structures (guard structures) between adjacent photodiodes that created optically dead zones. By extracting these structures, the patent achieves uniform light sensitivity across the entire photodiode array while maintaining electrical separation through other means, thereby eliminating the trade-off between electrical separation and light sensitivity uniformity
Solution Approach 2:
The patent merges the photodiodes by eliminating the isolation structures between them, allowing all photodiodes to exist in direct contact within a shared epitaxial structure. This merging creates a continuous, uniform light-sensitive surface across all photodiodes, ensuring uniform light sensitivity while electrical separation is maintained through alternative mechanisms
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 design enhances the ability to accurately track translational and rotational movements of input devices by minimizing optical isolation between photodiodes, improving sensitivity and reducing tracking errors.
Implementation Method 1
An optical sensor may also be used to track or determine the position of a light spot, light stripe, or other shape or pattern of light
Data Source
AI summary
An electronic device includes a shared epitaxial structure, an array of photodiodes formed in the shared epitaxial structure, and a readout circuit. The array of photodiodes is disposed between a first axis and a second axis, with the second axis orthogonal to the first axis. The array of photodiodes has an absence of guard structures between adjacent photodiodes. The readout circuit is electrically connected to the array of photodiodes and operable to read out values for different photodiodes or different subsets of photodiodes in the array of photodiodes.