Image Sensor Structure With Electro-Optic Modulation for TOF and PDAF
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Solution Overview
Problem
Existing image sensor technologies face interference issues and accuracy degradation due to neighboring sensor interference in Time-of-Flight (TOF) measurements and limited pixel coverage in Phase Detection Auto Focus (PDAF), leading to increased focusing time and precision issues.
Innovation Solution
Incorporating an electric-optical modulator between the color filter and the sensor, which adjusts focal length and refractive index in response to an applied electric field, allowing neighboring pixels to have different focal lengths and enhancing quantum efficiency for infrared light, thereby mitigating interference and increasing PDAF pixel coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional image sensor structures are used, then manufacturing is simpler, but neighboring sensor interference occurs in TOF measurements and pixel coverage is limited in PDAF
Solution Approach 1:
An electric-optical modulator is introduced as an intermediary component between the color filter and the photo-sensing element. This modulator adjusts the optical path and focal length for light from different directions, preventing neighboring sensor interference in TOF measurements and enabling accurate focus detection in PDAF applications without requiring complex sensor array configurations
Solution Approach 2:
The patent utilizes electric-field-controlled changes in the optical properties (focal length and refractive index) of the electric-optical modulator. By applying different electric fields, the modulator dynamically adjusts its optical parameters to differentiate between light from different directions, thereby resolving interference issues and improving measurement accuracy
2Measurement precision
If electric-optical modulator is added, then TOF measurement accuracy and PDAF pixel coverage improve, but device complexity increases
Solution Approach 1:
The electric-optical modulator serves multiple functions within a single component: it improves TOF measurement accuracy by eliminating neighboring sensor interference, enhances PDAF pixel coverage by adjusting focal lengths, and maintains compatibility with existing sensor architectures. This multi-functionality justifies the added complexity by delivering multiple performance improvements simultaneously
3Productivity
If electric-optical modulator is added, then PDAF focusing speed improves, but device complexity increases
Solution Approach 1:
The electric-optical modulator introduces dynamic control over the optical path by allowing real-time adjustment of focal lengths through electric field application. This dynamic capability enables faster focusing responses in PDAF applications, as the system can rapidly adjust optical parameters without mechanical movement, thereby improving productivity despite increased device complexity
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 solution improves the accuracy and speed of TOF measurements and PDAF by reducing interference and enhancing infrared light quantum efficiency, leading to more precise and faster focusing capabilities.
Implementation Method 1
The electro-optical modulator includes a first electrode, a second electrode over the first electrode, and a micro-lens between the first electrode and the second electrode. The electro-optical modulator may have various focal lengths in response to an applied electric field.
Implementation Method 2
The electro-optical modulator may have various refractive indices (also referred to as N values) in response to the applied electric field.
Implementation Method 3
a photo-sensing element disposed in the semiconductor substrate
Data Source
AI summary
A semiconductor image-sensing structure includes a semiconductor substrate having a front side and a back side, a photo-sensing element disposed in the semiconductor substrate, a color filter disposed over the back side of the semiconductor substrate, and an electric-optical modulator disposed between the color filter and the photo-sensing element. The electric-optical modulator includes a first electrode, a second electrode over the first electrode, and a micro-lens between the first electrode and the second electrode.