Light Receiving Element Lens Layout for Pixel Crosstalk Control
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Solution Overview
Problem
Incident light from the end portion of the pixel region mixes with adjacent pixels, causing noise such as flare and deteriorating image quality in imaging elements and light receiving elements used in distance measuring devices, particularly due to the use of avalanche photodiodes or single photon avalanche diodes.
Innovation Solution
The light receiving element incorporates a pixel region with on-chip lenses and wiring regions, and adjacent pixels with modified on-chip lenses, semiconductor region light-blocking walls, or altered wiring layers to redirect or block incident light, preventing leakage and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dummy pixels are arranged between the pixel region and the end portion of the semiconductor substrate to ensure uniformity of each pixel, then uniformity of pixels is improved, but incident light from dummy pixels reflects by the wiring region and mixes with the pixel region, causing noise such as flare and deteriorating image quality
Solution Approach 1:
The harmful function of the dummy pixel (light reflection and mixing) is extracted and eliminated by removing the dummy pixel configuration. The patent applies anti-reflection films and light-blocking structures to prevent light from dummy pixels from reflecting and mixing with the pixel region, thereby removing the harmful effect while maintaining the beneficial uniformity effect.
Solution Approach 2:
Anti-reflection films and light-blocking structures are introduced as intermediary elements between the dummy pixel and the pixel region. These intermediaries prevent the harmful light reflection and mixing while allowing the dummy pixel to maintain its uniformity-providing function.
2Reliability
If avalanche photodiodes are used to improve sensitivity, then sensitivity is improved, but leakage of incident light from dummy pixels causes malfunction
Solution Approach 1:
The patent converts the potentially harmful light leakage from dummy pixels into a beneficial effect by using anti-reflection films and light-blocking structures to control and redirect the light. The light that would otherwise cause malfunction is now controlled to prevent harmful effects while maintaining the high sensitivity of avalanche photodiodes.
Solution Approach 2:
Anti-reflection films and light-blocking structures serve as intermediary elements that control the behavior of light from dummy pixels. These intermediaries prevent direct light leakage to the pixel region while allowing the avalanche photodiode to maintain its high sensitivity for detecting intended light signals.
3Manufacturing precision
If on-chip lenses are arranged close to the semiconductor substrate to focus incident light, then focusing capability is improved, but light from adjacent pixels obliquely enters and causes crosstalk and color mixing
Solution Approach 1:
The patent divides the space between adjacent pixels by introducing element separation regions with insulating films. This segmentation prevents light from obliquely entering adjacent pixels, thereby eliminating crosstalk and color mixing while maintaining the close positioning of on-chip lenses for effective focusing.
Solution Approach 2:
Element separation regions with insulating films are introduced as intermediary structures between adjacent pixels. These intermediaries block oblique light paths while allowing the on-chip lenses to remain close to the substrate for effective focusing capability.
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 reduces crosstalk and flare, enhancing image quality and sensitivity by focusing incident light away from the pixel region and blocking unwanted reflections.
Implementation Method 1
a photodiode formed on a semiconductor substrate in which a charge generated by photoelectric conversion of incident light is multiplied with a high reverse bias voltage
Implementation Method 2
a photodiode formed on a semiconductor substrate in which a charge generated by photoelectric conversion of incident light is multiplied with a high reverse bias voltage
Implementation Method 3
an on-chip lens that focuses the incident light on the photodiode
Data Source
AI summary
To prevent leakage of incident light from pixels around a pixel region of a light receiving element. A light receiving element includes a pixel region and an adjacent pixel. In the pixel region, a plurality of pixels is arranged, the plurality of pixels including a photodiode formed on a semiconductor substrate in which a charge generated by photoelectric conversion of incident light is multiplied with a high reverse bias voltage, an on-chip lens that focuses the incident light on the photodiode, and a wiring region having a wiring layer connected to the photodiode and an insulating layer that insulates the wiring layer. The adjacent pixel is arranged adjacent to the pixel region and includes the photodiode, an on-chip lens having a curvature different from a curvature of the on-chip lens, and the wiring region.