Offset Lens Layout in Image Sensors to Bypass Metal Pad Shading
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Solution Overview
Problem
Conventional image sensors face challenges in efficiently aligning the focus of optical components with the centers of photodiodes, leading to suboptimal light convergence and potential interference from metal pads, which can block light intended for photodiodes.
Innovation Solution
The image sensor design incorporates a grid with apertures and optical components, including lenses that misalign their focus points with the photodiode centers, ensuring light convergence directly on the photodiodes while avoiding obstruction by metal pads, and optionally includes waveband filters within the apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the focus of optical components is aligned with the center of photodiodes, then light capture efficiency is improved, but interference from metal pads or waveband filters increases
Solution Approach 1:
The patent applies asymmetry by deliberately misaligning the optical components (lenses, mirrors, or reflective elements) relative to the photodiode centers. The optical components are positioned offset from the photodiode centers, creating an asymmetric configuration that allows light to bypass metal pads and waveband filters that would otherwise be in the direct light path. This asymmetric placement resolves the contradiction by sacrificing perfect alignment to avoid harmful interference from underlying structures.
Solution Approach 2:
The patent introduces an intermediary approach by positioning optical components between the light source and photodiodes in a misaligned configuration. These optical components act as mediators that redirect or reflect light around obstacles (metal pads and waveband filters) toward the photodiodes. The misalignment creates a path where light interacts with the optical intermediary elements first, which then guide the light to the photodiode centers, avoiding direct obstruction by the harmful structures.
2Object-affected harmful factors
If optical components are misaligned with photodiode centers, then interference from metal pads is reduced, but light capture precision deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the positional parameters of the optical components relative to the photodiode array. Specifically, the optical components are positioned at predetermined offset distances from the photodiode centers rather than at zero offset. This parameter adjustment (changing the alignment position from perfect center alignment to controlled misalignment) resolves the contradiction by optimizing the balance between avoiding metal pad interference and maintaining adequate light capture precision through calculated positional relationships.
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 light convergence efficiency by aligning focus points with photodiode centers, preventing light blockage by metal pads and allowing specific wavelength filtering, thereby improving image sensor performance.
Implementation Method 1
The optical components includes a first optical component above a first photodiode of the plurality of photodiodes, the first optical component includes at least one lens and provides at least one focus on the first photodiode
Implementation Method 2
solid-state imaging devices, for example charge-coupled device (CCD) sensors or complementary metal-oxide semiconductor (CMOS) sensors, have photoelectric transducers such as photodiodes for converting light into electric charges
Data Source
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AI summary
An image sensor includes a photodiode array having a plurality of photodiodes, a grid disposed over the photodiode array, and a plurality of optical components disposed over the grid and corresponding to the plurality of apertures, respectively. The grid defines a plurality of apertures corresponding to the plurality of photodiodes, respectively. The optical components includes a first optical component above a first photodiode of the plurality of photodiodes, the first optical component includes at least one lens and provides at least one focus on the first photodiode, in which the focus of the lens of the first optical component misaligns a center of the first photodiode, in a plan view.