Light Receiving Device Shallow Trench Isolation Crosstalk
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Solution Overview
Problem
The existing light receiving devices with deep trench isolation structures face a trade-off between preventing crosstalk between adjacent pixels and maintaining sensitivity, particularly in the wavelength range of 800 nm and higher, as the large area required for the quenching resistor reduces the effective light receiving area of the avalanche photo diode (APD).
Innovation Solution
The implementation of a light receiving device with a shallow trench isolation structure below the quenching resistor, allowing for sufficient insulation while minimizing the reduction in the effective light receiving area, by setting the width of the deep trench isolation portion independently of the quenching resistor, thereby expanding the effective light receiving area and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a deep trench isolation structure is used to separate adjacent pixels to prevent crosstalk, then crosstalk between pixels is reduced, but the effective light receiving area of the APD decreases and sensitivity decreases
Solution Approach 1:
The patent introduces a vertical dimension by forming the shallow trench isolation portion at a different depth level within the semiconductor substrate. The DTI structure extends from the surface to a first depth, while the STI portion is formed at a second depth below the first depth, creating a multi-level isolation architecture that prevents crosstalk without increasing lateral isolation width
Solution Approach 2:
The shallow trench isolation portion is nested within the semiconductor substrate at a depth below the deep trench isolation structure. This nested configuration allows the STI to provide additional insulation for the quenching resistor without interfering with the lateral light receiving area of the APD at the surface level
2Reliability
If the cross-sectional area of the DTI structure is increased to insulate the quenching resistor, then insulation is improved, but the effective light receiving area of the APD decreases
Solution Approach 1:
The patent moves the isolation function from a lateral dimension (increasing DTI width) to a vertical dimension (adding STI at a deeper level). This allows insulation of the quenching resistor without increasing the lateral cross-sectional area that would block incident light
Solution Approach 2:
The shallow trench isolation portion is locally positioned at a specific depth region where the quenching resistor is located, providing targeted insulation only where needed rather than increasing isolation across the entire pixel region
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 effectively reduces crosstalk while maintaining high sensitivity in the specified wavelength range, particularly above 800 nm, by allowing a wider light receiving area for the APD without compromising insulation of the quenching resistor.
Implementation Method 1
a photoelectric transducer connected to a quenching resistor... Each pixel region comprises an avalanche photo diode (APD)... for measuring the number of incident photons
Data Source
AI summary
According to one embodiment, a light receiving device, includes pixel regions, each comprising a photoelectric transducer. Each photoelectric transducer is connected to a quenching resistor. A deep trench isolation structure surrounds and separates each pixel region. A plurality of shallow trench isolation portions is in the light receiving device. Each shallow trench isolation portion is below a quenching resistor and on a portion the deep trench isolation structure.