Time-of-Flight Sensor Charge Extraction With N-Doped Readout
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Solution Overview
Problem
Current optical time-of-flight sensor devices face limitations in signal quality and efficiency due to the transport of photo-generated charge carriers, affecting signal-to-noise ratio and high-temperature operability.
Innovation Solution
The design incorporates a semiconductor substrate with a n-doped region and a control electrode to efficiently demodulate photo-generated charge carriers, using a buried doping layer and trench structure to enhance signal extraction and reduce noise, thereby improving the signal-to-noise ratio and operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photogate structures are used to redirect photo-generated charge carriers to readout nodes, then time of flight information can be obtained, but the signal quality and efficiency of charge carrier transport deteriorate
Solution Approach 1:
The patent changes the doping parameter from conventional p-type to n-type for the substrate doping region. This parameter change fundamentally alters the charge carrier transport mechanism, enabling direct drift-based transport of photo-generated electrons to the readout node without requiring photogate structures, thereby improving signal quality while maintaining time of flight measurement capability
Solution Approach 2:
The patent extracts and eliminates the photogate structures from the sensor design. By removing these intermediate redirecting structures and implementing direct charge carrier transport through the n-doped substrate, the patent simplifies the device architecture and improves signal efficiency while preserving the essential time of flight information extraction function
2Device complexity
If conventional doping structures are used, then device simplicity is maintained, but signal-to-noise ratio and high temperature operability deteriorate
Solution Approach 1:
The patent applies a parameter change by inverting the doping type from p-type to n-type in the substrate region. This single parameter change simultaneously improves signal-to-noise ratio through enhanced charge carrier collection efficiency and high temperature operability through reduced thermal generation of minority carriers, while maintaining relatively simple device structure
Solution Approach 2:
The patent implements local quality by creating an n-doped region specifically in the substrate where charge carrier transport occurs, while other regions of the device can maintain conventional structures. This localized modification targets the critical transport region to improve signal quality without requiring comprehensive redesign of the entire device
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
The solution effectively enhances the signal-to-noise ratio and maintains high operational efficiency across varying temperatures by efficiently demodulating and extracting photo-generated charge carriers, improving the overall performance of the time-of-flight sensor device.
Implementation Method 1
a conversion region 112 to convert an electromagnetic signal S1 in photo-generated charge carriers 114a, 114b
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
According to an embodiment, a time of flight sensor device 100 comprises: a semiconductor substrate 110 comprising a conversion region 112 to convert an electromagnetic signal S1 in photo-generated charge carriers 114a, 114b, and comprising a substrate doping region 116 having a n doping type, wherein the substrate doping region 116 extends from a first main surface region 110-A of the semiconductor substrate 110 into the semiconductor substrate 110, wherein the semiconductor substrate 110 has adjacent to the substrate doping region 116 a p doped region 110-1, and wherein the substrate doping region 116 at least partially forms the conversion region 112 in the semiconductor substrate 110, a readout node 120 arranged in the semiconductor substrate 110 within the substrate doping region 116 and having the n-doping type, wherein the readout node 120 is configured to readout the photo generated charge carriers 114b; and a control electrode 122 arranged in the substrate doping region 116 of the semiconductor substrate 110 and in the substrate doping region 116 and having the p-doping type.