Solid-State Image Pickup Device Capacitance Consistency
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Solution Overview
Problem
Conventional solid-state image pickup devices face challenges in achieving a high dynamic range and sensitivity, particularly under varying illumination conditions, due to limitations in capacitance adjustment and positional deviations during the manufacturing process affecting the additional capacitor's capacitance value.
Innovation Solution
The design incorporates a solid-state image pickup device with multiple pixels, each featuring a photoelectric conversion unit, amplification transistor, transfer transistor, additional capacitor, and reset transistor, where the additional capacitor can be switched on or off to adjust capacitance, and a specific semiconductor region arrangement to minimize positional deviations and enhance capacitance consistency across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional capacitor is connected to the floating diffusion to increase dynamic range, then the dynamic range is improved, but the capacitance value varies due to positional deviations in the manufacturing process
Solution Approach 1:
The patent merges the additional capacitor structure with the transistor gate structure by making the capacitor electrode coincide with the gate electrode. This integration ensures that the capacitance value is determined by the gate structure dimensions which are more controllable, thereby reducing variations in capacitance value while maintaining the dynamic range enhancement function.
Solution Approach 2:
The patent changes the parameter determination method for capacitance value from being dependent on separate capacitor electrode dimensions to being determined by the gate electrode dimensions. This parameter change links the capacitance value to the gate structure which has better manufacturing precision, thus reducing capacitance value variations.
2Reliability
If the additional capacitor is designed with separate electrodes, then the dynamic range can be increased, but the device complexity increases
Solution Approach 1:
The patent combines the additional capacitor function with the existing gate structure, eliminating the need for separate capacitor electrodes. The gate electrode serves dual purposes as both the control electrode for the transistor and the electrode for the additional capacitor, thereby reducing device complexity while maintaining dynamic range enhancement.
Solution Approach 2:
The gate electrode is designed to serve multiple functions: controlling the transistor channel and simultaneously acting as the capacitor electrode for the additional capacitor. This multi-functionality reduces the total number of components and simplifies the device structure while achieving the dynamic range increase.
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 improves the dynamic range and sensitivity of the image pickup device by allowing for adjustable capacitance, reducing variations in electrical charge voltage conversion efficiency, and enhancing image quality across different illumination conditions.
Implementation Method 1
a photoelectric conversion unit
Data Source
AI summary
One disclosed aspect of the embodiments relates to a solid-state image pickup device including a first semiconductor region, a second semiconductor region, a third semiconductor region, and a fourth semiconductor region of a same conduction type arranged in order along a first direction in an active region, and a first conduction pattern, a second conduction pattern, and a third conduction pattern provided above an active region disposed between the patterns and the semiconductor regions corresponding thereto with an insulating member interposed therebetween and electrically isolated from each other and arranged in order along the first direction.The first semiconductor region, the first conduction pattern, and the third semiconductor region constitute the transfer transistor. The first semiconductor region, the second conduction pattern, and the second semiconductor region constitute the additional capacitor, and the second semiconductor region, the third conduction pattern, and the fourth semiconductor region constitute the reset transistor.