N-type FD Region in P-type Well for Electron Multiplication
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Solution Overview
Problem
Solid state imaging devices with epitaxial layers of high electric resistance fail to perform electron multiplication effectively, limiting their resolution and light sensitivity.
Innovation Solution
A solid state imaging device with a P-type semiconductor substrate, a P-type epitaxial layer, an imaging region, a horizontal shift register, and a multiplication register, where the N-type semiconductor region extends into a P-type well region with higher impurity concentration, and a single SiO2 insulating layer, facilitating precise electron transfer and multiplication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a substrate having an epitaxial layer with high electric resistance is used, then light sensitivity and resolution are improved, but electron multiplication is insufficient
Solution Approach 1:
The patent introduces a P-type well region with higher impurity concentration than the surrounding epitaxial layer, creating a localized region with different electrical properties. This local quality change enables sufficient electron multiplication in the multiplication register while maintaining the high electric resistance of the overall epitaxial layer for good light sensitivity and resolution.
Solution Approach 2:
The patent changes the impurity concentration parameter by forming a P-type well region with higher P-type impurity concentration than the epitaxial layer. This parameter change creates the necessary conditions for electron multiplication in the multiplication register without compromising the high electric resistance property of the epitaxial layer that enables high light sensitivity and resolution.
2Object-generated harmful factors
If a P-type well region with higher impurity concentration is formed, then electron multiplication is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the multiplication register function with the P-type well region by forming the multiplication register within the well region. This integration allows the well region to serve dual purposes: providing the high impurity concentration environment necessary for electron multiplication and serving as the structural basis for the multiplication register, thereby reducing overall device complexity.
Solution Approach 2:
The P-type well region serves multiple functions: it provides the high impurity concentration environment for electron multiplication, acts as the substrate for the multiplication register, and maintains the overall device structure. This multi-functionality reduces the need for separate structures and simplifies the overall device design.
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 device achieves significant electron multiplication even with high electric resistance epitaxial layers, enhancing resolution and light sensitivity while maintaining mechanical and electrical durability.
Implementation Method 1
there takes place a precipitous electric potential change right below a transfer electrode of the multiplication register
Implementation Method 2
electron multiplication takes place when an electric potential of a next-stage transfer electrode (multiplication electrode) is greatly increased
Implementation Method 3
electrons in the horizontal shift register are transferred within the semiconductor having an excellent crystalline property
Data Source
AI summary
A solid state imaging device includes a P-type semiconductor substrate 1A, a P-type epitaxial layer 1B grown on the semiconductor substrate 1A, an imaging region VR grown within the epitaxial layer 1B, and an N-type semiconductor region 1C grown within the epitaxial layer 1B. The solid state imaging device further includes a horizontal shift register HR that transmits a signal from the imaging region VR, and a P-type well region 1D formed within the epitaxial layer 1B. The N-type semiconductor region 1C extends in the well region 1D. A P-type impurity concentration in the well region 1D is higher than a P-type impurity concentration in the epitaxial layer 1B. A multiplication register EM that multiplies electrons from the horizontal shift register HR is formed in the well region 1D.