Discrete Capacitor Impurity Diffusion Layer DC Bias
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Solution Overview
Problem
Existing discrete capacitors face challenges in achieving excellent DC bias characteristics due to high rates of change in capacitance values with respect to DC bias, which affects their reliability and performance.
Innovation Solution
A discrete capacitor design featuring an impurity diffusion layer with a concentration of not less than 5×10^19 cm^-3 and a dielectric film structure, including an ONO film, is used to minimize the rate of change of capacitance with respect to DC bias, with specific manufacturing methods such as thermal oxidation treatment at controlled temperatures to optimize impurity concentration and dielectric film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional discrete capacitor structures are used, then manufacturing is simpler, but DC bias characteristics deteriorate due to high rates of change in capacitance values
Solution Approach 1:
The capacitor structure is segmented into distinct functional layers: a substrate with controlled impurity diffusion layer, a dielectric film layer, and electrode layers. This segmentation allows independent optimization of each layer's properties to achieve excellent DC bias characteristics while maintaining manufacturability through standardized layer-by-layer fabrication processes.
Solution Approach 2:
The impurity concentration in the substrate is locally controlled to be not less than 5×10^19 cm^-3 in specific regions where the capacitor is formed. This local quality control ensures optimal DC bias characteristics in the capacitor region while allowing other parts of the substrate to have different properties suitable for their specific functions.
2Reliability
If impurity concentration is increased to improve DC bias characteristics, then capacitance stability improves, but manufacturing precision requirements increase
Solution Approach 1:
The impurity concentration parameter is changed to a specific range (not less than 5×10^19 cm^-3) that optimizes DC bias characteristics. This parameter change is achieved through controlled thermal diffusion processes during manufacturing, where temperature and time parameters are precisely controlled to achieve the desired impurity concentration without requiring excessively tight tolerances.
Solution Approach 2:
The impurity diffusion process is performed as a preliminary action during substrate preparation, before the dielectric film and electrode layers are formed. This preliminary establishment of optimal impurity concentration ensures that subsequent manufacturing steps operate on a substrate already optimized for DC bias characteristics, reducing the need for precise control in later steps.
3Reliability
If dielectric film thickness is optimized to reduce capacitance change, then DC bias characteristics improve, but manufacturing complexity increases
Solution Approach 1:
The dielectric film thickness is optimized to specific ranges that minimize the rate of change of capacitance value with respect to DC bias. This parameter optimization is achieved through controlled deposition or growth processes that can precisely control film thickness while maintaining simplicity in the overall manufacturing approach.
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 results in a discrete capacitor with a rate of change of capacitance value of |0.1|% or less over a DC bias range of -10V to +10V, enhancing DC bias characteristics and reliability by reducing impurity diffusion and optimizing dielectric film properties.
Implementation Method 1
an impurity diffusion layer formed on a front surface portion of the substrate, wherein a concentration of the impurity diffusion layer is not less than 5×10^19 cm^-3
Implementation Method 2
specific manufacturing methods such as thermal oxidation treatment at controlled temperatures to optimize impurity concentration and dielectric film thickness
Data Source
AI summary
A discrete capacitor of the present invention includes a substrate having a front surface portion, an impurity diffusion layer formed on the front surface portion of the substrate, an oxide film formed on the substrate and having a first opening to selectively expose the impurity diffusion layer, a dielectric film formed on the impurity region having been exposed from the oxide film, and a first electrode opposed to the impurity diffusion layer with the dielectric film therebetween, wherein the impurity concentration on the front surface portion of the impurity diffusion layer is 5×1019 cm−3 or more.