Stacked Analog Capacitor Parasitic Noise Compensation
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Solution Overview
Problem
Analog capacitors in semiconductor devices are prone to output voltage variation due to parasitic capacitance, especially when located near peripheral circuit regions, which affects noise immunity and accuracy.
Innovation Solution
The implementation of a multi-level stacked analog capacitor structure, comprising a semiconductor substrate, interlayer insulating layers, and multiple capacitors with floating electrodes, where only the top capacitor's first electrode is coupled to the output voltage terminal, effectively compensates for parasitic capacitance by stacking capacitors to reduce noise-induced voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single metal layer analog capacitor is located near the peripheral circuit region, then the device complexity is reduced, but parasitic capacitance induces noise in the output voltage
Solution Approach 1:
The patent transitions from a planar single-layer capacitor to a three-dimensional multi-level stacked capacitor structure. By stacking multiple capacitor layers vertically (first level, second level, third level capacitors), the design utilizes the vertical dimension to increase capacitance while maintaining a compact footprint, thereby reducing the impact of parasitic capacitance from peripheral circuits.
Solution Approach 2:
The patent implements nested capacitor structures where multiple capacitors are stacked one on top of another, with lower-level capacitors positioned beneath upper-level capacitors. The floating electrodes of upper capacitors are positioned near the output node of lower capacitors, creating a nested configuration that compensates for parasitic effects through mutual capacitance interaction.
2Object-affected harmful factors
If multiple stacked capacitors are implemented, then parasitic capacitance impact is reduced, but the manufacturing process complexity increases
Solution Approach 1:
The patent merges the formation of multiple capacitor layers into a unified manufacturing process. The first, second, and third level capacitors are formed using the same process steps (forming dielectric layers, forming electrode patterns, etching), allowing simultaneous fabrication of multiple stacked capacitors without requiring separate dedicated process sequences for each capacitor level.
Solution Approach 2:
The patent employs universal process steps that serve multiple functions: the same dielectric layer formation process creates insulation for multiple capacitor levels, the same electrode formation process creates electrodes for different capacitors, and the same etching process defines patterns for all capacitor levels. This multi-functionality reduces overall manufacturing complexity.
3Reliability
If floating electrodes are used in stacked capacitors, then noise immunity is improved, but the device complexity increases
Solution Approach 1:
The patent converts the potentially harmful effect of parasitic capacitance into a beneficial effect. The floating electrodes of upper capacitors, which could be seen as additional parasitic elements, actually provide mutual capacitance compensation that counteracts the negative effects of parasitic capacitance from peripheral circuits, thereby improving noise immunity and output voltage accuracy.
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 significantly reduces the impact of parasitic capacitance, maintaining the output voltage accuracy close to theoretical values by mutual capacitance compensation across stacked levels, enhancing noise immunity and process efficiency without requiring additional fabrication steps.
Implementation Method 1
parasitic capacitances may induce noise in an output voltage of the analog capacitor
Implementation Method 2
Each of the first to third level capacitors may include a first capacitor electrode and a second capacitor electrode insulated from each other to constitute a capacitor
Data Source
AI summary
An analog capacitor is disclosed. The analog capacitor may include a main analog capacitor, an interlayer insulating layer, and a plurality of stacked sub analog capacitors. The main analog capacitor may be formed over a semiconductor substrate. The interlayer insulating layer may be interposed between the semiconductor substrate and the main analog capacitor. The plurality of stacked sub analog capacitors may be inserted into the interlayer insulating layer.