Anti-parallel PIP and MIM Capacitors for Ultra-Low Voltage Coefficient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing integrated circuit capacitors, such as PIP and MIM capacitors, face challenges in achieving low voltage coefficient (VCC) values due to non-linear capacitance variations with applied voltage, which affect the precision of capacitive charge distribution in mixed signal circuits.
Innovation Solution
A composite capacitor array is formed using a common centroid pair of 'anti-parallel' PIP and MIM capacitors in a tessellated pattern, which minimizes both linear and quadratic voltage coefficient variations by canceling out capacitance changes through opposite curvatures of the dielectric materials, specifically silicon dioxide and silicon nitride, and optimizing the layout to reduce mechanical stress and parasitic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional single capacitor structures (PIP or MIM) are used, then the device complexity is low, but the voltage coefficient precision is insufficient due to non-linear capacitance variations
Solution Approach 1:
The capacitor structure is segmented into multiple distinct capacitor elements (first capacitor with positive curvature dielectric, second capacitor with negative curvature dielectric) that are connected in parallel. Each segment has opposite curvature characteristics that cancel out non-linear voltage coefficient variations when combined, achieving ultra-low VCC while maintaining manageable complexity through modular design
Solution Approach 2:
The invention uses composite dielectric materials with opposite curvature characteristics (positive curvature material like silicon dioxide and negative curvature material like silicon nitride) to form parallel capacitor structures. The composite arrangement exploits the opposing curvature effects to cancel non-linear voltage dependence, achieving precision unattainable with single-material capacitors
2Measurement precision
If anti-parallel capacitor connection is used, then linear voltage coefficient variation is eliminated, but non-linear capacitance variations remain unaffected
Solution Approach 1:
The invention changes the curvature parameter of the dielectric materials from uniform to opposite (positive and negative) to fundamentally alter the voltage-co capacitance relationship. By selecting dielectric materials with opposite curvature characteristics and configuring them in parallel, the system achieves cancellation of both linear and non-linear voltage coefficient variations, improving reliability beyond traditional anti-parallel connections
3Measurement precision
If multiple capacitor types are combined in parallel, then non-linear voltage coefficient variations are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The invention applies local quality by assigning different dielectric materials with opposite curvature characteristics to specific capacitor regions. The first capacitor uses positive curvature dielectric material while the second capacitor uses negative curvature dielectric material, creating localized property differences that collectively cancel non-linear voltage variations, thereby reducing overall VCC while managing manufacturing precision through targeted material selection
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 approach results in capacitors with significantly reduced VCC values, improving the accuracy of analog and mixed-signal circuits by minimizing capacitance variations, particularly in Analog to Digital Converters (ADCs), and enhancing the reliability and thermal stability of the capacitors.
Implementation Method 1
minimizes both linear and quadratic voltage coefficient variations by canceling out capacitance changes through opposite curvatures of the dielectric materials, specifically silicon dioxide and silicon nitride
Data Source
AI summary
A capacitor has first and second conducting plates and a dielectric region between the plates, wherein the dielectric region comprises two dielectric materials for each of which the variation of capacitance with voltage can be approximated by a polynomial having a linear coefficient and a quadratic coefficient, and wherein the quadratic coefficients of the two dielectric materials are of opposite sign. The capacitor comprises for example a first capacitor (42) and a second capacitor (44) that one connected in an anti-parallel manner. The insulating layer (18) of the first capacitor comprises silicon nitride and the insulating layer (16) of the second capacitor comprises silicon dioxide.