MIM Capacitor Metal Frame Equipotential Shielding
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Solution Overview
Problem
Metal-insulator-metal (MIM) capacitors in integrated chips experience a decrease in voltage breakdown value when exposed to wet, damp, or humid environments due to water molecules penetrating through the passivation layer, caused by a potential difference between the metal protection frame and the top metal plate.
Innovation Solution
A MIM capacitor design featuring a metal protection frame that contacts the top metal plate through an opening in the passivation layer, establishing an equal potential difference and preventing water molecules from penetrating, with the frame extending over the passivation layer and sidewalls to limit electrical gradients and enhance breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal protection frame is added to protect the MIM capacitor, then reliability is improved, but device complexity increases
Solution Approach 1:
The metal protection frame is electrically connected to the top metal plate through a conductive via that penetrates the passivation layer. This connection equalizes the electrical potential between the protection frame and the top metal plate, eliminating the potential difference that would otherwise drive water molecules through the passivation layer. By establishing equipotential conditions, the protection frame prevents moisture penetration without requiring additional complex isolation structures.
2Object-affected harmful factors
If the metal protection frame is electrically isolated from the top metal plate, then water penetration is prevented through potential difference, but manufacturing complexity increases
Solution Approach 1:
Instead of maintaining electrical isolation to prevent water penetration, the invention connects the metal protection frame to the top metal plate through a conductive via in the passivation layer. This creates equipotential conditions that eliminate the driving force for water molecule migration. The approach simplifies manufacturing by using a standard conductive via process rather than requiring complex isolation structures or multiple deposition steps.
3Object-affected harmful factors
If electrical gradient is present between metal frame and top electrode, then water molecules are driven through passivation layer, but voltage breakdown value decreases
Solution Approach 1:
The conductive via connects the metal protection frame to the top metal plate, equalizing their electrical potentials. This eliminates the electrical gradient that would otherwise exist between these structures. Without a potential difference, water molecules are not driven through the passivation layer via electrophoresis or electroosmosis, thereby maintaining the voltage breakdown value and preventing moisture-related degradation.
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 effectively prevents water molecules from reaching the top metal plate, thereby maintaining the voltage breakdown value of the MIM capacitor in humid environments by eliminating the electrical gradient between the metal frame and the top electrode.
Implementation Method 1
a potential difference between the metal protection frame and the top metal plate
Data Source
AI summary
The present disclosure relates to a MIM (metal-insulator-metal) capacitor having a top electrode overlying a substrate. A passivation layer overlies the top electrode. The passivation layer has a step region that continuously contacts and extends from a top surface of the top electrode to sidewalls of the top electrode. A metal frame overlies the passivation layer. The metal frame continuously contacts and extends from a top surface of the passivation layer to upper sidewalls of the passivation layer in the step region. The metal frame has a protrusion that extends through the passivation layer and contacts the top surface of the top electrode.