Planar MIM Capacitor Structure for Hillock-Free Breakdown Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MIM capacitors face challenges such as high manufacturing costs, narrow process margins, and susceptibility to hillock formation, which affect breakdown voltage and performance.
Innovation Solution
A MIM capacitor module is designed with a bottom electrode, an insulator cup, and a top electrode, where the top electrode is capacitively coupled through a laterally-extending insulator cup base, allowing for a planar capacitor structure that can be constructed concurrently with interconnect structures without additional mask layers, using a damascene process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MIM capacitors are constructed between two interconnect metal layers with multiple additional mask layers and process steps, then the capacitor performance is improved, but the manufacturing cost increases and device complexity increases
Solution Approach 1:
The patent merges the capacitor formation process with the existing interconnect metal layer formation process. The bottom electrode is formed using the same aluminum interconnect layer that forms the metal layers, eliminating the need for separate capacitor electrode formation steps and mask layers. This integration reduces device complexity while maintaining capacitor performance.
Solution Approach 2:
The aluminum interconnect layer serves multiple functions: it acts as both the interconnect metal layer and the bottom electrode of the MIM capacitor. This multi-functionality eliminates the need for dedicated capacitor electrode materials and additional processing steps, reducing both device complexity and manufacturing cost.
2Ease of manufacture
If conventional MIM capacitors use aluminum interconnect layers for the bottom electrode, then the manufacturing process is simplified, but hillock formation occurs at high temperatures affecting breakdown voltage
Solution Approach 1:
The patent introduces an insulator cup structure as an intermediary element that surrounds the bottom electrode. This insulator cup prevents direct contact between the aluminum bottom electrode and surrounding conductive structures, eliminating capacitive coupling that would otherwise be affected by hillock formation. The insulator cup acts as a mediator that protects the capacitor's electrical characteristics from the physical defects in the aluminum layer.
3Device complexity
If the top electrode is formed with thickness constraints and limited material choices, then the capacitor structure remains simple, but the top electrode resistance increases limiting performance
Solution Approach 1:
The patent changes the material parameter of the top electrode from conventional materials to tungsten, which has superior electrical conductivity and can be deposited as thin films. This material substitution allows the top electrode to achieve low resistance even with thickness constraints, improving capacitor performance without significantly increasing device complexity.
Data Source
AI summary
A metal-insulator-metal (MIM) capacitor includes a bottom electrode, an insulator cup formed on the bottom electrode, a top electrode formed in an opening defined by the insulator cup, a top electrode connection element electrically connected to the top electrode, a vertically-extending bottom electrode contact electrically connected to the bottom electrode, and a bottom electrode connection element electrically connected to the vertically-extending bottom electrode contact. The bottom electrode is formed in a lower metal layer. The insulator cup is formed in a tub opening in a dielectric region and includes a laterally extending insulator cup base formed on the bottom electrode and a vertically-extending insulator cup sidewall extending upwardly from the laterally extending insulator cup base. The top electrode connection element and bottom electrode connection element are formed in an upper metal layer.