MIM Capacitor Cup-Shaped Structure with Rounded Insulator Flange

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Solution Overview

Problem

Conventional MIM capacitors are expensive to manufacture, inefficient in area usage, and have unpredictable breakdown voltage due to hillock formation during fabrication processes.

Innovation Solution

A MIM capacitor module design featuring a bottom electrode cup with a shortened sidewall and a rounded insulator flange that covers the upper surface, formed using a CMP process with a soft polishing pad, allowing for concurrent construction with interconnect structures and avoiding additional photomasks, which results in consistent breakdown voltage and low series resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional MIM capacitor fabrication processes are used, then the capacitor can be manufactured, but the breakdown voltage is low and unpredictable due to hillock formation

Engineering Contradiction:

Improvebreakdown voltageVSAvoidbreakdown voltage control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent converts the harmful effect of hillock formation into a beneficial feature by intentionally creating a rounded corner region with controlled curvature radius. Instead of trying to eliminate surface irregularities, the invention embraces them and controls their geometry to ensure that the rounded corner has a larger curvature radius than the hillocks, thereby preventing hillock-induced breakdown while maintaining manufacturing simplicity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the geometric parameters of the capacitor structure by specifying that the rounded corner region must have a curvature radius larger than any hillocks that may form during fabrication. This parameter control transforms an uncontrolled defect into a controlled feature that guarantees reliable breakdown voltage

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If conventional MIM capacitor designs are used, then the capacitor can be formed, but the area usage is inefficient particularly for large capacitors

Engineering Contradiction:

Improvesilicon areaVSAvoidarea usage efficiency

Core Design Contradiction:

Area of stationary objectVSProductivity

Solution Approach 1:

The patent transitions from a planar capacitor design to a three-dimensional structure by creating a rounded corner region that extends vertically. This dimensional change allows the capacitor to utilize vertical space more effectively, increasing the effective capacitance area without proportionally increasing the silicon footprint

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If conventional MIM capacitor fabrication is used, then the capacitor can be manufactured, but multiple additional mask layers and process steps are required increasing cost

Engineering Contradiction:

Improvemanufacturing costVSAvoidprocess steps

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the rounded corner formation process with the existing capacitor fabrication sequence by integrating it into the metal layer deposition and CMP process. Instead of adding separate masking and etching steps, the rounded corner geometry is achieved through the natural interaction of conformal deposition and planarization processes that are already part of the manufacturing flow

Inventive Principle:

Principle #5Merging (Combining)

4Area of stationary object

If the top plate is made thin to reduce area, then area usage improves, but series resistance increases

Engineering Contradiction:

Improvetop plate areaVSAvoidseries resistance

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent implements a nested structure where the top plate is positioned within the rounded corner region that extends vertically. This nesting allows the top plate to be thinner in the horizontal plane while the rounded corner provides additional vertical capacitance area, effectively decoupling the relationship between plate thickness and series resistance

Inventive Principle:

Principle #7Nested doll (Nesting)

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 design reduces manufacturing costs, improves spatial density, and ensures consistent breakdown voltage by preventing hillock formation, thus enhancing the performance and efficiency of MIM capacitors.

Implementation Method 1

The rounded insulator flange may be formed in this rounded depression, and extends over the upper surface of the bottom electrode cup sidewall

Methodology Applied

Scientific EffectChemical-Mechanical Polishing:

Data Source

PatentUS20230207615A1Metal-insulator-metal (MIM) capacitor module including a cup-shaped structure with a rounded corner region

Publication Date: 2023.06.29 MICROCHIP TECHNOLOGY INC

AI summary

A metal-insulator-metal (MIM) capacitor includes a bottom electrode cup, an insulator, and a top electrode. The bottom electrode cup includes a laterally-extending bottom electrode cup base and a bottom electrode cup sidewall extending upwardly from the laterally-extending bottom electrode cup base. The insulator includes an insulator cup formed in an opening defined by the bottom electrode cup, and a rounded insulator flange extending laterally outwardly and curving upwardly from the insulator cup, the rounded insulator flange covering an upper surface of the bottom electrode cup sidewall. The top electrode is formed in an opening defined by the insulator cup. The top electrode is insulated from the upper surface of the bottom electrode cup sidewall by the rounded insulator flange.