MIM Capacitor Protection via PN Junction Diode in DRAM

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Solution Overview

Problem

Plasma-induced charge damage during the fabrication of metal-insulator-metal (MIM) capacitors in semiconductor devices, particularly in back-end-of-line (BEOL) wiring levels, degrades the electrical performance and reliability of MIM capacitors in memory devices.

Innovation Solution

A metal-insulator-metal (MIM) capacitor is electrically connected to a PN junction diode through a conductive structure, forming a protection device region that mitigates plasma-induced charge damage during the BEOL process by acting as an antenna for the connected plate, reducing damage and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If plasma etching processes are used in BEOL wiring levels, then wiring fabrication is enabled, but charge damage is induced to MIM capacitor electrodes degrading electrical performance

Engineering Contradiction:

Improvewiring fabricationVSAvoidcapacitor electrical performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A diode structure is introduced as an intermediary element between the plasma environment and the MIM capacitor. The diode's heavily doped substrate and junction region act as a mediator that captures and dissipates plasma-induced charges before they can reach and damage the capacitor electrodes, thereby protecting the capacitor while allowing plasma etching to proceed in the BEOL wiring levels.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The diode protection structure is formed in the substrate before the BEOL plasma etching processes occur. By pre-positioning the diode with its heavily doped regions and junction structure, the system is prepared in advance to intercept and neutralize charges that will be generated during subsequent plasma processing, preventing charge accumulation on the capacitor electrodes.

Inventive Principle:

Principle #10Preliminary action

2Area of stationary object

If MIM capacitors are used in stacked configuration, then space efficiency is improved, but susceptibility to plasma charge damage increases

Engineering Contradiction:

Improvechip area utilizationVSAvoidplasma charge damage

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The diode structure serves as a protective intermediary positioned in the substrate beneath the stacked MIM capacitor. Its heavily doped substrate and junction region create a charge dissipation path that intercepts plasma-induced charges before they can travel through the capacitor structure, thereby protecting the compact stacked capacitor from charge damage while maintaining space efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If protection structures are added to MIM capacitors, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvecapacitor performance protectionVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protection diode structure is merged with the existing substrate and integrated into the same device region as the MIM capacitor. By combining the protection function with the substrate infrastructure and using shared fabrication processes, the design adds reliability without proportionally increasing overall device complexity or requiring separate protection modules.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The diode structure serves multiple functions: it acts as a protection element for the MIM capacitor, utilizes the existing substrate infrastructure, and can be formed using standard semiconductor fabrication processes. This multi-functionality reduces the net increase in device complexity while providing robust charge damage protection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 protects MIM capacitors from plasma-induced charge damage, improving their electrical performance and reliability while being fully compatible with existing fabrication processes, simplifying the process flow, and increasing yield without additional costs.

Implementation Method 1

plasma-induced charge damage during deposition or etching process

Methodology Applied

Scientific EffectPlasma-induced charge damage: Plasma

Implementation Method 2

acting as an antenna for the connected plate, reducing damage

Methodology Applied

Scientific EffectAntenna effect:

Data Source

PatentUS8853762B2Structure for protecting metal-insulator-metal capacitor in memory device from charge damage

Publication Date: 2014.10.07 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A dynamic random access memory (DRAM) device has a metal-insulator-metal (MIM) capacitor electrically connected to a PN junction diode through a metal bridge for protecting the MIM capacitor from charge damage generated in back end of line (BEOL) plasma process.