Capacitor Electrode Formation Using Protective Covering Layer

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Solution Overview

Problem

In the fabrication of integrated circuits, particularly in DRAM circuitry, the challenge lies in maintaining high storage capacitance as integrated circuit density increases, leading to difficulties in etching capacitor electrode openings within insulative materials, which can result in capacitor electrodes toppling due to their tall and narrow structure, and the risk of etchant seeping through cracks or pinholes in the titanium nitride layer, causing shorts in peripheral circuitry.

Innovation Solution

The formation of a conductive covering material, such as polysilicon or silicon nitride, is used to line the internal portions of capacitor electrodes and the titanium nitride layer, preventing etchant seepage and subsequent etching of peripheral circuitry material, while a dedicated wet etch process selectively removes the covering material after exposing outer sidewalls of the capacitor electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If capacitor electrodes are formed in deep openings to increase vertical dimension and capacitance, then storage capacitance is improved, but the electrodes become tall and narrow leading to toppling during etching and transport

Engineering Contradiction:

ImprovecapacitanceVSAvoidelectrode stability

Core Design Contradiction:

Volume of stationary objectVSStability of the object's composition

Solution Approach 1:

A conductive covering material (polysilicon or silicon nitride) is deposited as an intermediary layer over the titanium nitride layer and capacitor electrodes. This covering material acts as a protective mediator that prevents etchant from reaching and damaging the peripheral circuitry while allowing the capacitor electrodes to maintain their tall, narrow structure for increased capacitance without toppling during processing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If titanium nitride layer is used to line capacitor electrode openings, then electrode formation is enabled, but etchant can seep through cracks or pinholes causing shorts in peripheral circuitry

Engineering Contradiction:

Improveelectrode formationVSAvoidcircuitry integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A conductive covering material is deposited as a flexible protective film over the titanium nitride layer. This thin film shell conforms to the underlying structure and provides continuous coverage that seals against etchant seepage through cracks or pinholes in the titanium nitride, preventing shorts in peripheral circuitry while maintaining the ease of electrode formation

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The conductive covering material is deposited beforehand to protect the peripheral circuitry from potential etchant damage. This prior protective layer cushions against the harmful effect of etchant seepage that could occur through defects in the titanium nitride layer, ensuring circuitry integrity before the etching process begins

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Volume of stationary object

If insulative material is etched away to expose outer sidewall surfaces for increased capacitance, then capacitance is improved, but peripheral circuitry material may be damaged by etchant

Engineering Contradiction:

ImprovecapacitanceVSAvoidetchant damage to peripheral circuitry

Core Design Contradiction:

Volume of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The conductive covering material serves as an intermediary protective layer between the etchant and the peripheral circuitry material. It allows the etching process to proceed to expose outer sidewall surfaces for increased capacitance while simultaneously protecting the peripheral circuitry from etchant damage through its continuous coverage and etchant resistance

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively prevents etchant-induced shorts in peripheral circuitry and ensures the exposure of outer sidewall surfaces of capacitor electrodes, maintaining structural integrity and increasing capacitance without damaging the insulative material in the peripheral circuitry area.

Implementation Method 1

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

a dedicated wet etch process selectively removes the covering material after exposing outer sidewalls of the capacitor electrodes

Methodology Applied

Scientific EffectSelective wet etching:

Data Source

PatentUS8450164B2Methods of forming a plurality of capacitors

Publication Date: 2013.05.28 MICRON TECHNOLOGY INC

AI summary

A method of forming a plurality of capacitors includes an insulative material received over a capacitor array area and a circuitry area. The array area comprises a plurality of capacitor electrode openings within the insulative material received over individual capacitor storage node locations. The intervening area comprises a trench. Conductive material is formed within the openings and against a sidewall portion of the trench to less than completely fill the trench. Covering material is formed over an elevationally outer lateral interface of the conductive material within the trench and the insulative material of the circuitry area. The insulative material within the array area is etched with a liquid etching solution effective to expose outer sidewall portions of the conductive material within the array area and to expose the conductive material within the trench. The conductive material within the array area is incorporated into a plurality of capacitors.