Storage Capacitor Titanium Oxide Nitride Barrier

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Solution Overview

Problem

Conventional methods for forming storage capacitors in semiconductor memory devices face challenges such as reduced capacitance and increased ohmic contact resistance due to the use of high dielectric constant materials and buffer solutions that can damage titanium silicide layers and contact plugs during processing.

Innovation Solution

The formation of a titanium oxide nitride layer on a titanium nitride layer within the storage electrode structure, which acts as a protective barrier against buffer solutions and maintains capacitance while reducing ohmic contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal silicide layer is formed between the contact plug and storage electrode to reduce ohmic contact resistance, then the ohmic contact resistance decreases, but the titanium silicide layer and contact plug become vulnerable to damage from buffer solutions during processing

Engineering Contradiction:

Improveohmic contact resistanceVSAvoiddamage from buffer solutions

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A titanium oxide nitride layer is introduced as an intermediary protective barrier between the buffer solution and the titanium silicide layer. This layer prevents the buffer solution from directly contacting and damaging the titanium silicide layer while allowing the ohmic contact function to be maintained through the titanium nitride layer beneath it.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The titanium oxide nitride layer is formed in advance before the buffer solution processing step, providing pre-protection to the titanium silicide layer. This beforehand cushioning prevents potential damage from the buffer solution during subsequent processing steps.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If high dielectric constant materials are used to increase storage capacitor capacitance, then the capacitance increases, but the interface quality between the dielectric and polysilicon electrode deteriorates

Engineering Contradiction:

ImprovecapacitanceVSAvoidinterface quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

A composite electrode structure is used consisting of multiple layers (titanium layer, titanium nitride layer, and titanium oxide nitride layer) instead of a single polysilicon electrode. This composite structure maintains good interface quality with the high dielectric constant material while enabling the formation of a protective oxide nitride layer.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The electrode material parameters are changed from pure polysilicon to a multi-layer titanium-based structure. This parameter change allows for better interface compatibility with high dielectric constant materials and enables the formation of protective oxide nitride layers through oxidation processes.

Inventive Principle:

Principle #35Parameter changes

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 enhances the production yield of memory devices by preventing damage to the titanium silicide layer and contact plug, maintaining capacitance, and reducing defects in DRAM cells.

Implementation Method 1

When a TiN layer having a high work function is used as a storage electrode that is electrically connected with a contact plug formed of a silicon-containing material such as polysilicon, the ohmic contact resistance between the electrode and the contact plug may increase. Thus, a metal silicide layer may be formed between the contact plug and the storage electrode, so as to reduce the ohmic contact resistance therebetween.

Methodology Applied

Scientific EffectSilicide formation: Chemical Bonding

Implementation Method 2

forming a titanium oxide nitride layer on the titanium layer... acts as a protective barrier against buffer solutions and maintains capacitance while reducing ohmic contact resistance... preventing damage to the titanium silicide layer and contact plug

Methodology Applied

Scientific EffectPhysical barrier protection: Physical Containment

Data Source

PatentUS7364967B2Methods of forming storage capacitors for semiconductor devices

Publication Date: 2008.04.29 SAMSUNG ELECTRONICS CO LTD

AI summary

Methods of forming a storage capacitor include forming an interlayer insulation layer having an opening therethrough on a semiconductor substrate, forming a contact plug in the opening, forming a molding oxide layer on the interlayer insulation layer and the contact plug, selectively removing portions of the molding oxide layer to form a recess above the contact plug, forming a titanium layer on a bottom surface and side surfaces of the recess, forming a titanium nitride layer on the titanium layer, and forming a titanium oxide nitride layer on the titanium nitride layer. A storage capacitor includes a semiconductor substrate, an interlayer insulation layer having a contact plug therein on the substrate, and a storage electrode on the contact plug including a titanium silicide layer, a titanium nitride layer on the titanium silicide layer, and a titanium oxide nitride layer on the titanium nitride layer.