Composite Plug Phase Change Memory Device Structure

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Solution Overview

Problem

Conventional phase change memory devices require a multilayer structure, increasing size, complexity, and manufacturing steps, and suffer from heat radiation issues due to the upper electrode's high thermal conductivity, which lowers thermal efficiency.

Innovation Solution

A phase change memory device with a composite plug structure where a first conductive material with high resistivity acts as both a heater electrode and contact plug, and a second conductive material with lower resistivity reduces electric resistance, eliminating the need for a separate heater electrode and simplifying the structure, while inhibiting heat radiation by removing the upper electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a multilayer structure with separate heater electrode and contact plug is used, then the device structure is more complete and reliable, but the device size increases and manufacturing complexity increases

Engineering Contradiction:

Improvedevice structure completenessVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the heater electrode and contact plug into a single integrated composite plug structure. The composite plug includes a first conductive material (heater electrode portion) and a second conductive material (contact plug portion) that are electrically connected and functionally integrated, eliminating the need for separate heater electrode and contact plug layers. This merging reduces the number of layers and manufacturing steps while maintaining the necessary functions of both components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The composite plug serves multiple functions simultaneously: it acts as both the heater electrode (generating Joule heat for phase change) and the contact plug (providing electrical connection). The first conductive material portion provides heating functionality while the second conductive material portion provides low-resistance electrical connection, allowing a single structure to fulfill multiple roles that previously required separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a multilayer structure with separate heater electrode and contact plug is used, then the device structure is more complete and reliable, but the manufacturing steps increase

Engineering Contradiction:

Improvedevice structure completenessVSAvoidmanufacturing process simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the formation of heater electrode and contact plug into a single manufacturing step. The composite plug is formed by depositing and patterning a combined structure containing both conductive materials in one process flow, rather than requiring separate deposition, patterning, and alignment steps for the heater electrode and contact plug. This significantly reduces manufacturing complexity and improves ease of production.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If an upper electrode is present on the phase change layer, then the device structure is complete, but heat radiation increases and thermal efficiency decreases

Engineering Contradiction:

Improvedevice structure completenessVSAvoidheat loss through radiation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent removes (extracts) the upper electrode from the device structure. By eliminating the upper electrode that was previously present on top of the phase change layer, the patent prevents the heat radiation pathway that the upper electrode created. This extraction of the harmful component (upper electrode) directly reduces heat loss and improves thermal efficiency while maintaining the essential functionality of the phase change memory device.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration reduces the size and complexity of the device, enhances thermal efficiency by minimizing heat loss, and simplifies the manufacturing process, enabling mass production of large-scale phase change memory devices.

Implementation Method 1

a current is passed through a current path composed of a conductor layer, a first contact plug connected to the conductor layer, a heater electrode connected to the contact plug, and a phase change layer connected to the heater electrode to generate Joule heat at an interface between the phase change layer and the heater electrode

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS7532507B2Phase change memory device and method for manufacturing phase change memory device

Publication Date: 2009.05.12 MICRON TECHNOLOGY INC

AI summary

A composite plug 104 is formed, and both a first plug (TiN) 106 and a second plug (W) 108 are disposed in one contact hole; the first plug (TiN) 106 functions as a heater electrode and the second plug (W) 108 functions as a contact plug. This eliminates the need to stack the heater electrode on the contact plug. The resistivities R11 and R12 of the first and second plugs of the composite plug 104 are in a relationship R11>R12.