Phase Change Element Composition for Low-Drift Multi-State Memory

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Solution Overview

Problem

Phase change memory (PCM) cells with germanium-based phase change elements experience resistance drift over time, leading to reduced discrete data states and endurance, making it difficult to accurately read and write data.

Innovation Solution

Incorporating enhancement elements such as nitrogen, scandium, silicon, or carbon into the phase change element (PCE) composition, eliminating or reducing germanium content, thereby reducing the resistance drift coefficient and enhancing data retention and endurance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If germanium-based phase change elements are used, then fast read and write times are achieved, but resistance drift occurs over time reducing data states and endurance

Engineering Contradiction:

Improveread and write timesVSAvoidresistance stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent modifies the chemical composition parameters of the phase change element by incorporating enhancement elements (nitrogen, scandium, silicon, or carbon) at specific atomic percentages (0.1-20%, 1-10%, or 0.1-5%). This parameter change resolves the contradiction by maintaining the fast switching speed of germanium-based materials while reducing resistance drift through optimized compositional parameters.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite phase change material by combining germanium with enhancement elements (forming Ge-Sb-Te-N, Ge-Sb-Te-Sc, Ge-Sb-Te-Si, or Ge-Sb-Te-C compositions). This composite approach maintains the beneficial fast switching characteristics of germanium while introducing elements that reduce resistance drift, thereby improving both speed and reliability simultaneously.

Inventive Principle:

Principle #40Composite materials

2Speed

If germanium content is increased to improve switching speed, then read and write performance improves, but resistance drift coefficient increases

Engineering Contradiction:

Improveswitching speedVSAvoidresistance drift coefficient

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by introducing enhancement elements at specific concentrations within the phase change layer. Rather than uniformly distributing all elements, the enhancement elements are incorporated at optimized atomic percentages (0.1-20%) to locally modify the material properties, reducing resistance drift while preserving the fast switching capability provided by germanium.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent systematically varies the atomic percentage of enhancement elements (nitrogen: 0.1-20%, scandium: 1-10%, silicon: 0.1-20%, carbon: 0.1-5%) to optimize the balance between switching speed and resistance stability. This parameter optimization allows the material to achieve both high speed performance and low resistance drift coefficient.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If phase change element composition is simplified, then manufacturing process is easier, but data retention and endurance are reduced

Engineering Contradiction:

Improvefabrication simplicityVSAvoiddata retention

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent achieves multi-functionality by selecting enhancement elements that simultaneously provide multiple benefits: nitrogen improves data retention and reduces resistance drift; scandium enhances endurance and stabilizes resistance; silicon improves data retention; carbon reduces resistance drift. This universal approach allows a single enhancement element addition to address multiple performance requirements without complicating the manufacturing process.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses small atomic percentages (0.1-20%) of enhancement elements, which can be incorporated through standard deposition processes without requiring complex additional manufacturing steps. The low concentration requirements make the process economically viable and manufacturable while still achieving significant improvements in data retention and endurance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 increases discrete data states and stability of PCM cells by minimizing resistance changes over time, improving data retention and endurance, and reducing power consumption.

Implementation Method 1

Phase change memory (PCM) is a type of nonvolatile memory in which a phase of a phase change element is employed to represent a unit of data

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

Methodology Applied

Scientific EffectResistance drift reduction:

Data Source

PatentUS12603127B2Phase change element configured to increase discrete data states

Publication Date: 2026.04.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Some embodiments relate to a memory device. The memory device includes a phase change element (PCE) overlying a substrate. A bottom electrode via is disposed over the substrate. A top electrode overlies the bottom electrode via. The PCE is disposed between the bottom electrode via and the top electrode. The PCE comprises a chalcogenide material. The chalcogenide material comprises a first atomic percentage of a first element, a second atomic percentage of a chalcogen element, and a third atomic percentage of a first dopant. The third atomic percentage is less than the first atomic percentage and is less than the second atomic percentage.