Silicided FinFET Heater for Phase Change Memory

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Solution Overview

Problem

Phase change memory cells face challenges in achieving sufficient heat for phase change due to inefficient heater designs, which require multiple vias and large PCM sizes, leading to high resistance and power consumption issues.

Innovation Solution

A semiconductor device with a phase change material (PCM) contacted by silicide on silicon, where the silicon is shaped to provide high resistance and the silicide is formed as a heater, utilizing a FinFET transistor with a silicided fin to efficiently generate heat by increasing current density and reducing capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If metal heaters are used over and under the PCM, then heating capability is improved, but device complexity increases due to multiple levels of vias

Engineering Contradiction:

Improveheating capabilityVSAvoidmultiple levels of vias

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent combines the heater function with the FinFET transistor structure by siliciding the fin, merging two separate components (heater and transistor) into a single integrated structure, thereby eliminating the need for multiple vias while maintaining heating capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The FinFET transistor structure serves dual purposes: as the switching element and as the heater for the PCM. The silicided fin acts as both the transistor's current path and the heating element, providing multi-functionality that reduces device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Use of energy by moving object

If two contacts are made to the top side of the PCM, then heating efficiency is improved through increased resistance, but the PCM size must be increased

Engineering Contradiction:

Improveheating efficiencyVSAvoidPCM size

Core Design Contradiction:

Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

The patent applies silicide locally to the fin structure at specific contact points with the PCM, creating high resistance zones only where needed for heating, rather than requiring the entire PCM to be larger. This localized modification achieves heating efficiency without increasing overall PCM volume

Inventive Principle:

Principle #3Local quality

3Temperature

If contacts are tapered to increase resistance, then heating is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveheating efficiencyVSAvoidcontact fabrication

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter of the fin from pure silicon to silicided silicon, which inherently provides the desired high resistance characteristic. This material parameter change achieves the heating effect without requiring complex tapered geometries, simplifying manufacturing

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

The solution effectively lowers power consumption and improves heating efficiency by using a silicided FinFET transistor to generate heat from both sides of the PCM, ensuring adequate heating and reducing the need for multiple vias, thus enhancing the performance of phase change memory cells.

Implementation Method 1

The PCM is heated for a relatively short time and quickly cooled to achieve an amorphous state, which is high resistance. The PCM is heated at a lower temperature but for a longer time to achieve a crystalline state, which is low resistance.

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

there are phase change materials (PCMs) that change resistance upon a phase change and this change in resistance is reversible

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentUS8563355B2Method of making a phase change memory cell having a silicide heater in conjunction with a FinFET

Publication Date: 2013.10.22 NXP USA INC

AI summary

A phase change memory (PCM) cell includes a transistor, a PCM structure, and a heater. The transistor has a first current electrode and a second current electrode in a structure, and a channel region having a first portion along a first sidewall of the structure and having a second portion along a second sidewall of the structure. The second sidewall is opposite the first sidewall. The transistor has a control electrode that has a first portion adjacent to the first sidewall and a second portion adjacent to the second sidewall. The PCM structure exhibits first and second resistive values when in first and second phase states, respectively. The heater is on the structure and produces heat when current flows through the heater for changing the phase state of the phase change structure.