Programmable Fuse Using Externally Heated Phase Change Material

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Solution Overview

Problem

Existing electrically programmable fuse (eFUSE) technologies are 'one-shot,' occupy large areas, require high power/current, and are slow to program, while reprogrammable fuses using chalcogenide materials face issues with heat emission and inconvenient design due to high switching currents.

Innovation Solution

A programmable phase change material (PCM) structure is integrated at the transistor gate level of a semiconductor device, featuring a heater element with electrodes connected by a thin wire and a layer of phase change material that can be programmed between a low resistance crystalline and high resistance amorphous state using externally controlled heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If reprogrammable fuses using chalcogenide materials are used, then reprogrammability is achieved, but switching currents are high (on the order of 15 mA) resulting in large device area

Engineering Contradiction:

ImprovereprogrammabilityVSAvoiddevice area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent changes the material parameter by using phase change material (PCM) instead of chalcogenide materials, and changes the heating mechanism parameter from direct resistive heating to external heating via a separate heater element. This allows achieving reprogrammability with much lower current requirements and smaller device area.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the heating function from the memory element itself by introducing a separate heater element. This external heating approach allows the memory cell to be smaller since the heating function is performed by a dedicated component rather than requiring high current through the memory element itself.

Inventive Principle:

Principle #1Segmentation

2Productivity

If existing eFUSE technology is used, then programming is achieved, but programming speed is slow (several microseconds)

Engineering Contradiction:

Improveprogramming speedVSAvoidprogramming time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent changes the heating mechanism parameter from slow resistive heating through high current to faster external heating via a dedicated heater element. This enables much faster programming speeds while using lower current, directly addressing the speed limitation of existing eFUSE technology.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If existing eFUSE technology is used, then fuse programming is achieved, but device area is large

Engineering Contradiction:

Improveprogramming capabilityVSAvoiddevice area

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

The patent segments the heating function from the memory element by introducing a separate heater element, allowing the memory cell to be much smaller. The heater element performs the heating function externally, enabling compact memory cell design while maintaining full programming capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the heating mechanism from high-current resistive heating to low-current external heating, enabling significant reduction in device area while maintaining programming functionality.

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If reprogrammable fuses using chalcogenide materials are used, then reprogrammability is achieved, but power consumption is high

Engineering Contradiction:

ImprovereprogrammabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the material parameter to phase change material (PCM) and changes the heating mechanism to external heating via a separate heater element. This combination achieves reprogrammability with much lower power consumption compared to chalcogenide materials that require high switching currents.

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 PCM structure enables multishot reprogrammability, reduces device area, minimizes power/current requirements, and enhances programming speed, allowing for efficient and repeatable switching between resistance states.

Implementation Method 1

the heater element configured to receive programming current passed therethrough

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a layer of phase change material disposed on top of a portion of the thin wire structure

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentUS7411818B1Programmable fuse/non-volatile memory structures using externally heated phase change material

Publication Date: 2008.08.12 GLOBALFOUNDRIES US INC

AI summary

A programmable phase change material (PCM) structure includes a heater element formed at a transistor gate level of a semiconductor device, the heater element further including a pair of electrodes connected by a thin wire structure with respect to the electrodes, the heater element configured to receive programming current passed therethrough, a layer of phase change material disposed on top of a portion of the thin wire structure, and sensing circuitry configured to sense the resistance of the phase change material.