Back-Gate Bias Enhances eFuse Silicide Migration
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Solution Overview
Problem
Conventional electrically programmable fuses (eFuses) face challenges in silicide migration due to scaling down of poly gate dimensions, leading to non-functional eFuses and malfunctions related to full silicidation, especially when the medium becomes smaller than a critical dimension.
Innovation Solution
The introduction of a back gate bias under the cathode in the eFuse structure enhances silicide migration from the cathode to the anode, utilizing transistor characteristics and a back gate structure with a gate dielectric layer, which accelerates silicide migration through Joule-heating and self-heating mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If poly gate dimensions are scaled down to smaller dimensions, then device integration density is improved, but silicide migration becomes more difficult and full silicidation causes malfunction
Solution Approach 1:
The patent introduces a back gate structure that operates in a different dimensional space (underneath the semiconductor layer) to influence silicide migration. By applying voltage to the back gate, electric field lines are created that extend through the semiconductor layer to enhance silicide migration from cathode to anode, effectively adding a vertical dimension to the migration control mechanism.
Solution Approach 2:
The patent changes the electrical parameters by applying a voltage potential to the back gate structure during programming. This voltage modulation creates enhanced electric fields that accelerate silicide migration, allowing complete migration even when the poly gate dimensions are scaled down to sub-critical sizes where conventional migration would fail.
2Speed
If high current is forced through the eFuse for programming, then silicide migration is accelerated, but incomplete migration renders the eFuse non-functional
Solution Approach 1:
The back gate structure serves as an intermediary element that mediates the silicide migration process. Instead of relying solely on high current through the eFuse, the back gate acts as a mediator that generates additional electric fields to facilitate complete silicide migration, ensuring reliable programming without risking incomplete migration.
Solution Approach 2:
The back gate structure is positioned and configured in advance to provide enhanced electric field assistance during the programming process. This preliminary structural arrangement ensures that when programming current is applied, the silicide migration is immediately enhanced by the back gate's electric field, preventing incomplete migration before it can occur.
3Ease of manufacture
If conventional eFuse structure is used with scaled poly gates, then manufacturing cost is reduced, but silicide migration completeness cannot be ensured
Solution Approach 1:
The back gate structure is designed to serve multiple functions: it acts as a control element for silicide migration enhancement, provides voltage modulation capability, and maintains compatibility with existing scaled poly gate manufacturing processes. This multi-functionality allows the structure to improve migration completeness without adding significant manufacturing complexity.
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 ensures effective silicide migration with an absence of residue in the back-gate structure region, enhancing the programming efficiency and reliability of eFuses by ensuring complete silicide migration from cathode to anode, even at smaller dimensions.
Implementation Method 1
accelerates silicide migration through Joule-heating and self-heating mechanisms
Implementation Method 2
accelerates silicide migration through Joule-heating and self-heating mechanisms
Data Source
AI summary
An electrically programmable fuse (eFuse) comprises a semiconductor layer, a silicide layer overlying the semiconductor layer, and first and second contact structures electrically coupled to the silicide layer. The first contact structure is configured to function as an anode and the second contact structure is configured to function as a cathode. The eFuse further comprises a back-gate structure disposed underneath the semiconductor layer in a back-gate structure region proximate the second contact structure, the back-gate structure region excluding a region proximate the first contact structure. Responsive to (i) a programming voltage potential supplied between the first and second contact structures and (ii) a voltage potential supplied to the back-gate structure, silicide of the silicide layer operates to migrate, with an enhanced migration, into the semiconductor layer from the cathode to the anode with an absence of silicide residue in at least the back-gate structure region of the semiconductor layer between the first and second contact structures.