E-fuses With Tungsten Contacts For Reliable Programming
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Solution Overview
Problem
Current semiconductor fuses for high-speed applications face challenges in achieving low resistance and high density due to the limitations of existing programmable interconnect elements, particularly with the use of copper contacts which affect reliability.
Innovation Solution
The semiconductor structure incorporates a fuse element with at least one underlying tungsten contact for programming, eliminating the need for copper contacts and enhancing reliability by using a dielectric material with conductive regions and a specific configuration that allows for improved thermal budget and programming modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper contacts are used for programming the fuse element, then electrical conductivity is improved, but reliability deteriorates due to thermal budget limitations and programming failures
Solution Approach 1:
The patent changes the material parameter of the contact from copper to tungsten, which fundamentally alters the thermal and electrical properties. Tungsten's higher melting point and thermal stability enable it to withstand the thermal budget of semiconductor processing without failing, while maintaining sufficient electrical conductivity for fuse programming. This material parameter change resolves the reliability issue without adding structural complexity.
Solution Approach 2:
The patent employs a composite contact structure where tungsten serves as the primary contact material, potentially combined with other materials or structures to optimize both electrical conductivity and thermal stability. This composite approach allows the contact to simultaneously achieve the electrical performance needed for programming and the thermal resistance required for high-temperature processing, thereby improving reliability without significant complexity increase.
2Productivity
If the fuse element is made small to achieve high density, then integration density is improved, but programming reliability deteriorates due to insufficient current handling
Solution Approach 1:
The patent changes the contact material to tungsten, which has superior electrical and thermal properties compared to copper. This material parameter change enables the contact to handle higher programming currents effectively, ensuring reliable fuse programming even when the fuse element dimensions are reduced for high density. The tungsten contact's ability to withstand high current density without failure allows small fuse elements to maintain programming reliability.
3Adaptability or versatility
If a thermal budget is increased to improve manufacturing flexibility, then process adaptability is improved, but copper contact integrity deteriorates due to oxidation and diffusion
Solution Approach 1:
The patent changes the contact material from copper to tungsten, fundamentally altering the material's resistance to thermal degradation. Tungsten's extremely high melting point and low reactivity allow it to withstand elevated temperatures and extended thermal budgets without oxidation or diffusion issues that plague copper. This material substitution enables the manufacturing process to use higher thermal budgets for improved process flexibility and integration with other high-temperature semiconductor processes, while the tungsten contact maintains its structural and electrical integrity throughout.
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 provides improved reliability and thermal budget for semiconductor structures by using tungsten contacts for programming, enabling efficient and reliable operation without copper contacts, thus addressing the limitations of existing technologies.
Implementation Method 1
The third category includes electrically blown anti-fuses, where the fuse is programmed with an electric current, which reduces the resistance across the fuse
Implementation Method 2
a fuse element, e.g., sacrificial metal lines buried in a dielectric layer in the circuits (which are normally closed) are blown by vaporizing the fuse element with laser energy to open the circuit
Data Source
AI summary
Semiconductor structures are provided containing an electronic fuse (E-fuse) that includes a fuse element and at least one underlying tungsten contact that is used for programming the fuse element. In some embodiments, a pair of neighboring tungsten contacts is used for programming the fuse element. In another embodiment, an overlying conductive region can be used in conjunction with one of the underlying tungsten contacts to program the fuse element. In the disclosed structures, the fuse element is in direct contact with upper surfaces of a pair of underlying tungsten contacts. In one embodiment, the semiconductor structures may include an interconnect level located atop the fuse element. The interconnect level has a plurality of conductive regions embedded therein. In other embodiments, the fuse element is located within an interconnect level that is located atop the tungsten contacts.