E-Fuse Element as Diffusion Barrier for Copper Terminals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the integrated circuit industry, there is a need for improved electronic fuses (e-fuses) that can be fabricated cheaply, reliably, and with high density, especially in copper interconnect structures, which are prone to copper diffusion and corrosion, and require a dedicated e-fuse metal that acts as both a fusible element and a diffusion barrier.
Innovation Solution
The development of e-fuse modules formed in copper damascene interconnect structures, where a metal e-fuse element, such as titanium tungsten (TiW) or titanium tungsten nitride (TiW2N), serves as both a conductive path and a diffusion barrier for copper e-fuse terminals, with optional supplemental dielectric barriers like silicon nitride (SiN) or silicon carbide (SiC) to enhance protection against metal diffusion and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper interconnect structures are used for e-fuse modules, then integration with common IC manufacturing processes is improved, but copper diffusion and corrosion occur which degrade transistor performance and reliability
Solution Approach 1:
A titanium tungsten (TiW) layer is introduced as an intermediary between the copper e-fuse terminals and the underlying transistor structures. This TiW layer serves dual functions: it acts as a diffusion barrier to prevent copper atoms from migrating into the transistor region, and it provides a corrosion-resistant protective layer. The intermediary TiW layer thus resolves the contradiction by enabling copper interconnect integration while protecting against copper diffusion and corrosion that would otherwise degrade transistor performance.
Solution Approach 2:
The e-fuse terminal structure employs a composite material system consisting of copper e-fuse terminals combined with a titanium tungsten (TiW) barrier layer. The copper provides excellent electrical conductivity for the e-fuse function, while the TiW layer provides diffusion barrier and corrosion protection properties. This composite material approach allows the system to simultaneously achieve the electrical performance needed for e-fuse operation and the protective properties needed to prevent copper diffusion and corrosion that would harm transistor performance.
2Reliability
If a dielectric barrier layer is formed over copper structures to prevent diffusion, then copper diffusion is prevented, but connection of e-fuse element to copper terminals becomes challenging
Solution Approach 1:
The titanium tungsten (TiW) layer is designed to perform multiple functions simultaneously: it serves as a diffusion barrier to prevent copper from migrating into underlying structures, acts as a corrosion protection layer for the copper terminals, and provides a conductive pathway that enables electrical connection between the e-fuse element and the copper terminals. This multi-functional TiW layer resolves the contradiction by eliminating the need for a separate dielectric barrier layer that would insulate and complicate connections, while still providing the necessary diffusion protection.
Solution Approach 2:
The invention merges the diffusion barrier function and the electrical connection function into a single titanium tungsten (TiW) layer. Rather than using a dielectric barrier layer that would prevent electrical contact, the TiW layer combines the barrier properties needed to stop copper diffusion with the conductive properties needed to enable e-fuse element connection to copper terminals. This merging of functions simplifies the manufacturing process while maintaining both protection and connectivity.
3Reliability
If silicide polysilicon e-fuse is used, then low resistance path is achieved, but it is not available in high-k dielectric and metal gate transistor technology
Solution Approach 1:
The invention changes the material parameter of the e-fuse terminal from silicide polysilicon to copper, which has superior electrical conductivity and enables a lower resistance path. Simultaneously, the introduction of a titanium tungsten (TiW) barrier layer changes the structural parameters to ensure compatibility with high-k dielectric and metal gate transistor technologies. The TiW layer prevents copper diffusion into sensitive transistor regions, thereby enabling the use of copper's excellent electrical properties in advanced transistor technologies where silicide polysilicon is no longer available.
Solution Approach 2:
The titanium tungsten (TiW) layer acts as an intermediary that enables the use of copper e-fuse terminals in high-k dielectric and metal gate transistor technologies. Without this intermediary barrier layer, copper diffusion would contaminate and degrade the performance of high-k dielectric and metal gate structures. The TiW layer thus mediates between the desire to use copper's superior electrical conductivity and the need to protect sensitive transistor structures, making the e-fuse compatible with advanced transistor technologies.
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
These e-fuse modules provide reliable resistance switching between low and high resistance states, effectively preventing copper diffusion and corrosion, while simplifying the manufacturing process by reducing the number of mask layers needed, thus enhancing device reliability and performance.
Implementation Method 1
The e-fuse element may be formed from a material that provides a barrier against metal diffusion (e.g., copper diffusion) from each of the metal e-fuse terminals
Implementation Method 2
an e-fuse element formed directly on the metal e-fuse terminals to define a conductive path between the pair of metal e-fuse terminals through the e-fuse element
Implementation Method 3
copper is also susceptible to corrosion. Thus there is a need for e-fuses, formed of metal, constructed in a copper interconnect structure which copper interconnect structure is protected against copper diffusion and corrosion
Data Source
AI summary
An electronic fuse (e-fuse) module may be formed in an integrated circuit device. The e-fuse module may include a pair of metal e-fuse terminals (e.g., copper terminals) and an e-fuse element formed directly on the metal e-fuse terminals to define a conductive path between the pair of metal e-fuse terminals through the e-fuse element. The metal e-fuse terminals may be formed in a metal interconnect layer, along with various interconnect elements of the integrated circuit device. The e-fuse element may be formed by depositing and patterning a diffusion barrier layer over the metal e-fuse terminals and interconnect elements formed in the metal interconnect layer. The e-fuse element may be formed from a material that provides a barrier against metal diffusion (e.g., copper diffusion) from each of the metal e-fuse terminals and interconnect elements. For example, the e-fuse element may be formed from titanium tungsten (TiW) or titanium tungsten nitride (TiW2N).