Semiconductor Interconnects Using Titanium Nitride Overlayers
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Solution Overview
Problem
The challenge in semiconductor device fabrication lies in the electrical performance issues caused by diffusion or electromigration of metal materials in interlayer dielectrics, contamination, shorting, and non-uniformity of intermetallic composites (IMCs) at the interfaces between different conductive materials in interconnect components, which affect device density and speed.
Innovation Solution
The solution involves forming a conductive structure with a liner of barrier materials like Titanium (Ti), Tantalum (Ta), or Chromium (Cr) to prevent diffusion, using an interposing layer of uniform TiAl composition to maintain electrical properties, and applying an overlayer with a titanium-nitride composition having varying gradient content to reduce surface reflectivity and enhance photolithography accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different conductive materials are used in different interconnect components, then device functionality is enhanced, but intermetallic composite non-uniformity occurs at interfaces leading to reduced electrical performance
Solution Approach 1:
A titanium nitride overlayer is introduced as an intermediary layer between different conductive materials (e.g., tungsten and copper) in interconnect components. This overlayer prevents direct contact and spontaneous reactions between dissimilar metals, eliminating intermetallic composite non-uniformity and ensuring uniform electrical characteristics at material interfaces.
Solution Approach 2:
The interconnect structure employs a composite material system consisting of multiple layers: conductive materials (tungsten, copper), barrier materials (titanium nitride), and overlayer materials. This composite approach allows different materials to perform their specialized functions while the titanium nitride overlayer ensures uniformity at interfaces, resolving the contradiction between material diversity and interface uniformity.
2Reliability
If metal materials are used in interlayer dielectrics for interconnect components, then electrical conductivity is improved, but diffusion or electromigration generates contamination and shorting issues
Solution Approach 1:
The titanium nitride overlayer serves as a protective intermediary between metal interconnect materials and the interlayer dielectric. It acts as a diffusion barrier that prevents metal atoms from migrating into the dielectric material, thereby eliminating contamination and shorting issues while maintaining the electrical conductivity benefits of metal interconnects.
Solution Approach 2:
The solution applies a localized protective overlayer specifically at the metal-dielectric interface where diffusion and electromigration occur. This localized approach addresses the harmful effects at critical interfaces without requiring changes to the bulk metal interconnect materials, preserving their electrical conductivity properties.
3Manufacturing precision
If photolithography process is used for patterning interconnect metal, then manufacturing precision is achieved, but low exposure efficiency occurs due to high surface reflectivity
Solution Approach 1:
The titanium nitride overlayer modifies the optical properties (reflectivity) of the metal surface. By changing the surface characteristics from highly reflective metal to titanium nitride with different optical properties, the photolithography exposure process becomes more efficient with better light absorption and reduced reflectivity, thereby improving both exposure efficiency and patterning precision.
4Manufacturing precision
If photolithography process is used for patterning interconnect metal, then manufacturing precision is achieved, but defect issues occur due to etching chemical corrosion
Solution Approach 1:
The titanium nitride overlayer acts as a protective intermediary during the photolithography etching process. It shields the underlying metal interconnect material from direct exposure to etching chemicals, preventing chemical corrosion and associated defects while allowing precise patterning to be achieved through the overlayer.
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 improves adhesion, reduces electrical resistance, maintains uniformity of intermetallic layers, and enhances the reliability and performance of interconnect structures by preventing spontaneous reactions and ensuring predictable electrical characteristics.
Implementation Method 1
forming a conductive structure with a liner of barrier materials like Titanium (Ti), Tantalum (Ta), or Chromium (Cr) to prevent diffusion
Implementation Method 2
applying an overlayer with a titanium-nitride composition having varying gradient content to reduce surface reflectivity and enhance photolithography accuracy
Data Source
AI summary
A semiconductor structure and a method of fabricating the same is disclosed. The semiconductor device includes a conductive structure that comprises: an upper conductive line arranged above and in electrical connection with a circuit component in a lower device layer through a via plug, wherein the upper conductive line extends laterally over the via plug; an interposing layer having a substantially uniform thickness arranged between the via plug and the upper conductive line, and extending laterally beyond a planar projection of the via plug, wherein the upper conductive line is in electrical connection with the via plug through the interposing layer; and an overlayer is disposed over the upper conductive line.