Low-k Interconnect Dielectrics for Misaligned Copper Bonding
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Solution Overview
Problem
The reliability of integrated circuits is compromised due to copper diffusion issues arising from misalignment and bonding of copper elements with different sizes or patterns, which can lead to unwanted copper diffusion into dielectric layers, affecting device performance and reliability.
Innovation Solution
The use of silicon carbonitride and silicon oxycarbonitride low-k interlevel dielectric layers with a composition of greater than fifty atomic percent carbon, less than ten atomic percent nitrogen, and less than ten atomic percent oxygen, which act as effective copper diffusion and oxidation barriers, reducing copper diffusion and enhancing the modulus and thermal conductivity, thereby improving the bonding process and device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric layers (SiOx, SiOxFy, SiCOH) are used in metal interconnect structures, then manufacturing is easier and cost is lower, but copper diffusion into the dielectric layer occurs due to misalignment and bonding issues, compromising device reliability
Solution Approach 1:
The patent changes the compositional parameters of the interlevel dielectric layer by incorporating silicon carbonitride and silicon oxycarbonitride materials with specific atomic percentages (greater than 50% carbon, less than 10% nitrogen, less than 10% oxygen). This compositional modification provides inherent copper diffusion barrier properties without requiring additional barrier layers, thereby improving reliability while managing complexity through material optimization
Solution Approach 2:
The patent employs composite dielectric materials (silicon carbonitride and silicon oxycarbonitride) that combine multiple elements (Si, C, N, O) in specific ratios to achieve both low-k properties and copper diffusion resistance. This composite approach integrates multiple functions (dielectric, diffusion barrier, mechanical support) into a single layer, improving reliability without proportionally increasing device complexity
2Adaptability or versatility
If copper elements with different sizes or patterns are bonded, then circuit functionality is achieved, but misalignment causes copper diffusion into the dielectric layer, reducing manufacturing precision
Solution Approach 1:
The silicon carbonitride and silicon oxycarbonitride dielectric layers serve as an intermediary barrier between copper interconnect layers. This intermediate material layer prevents direct copper-to-copper diffusion that would occur during bonding of misaligned copper elements, allowing bonding flexibility while maintaining manufacturing precision through the protective dielectric interface
3Device complexity
If barrier liner thickness is reduced, then manufacturing cost decreases and device complexity reduces, but copper diffusion protection is compromised
Solution Approach 1:
The patent changes the material parameters of the dielectric layer itself to provide inherent copper diffusion resistance. By using silicon carbonitride and silicon oxycarbonitride with specific compositional parameters, the dielectric layer becomes self-protecting against copper diffusion, eliminating the need for thick barrier liners and reducing overall structure complexity while maintaining reliability
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 low-k interlevel dielectric layers provide improved contact routing, high modulus, low plasma-induced damage, and superior time-dependent dielectric breakdown properties, allowing for thinner barrier liners and better tolerance of misalignment in copper-to-copper bonding, thereby enhancing the reliability and performance of integrated circuits.
Implementation Method 1
The low-k interlevel dielectric layer and the top metal interconnect layer are bonded to a second metal interconnect layer in a copper-to-copper or copper-to-metal bonding process. The silicon carbonitride and silicon oxycarbonitride low-k interlevel dielectric layer provides effective copper diffusion and oxidation barrier properties.
Implementation Method 2
The low-k interlevel dielectric layer beneath the silicon substrate exhibits compressive stress and has high thermal conductivity
Data Source
AI summary
Low-k, carbon-rich silicon carbonitride or silicon oxycarbonitride interlevel dielectric layers having good copper and oxidation barrier properties are employed to facilitate the manufacture and reliability of integrated circuits, including structures including back side power rails. Such interlevel dielectric layers enable copper to copper or copper to metal bonding without copper or metal diffusion into dielectric material, even with some misalignment.