ELK Inter-Metal Dielectric Stack for Low Capacitance and Process Reliability
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Solution Overview
Problem
Advanced semiconductor technologies, such as the 5-nanometer node and beyond, face challenges in achieving desired capacitance, yield, and reliability due to the susceptibility of low dielectric constant materials to damage during processing, which affects signal transport speed and device performance.
Innovation Solution
A method for manufacturing an extra low-k (ELK) dielectric layer involving a stacked structure of dielectric material layers, including an aluminum nitride layer, oxygen-doped carbide layers, and an aluminum oxide layer, with a carbon-doped oxygen-rich silicon oxide ELK dielectric layer formed using PECVD or PVD processes, and a nitrogen-free antireflection layer for protection, to enhance adhesion and reduce capacitance while improving hardness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low dielectric constant (low-k) material is used to form IMD layers, then capacitance contribution is reduced and signal transport speed is improved, but the material becomes susceptible to damage during etching, deposition, and wet processes
Solution Approach 1:
The patent uses a composite dielectric structure consisting of a first dielectric layer (lower k-value, higher porosity) and a second dielectric layer (higher k-value, lower porosity). The first layer provides low capacitance for signal speed, while the second layer provides mechanical strength and process resistance. This composite approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent applies different dielectric properties to different regions/layers of the interconnect structure. The first dielectric layer near the metal interconnect has lower k-value to reduce coupling capacitance, while the second dielectric layer has higher k-value and greater density to provide mechanical support and process resistance. Each layer is optimized for its specific function.
2Quantity of substance
If low-k dielectric material with high porosity is used, then capacitance is reduced, but the material is damaged during semiconductor processes such as etching, deposition, and wet processes
Solution Approach 1:
The patent combines a porous low-k dielectric layer with a denser dielectric layer. The porous first layer achieves low capacitance (low k-value), while the second layer with lower porosity provides mechanical integrity and resistance to process damage. The composite structure allows each layer to optimize for its primary function.
Solution Approach 2:
The patent places a more robust second dielectric layer above the fragile first low-k dielectric layer to act as a protective cushion during subsequent semiconductor processes. This protective layer absorbs mechanical and chemical stresses that would otherwise damage the porous low-k material, allowing the low-k layer to maintain its low capacitance properties.
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 ELK dielectric layer improves signal transport speed by reducing coupling capacitance and increasing reliability, making it less prone to damage compared to traditional low-k materials, thus addressing the limitations of existing technologies.
Implementation Method 1
formed using PECVD or PVD processes
Implementation Method 2
formed using PECVD or PVD processes
Data Source
AI summary
A method for manufacturing an extra low-k (ELK) inter-metal dielectric (IMD) layer includes forming a first IMD layer including a plurality of dielectric material layers over a substrate. An adhesion layer is formed over the first IMD layer. An ELK dielectric layer is formed over the adhesion layer. A protection layer is formed over the ELK dielectric layer. A hard mask is formed over the protection layer and is patterned to create a window. Layers underneath the window are removed to create an opening. The removed layers include the protection layer, the ELK dielectric layer, the adhesion layer, and the first IMD layer. A metal layer is formed in the opening.