Air Gap Metal Interconnects for RC Delay and Mechanical Strength
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Solution Overview
Problem
As device dimensions shrink, increased line resistance and parasitic capacitance lead to slower chip speeds and higher power consumption, and while air gaps can reduce RC signal delay, their implementation is hindered by reduced mechanical strength and structural deformation in integrated circuit fabrication.
Innovation Solution
A method involving a substrate with a first inter-metal dielectric layer, forming metal interconnections, creating a recess between them, and performing a curing process to form air gaps with a second IMD layer, ensuring the air gap's vertex is higher than the metal interconnection's top surface, using controlled etching and curing processes to enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air gaps are formed between metal interconnects to reduce RC signal delay, then chip performance improves and power consumption decreases, but mechanical strength is reduced and structural deformation occurs
Solution Approach 1:
The patent uses a composite structure combining organic dielectric material and inorganic dielectric layer to form the inter-metal dielectric layer. This composite approach allows the organic material to provide low-k properties for reduced RC delay while the inorganic layer adds mechanical strength and structural stability, resolving the contradiction between performance improvement and mechanical strength maintenance.
Solution Approach 2:
The patent applies different dielectric materials in different locations: organic dielectric material is used where low-k properties are needed for RC delay reduction, while inorganic dielectric layers are applied in specific regions to provide mechanical support and prevent structural deformation. This localized application of different material properties resolves the contradiction between reducing RC delay and maintaining mechanical strength.
2Reliability
If air gap structures are implemented to reduce parasitic capacitance, then RC signal delay decreases, but the device structure becomes weaker and more prone to deformation
Solution Approach 1:
The inter-metal dielectric layer is formed as a composite of organic dielectric material and inorganic dielectric layer. The organic material provides the low-k property necessary for reducing parasitic capacitance and RC signal delay, while the inorganic dielectric layer provides structural integrity and resistance to deformation, thus resolving the contradiction between RC delay reduction and structural stability.
Solution Approach 2:
The dielectric structure is segmented into multiple functional layers: the organic dielectric material layer for electrical performance and the inorganic dielectric layer for mechanical stability. This segmentation allows each layer to specialize in its primary function, with the organic layer reducing RC delay and the inorganic layer maintaining structural integrity.
3Ease of manufacture
If conventional oxide etching techniques are used for high-aspect-ratio contacts, then manufacturing is easier, but dielectric constant cannot be reduced sufficiently to lower RC values
Solution Approach 1:
The patent changes the dielectric constant parameter by introducing organic dielectric materials with inherently lower k-values compared to conventional silicon dioxide. This parameter change allows for reduced RC values while the curing process and inorganic dielectric layer ensure the material can still be manufactured using adapted conventional techniques.
Solution Approach 2:
The patent replaces the conventional inorganic oxide etching approach with a process that forms organic dielectric material layers followed by curing. This substitution enables access to lower dielectric constants that are not achievable with traditional oxide materials, while the curing process provides the necessary structural consolidation.
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 reduces RC signal delay and power consumption while maintaining mechanical strength by effectively forming air gaps between metal interconnects, improving chip performance and structural integrity.
Implementation Method 1
performing a curing process
Data Source
AI summary
A method for fabricating semiconductor device includes the steps of: providing a substrate having a first inter-metal dielectric (IMD) layer thereon; forming a first metal interconnection and a second metal interconnection in the first IMD layer; removing part of the first IMD layer to form a recess between the first metal interconnection and the second metal interconnection; performing a curing process; and forming a second IMD layer on the first metal interconnection and the second metal interconnection.