Wet Etch Air Gaps Between Metal Interconnects Without Dry Etching
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Solution Overview
Problem
Conventional air gap integration processes in integrated circuits face challenges with mechanical integrity due to the use of low-k dielectric materials, leading to potential electrical failures during packaging, and require multiple etch processes that can damage metal interconnects and dielectric materials.
Innovation Solution
A wet etch process is used to form air gaps between metal interconnects with CD-dependent etching, eliminating the need for dry etch processes and reducing the number of processing steps, while maintaining mechanical integrity by using non-aqueous or aqueous-based etch solutions that selectively etch dielectric material between interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional air gap integration processes are used to form air gaps between metal interconnects, then capacitance is reduced and circuit performance is enhanced, but mechanical integrity deteriorates leading to potential electrical failures during packaging
Solution Approach 1:
The patent introduces an inorganic dielectric material as an intermediary substance to fill the air gaps between metal interconnects. This mediator provides the necessary mechanical strength and integrity to prevent packaging-induced cracks while maintaining the electrical isolation function, thus resolving the contradiction between mechanical reliability and electrical performance
Solution Approach 2:
The patent creates a composite structure by combining inorganic dielectric material with the existing metal interconnect architecture. This composite approach allows the system to simultaneously achieve the electrical benefits of air gaps (low capacitance) and the mechanical benefits of solid dielectric filling (enhanced integrity and crack resistance)
2Manufacturing precision
If multiple etch processes are used to form air gaps, then manufacturing precision is improved, but metal interconnects and dielectric materials are damaged
Solution Approach 1:
The patent extracts and eliminates the harmful multiple etch processes from the manufacturing sequence, replacing them with a single wet etch process followed by dielectric filling. This removal of excessive processing steps prevents damage to metal interconnects and dielectric materials while maintaining the precision needed for air gap formation
Solution Approach 2:
The patent substitutes mechanical/dry etching processes with a wet chemical etching process. This substitution uses chemical reactions rather than mechanical removal to achieve the desired air gap formation, thereby preventing physical damage to the metal interconnects and dielectric materials that would occur with aggressive dry etching or multiple etch steps
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 method forms air gaps efficiently without damaging metal interconnects, reduces processing steps, and maintains mechanical integrity by using CD-dependent wet etching to form recesses to target depth, enhancing the reliability of the IC stack.
Implementation Method 1
utilize the critical dimension (CD) dependent etching provided by wet etch processes to etch an intermetal dielectric material formed between the metal interconnects at a faster rate than the intermetal dielectric material is etched in surrounding areas of the patterned substrate
Implementation Method 2
exposing the patterned substrate to an etch solution to etch the first dielectric material layer and form recesses between the plurality of metal interconnects
Data Source
AI summary
Embodiments of improved process flows and methods are provided in the present disclosure to form air gaps between metal interconnects. More specifically, the present disclosure provides improved process flows and methods that utilize a wet etch process to form recesses between metal interconnects formed on a patterned substrate. Unlike conventional air gap integration methods, the improved process flows and methods described herein utilize the critical dimension (CD) dependent etching provided by wet etch processes to etch an intermetal dielectric material formed between the metal interconnects at a faster rate than the intermetal dielectric material is etched in surrounding areas of the patterned substrate. This enables the improved process flows and methods described herein to form recesses (and subsequently form air gaps) between the metal interconnects without using a dry etch process.