Multi-Height Interconnect Trenches for Signal Delay Optimization
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Solution Overview
Problem
In semiconductor devices, there is a tradeoff between resistance and capacitance in interconnects, where increasing height reduces resistance but increases capacitance, leading to a balance issue between signal delay and power consumption, with existing uniform height interconnect layers resulting in area penalties and limited design optimizations.
Innovation Solution
Implementing multi-height interconnect trenches and air gap dielectrics allows for optimized signal path routing by selecting taller interconnects for timing-critical paths and shorter ones for others, maintaining power efficiency while meeting delay metrics, and using air gaps to further reduce capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the height of interconnects is increased to decrease resistance, then signal delay is improved, but capacitance increases leading to higher power consumption
Solution Approach 1:
The patent implements multi-height interconnect trenches within a single interconnect layer, allowing different regions to have different interconnect heights. Timing-critical paths use taller interconnects to reduce resistance and delay, while non-critical paths use shorter interconnects to minimize capacitance and power consumption. This local differentiation resolves the contradiction by optimizing each path independently rather than uniformly across the entire layer.
Solution Approach 2:
The patent introduces vertical dimensionality variation within a single interconnect layer by creating trenches at different depths (multi-height). Instead of relying solely on moving to higher layers (horizontal/layer dimension) to reduce resistance, the invention exploits the vertical depth dimension within the same layer, enabling resistance reduction without the associated capacitance penalty of higher layers.
2Loss of time
If the width of interconnects is increased to decrease resistance, then signal delay is improved, but area occupied increases
Solution Approach 1:
The patent changes the height parameter of interconnects instead of the width parameter to reduce resistance. By increasing interconnect height within the same planar footprint, the invention achieves resistance reduction without increasing the area occupied by the interconnect, thereby resolving the contradiction between delay improvement and area consumption.
3Use of energy by moving object
If side-to-side spacing is increased to decrease capacitance, then power consumption is reduced, but area occupied increases
Solution Approach 1:
The patent applies air gap dielectric material selectively around specific interconnects based on their capacitance requirements. Timing-critical interconnects may have different air gap configurations compared to non-critical interconnects, allowing localized capacitance reduction without uniformly increasing spacing across the entire interconnect layer, thus minimizing area overhead.
4Loss of time
If all interconnects in a layer are made uniformly tall to reduce resistance, then delay is improved, but capacitance increases significantly reducing power efficiency
Solution Approach 1:
The patent implements selective height optimization where only specific interconnects that are timing-critical are made taller, while other interconnects maintain shorter heights. This localized approach ensures that delay improvement is achieved only where necessary, while power efficiency is maintained in non-critical regions, resolving the contradiction between delay and power efficiency.
5Loss of time
If timing critical electrical paths are moved to higher layers where interconnects are typically larger, then resistance is decreased, but pitch increases reducing the number of available interconnects
Solution Approach 1:
The patent exploits the vertical depth dimension within the same interconnect layer by creating multi-height trenches. This allows timing-critical paths to achieve lower resistance through taller interconnects within the current layer, eliminating the need to move to higher layers and thereby avoiding the pitch increase and congestion issues associated with higher layer usage.
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 enables improved delay characteristics without area penalties, reduces congestion in higher layers, and allows for both high performance and low power consumption, supporting both CPU and SOC design optimizations within the same process.
Implementation Method 1
air gap dielectrics surrounding the first interconnects and/or the second interconnects
Data Source
AI summary
Embodiments disclosed herein include a semiconductor device with interconnects with non-uniform heights. In an embodiment, the semiconductor device comprises a semiconductor substrate, and a back end of line (BEOL) stack over the semiconductor substrate. In an embodiment, the BEOL stack comprises first interconnects and second interconnects in an interconnect layer of the BEOL stack. In an embodiment, the first interconnects have a first height and the second interconnects have a second height that is different than the first height.