Backside Power Via Layout Using Boron Nitride for Leakage Control
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Solution Overview
Problem
The integration density of electronic components in semiconductor devices is limited by the challenges in forming efficient backside power vias that provide improved breakdown voltage, reduced leakage, and thermal dissipation while allowing for greater material flexibility in conductive materials.
Innovation Solution
The formation of a backside power via adjacent an epitaxial source/drain region, utilizing a barrier layer of boron nitride and a conductive material like copper, which enhances device performance and reduces defects by providing improved breakdown voltage, reduced leakage, and thermal dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used for backside power vias, then manufacturing is simpler, but breakdown voltage is insufficient and leakage is high
Solution Approach 1:
The patent employs composite material structures for backside power vias, combining multiple materials with complementary properties. Specifically, it uses a low-resistance conductive material (such as copper or cobalt) combined with a diffusion barrier layer (such as tantalum or tungsten nitride), and in some embodiments, a liner layer (such as boron nitride). This composite approach achieves high breakdown voltage and low leakage while maintaining manufacturability through established deposition and patterning processes.
Solution Approach 2:
The patent optimizes various parameters of the backside power via structure, including the thickness of barrier and liner layers (e.g., 5-50 nm for diffusion barriers, 2-20 nm for liners), the composition ratios of conductive materials, and the geometric dimensions of vias. These parameter adjustments enable achievement of high breakdown voltage and low leakage characteristics while maintaining compatibility with existing manufacturing processes.
2Reliability
If copper is used as conductive material, then resistance is reduced, but diffusion into semiconductor layers occurs
Solution Approach 1:
The patent introduces intermediary layers between copper and semiconductor materials to prevent direct contact and diffusion. A diffusion barrier layer (such as tantalum nitride, tungsten nitride, or titanium nitride with thickness of 5-50 nm) is deposited between the copper conductive material and the semiconductor layers. This intermediary barrier effectively blocks copper diffusion while maintaining low electrical resistance of the overall via structure.
Solution Approach 2:
The patent creates a composite via structure with copper as the core conductive material surrounded by protective barrier and liner layers. This composite configuration allows copper to provide low resistance while the surrounding barrier layers (diffusion barriers and liners) prevent copper from diffusing into adjacent semiconductor layers, thus maintaining both electrical performance and compositional stability.
3Productivity
If integration density is increased, then more components fit in given area, but thermal dissipation becomes more difficult
Solution Approach 1:
The patent utilizes the backside dimension of the semiconductor device for power via connections, moving interconnect pathways from the planar surface to the vertical backside interface. This dimensional transition allows power delivery networks to be established without occupying additional surface area, thereby maintaining high integration density while providing dedicated thermal management pathways through the substrate.
Solution Approach 2:
The patent introduces thermal interface materials and conductive structures as intermediaries between high-power regions and heat sinks. Thermal vias and heat spreaders are positioned adjacent to backside power vias, acting as intermediary thermal pathways that conduct heat away from densely integrated components without interfering with electrical interconnects, thus enabling effective thermal dissipation at high integration densities.
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 solution enables improved device performance and reduced defects by using boron nitride as a diffusion barrier, allowing for conductive materials with reduced resistance and flexibility, thus enhancing the integration density of semiconductor devices.
Implementation Method 1
The liner layer may include materials such as boron nitride (e.g., amorphous boron nitride (a-BN), hexagonal boron nitride (h-BN), or the like), and the conductive material may include materials such as copper, cobalt, tungsten, or the like. Boron nitride has an improved breakdown voltage, provides reduced leakage, acts as a diffusion barrier
Implementation Method 2
conductive material on the barrier/liner layer... electrically coupled to the front-side source/drain contact and the backside power via
Implementation Method 3
a backside thinning process is performed to expose a backside of the backside power via
Data Source
AI summary
Methods of forming vias for coupling source/drain regions to backside interconnect structures in semiconductor devices and semiconductor devices including the same are disclosed. In an embodiment, a semiconductor device includes a conductive feature adjacent a gate structure; a dielectric layer on the conductive feature and the gate structure; a metal via embedded in the dielectric layer; and a liner layer between and in contact with the metal via and the dielectric layer, the liner layer being boron nitride.