Stacked Semiconductor Bonding Pads With Diffusion Barrier Openings
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Solution Overview
Problem
Semiconductor devices face challenges in maintaining excellent electrical connection characteristics between stacked semiconductor structures due to metal diffusion from bonding pads into dielectric layers, especially when misalignment occurs during bonding processes, leading to increased contact resistance.
Innovation Solution
Incorporating a diffusion barrier layer along the inner walls of openings between bonding pads and dielectric layers, and filling these openings with a metal-containing layer to prevent metal diffusion, ensuring the barrier layer surrounds the metal-containing layer on all surfaces except the uppermost contact interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding pads are directly connected between stacked semiconductor structures, then electrical connection is achieved, but metal diffusion into dielectric layers occurs causing increased contact resistance
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the metal-containing bonding pad and the dielectric layer. This barrier layer (comprising materials such as tungsten, molybdenum, titanium nitride, or tantalum nitride) prevents metal atoms from diffusing into the dielectric layer while maintaining electrical conductivity, thereby resolving the contradiction between achieving electrical connection and preventing metal diffusion.
Solution Approach 2:
The bonding pad structure is designed as a composite material system consisting of multiple layers: a metal-containing layer (such as copper or aluminum) for electrical conductivity, a diffusion barrier layer (such as tungsten or titanium nitride) for preventing metal diffusion, and a dielectric layer for insulation. This composite structure simultaneously provides electrical connection while preventing harmful metal diffusion into the dielectric layer.
2Ease of manufacture
If misalignment occurs during bonding processes, then manufacturing simplicity is maintained, but metal diffusion increases leading to higher contact resistance
Solution Approach 1:
The diffusion barrier layer is formed in advance within the openings of the dielectric layer before the metal-containing bonding pad is applied. This preliminary formation of the barrier layer ensures that even if misalignment occurs during the bonding process, the barrier layer remains in position to prevent metal diffusion, thereby maintaining manufacturing flexibility without sacrificing alignment precision.
Solution Approach 2:
The diffusion barrier layer serves as a mediator that decouples the alignment precision requirement from the bonding process. By having the barrier layer pre-formed in the dielectric layer openings, the system can tolerate greater misalignment during bonding while still preventing metal diffusion, thus improving ease of manufacture without compromising the effectiveness of metal diffusion prevention.
3Object-generated harmful factors
If diffusion barrier layer is formed along inner walls of openings, then metal diffusion is prevented, but device structure complexity increases
Solution Approach 1:
The dielectric layer openings serve multiple functions: they provide the structural framework for the bonding pad, act as the location for forming the diffusion barrier layer, and define the connection path between stacked semiconductor structures. By making the openings multi-functional, the patent avoids adding separate structural elements, thereby preventing metal diffusion while minimizing increases in device complexity.
Solution Approach 2:
The diffusion barrier layer formation process is merged with the existing dielectric layer processing steps. The barrier layer is formed within the same openings that are already created for the bonding pad structure, combining the diffusion prevention function with the existing electrical connection pathway without requiring separate additional structural components.
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 solution effectively prevents metal diffusion into dielectric layers, maintains low contact resistance, and ensures reliable electrical connections even with misalignment between bonding pads, enhancing the overall performance of semiconductor devices.
Implementation Method 1
a diffusion barrier layer formed along inner walls of the first and second openings
Data Source
AI summary
A semiconductor device includes: a first semiconductor structure including a first bonding dielectric layer that is positioned in an uppermost portion of the first semiconductor structure and that includes a first opening; a second semiconductor structure positioned over the first semiconductor structure and including a second bonding dielectric layer that is positioned in a lowermost portion of the second semiconductor structure and that includes a second opening connected to the first opening; a diffusion barrier layer formed along inner walls of the first and second openings; and a metal-containing layer filling the first and second openings where the diffusion barrier layer is formed.