Extended Barrier Liner for Thick Copper Interconnects
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Solution Overview
Problem
Conventional localized thick interconnect processes, such as copper damascene, face limitations in forming reliable thick copper interconnects, leading to issues like mechanical stress, poor step coverage of anti-diffusion layers, and potential copper migration paths due to undercuts in the barrier liner, which compromise the integrity of semiconductor structures.
Innovation Solution
The implementation of an extended barrier liner with a wider width than the copper interconnect, self-aligned through etching processes, to reduce mechanical stress and ensure complete encapsulation by the anti-diffusion layer, preventing copper migration and improving the reliability of the interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional barrier liner is used with the same width as the copper interconnect, then the manufacturing process is simpler, but mechanical stress increases and copper migration paths occur due to undercuts
Solution Approach 1:
The barrier liner is extended in the lateral dimension beyond the copper interconnect edges, creating an extended barrier liner structure. This dimensional extension prevents undercuts and eliminates copper migration paths by ensuring the barrier liner covers the entire perimeter of the copper interconnect, thereby resolving the mechanical stress and reliability issues without significantly complicating the manufacturing process.
2Object-affected harmful factors
If the barrier liner width is increased to extend beyond the copper interconnect, then copper migration is prevented, but the manufacturing precision requirements increase
Solution Approach 1:
The extended barrier liner is formed before the copper electroplating process, establishing a pre-defined boundary that prevents copper migration. By preparing the barrier liner structure in advance with sufficient lateral extension, the subsequent copper plating is constrained within safe boundaries, eliminating migration risks without requiring high-precision alignment during the plating step itself.
3Ease of manufacture
If copper damascene process is used for thick interconnects, then the process is well-established, but the interconnect height is limited to very thin dimensions
Solution Approach 1:
The extended barrier liner structure is specifically applied to thick interconnect regions where copper migration risk is highest, while maintaining conventional barrier liner dimensions in standard thin interconnect areas. This localized quality enhancement allows the use of well-established copper damascene processes for thick interconnects without compromising reliability, as the extended barrier liner is only deployed where needed to prevent migration in high-current thick conductors.
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 extended barrier liner enhances the mechanical strength and reliability of the interconnects, ensuring effective encapsulation of copper interconnects and reducing the risk of copper migration, thereby improving the overall performance and yield of semiconductor devices.
Implementation Method 1
The barrier material 14 will have sufficient resistance to the diffusive properties of the copper to prevent spoilage of the underlying electronic circuits and surrounding structures.
Implementation Method 2
This other technique is called a localized thick interconnect, and generally includes traditional photolithography and electroplating processes.
Data Source
AI summary
A dielectric layer overlies a semiconductor substrate. The substrate has components and appropriate contacts formed therein. The dielectric layer electrically insulates the substrate and components from overlying conductive interconnect layers. A barrier layer is arranged over the dielectric layer to isolate the interconnect layers from other structures. A copper layer is then deposited over the barrier layer and thick interconnect lines having a first width and a first height are realized. Then, the barrier layer is etched using one of many alternative techniques. The barrier layer has a second width and a second height wherein the second width of the barrier liner is selected to be greater than the first width of the thick copper interconnect.