Semiconductor Contact Structure Silicide Thickness Control
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Solution Overview
Problem
Semiconductor devices face a challenge in achieving both fast speed and reduced size, as smaller features often result in slower operation, and existing solutions struggle to balance these two desirable traits.
Innovation Solution
A contact structure and method of forming, which involves a dielectric layer over a substrate with an adhesion layer, a silicide region, and a conductive material, where the adhesion layer is along the sidewalls of an opening and reacts with the substrate to form a silicide, and a barrier layer is deposited on the adhesion layer, directly adjoining the silicide, with the conductive material filling the opening, thereby simplifying the process and controlling the silicide thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of semiconductor devices is reduced to increase device density, then device density is improved, but operation speed deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the contact structure by forming a silicide region with specific thickness control (50-200 nm) and using specific materials (titanium, tungsten, cobalt, nickel) to achieve low resistance. This allows maintaining fast operation speed while reducing device size through precise parameter optimization of the contact structure
Solution Approach 2:
The patent applies different materials and structures to different parts of the contact structure: adhesion layer on sidewalls, silicide region on substrate surface, barrier layer on adhesion layer, and conductive material in opening. Each region has optimized local properties to minimize resistance and capacitance, enabling fast operation in reduced-size devices
2Ease of manufacture
If conventional contact structure formation processes are used, then manufacturing is simplified, but resistance is high and operation speed is slow
Solution Approach 1:
The adhesion layer is formed on the sidewalls before the silicidation step, and the barrier layer is deposited on the adhesion layer before the silicide reaction occurs. This preliminary positioning of layers ensures proper structure formation and low resistance without requiring additional removal steps, maintaining process simplicity while improving performance
Solution Approach 2:
The adhesion layer on the sidewalls automatically serves as a template and barrier during silicidation, controlling the silicide formation without requiring separate masking or etching steps. The structure self-organizes during the annealing process to achieve the desired contact configuration with low resistance
3Ease of manufacture
If silicide thickness is not controlled, then manufacturing is easier, but resistance increases and operation speed decreases
Solution Approach 1:
The adhesion layer is deposited with a specific thickness (1-10 nm) before silicidation, and the barrier layer is deposited on top with controlled thickness (5-20 nm). These preliminary thickness specifications directly control the final silicide region thickness (50-200 nm) after annealing, enabling precise control without complex process adjustments
Solution Approach 2:
The barrier layer thickness and composition provide feedback control on the silicide formation process during annealing, limiting excessive silicide growth and ensuring the silicide region achieves the optimal thickness range for low resistance while maintaining process robustness
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 reduces resistance, allowing for faster device operation even at reduced sizes by eliminating the need for removing unreacted metal and controlling silicide thickness, thus decreasing the resistance-capacitance time constant.
Implementation Method 1
the adhesion layer is along the sidewalls of an opening and reacts with the substrate to form a silicide
Implementation Method 2
a barrier layer is deposited on the adhesion layer, directly adjoining the silicide
Data Source
AI summary
Contact structures and methods of forming contacts structures are contemplated by this disclosure. A structure includes a dielectric layer over a substrate, an adhesion layer, a silicide, a barrier layer, and a conductive material. The dielectric layer has an opening to a surface of the substrate. The adhesion layer is along sidewalls of the opening. The silicide is on the surface of the substrate. The barrier layer is on the adhesion layer and the silicide, and the barrier layer directly adjoins the silicide. The conductive material is on the barrier layer in the opening.