Uniformity improvement at Cu-electroplating - PRIZ Analysis
Current situation
The copper electroplating process in semiconductor manufacturing faces significant challenges related to radial non-uniformity in deposition thickness. While the theoretical framework suggests uniform deposition due to applied voltage, practical realities reveal that the thin seed layer's finite sheet resistance leads to high current density near the wafer edge and reduced current density towards the center. This results in a thicker copper layer at the edges and a noticeably thinner layer in the center, necessitating overplating and subsequent removal through Chemical Mechanical Polishing (CMP) to achieve planarity and thickness control. This approach increases costs and material waste, highlighting the need for innovative solutions to enhance uniformity without compromising efficiency or resource utilization.
Disadvantages
The radial non-uniformity in deposition thickness leads to inconsistent electrical performance across the semiconductor devices, potentially affecting their reliability and functionality.
The necessity for overplating and subsequent removal through Chemical Mechanical Polishing (CMP) increases production costs and resource consumption, making the process less economically viable.
The increased material waste due to uneven deposition not only impacts the cost but also raises environmental concerns related to the disposal of excess copper and chemicals used in the CMP process.
Ideal final result
Achieve uniform copper deposition thickness across the entire wafer surface, minimizing radial non-uniformity.
Gaps
Inadequate understanding of the relationship between seed layer thickness and current distribution across the wafer, leading to non-uniform deposition.
Lack of innovative electroplating techniques or equipment modifications that can mitigate the effects of finite sheet resistance in the seed layer.
Insufficient optimization of electrolyte composition and flow dynamics to enhance mass transport and improve uniformity during the electroplating process.
Problem statement
The current copper electroplating process in semiconductor manufacturing suffers from radial non-uniformity in deposition thickness due to the finite sheet resistance of the thin seed layer, leading to increased costs and material waste.
Similar projects
This project investigates how to increase the copper removal rate during Chemical Mechanical Planarization (CMP). Functional modeling revealed that increasing H₂O₂ alone is ineffective beyond an optimum level because rapid oxidation creates a thick, passivating Cu₂O/CuO layer that must be mechanically removed. The winning direction is to balance faster oxidation with stronger mechanical removal by optimizing pad speed, abrasive concentration, pressure, conditioning, and slurry transport.
Wet cleaning is widely used in microchip manufacturing. Single wafer equipment is working as follows. A wafer rotates, and chemistry is poured from a movable nozzle. Water rinsing is performed at the end of the process. Loading of a new batch of the chemistry resulted in excursion - a strongly increased amount of defects was observed on the wafer after the processing. The project is dedicated to the failure analysis and creation of innovative solutions.
Semiconductor devices are becoming more complex and expensive. But what exactly are we paying for when we buy a computer, cellphone, or any device containing a microchip? It’s not for radically new functions—the core components remain the same: transistors and interconnections. According to Moore’s law, transistors are getting smaller, with more interconnection layers added, making the manufacturing process longer and more costly. In reality, we’re paying for the inability of engineers to efficiently solve engineering challenges. This project leverages System Functional Modeling (SFM) to analyze the IC interconnection layer and Process Functional Modeling (PFM) to evaluate its manufacturing process. These analyses aim to deepen our understanding of both the device and the production process, generating innovative solutions for cost reduction and improved efficiency.