Void-Free Electroplating in Recessed Features
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Solution Overview
Problem
The challenge in damascene processing is the difficulty of growing metal films within recessed features without forming voids, which can lead to increased resistance and potential corrosion from trapped electroplating solution, causing degraded device performance or failure.
Innovation Solution
A method of electroplating metal into recessed features by controlling the composition ratio of components in the electroplating solution, specifically using a higher molar concentration of accelerator additive compared to suppressor and leveler additives to prevent void formation, ensuring complete filling of the cross region without trapped solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electroplating is performed in recessed features with conventional electroplating solution composition, then metal deposition occurs on exposed surfaces, but voids form within the recessed features leading to increased resistance and potential corrosion
Solution Approach 1:
The patent applies parameter changes by modifying the composition ratios of additives in the electroplating solution. Specifically, it adjusts the concentrations of accelerator additive, suppressor additive, and leveler additive to achieve optimal deposition control. This chemical parameter optimization enables complete filling of recessed features while preventing void formation, thereby resolving the contradiction between manufacturing precision and device reliability.
Solution Approach 2:
The patent implements local quality by creating spatially varying deposition rates through controlled additive interactions. The accelerator additive promotes rapid deposition at the bottom of recessed features where it is most needed, while the suppressor and leveler additives moderate deposition on upper surfaces. This localized control of deposition quality ensures complete filling without voids, simultaneously improving both filling completeness and preventing corrosion-related failures.
2Manufacturing precision
If electroplating solution composition is optimized for complete filling, then void-free deposition is achieved, but process control complexity increases
Solution Approach 1:
The patent establishes specific numerical ranges for additive concentrations (accelerator: suppressor: leveler in ratios of 8-15:1.5-3:0.5-2) to simplify process control. By defining precise parameter windows rather than requiring complex real-time adjustments, the patent achieves void-free deposition while maintaining manageable process complexity. This standardized composition framework makes the advanced filling control accessible for manufacturing.
3Productivity
If metal film grows rapidly to fill recessed features, then filling efficiency improves, but void formation increases due to trapped electroplating solution
Solution Approach 1:
The patent applies local quality by enabling different deposition rates in different spatial zones through controlled additive distribution. The accelerator additive concentrates at the bottom of recessed features promoting rapid local deposition to fill the feature quickly, while suppressor and leveler additives control the overall deposition rate to prevent solution entrapment. This spatially differentiated growth control achieves both high filling efficiency and void-free structures.
Solution Approach 2:
The patent implements continuity of useful action by maintaining steady-state deposition throughout the electroplating process. The balanced additive composition ensures continuous metal ion reduction and film growth without interruption or instability. This continuous, controlled deposition prevents the formation of voids that would occur with intermittent or uncontrolled growth, while maintaining high overall filling rates for improved productivity.
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 method achieves a void-free electroplating layer with a low carbon-to-metal atomic ratio, reducing the risk of corrosion and enhancing device performance by ensuring the cross region is filled without void spaces, thereby improving the electrical conductivity of the metal features.
Implementation Method 1
The wafer is immersed in an electrolytic bath containing metal ions and is biased as the cathode in an electric circuit. With the solution biased positively, the metal ions become current carriers, which flow towards and are deposited on the exposed surfaces of the wafer.
Implementation Method 2
Techniques for forming such metal features include physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD) and electrochemical deposition (also referred to as electroplating or electrodeposition).
Data Source
AI summary
A method of electroplating a metal into a recessed feature is provided, which includes: contacting a surface of the recessed feature with an electroplating solution comprising metal ions, an accelerator additive, a suppressor additive and a leveler additive, in which the recessed feature has at least two elongated regions and a cross region laterally between the two elongated regions, and a molar concentration ratio of the accelerator additive:the suppressor additive:the leveler additive is (8-15):(1.5-3):(0.5-2); and electroplating the metal to form an electroplating layer in the recessed feature. An electroplating layer in a recessed feature is also provided.