Ruthenium Step Coverage Control via CO Pressure Variation
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Solution Overview
Problem
Current Ru deposition processes face challenges with low deposition rates and unacceptable step coverage over high-aspect-ratio features, limiting their practicality and effectiveness in semiconductor manufacturing.
Innovation Solution
A method involving the use of a ruthenium carbonyl precursor and CO gas in a chemical vapor deposition process, where the CO partial pressure and substrate temperature are varied to control the step coverage of the Ru layer, allowing for high deposition rates and improved coverage over complex features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Ru deposition processes are used to achieve good step coverage over high-aspect-ratio features, then step coverage is improved, but deposition rate becomes too low to be practical
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the deposition process gas. Specifically, it introduces a hydrogen-containing gas (such as H2, SiH4, or GeH4) into the Ru deposition process gas, which chemically reacts with Ru atoms during deposition to form volatile Ru-H, Ru-Si, or Ru-Ge species. This parameter change enables the Ru layer to deposit at practical rates while maintaining good step coverage, as the volatile compounds facilitate uniform deposition over high-aspect-ratio features without sacrificing speed.
2Productivity
If Ru deposition processes are used to achieve high deposition rates for manufacturing, then productivity is improved, but step coverage over high-aspect-ratio features becomes unacceptable
Solution Approach 1:
The patent resolves this contradiction by changing the chemical parameters of the deposition process. By adding hydrogen-containing gas to the process gas mixture, the deposition mechanism changes from conventional physical vapor deposition to a chemical process that forms volatile Ru-H, Ru-Si, or Ru-Ge compounds. This chemical transformation allows the process to achieve both high deposition rates and acceptable step coverage simultaneously, as the volatile compounds can transport Ru material uniformly into high-aspect-ratio features while maintaining high overall deposition speed.
3Device complexity
If conventional Ru deposition is used, then process simplicity is maintained, but both deposition rate and step coverage are insufficient for practical manufacturing
Solution Approach 1:
The patent maintains relative process simplicity while dramatically improving performance by making a single key parameter change: adding a hydrogen-containing gas (such as H2, SiH4, or GeH4) to the existing Ru deposition process gas. This modification is straightforward to implement and does not require complex new equipment, yet it transforms the deposition mechanism to produce volatile Ru-H, Ru-Si, or Ru-Ge compounds that enable both practical deposition rates and good step coverage.
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 enables the formation of Ru layers with controlled step coverage, addressing the limitations of existing methods by achieving both high deposition rates and desired coverage, making it suitable for barrier and seed layer applications in Cu metallization technology.
Implementation Method 1
a Ru layer is formed on a patterned substrate from a process gas containing a ruthenium carbonyl precursor and CO gas in a chemical vapor deposition process
Data Source
AI summary
A method for forming a Ru layer for an integrated circuit by providing a patterned substrate in a process chamber, and exposing the substrate to a process gas comprising a ruthenium carbonyl precursor and a CO gas to form a Ru layer over a feature of the patterned substrate. In one embodiment, the CO partial pressure in the process chamber is varied during the exposing to control the step coverage of the Ru layer over the feature. In an alternative or further embodiment, the step coverage can be controlled by varying the substrate temperature during the exposure.