TaCx Metal Film Deposition Initiation Layer
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Solution Overview
Problem
The deposition of N-Metal films such as TaCx onto gate insulating substrates like HfO2 or TiN is challenging due to slow process rates and instability, making it difficult to achieve stable insulating characteristics and minimize polysilicon gate depletion.
Innovation Solution
The use of an initiation layer comprising metals like cobalt, tantalum, nickel, titanium, or TaAlC, which catalyzes the deposition of TaCx by exposing the substrate to tantalum halides and hydrocarbon gases, allowing for efficient deposition at temperatures below 615°C, facilitating integration and improving deposition rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If N-Metal films such as TaCx are deposited directly onto gate insulating substrates like HfO2 or TiN, then the deposition process can be performed, but the deposition rate is extremely slow and deposition stability is poor
Solution Approach 1:
The patent applies preliminary action by depositing an initiation layer (comprising Co, Ta, Ni, Ti, or TaAlC) onto the substrate before depositing the TaCx film. This initiation layer is deposited in advance to create a suitable surface that enables subsequent fast and stable TaCx deposition, resolving the contradiction between deposition rate and stability.
Solution Approach 2:
The initiation layer acts as an intermediary between the substrate and the TaCx film. It mediates the deposition process by providing a surface that facilitates TaCx formation, enabling both high deposition rates and stable film growth that cannot be achieved by direct deposition onto the substrate.
2Length of moving object
If the thickness of the gate insulating film is reduced to achieve higher integration, then the line width can be reduced, but the insulating characteristic becomes unstable due to increased leakage current from direct tunneling
Solution Approach 1:
The patent changes the material parameter of the gate insulating film from conventional silicon oxide to high dielectric constant materials like HfO2. This parameter change allows maintaining thin film thickness (enabling reduced line width) while preserving stable insulating characteristics by reducing leakage current through the higher dielectric constant.
3Ease of manufacture
If polysilicon gate is used to implement the gate, then the gate can be formed, but the polysilicon gate depletion effect occurs
Solution Approach 1:
The patent changes the material parameter of the gate from polysilicon to metal gate (using TaCx or similar materials). This parameter change eliminates the polysilicon gate depletion effect while maintaining ease of manufacture through established deposition processes, thereby improving device performance.
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 method enables consistent and efficient deposition of TaCx onto various substrates, enhancing the stability of gate insulating films and reducing leakage currents, thereby addressing the limitations of previous deposition methods.
Implementation Method 1
The initiation layer may comprise cobalt, tantalum, nickel, titanium or TaAlC. These initiation layers can be used to deposit TaCx
Implementation Method 2
sequentially exposing a surface of the substrate containing the initiation layer to a TaCl5 gas and a hydrocarbon gas to form a layer of TaCx on the initiation layer
Data Source
AI summary
Provided are methods of depositing N-Metals onto a substrate. Methods include first depositing an initiation layer. The initiation layer may comprise or consist of cobalt, tantalum, nickel, titanium or TaAlC. These initiation layers can be used to deposit TaCx.