Atomic Oxygen Substrate Cleaning for Low-k Dielectric Protection
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Solution Overview
Problem
Current substrate cleaning methods using UV radiation or lasers for pre-treatment in semiconductor processing can damage the underlying low-k dielectric layer and increase its k-value, leading to increased costs and complexity in equipment and maintenance, especially in FEOL and BEOL processes, where there is a need for a cost-effective and non-damaging method to clean post-etch polymers without UV light.
Innovation Solution
A method and system utilizing an atomic oxygen generator to deliver a process gas containing atomic oxygen for pre-treatment, which is followed by a wet cleaning process, allowing for controlled cleaning of substrates with reduced k-value changes and minimizing equipment complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UV radiation or lasers are used for pre-treatment to clean substrates, then polymer removal ability is improved, but damage to the underlying low-k dielectric layer and increase in k-value occur
Solution Approach 1:
The patent changes the physical-chemical parameters of the cleaning process by using atomic oxygen (a chemical species) instead of UV radiation or lasers (electromagnetic energy). This parameter change allows effective polymer removal through chemical reaction while avoiding the harmful thermal and photochemical effects that damage low-k dielectrics and increase k-values.
Solution Approach 2:
The patent replaces the electromagnetic field-based cleaning mechanism (UV/laser) with a chemical field-based mechanism (atomic oxygen). The atomic oxygen chemically reacts with and removes organic polymers through oxidation, substituting the physical energy-based approach with a chemical reaction approach that is gentler on the dielectric layer.
2Productivity
If excimer lamps or lasers are used for pre-treatment, then cleaning effectiveness is improved, but equipment cost and complexity increase
Solution Approach 1:
The patent uses atomic oxygen, which can be generated on-demand through simple plasma discharge or photolysis of oxygen, replacing expensive and complex excimer lamp systems. The atomic oxygen acts as a transient, easily generated reactive species that provides effective cleaning without requiring costly maintenance of UV light sources.
Solution Approach 2:
The patent changes the energy delivery mechanism from complex electromagnetic sources (excimer lamps, lasers) to simpler plasma or photolytic generation of atomic oxygen. This parameter change in the energy conversion pathway reduces equipment complexity while maintaining or improving cleaning effectiveness through the highly reactive atomic oxygen species.
3Productivity
If UV irradiation is used for pre-treatment, then polymer decomposition is improved, but periodic maintenance is required due to light intensity deterioration
Solution Approach 1:
The patent replaces the UV irradiation system (which suffers from lamp aging and intensity deterioration) with an atomic oxygen generation system using plasma or photolysis. This substitution eliminates the need for periodic replacement of UV lamps, as atomic oxygen can be continuously generated through electrical discharge or simple photolysis without the same degradation issues.
Solution Approach 2:
The atomic oxygen generation system is more self-maintaining compared to UV lamps. The plasma or photolytic generation of atomic oxygen does not suffer from the same aging and intensity deterioration problems, reducing the need for periodic maintenance and ensuring more reliable continuous operation.
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 use of atomic oxygen for pre-treatment effectively cleans substrates with minimal k-value alteration, reducing the risk of damage to the dielectric layer and lowering the cost of ownership by simplifying the hardware system and reducing the need for expensive UV-based equipment.
Implementation Method 1
Pre-treatment gas comprising oxygen and an inert gas are delivered into an atomic oxygen generator, generating a process gas containing atomic oxygen
Implementation Method 2
Gas including the oxygen radical is passed along the surface of the substrate to cause degeneration of the organic material thereon
Data Source
AI summary
Provided is a method and system for cleaning a substrate with a cleaning system comprising a pre-treatment system using an atomic oxygen generator. The substrate includes a layer to be cleaned and an underlying dielectric layer having a k-value. Pre-treatment gas comprising oxygen and an inert gas are delivered into an atomic oxygen generator, generating a process gas containing atomic oxygen. A portion of a surface of the substrate is exposed to the process gas while controlling two or more cleaning operating variables to ensure meeting two or more cleaning objectives and ensure completion of cleaning in the pre-treatment process time. In an embodiment, cleaning of the substrate in the pre-treatment process is set at less than 100 percent and a subsequent wet cleaning process is used to complete the substrate cleaning. In another embodiment, the pre-treatment system is configured to complete cleaning of the substrate.