Low-K Dielectric Film Patterning via Oxygen Plasma Modification
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Solution Overview
Problem
Conventional low-k dielectric film patterning processes, particularly those using fluorocarbon-based etching, cause damage to the Si—CH3 network and result in undesirable moisture absorption due to the deposition and subsequent removal of CF polymer, leading to increased dielectric constant and mechanical integrity issues.
Innovation Solution
A fluorocarbon-free etching method is employed, where exposed portions of the low-k dielectric film are modified using a plasma process to convert them into silicon oxide, followed by selective removal using a dry etch or wet chemistry, avoiding halogen and oxygen radicals that damage the Si—CH3 network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorocarbon-based etching is used to pattern low-k dielectric film, then etching capability is improved, but damage to Si-CH3 network and moisture absorption increase
Solution Approach 1:
The patent extracts and removes the harmful fluorocarbon-based etching process from the low-k dielectric patterning workflow. Instead, it employs a two-step approach: first modifying the low-k dielectric surface with oxygen plasma to create a temporary oxide layer, then using a fluorocarbon-free etch chemistry (such as sulfur hexafluoride or carbon tetrafluoride) that does not deposit damaging CF polymer, thereby eliminating the source of mechanical integrity damage while maintaining etching capability
Solution Approach 2:
The patent introduces an intermediary oxygen plasma modification step that temporarily converts the low-k dielectric surface to silicon oxide. This intermediary layer serves as a protective barrier during the etching process, preventing direct damage to the Si-CH3 network from the etch chemistry, and is subsequently removed to reveal the patterned low-k dielectric with preserved mechanical properties
2Productivity
If CF polymer is deposited and removed during etching process, then etching is achieved, but dielectric constant increases and mechanical integrity deteriorates
Solution Approach 1:
The patent completely eliminates the CF polymer deposition step from the process by avoiding fluorocarbon-based etching chemistry. The modified approach uses alternative etch gases that do not form adherent polymer layers on the low-k dielectric surface, thereby preventing the subsequent moisture absorption and dielectric constant increase that would result from polymer removal
Solution Approach 2:
The patent converts the potential harm of aggressive etching chemistry into a benefit by first using oxygen plasma to create a temporary protective oxide layer on the low-k dielectric surface. This layer protects the underlying material during etching, and its controlled removal leaves a clean, damage-free surface that maintains original dielectric properties
3Manufacturing precision
If plasma process modifies exposed portions of low-k dielectric, then selective removal is enabled, but process complexity increases
Solution Approach 1:
The patent exploits parameter changes in the low-k dielectric material's chemical composition and surface properties through controlled oxygen plasma exposure. By adjusting plasma power, pressure, and exposure time, the process creates a temporary oxide layer with distinct etch selectivity, enabling precise patterning without requiring additional mask layers or complex process sequences
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 minimizes damage to the low-k dielectric film, prevents moisture absorption, and maintains the dielectric constant, enabling more effective patterning with reduced parasitic capacitance and improved mechanical integrity.
Implementation Method 1
Exposed portions of the low-k dielectric layer are modified with a plasma process
Implementation Method 2
modifying exposed portions of the low-k dielectric layer with a plasma process
Implementation Method 3
The modified portions of the low-k dielectric layer are removed selective to the mask layer and unmodified portions of the low-k dielectric layer
Data Source
AI summary
Methods of patterning low-k dielectric films are described. For example, a method includes forming and patterning a mask layer above a low-k dielectric layer, the low-k dielectric layer disposed above a substrate. Exposed portions of the low-k dielectric layer are modified with a plasma process. The modified portions of the low-k dielectric layer are removed selective to the mask layer and unmodified portions of the low-k dielectric layer.