Superheated Steam Cleaning for Semiconductor Interconnection Structures
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Solution Overview
Problem
In semiconductor device fabrication, the oxidation of barrier metal films due to water and fluorine residues in the interlayer insulation film leads to issues like dilatation, cracking, and increased specific dielectric constant, which affects the adhesion and electric properties of Cu interconnection structures.
Innovation Solution
A method using superheated steam to remove CFx molecules and terminating fluorine from the sidewall and bottom surfaces of openings in the interlayer insulation film, preventing oxidation of refractory metal barrier films and maintaining the low dielectric constant of low-K dielectric films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dry etching process using fluorine-containing etching gas is used to form openings in the interlayer insulation film, then the openings can be effectively formed, but water and fluorine residues remain on the sidewall and bottom surfaces, causing oxidation of barrier metal films
Solution Approach 1:
The patent applies a preliminary cleaning action using superheated steam before depositing the barrier metal film. This removes water and fluorine residues from the opening surfaces in advance, preventing oxidation of the barrier metal film that would otherwise occur during subsequent processing steps.
Solution Approach 2:
The patent changes the physical parameters of the cleaning medium by using superheated steam instead of conventional cleaning methods. The high temperature and specific humidity conditions of superheated steam effectively remove residues without causing oxidation, resolving the contradiction between thorough cleaning and oxidation prevention.
2Reliability
If barrier metal films are deposited to prevent Cu diffusion into the interlayer insulation film, then short circuits are avoided, but the barrier metal films oxidize due to water and fluorine residues, leading to dilatation and cracking
Solution Approach 1:
The superheated steam cleaning is performed as a preliminary step before barrier metal deposition. This removes the harmful residues that would cause oxidation, allowing the barrier metal film to be deposited in a clean environment where it can form a continuous, intact structure without dilatation or cracking.
Solution Approach 2:
Superheated steam acts as an intermediary cleaning medium between the dry etching process and barrier metal deposition. It effectively removes residues without introducing oxygen that would cause oxidation, thus protecting the barrier metal film integrity while maintaining reliability.
3Ease of manufacture
If conventional cleaning methods are used after dry etching, then the process is simple, but water and fluorine residues remain, causing oxidation and increasing dielectric constant of low-K films
Solution Approach 1:
The patent changes the parameters of the cleaning process by using superheated steam with specific temperature and humidity conditions. This effectively removes fluorine residues and prevents oxidation of barrier metals while maintaining process simplicity, thus preserving the low dielectric constant of low-K films.
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 effectively suppresses oxidation of barrier metal films, improves adhesion, and reduces contact resistance in multilayer interconnection structures, enhancing the yield and stability of semiconductor devices.
Implementation Method 1
cleaning a bottom surface and a sidewall surface of the opening by exposing to a superheated steam
Implementation Method 2
covering the bottom surface and the sidewall surface of the opening with a barrier metal film
Implementation Method 3
depositing a conductor film on the insulation film and filling said opening with said conductor film via said barrier metal film
Implementation Method 4
forming an interconnection pattern by the conductor film in the opening by polishing the conductor film and the barrier metal film underneath the conductor film by a chemical mechanical polishing process
Data Source
AI summary
A method of forming an interconnection structure includes forming an opening in an insulation film by a dry etching process that uses an etching gas containing fluorine; cleaning a bottom surface and a sidewall surface of the opening by exposing to a superheated steam; covering the bottom surface and the sidewall surface of the opening with a barrier metal film; depositing a conductor film on the insulation film via the barrier metal film to fill the opening with the conductor film; forming an interconnection pattern by the conductor film in the opening by polishing the conductor film and the barrier metal film underneath the conductor film by a chemical mechanical polishing process until a surface of the insulation film is exposed.