Etchant Composition for Metal Film Selectivity and Pattern Leaning
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Solution Overview
Problem
As IC devices downscale, achieving precise etching of metal interconnection patterns with high selectivity while minimizing impact on neighboring insulating films becomes increasingly difficult due to reduced widths and increased aspect ratios, leading to issues like pattern leaning and undesired chemical reactions during etching and rinse processes.
Innovation Solution
A metal-containing film etchant composition comprising hydrogen peroxide, phosphoric acid, and a heterocyclic organic amine compound is used, which provides high etch selectivity for metal films over insulating films, ensuring uniform etching rates and preventing pattern leaning by avoiding sulfuric acid, thus reducing exothermal reactions during rinse and dry processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for downscaled IC devices, then etching of metal interconnection patterns can be performed, but etch selectivity to metal-containing films decreases and neighboring insulating films are adversely affected
Solution Approach 1:
The patent modifies the chemical composition parameters of the etchant by incorporating hydrogen peroxide, phosphoric acid, and heterocyclic organic amine compounds in specific concentrations. This parameter change enables selective etching of metal-containing films while protecting insulating films from damage, directly resolving the selectivity issue in downscaled IC devices.
Solution Approach 2:
The etchant uses a composite chemical system combining hydrogen peroxide, phosphoric acid, and heterocyclic organic amine compounds. This composite formulation provides synergistic effects that enhance etch selectivity for metal-containing films while preventing adverse effects on neighboring insulating films, addressing the contradiction between etching effectiveness and film protection.
2Productivity
If etching is performed on metal interconnection patterns with reduced width and increased aspect ratio, then downscaled IC devices can be manufactured, but etching uniformity decreases and pattern leaning occurs
Solution Approach 1:
The patent optimizes etching parameters including pH control through phosphoric acid, oxidation potential via hydrogen peroxide, and surface interaction modifiers using heterocyclic organic amine compounds. These parameter adjustments ensure uniform etch rates across metal interconnection patterns with high aspect ratios, preventing pattern leaning while enabling continued downsaling.
Solution Approach 2:
The heterocyclic organic amine compounds act as intermediary substances that mediate between the etchant and the metal-containing film surface. These intermediaries promote uniform chemical interaction across the entire pattern surface, including high aspect ratio regions, thereby maintaining etching uniformity as device dimensions are reduced.
3Power
If sulfuric acid is used in etching processes, then etching power is increased, but exothermal reactions occur during rinse and dry processes causing manufacturing instability
Solution Approach 1:
The patent extracts sulfuric acid from the etching formulation and replaces it with hydrogen peroxide and phosphoric acid. This removal eliminates the source of exothermal reactions during rinse and dry processes, while the alternative chemicals maintain sufficient etching power for metal-containing films, thereby improving manufacturing process stability.
Solution Approach 2:
The patent converts the potentially harmful exothermal reaction issue into a benefit by selecting etchant components that provide adequate etching power without the sulfuric acid-related thermal instability. The hydrogen peroxide-based system delivers necessary etching aggressiveness while ensuring safe and stable rinse and dry processes, transforming a process reliability problem into a solved challenge.
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 etchant composition effectively etches metal interconnection patterns with high selectivity, maintaining insulating film integrity and preventing pattern leaning, thereby enhancing the manufacturing process stability and reducing the risk of short circuits and resistance increases in IC devices.
Implementation Method 1
aqueous hydrogen peroxide (H2O2.nH2O)...hydrogen peroxide (H2O2)
Implementation Method 2
a phosphoric acid compound...phosphoric acid having a purity of 85%
Implementation Method 3
a heterocyclic organic amine compound containing at least one hetero atom in a ring
Data Source
AI summary
Metal-containing film etchant compositions may include hydrogen peroxide (H2O2), a phosphoric acid compound, a heterocyclic organic amine compound including at least one heteroatom in a ring, and water. Manufacturing methods of an integrated circuit (IC) may include performing a dry etch process on a conductive structure including a metal nitride film and a metal film to form a conductive pattern intermediate product and performing a wet etch process on the conductive pattern intermediate product using an etching atmosphere providing a higher etch selectivity with respect to the metal nitride film than the metal film. The etching atmosphere may include an etchant composition including hydrogen peroxide, a phosphoric acid compound, a heterocyclic organic amine compound including at least one heteroatom in a ring, and water.