Cobalt Alloy Electroless Plating Solution Stabilizer
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Solution Overview
Problem
Conventional electroless plating solutions for cobalt-based alloys used in semiconductor wiring are unstable due to autolysis, leading to precipitate formation and reduced durability, which affects the quality of metal thin-films and requires high temperatures for effective plating on copper wiring.
Innovation Solution
A cobalt-based alloy electroless plating solution comprising a cobalt precursor, tungsten precursor, phosphorus precursor, reducing agent (dimethylamine borane or borohydride), complexing agent, pH regulator, and stabilizer (imidazole derivatives) is developed to inhibit autolysis and maintain solution stability, allowing for reuse and improved thin-film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dimethylamine borane (DMAB) is used as a reducing agent for electroless plating on copper wiring, then adhesion to copper wiring is improved, but solution stability deteriorates causing autolysis
Solution Approach 1:
A stabilizer compound is introduced as an intermediary substance that mediates between the reducing agent (DMAB) and metal ions in the plating solution. The stabilizer prevents direct unwanted reactions (autolysis) while allowing controlled reduction on the copper substrate, thus maintaining both adhesion quality and solution stability simultaneously.
Solution Approach 2:
The invention modifies the chemical environment of the plating solution by adding specific stabilizer compounds that change the reaction parameters. This allows the system to maintain DMAB as the reducing agent for good adhesion while controlling the reaction rate and preventing autolysis through altered chemical conditions.
2Productivity
If high temperature is used for electroless plating with DMAB, then plating effectiveness is improved, but autolysis occurs more easily
Solution Approach 1:
The stabilizer compound is added to the plating solution in advance to prevent autolysis before it occurs. This preliminary protective action counteracts the tendency toward decomposition that arises at high temperatures, allowing effective plating to proceed without the harmful side effects of autolysis.
3Stability of the object's composition
If conventional reducing agents are used, then solution stability is maintained, but plating on copper wiring is ineffective due to low catalytic activity
Solution Approach 1:
The stabilizer acts as an intermediary that enables the use of DMAB (a strong reducing agent) without causing uncontrolled reactions. This allows the system to achieve both good plating effectiveness on copper and adequate solution stability, resolving the trade-off between reactivity and stability.
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 solution provides a stable electroless plating process that prevents precipitate formation, extends solution lifespan, and maintains metal thin-film quality, enabling effective cobalt-based alloy deposition on copper wiring with improved adhesion and reduced parasitic capacitance.
Implementation Method 1
Electroless plating is a method of forming a metal thin-film by reducing a metal ion using an electron generated through oxidation of a reducing agent on the surface of a catalyst substrate without any externally supplied electrons
Implementation Method 2
reducing a metal ion using an electron generated through oxidation of a reducing agent
Implementation Method 3
the stabilizer is one or more compounds selected from a group consisting of imidazole, thiazole, triazole, disulfide and their derivatives... the reducing agent is dimethylamine borane (DMAB) or borohydride and the stabilizer is one or more compounds selected from a group consisting of imidazole, thiazole, triazole, disulfide and their derivatives
Data Source
AI summary
A cobalt-based alloy electroless plating solution according to the present invention comprises a cobalt precursor, a tungsten precursor, a phosphorus precursor, a reducing agent, a complexing agent, a pH regulator and a stabilizer, in which the reducing agent is dimethylamine borane (DMAB) or borohydride and the stabilizer is one or more compounds selected from a group consisting of imidazole, thiazole, triazole, disulfide and their derivatives; and which is stable enough for long-term reuse and prevents deterioration of metal thin-film quality by inhibiting the formation of a precipitate.