Nickel Silicide Silicon Etching Without Deep-Level Impurities
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Solution Overview
Problem
Noble metals like gold and silver used in metal catalyst chemical etching for silicon substrates can introduce deep-level impurities, degrading device performance in CMOS processes.
Innovation Solution
Forming a metal catalyst containing nickel silicide on a silicon substrate, followed by heat treatment to create a stable nickel silicide layer, and using an etching solution with H2O2 and HF for selective etching, which prevents the formation of deep-level impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If noble metals (gold or silver) are used as metal catalysts for chemical etching of silicon substrates, then etching can be performed effectively, but deep-level impurities are introduced into the silicon substrate, degrading device performance
Solution Approach 1:
The patent replaces expensive noble metals (gold, silver) with nickel, which is cheaper and does not introduce deep-level impurities into the silicon substrate. The nickel catalyst is deposited as a thin layer (5-20 nm) that serves its purpose during etching without contaminating the substrate, effectively acting as a disposable catalyst that maintains both productivity and reliability.
Solution Approach 2:
The patent changes the material parameter of the catalyst from noble metals to nickel, and controls the thickness parameter of the nickel layer (5-20 nm) to optimize etching performance while preventing impurity formation. This parameter change allows the system to achieve effective etching without the harmful side effects of noble metal catalysts.
2Stability of the object's composition
If nickel is deposited with thickness greater than 3 nm, then the metal catalyst layer is stable, but the etching rate decreases
Solution Approach 1:
The patent optimizes the nickel layer thickness parameter to a specific range (5-20 nm) that balances stability and etching rate. This precise parameter control ensures the catalyst layer is stable enough to withstand the etching process while remaining thin enough to maintain high etching rates, resolving the contradiction between stability and productivity.
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 method allows for stable and anisotropic etching of silicon substrates without introducing deep-level impurities, maintaining device performance and achieving high etching rates, with nickel silicide providing improved etching rates when platinum is incorporated.
Implementation Method 1
metal catalyst chemical etching is a method, in which a metal catalyst is formed on a silicon substrate, and then etching is performed using an etching solution, and the silicon substrate in contact with the metal catalyst is etched
Implementation Method 2
selectively etching the silicon substrate in contact with the metal catalyst by reacting the silicon substrate, on which the metal catalyst is formed, with an etching solution containing H2O2 and HF
Implementation Method 3
heat treating the silicon substrate, on which the nickel is formed, at a temperature of 300 to 600° C. to form a metal catalyst containing nickel silicide
Implementation Method 4
forming nickel on a silicon substrate with a thickness of 10 nm to 30 nm, heat treating the silicon substrate, on which the nickel is formed, at a temperature of 300 to 600° C. to form a metal catalyst containing nickel silicide
Data Source
AI summary
A chemical etching method using a metal catalyst is provided that prevents deterioration of device performance by preventing the formation of deep-level impurities inside silicon. The etching method comprises forming a metal catalyst containing nickel silicide on a silicon substrate, and selectively etching the silicon substrate in contact with the metal catalyst through chemical etching of the metal catalyst.