Silicon Etching Fluid Selective Dummy Gate Removal
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Solution Overview
Problem
Current methods for etching polysilicon in transistors are inefficient, leading to prolonged processing times, increased production costs, and potential damage to high dielectric materials and metal gates, particularly when using dry etching or alkaline solutions, which do not effectively achieve a high etch rate without compromising transistor performance.
Innovation Solution
A silicon etching solution comprising 0.1 to 40% by weight of alkali compounds like ammonia or polyamines, 0.01 to 40% by weight of polyhydric alcohols, and 40 to 99.89% by weight of water, specifically designed to selectively etch silicon dummy gates without damaging metal gates or high dielectric materials, allowing for efficient replacement with metal gates containing hafnium, zirconium, titanium, tantalum, or tungsten.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry etching is used to etch polysilicon, then the etching speed is improved, but the side wall and interlayer insulating film are also etched requiring protective films
Solution Approach 1:
The invention changes the chemical composition parameters of the etching solution by formulating a specific alkaline solution containing sugar alcohols and other additives that selectively etch polysilicon at high speeds while being inert to side walls and interlayer insulating films, eliminating the need for protective films
Solution Approach 2:
The invention replaces the physical/mechanical dry etching process with a chemical wet etching process using a specially formulated alkaline solution, achieving high etching speeds through chemical reactions rather than physical sputtering
2Manufacturing precision
If overetching is performed to prevent fine silicon residues, then the silicon etching is improved, but the high dielectric material is etched or deteriorated
Solution Approach 1:
The invention modifies the chemical parameters of the etching solution by adding sugar alcohols and other selective agents that enhance the etching rate for silicon while simultaneously providing selectivity to stop etching before damaging the high dielectric material, allowing complete silicon removal without overetching damage
Solution Approach 2:
The sugar alcohols act as intermediary substances that mediate the etching reaction, facilitating complete silicon removal while protecting the high dielectric material from damage during the etching process
3Reliability
If conventional alkaline cleaning solutions are used for silicon etching, then the selectivity is improved, but the etching time is prolonged reducing production output
Solution Approach 1:
The invention dramatically changes the concentration and composition parameters of the alkaline solution, using high concentrations of sugar alcohols and other additives to achieve both high etching speeds and high selectivity, simultaneously improving productivity and reliability
Solution Approach 2:
The invention creates a composite etching solution containing multiple components including sugar alcohols, alkaline agents, and other additives that work synergistically to provide both high etching speed and high selectivity for silicon
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 enables high-precision and high-quality transistor production with a high yield by selectively removing silicon dummy gates, preventing damage to metal gates and high dielectric materials, thus improving production efficiency and reducing costs.
Implementation Method 1
subjecting the polysilicon to wet-etching
Implementation Method 2
a sheet cleaning apparatus for cleaning a silicon wafer one by one to suppress generation of particles has been frequently used
Data Source
AI summary
The present invention relates to a silicon etching solution which is used for selectively etching a dummy gate made of silicon in a process for producing a transistor including a laminate formed of at least a high dielectric material film and a metal gate containing hafnium, zirconium, titanium, tantalum or tungsten by the method of removing the dummy gate made of silicon to replace the dummy gate with the metal gate and which includes 0.1 to 40% by weight of at least one alkali compound selected from the group consisting of ammonia, a diamine and a polyamine represented by the general formula (1), 0.01 to 40% by weight of at least one polyhydric alcohol selected from the group consisting of specific polyhydric alcohols and a non-reducing sugar, and 40 to 99.89% by weight of water, and a process for producing a transistor using the silicon etching solution.