Phosphoric Acid Etching Control for Silicon Nitride Selectivity
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Solution Overview
Problem
Existing substrate processing systems require constant replenishment of etching liquids containing phosphoric acid to maintain silicic acid concentration, leading to increased consumption and inefficiency.
Innovation Solution
A substrate processing apparatus and method that controls the concentration of phosphoric acid in the etching liquid using a concentration control unit to maintain etching selectivity within a given range, reducing the need for continuous replenishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a low silicic acid concentration etching liquid is continuously supplied to maintain etching selectivity, then etching precision is improved, but liquid consumption increases
Solution Approach 1:
The patent changes the chemical parameters of the etching liquid by adding silicic acid compounds to suppress silicic acid concentration. This allows the use of higher phosphoric acid concentrations (improving etching selectivity) while preventing the harmful accumulation of silicic acid that would otherwise require continuous replenishment of fresh etching liquid.
2Manufacturing precision
If phosphoric acid concentration is increased to improve etching selectivity, then manufacturing precision is improved, but silicic acid accumulation occurs
Solution Approach 1:
The patent converts the harmful effect of silicic acid accumulation into a beneficial control mechanism. By intentionally adding silicic acid compounds to the etching liquid, the system suppresses further silicic acid accumulation from substrate etching, thereby maintaining stable composition and high etching selectivity throughout the processing period.
3Manufacturing precision
If etching liquid is frequently replenished to maintain concentration, then etching precision is maintained, but processing time increases
Solution Approach 1:
The patent enables continuous etching processing without interruption for liquid replenishment. By adding silicic acid compounds to suppress concentration changes, the etching liquid maintains its selective etching capability throughout the entire processing period, allowing uninterrupted batch processing of multiple substrates.
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
Reduces the consumption of etching liquid by maintaining etching selectivity without constant replenishment, ensuring precise and efficient etching processes.
Implementation Method 1
selectively etching, between a silicon nitride film and a silicon oxide film formed on a substrate, the silicon nitride film by using an etching liquid containing a phosphoric acid aqueous solution
Implementation Method 2
controlling a phosphoric acid concentration of the processing liquid such that etching selectivity of the silicon nitride film with respect to the silicon oxide film falls within a given range
Data Source
AI summary
A substrate processing apparatus includes a substrate processing unit and a controller. The substrate processing unit is configured to perform an etching processing on one or more substrates each having a silicon nitride film and a silicon oxide film on a surface thereof with a processing liquid containing a phosphoric acid aqueous solution and a silicic acid compound. The controller is configured to control individual components of the substrate processing apparatus. The controller includes a concentration control unit configured to control a phosphoric acid concentration of the processing liquid such that etching selectivity of the silicon nitride film with respect to the silicon oxide film falls within a given range from a beginning of the etching processing to an end thereof.