Substrate Etching Control for Constant Nitride-Oxide Selectivity
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Solution Overview
Problem
In substrate processing systems, maintaining constant etching selectivity between silicon nitride and silicon oxide films using phosphoric acid aqueous solutions requires continuous replenishment of etching liquid, leading to increased consumption and costs.
Innovation Solution
A substrate processing apparatus with a controller that adjusts the phosphoric acid concentration in real-time using a correction unit, ensuring constant etching selectivity from start to finish by monitoring and controlling the silicic acid concentration, thereby reducing the need for continuous liquid replenishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphoric acid aqueous solution is used for selective etching of silicon nitride film, then etching selectivity is achieved, but phosphoric acid concentration changes during processing causing etching selectivity to vary
Solution Approach 1:
The patent changes the concentration parameter of phosphoric acid during the etching process to compensate for consumption. The controller adjusts the phosphoric acid concentration dynamically to maintain constant etching selectivity, transforming a static concentration system into a dynamic one that adapts to processing conditions.
Solution Approach 2:
The system implements feedback control by monitoring the etching progress and phosphoric acid concentration, then adjusting the acid concentration accordingly. The controller receives information about concentration changes and modifies the etching parameters to maintain desired selectivity, creating a closed-loop control system.
2Manufacturing precision
If phosphoric acid concentration is increased to maintain etching selectivity, then etching performance is improved, but consumption of etching liquid increases
Solution Approach 1:
The patent transforms the static etching liquid concentration into a dynamic parameter that changes over time during processing. By making the phosphoric acid concentration dynamic and adjusting it according to consumption rates, the system maintains effective etching selectivity without requiring excessive liquid replenishment.
Solution Approach 2:
The system deliberately changes the phosphoric acid concentration parameter during the etching process to match the consumption rate. This parameter adjustment strategy allows the system to maintain optimal etching performance while accounting for liquid consumption, rather than simply replenishing liquid to maintain initial concentration.
3Manufacturing precision
If continuous replenishment of etching liquid is performed to maintain selectivity, then etching precision is maintained, but processing efficiency decreases
Solution Approach 1:
The system performs preliminary calculation of phosphoric acid consumption based on processing conditions, substrate area, and etching rate. This advance planning allows the controller to pre-determine the concentration adjustment schedule, eliminating the need for frequent interruptions to replenish liquid during the actual etching process.
Solution Approach 2:
The patent maintains continuous etching action by smoothly adjusting phosphoric acid concentration rather than interrupting the process for liquid replenishment. The etching operation continues uninterrupted while the controller dynamically modifies the acid concentration to compensate for consumption, ensuring both precision 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 approach stabilizes etching selectivity and reduces the consumption of etching liquid, optimizing processing efficiency and cost by allowing multiple batches to be processed with the same liquid.
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
a correction unit configured to correct a phosphoric acid concentration of the processing liquid such that etching selectivity of the silicon nitride film with respect to the silicon oxide film becomes constant at a given value from a beginning of the etching processing to an end thereof
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 correction unit configured to correct a phosphoric acid concentration of the processing liquid such that etching selectivity of the silicon nitride film with respect to the silicon oxide film becomes constant at a given value from a beginning of the etching processing to an end thereof.