Phosphoric Acid Etching Bath with Silicon Oxide Precipitation Control
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Solution Overview
Problem
In substrate processing systems, excessive silicon concentration in etching liquids can lead to silicon oxide deposition, suppressing etching processing due to the precipitation of silicon oxide, which affects the etching selectivity between silicon nitride and silicon oxide films.
Innovation Solution
A substrate processing apparatus that includes a mixing device generating a mixture liquid by combining phosphoric acid with a precipitation inhibitor to prevent silicon oxide precipitation, and a silicon solution supply to adjust the silicon concentration in the etching liquid, ensuring proper etching processing by immersing substrates in a phosphoric acid-based etching liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silicon solution is added to phosphoric acid aqueous solution for etching processing, then etching capability is improved, but silicon oxide precipitation occurs suppressing etching processing
Solution Approach 1:
A silicon oxide precipitation inhibitor is introduced as an intermediary substance that mediates between the phosphoric acid aqueous solution and silicon solution. The inhibitor prevents silicon oxide precipitation without interfering with the etching reaction, allowing both high etching capability and prevention of harmful precipitation simultaneously
Solution Approach 2:
The chemical composition parameters of the etching liquid are modified by adding a silicon oxide precipitation inhibitor. This changes the chemical environment to suppress silicon oxide formation while maintaining the etching effectiveness of the phosphoric acid-silicon solution system
2Manufacturing precision
If silicon concentration is increased to enhance etching selectivity, then etching performance is improved, but silicon oxide deposition increases suppressing processing
Solution Approach 1:
The silicon oxide precipitation inhibitor acts as a mediator that allows high silicon concentration to be maintained for etching selectivity while preventing the harmful side effect of silicon oxide deposition. The inhibitor specifically targets the precipitation mechanism without affecting the etching selectivity
Solution Approach 2:
The invention converts the potentially harmful silicon oxide precipitation into a beneficial situation by using the inhibitor to control silicon oxide formation. The high silicon concentration that would normally cause deposition is now harnessed to improve etching selectivity while the inhibitor prevents the harmful deposition
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 effectively maintains optimal silicon concentration in the etching liquid, enhancing etching selectivity and preventing silicon oxide deposition, thus ensuring efficient and selective etching of silicon nitride films over silicon oxide films.
Implementation Method 1
The mixing device generates a mixture liquid by mixing a phosphoric acid aqueous solution with an additive that suppresses precipitation of silicon oxide
Implementation Method 2
an additive that suppresses precipitation of silicon oxide
Implementation Method 3
The liquid sending path sends the mixture liquid from the mixing device to the processing bath
Implementation Method 4
The silicon solution supply is connected to at least one of the liquid sending path and the processing bath, and supplies a silicon-containing compound aqueous solution to the mixture liquid
Implementation Method 5
The processing bath processes a substrate through immersion
Data Source
AI summary
A substrate processing apparatus includes a processing bath in which a substate is immersed to be processed; a mixer that generates a mixture liquid by mixing a phosphoric acid aqueous solution with an additive that suppresses precipitation of silicon oxide; a liquid path that supplies the mixture liquid from the mixer to the processing bath; a silicon solution supply that supplies a silicon-containing compound aqueous to the mixture liquid supplied from the mixer; and a controller that controls the processing bath, the mixer, the liquid path, and the silicon solution supply. When the substrate is immersed in the processing bath, the controller supplies the mixture liquid without the silicon-containing compound aqueous solution to the processing bath.