Substrate Processing Apparatus for Selective Silicon Nitride Etching
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Solution Overview
Problem
The existing substrate processing technologies face challenges in achieving high etching selectivity between silicon nitride and silicon oxide films using phosphoric acid, as pyrophosphoric acid generated during the etching process can inadvertently etch the silicon oxide film, reducing selectivity and uniformity.
Innovation Solution
A substrate processing apparatus is designed with a phosphoric acid supply system, a heater, and a water nozzle to form a puddle-shaped phosphoric acid film on the substrate, with controlled water supply to reduce pyrophosphoric acid generation and maintain etching selectivity, using a heater moving device to ensure uniform heating and a control device to adjust water distribution based on substrate rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-temperature phosphoric acid aqueous solution is supplied onto the substrate to increase etching rate, then etching speed improves, but pyrophosphoric acid generation increases causing silicon oxide film etching and reducing selectivity
Solution Approach 1:
The patent controls the temperature parameter of the phosphoric acid aqueous solution to prevent pyrophosphoric acid generation. By maintaining the solution temperature below the threshold that triggers significant pyrophosphoric acid formation, the system achieves high etching rates while preserving etching selectivity between silicon nitride and silicon oxide films.
Solution Approach 2:
The patent employs temperature sensing and control mechanisms to monitor and adjust the phosphoric acid solution temperature in real-time. This feedback system ensures the temperature remains within the optimal range for high etching rates while preventing pyrophosphoric acid generation that would compromise selectivity.
2Productivity
If phosphoric acid aqueous solution is heated to increase etching activity, then etching efficiency improves, but uniformity of heating and pyrophosphoric acid distribution deteriorates
Solution Approach 1:
The patent divides the heating function into multiple heating regions or zones across the substrate surface. This segmentation allows independent temperature control in different areas, ensuring uniform heating without creating hot spots that would lead to non-uniform pyrophosphoric acid distribution and inconsistent etching results.
Solution Approach 2:
The patent employs dynamic temperature control that adjusts heating parameters based on real-time conditions. The system can modify heating intensity and distribution during the etching process to maintain optimal temperature uniformity across the substrate, preventing localized pyrophosphoric acid generation while preserving overall etching efficiency.
3Manufacturing precision
If water is supplied to suppress pyrophosphoric acid generation, then etching selectivity improves, but phosphoric acid activity and etching rate decrease
Solution Approach 1:
The patent optimizes the water content parameter in the phosphoric acid aqueous solution. By controlling the precise amount of water added, the system suppresses pyrophosphoric acid generation enough to maintain selectivity while preserving sufficient phosphoric acid concentration and activity to sustain high etching rates. This involves finding the optimal water concentration threshold.
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 enhances etching selectivity and uniformity by minimizing pyrophosphoric acid formation, maintaining efficient phosphoric acid activity, and stabilizing etching rates, thereby improving the processing of silicon nitride films while protecting silicon oxide films.
Implementation Method 1
a heater for heating the liquid film of phosphoric acid aqueous solution from the upper surface side of the substrate
Implementation Method 2
a water nozzle for discharging water therethrough toward the liquid film of phosphoric acid aqueous solution to cause the water to reach the liquid film
Implementation Method 3
a phosphoric acid supply device for supplying phosphoric acid aqueous solution onto the upper surface of the substrate held on the substrate holding device
Data Source
AI summary
A substrate processing apparatus includes a phosphoric acid supply device for supplying phosphoric acid aqueous solution onto the upper surface of a substrate held on a spin chuck, a heater for emitting heat toward a portion of the upper surface of the substrate with the phosphoric acid aqueous solution being held on the substrate, a heater moving device for moving the heater to move a position heated by the heater within the upper surface of the substrate, a water nozzle for discharging water therethrough toward a portion of the upper surface of the substrate with the phosphoric acid aqueous solution being held on the substrate and a water nozzle moving device for moving the water nozzle to move the water landing position within the upper surface of the substrate.