Phosphoric Acid Etch Selectivity Control via Dynamic Flow Rates
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Solution Overview
Problem
Existing substrate liquid treatment processes using phosphoric acid solutions for semiconductor manufacturing cannot dynamically control etch selectivity during the processing of a single substrate lot, leading to inefficiencies in silicon nitride film etching.
Innovation Solution
A substrate liquid treatment apparatus and method that control the flow rates of phosphoric acid solution supply and drainage to adjust silicon concentration in real-time, allowing for different etching rates by varying the drainage and supply flow rates during different periods of substrate immersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the phosphoric acid solution is continuously drained and supplied at a constant flow rate, then the silicon concentration can be maintained within a predetermined range, but the etch selectivity cannot be dynamically adjusted during substrate processing
Solution Approach 1:
The patent applies the dynamics principle by transitioning from constant flow rate drainage and supply to variable flow rate control. The drainage flow rate and supply flow rate are dynamically adjusted during substrate processing based on real-time silicon concentration measurements, enabling the etch selectivity to be optimized at different stages of the etching process
Solution Approach 2:
The patent implements feedback control by using a silicon concentration sensor to continuously monitor the silicon concentration in the phosphoric acid solution and adjusting the drainage and supply flow rates accordingly. This closed-loop control system allows the etch selectivity to be dynamically optimized based on actual process conditions
2Productivity
If the silicon concentration is maintained within a predetermined range, then particle reduction is achieved, but the etching rate cannot be optimized for different processing stages
Solution Approach 1:
The patent applies periodic action by dividing the etching process into multiple stages with different target silicon concentration ranges. The drainage and supply flow rates are periodically adjusted to achieve different silicon concentration levels at different time periods, allowing the etching rate to be optimized for each stage while maintaining particle control
3Manufacturing precision
If the phosphoric acid solution is drained and replenished between substrate lots, then silicon concentration is controlled, but continuous process optimization during a single lot is not possible
Solution Approach 1:
The patent implements continuity of useful action by enabling continuous optimization of the etching process during substrate lot processing. Instead of interrupting the process to drain and replenish the phosphoric acid solution between lots, the system continuously adjusts the drainage and supply flow rates to maintain optimal silicon concentration and etch selectivity throughout the entire processing period
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
Enables optimal etch selectivity by dynamically managing the silicon concentration in the phosphoric acid solution, improving the etching process by adjusting the flow rates to match the etching progress, thus maintaining the silicon concentration within a desired range.
Implementation Method 1
During etching, silicon derived from the silicon nitride film dissolves in the phosphoric acid solution
Data Source
AI summary
A substrate liquid treatment method in one embodiment includes, storing a phosphoric acid solution in a processing bath provided in a liquid treatment unit, and immersing a substrate into the stored phosphoric acid solution to process the substrate, draining a phosphoric acid solution at a first drainage flow rate from the liquid treatment unit, and supplying a phosphoric acid solution to the liquid treatment unit, in a first time period in which the substrate is immersed in the phosphoric acid solution in the processing bath, and draining a phosphoric acid solution at a second drainage flow rate different from the first drainage flow rate, from the liquid treatment unit, and supplying a phosphoric acid solution to the liquid treatment unit, in a second time period in which the substrate is immersed in the phosphoric acid solution in the processing bath.