Ketone-Modified Substrate Processing Liquid for Etching Uniformity
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Solution Overview
Problem
High viscosity of mixed acid used in batch wet etching for semiconductor devices leads to in-plane uniformity issues and circulation flow rate errors due to evaporation of acetic acid when heated, causing viscosity increase.
Innovation Solution
Incorporating ketone as a viscosity adjusting agent in the substrate processing liquid, which reduces viscosity and suppresses evaporation, maintaining consistent flow and uniformity by using a substrate processing apparatus with a circulating system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If acetic acid is added to reduce the viscosity of mixed acid, then the viscosity decreases and circulation is improved, but the acetic acid evaporates during heating, causing viscosity to increase again and creating flow rate errors
Solution Approach 1:
The patent changes the chemical composition parameter by replacing acetic acid with ketone (specifically methyl ethyl ketone or methyl isobutyl ketone) as the viscosity-reducing agent. This substitution maintains the desired low viscosity while eliminating the evaporation problem, as ketone has lower volatility than acetic acid at the processing temperatures used in batch wet etching
Solution Approach 2:
The patent uses a small amount of ketone (0.1-10 wt%) as a temporary additive that performs its viscosity-reducing function during the etching process without requiring long-term stability. The ketone is consumed or evaporated in controlled amounts, and the system is designed to accommodate this by maintaining the overall composition within acceptable ranges throughout the batch process
2Speed
If mixed acid is heated at high temperature to be circulated, then the circulation flow rate is improved, but the acetic acid evaporates during circulation, causing viscosity increase and in-plane uniformity deterioration
Solution Approach 1:
The patent changes the chemical composition by substituting ketone for acetic acid. This parameter change allows the mixed acid to be heated to high temperatures for circulation without the severe evaporation losses that would otherwise occur with acetic acid, thereby maintaining both high circulation flow rates and in-plane uniformity of the etching process
Solution Approach 2:
The patent applies preliminary anti-action by pre-selecting ketone as the viscosity-reducing agent before the circulation process begins. This preventive measure ensures that the composition remains stable during heating and circulation, counteracting the potential harmful effect of evaporation before it can occur and affect the etching uniformity
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 use of ketone in the substrate processing liquid maintains low viscosity and prevents evaporation, ensuring consistent etching performance and reducing errors in the etching process.
Implementation Method 1
the ketone is used as a viscosity adjusting agent
Implementation Method 2
when the mixed acid is heated at high temperature to be circulated
Implementation Method 3
the acetic acid is evaporated from the mixed acid during the circulation of the mixed acid
Data Source
AI summary
In one embodiment, a substrate processing liquid contains phosphoric acid as a primary component and contains water and ketone. In another embodiment, a substrate processing method includes processing a substrate in a substrate processing bath with a substrate processing liquid containing phosphoric acid, water and ketone. The method further includes discharging the substrate processing liquid from the substrate processing bath to a circulating flow channel, heating the substrate processing liquid flowing through the circulating flow channel at a temperature between 50° C. and 90° C., and supplying the substrate processing liquid again from the circulating flow channel to the substrate processing bath to circulate the substrate processing liquid under heating.