Mixed Acid Etching Rate Stabilization via Water Addition
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Solution Overview
Problem
The etching characteristics of metallic films, such as tungsten, deteriorate due to their slight insolubility in acids, leading to a decrease in etching rate over time during the use of mixed acid processes in semiconductor device manufacturing, particularly in three-dimensionally processed stack films.
Innovation Solution
A substrate treatment method involving a mixed acid with an oxidizing agent, complexing agent, and water is used, where pure water is added during etching to maintain the etching rate by adjusting the water content ratio, stabilizing the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mixed acid (phosphoric acid and nitric acid) is used for etching metallic films, then the etching process can be performed, but the etching rate decreases over time due to film insolubility
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by adding hydrofluoric acid to the mixed acid composition. This parameter change modifies the solution's ability to dissolve metallic films, preventing the decrease in etching rate over time and maintaining stable etching characteristics throughout the process.
2Ease of manufacture
If conventional mixed acid process is used, then the process is simple, but etching characteristics deteriorate for slightly insoluble films
Solution Approach 1:
The patent creates a composite etching solution by combining multiple acids (phosphoric acid, nitric acid, and hydrofluoric acid). This composite chemical system leverages the complementary properties of each acid to achieve both process simplicity and reliable etching characteristics for slightly insoluble metallic films.
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 method stabilizes the etching rate of metallic films, enabling stable and controllable etching of metallic films like tungsten, aluminum, and titanium nitride, even as the etching progresses.
Implementation Method 1
The first liquid includes an oxidizing agent, a complexing agent, and water (H2O) of a first content rate to etch the first metallic film
Implementation Method 2
The first liquid includes an oxidizing agent, a complexing agent, and water (H2O) of a first content rate to etch the first metallic film
Data Source
AI summary
In accordance with an embodiment, a substrate treatment method includes bringing a first metallic film on a substrate into contact with a first liquid, mixing a second liquid into the first liquid, and bringing the first metallic film or a second metallic film different from the first metallic film into contact with a liquid in which the first liquid and the second liquid are mixed together to etch the first or second metallic film. The first liquid includes an oxidizing agent, a complexing agent, and water (H2O) of a first content rate to etch the first metallic film. The second liquid includes water (H2O) at a second content rate higher than the first content rate after the etching has started.