Substrate Drying Humidity Control for Watermark Prevention
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Solution Overview
Problem
The high cost of reducing ambient humidity in semiconductor wafer processing due to the need for extensive dehumidified air supplies, particularly when multiple processing steps are conducted in a single chamber, and the challenge of preventing water marks during the drying process.
Innovation Solution
A substrate processing method that dynamically controls ambient humidity based on the type of chemical liquid used, employing a humidity control mechanism to adjust humidity levels during chemical liquid processing, rinse, and drying steps, using clean air or low dew point gases like CDA or nitrogen, and optionally forming an IPA liquid film to enhance drying efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If dehumidified air is supplied to lower ambient humidity around the wafer during drying step, then water mark generation is suppressed, but processing cost increases remarkably
Solution Approach 1:
The invention applies local quality by creating a dehumidified atmosphere only in the specific region where the wafer is dried, rather than dehumidifying the entire processing chamber. The wafer drying step is performed in a separate drying chamber or isolated zone where dehumidified air is supplied locally, while other processing steps can proceed in the main chamber without requiring dehumidified conditions. This localized approach reduces the total amount of dehumidified air needed while still preventing water marks on the wafer.
2Object-affected harmful factors
If a great amount of dehumidified air is supplied to lower ambient humidity, then water mark generation is prevented, but the cost requiring for wafer processing increases
Solution Approach 1:
The invention applies preliminary action by performing an IPA (isopropyl alcohol) treatment step before the drying step. The IPA is supplied to the wafer surface in advance of drying, replacing water and reducing surface tension. This preliminary IPA treatment allows the subsequent drying step to be performed with less dehumidified air, as the IPA facilitates easier evaporation and reduces the tendency for water marks to form. The preliminary action of IPA treatment thus reduces the amount of dehumidified air needed in the drying step, lowering processing costs while still preventing water marks.
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 reduces processing costs by minimizing the use of low dew point gases and effectively prevents water marks on substrates by optimizing humidity control during processing, ensuring efficient drying and maintaining substrate quality.
Implementation Method 1
a liquid film forming step that supplies a fluid containing IPA to an upper surface of the substrate to form a liquid film thereon
Implementation Method 2
a drying step that dries the substrate
Implementation Method 3
controlling an ambient humidity around the substrate depending on a kind of the chemical liquid
Data Source
AI summary
Provided is a substrate processing method that prevents generation of watermarks on a substrate and can be performed at a low cost. The method controls the ambient humidity around the substrate depending on the kind of the chemical liquid, when the substrate is processed with the chemical liquid. The control of the humidity is performed at least in a drying step that dries the substrate W. In one embodiment, the ambient humidity around the substrate is controlled when a fluid containing IPA as a drying fluid is supplied to the substrate W after processing the substrate W with the chemical liquid.