IPA Supply Control for Low-Oxygen Substrate Processing
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the formation of bubbles due to dissolved oxygen in IPA during supercritical drying, which can cause pattern collapse on substrates, and existing technologies lack effective methods to maintain low dissolved oxygen concentrations in IPA.
Innovation Solution
A substrate processing apparatus with a dissolved oxygen concentration measuring device and a control system that determines and adjusts the supply of IPA based on measured oxygen levels, using an IPA supply mechanism with a buffer tank and inert gas atmosphere to minimize oxygen absorption, ensuring IPA with low dissolved oxygen is used for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IPA is supplied from the processing liquid source directly to the nozzle, then the processing can be performed continuously, but the dissolved oxygen concentration in IPA increases causing pattern collapse
Solution Approach 1:
The buffer tank stores IPA in advance under an inert gas atmosphere, preparing low-dissolved-oxygen IPA before it is needed for processing. This preliminary preparation prevents oxygen dissolution during supply while maintaining processing continuity.
Solution Approach 2:
Inert gas (nitrogen or argon) is introduced as an intermediary substance to displace oxygen in the buffer tank and supply line. This intermediary prevents oxygen from dissolving in the IPA while allowing continuous supply to the nozzle.
2Reliability
If the buffer tank is equipped with inert gas atmosphere, then dissolved oxygen concentration in IPA is reduced, but the device complexity increases
Solution Approach 1:
The buffer tank is configured with an inert gas atmosphere (nitrogen or argon) to prevent oxygen from dissolving in the IPA. This creates a controlled environment that maintains low dissolved oxygen concentrations without requiring complex additional equipment.
3Measurement precision
If dissolved oxygen concentration measuring device is added, then oxygen levels can be monitored and controlled, but the device complexity and cost increase
Solution Approach 1:
The dissolved oxygen concentration measuring device provides real-time feedback on the oxygen levels in the IPA supply line. The controller uses this feedback information to monitor and maintain acceptable oxygen levels, enabling precise control of the processing liquid quality.
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 effectively reduces dissolved oxygen in IPA, preventing pattern collapse during supercritical drying and ensuring reliable substrate processing.
Implementation Method 1
a dissolved oxygen concentration measuring device provided in the supply pipe or in a drain pipe branched off from the supply pipe, and configured to measure a dissolved oxygen concentration in the processing liquid present in the supply pipe or in the processing liquid taken out from the supply pipe through the drain pipe
Implementation Method 2
a buffer tank configured to temporarily store therein the processing liquid supplied from a processing liquid source
Implementation Method 3
a supply controller configured to at least perform a supply and a stop of the supply of the processing liquid to the nozzle
Data Source
AI summary
A substrate processing apparatus includes a liquid processing device configured to supply a processing liquid onto a substrate from a nozzle and form a liquid film of the processing liquid on a surface of the substrate; a processing liquid supply comprising: a buffer tank configured to store therein the processing liquid supplied from a processing liquid source; a supply pipe configured to connect the processing liquid source, the buffer tank and the nozzle; and a supply controller configured to perform a supply and a stop of the supply of the processing liquid to the nozzle; a dissolved oxygen concentration measuring device configured to measure a dissolved oxygen concentration in the processing liquid; and a controller configured to determine whether or not to supply the processing liquid to the substrate based on a measurement result, and configured to control the supply controller based on a determination result.