Substrate Edge Cleaning Using CO2 Gas and Annular Body
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Solution Overview
Problem
Contaminants adhering to the edge and backside of semiconductor substrates during manufacturing processes migrate to the front side, causing yield loss, and existing cleaning methods are costly and inefficient.
Innovation Solution
A substrate cleaning apparatus and method using a rotatable substrate support with nozzles providing a stream of solid and gaseous carbon dioxide to remove contaminants from the edge, followed by a second gas to remove residue, while an annular body with a central opening prevents contaminants from reaching the front side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet chemicals and backside scrubbing are used to remove contaminants, then cleaning effectiveness is improved, but equipment cost and consumable cost increase
Solution Approach 1:
The patent replaces wet chemical cleaning and mechanical backside scrubbing with a gas-based cleaning system using CO2. The gas delivery system introduces CO2 gas to the substrate backside, where it expands and lifts contaminants away from the substrate surface through pressure differential, eliminating the need for complex wet chemical delivery systems and mechanical scrubbing apparatus.
Solution Approach 2:
The invention utilizes pneumatic principles by introducing CO2 gas under pressure to the substrate backside. The gas expands upon contact with the lower pressure environment, creating a pressure differential that lifts and removes contaminants. This pneumatic approach replaces complex mechanical and chemical cleaning systems with a simpler gas delivery mechanism.
2Reliability
If wet chemicals are used for cleaning, then contaminant removal is improved, but chemical consumption and environmental impact increase
Solution Approach 1:
The patent changes the physical state and properties of the cleaning agent from liquid wet chemicals to gaseous CO2. This parameter change eliminates chemical consumption issues and environmental concerns associated with liquid chemicals, while maintaining effective contaminant removal through the gas expansion mechanism.
Solution Approach 2:
The invention uses CO2 gas, which can be readily obtained and is environmentally benign compared to specialized wet chemicals. The CO2 is introduced, performs its cleaning function through expansion, and then dissipates harmlessly, eliminating the need for chemical disposal and reduction programs associated with traditional wet cleaning methods.
3Reliability
If frequent cleaning of process tools is performed, then yield loss is reduced, but productivity decreases
Solution Approach 1:
The patent performs cleaning action at the moment of substrate handling rather than requiring separate frequent cleaning cycles. By integrating the gas delivery system into the substrate transfer process, contaminants are removed preventively during normal handling operations, eliminating the need for dedicated frequent cleaning stops that would reduce productivity.
Solution Approach 2:
The cleaning system operates automatically during substrate handling without requiring separate intervention or stopping the manufacturing process. The gas delivery system is self-regulating, introducing CO2 only when needed during substrate transfer, thereby maintaining continuous production flow while preventing contaminant-related yield loss.
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
Effectively removes contaminants from the substrate edge without damaging the substrate, reduces yield loss, and minimizes residue deposition, using carbon dioxide as a cleaning agent to reduce chemical costs and environmental impact.
Implementation Method 1
directing a first cleaning gas of solid and gaseous carbon dioxide from a liquid carbon dioxide source
Implementation Method 2
flowing a first gas over the first side of the substrate such that a velocity of the first gas as it flows past the edge of the substrate increases
Data Source
AI summary
A substrate cleaning apparatus may include a substrate support having a support surface to support a substrate to be cleaned, wherein the substrate support is rotatable about a central axis normal to the support surface; a first nozzle to provide a first cleaning gas to a region of the inner volume corresponding to the position of an edge of the substrate when the substrate is supported by the support surface of the substrate support; a first annular body disposed opposite and spaced apart from the support surface of the substrate support by a gap, the first annular body having a central opening defined by an inner wall shaped to provide a reducing size of the gap between the first annular body and the support surface in a radially outward direction; and a first gas inlet to provide a first gas to the central opening of the first annular body.