Wafer Drying Fluid Supply Sequence for Particle Prevention
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Solution Overview
Problem
Conventional methods for drying semiconductor wafers are ineffective in preventing particle generation, especially on high hydrophobic wafers and larger diameters, often requiring increased fluid usage which is costly.
Innovation Solution
A substrate processing method involving the sequential supply of a first fluid with higher volatility than the process liquid to form a liquid film, followed by a second fluid with even higher volatility, while rotating the substrate, with the supply positions moved radially outward from the rotational center, and optionally using a drying gas to enhance drying efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the supply amount of drying fluid (IPA) is increased to prevent particle generation on high hydrophobic wafers, then particle generation is suppressed, but the cost increases due to larger fluid consumption
Solution Approach 1:
The drying process is divided into multiple stages with different fluid supply strategies. The first drying fluid supply targets the peripheral portion specifically, while the second supply addresses the entire surface. This segmentation allows optimized fluid distribution that prevents particles without excessive overall consumption.
Solution Approach 2:
The invention applies different drying strategies to different regions of the wafer. The peripheral portion receives targeted drying fluid supply first, recognizing that this is where particles most commonly form on high hydrophobic wafers. This local quality approach ensures effective particle prevention where needed most while reducing overall fluid usage.
2Device complexity
If conventional drying methods are used on larger diameter wafers, then the drying process is simple, but particles (such as stripe water marks) appear near the peripheral portion
Solution Approach 1:
The drying process is segmented into two distinct supply phases: first targeting the peripheral portion, then covering the entire surface. This segmentation specifically addresses the particle formation issue at the periphery of large diameter wafers without requiring overly complex equipment modifications.
Solution Approach 2:
The drying fluid is supplied to the peripheral portion before the entire surface. This preliminary action prevents particle formation at the vulnerable peripheral region first, then completes the drying of the whole wafer, thereby preventing stripe water marks on large diameter wafers.
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 method effectively prevents particle generation on the substrate after drying, reduces the amount of fluid used for drying, and enhances the drying efficiency by using a controlled sequence of fluid supply and gas assistance.
Implementation Method 1
forming a liquid film on an upper surface of the substrate by supplying thereon a first fluid having a higher volatility than that of the process liquid
Implementation Method 2
supplying a second fluid having a higher volatility than that of the process liquid to the upper surface of the substrate, while rotating the substrate
Implementation Method 3
the wafer is rotated to remove liquid droplets therefrom due to the centrifugal force
Implementation Method 4
a drying gas may be further supplied to the upper surface of the substrate
Data Source
AI summary
A substrate (W) is processed with the use of a process liquid such as a deionized water. Then, a first fluid which is more volatile than the process liquid is supplied to an upper surface of the substrate (W) from a fluid nozzle (12) to form a liquid film. Next, a second fluid which is more volatile than the process liquid is supplied to the upper surface of the substrate (W) from the fluid nozzle (12), while the wafer (W) is being rotated. During this supply operation, a supply position (Sf) of the second fluid to the substrate (W) is moved radially outward from a rotational center (Po) of the substrate (W). As a result, it is possible to prevent the generation of particles on the substrate (W) after it is dried by using the first and second fluids.