Wafer Developing Apparatus Uniform Developer Spreading
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Solution Overview
Problem
High water repellency on semiconductor wafers complicates uniform developer spreading during the developing process, leading to increased defects in photoresist pattern formation, especially as feature sizes minimize.
Innovation Solution
A developing apparatus and method that utilize a diffusion-assisting liquid to form a puddle on the substrate, followed by developer application in a controlled manner to ensure uniform coverage and effective development, even on highly water-repellent surfaces, by rotating the substrate in both directions and positioning the developer nozzle to facilitate uniform distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a highly water repellent protective film is formed on the resist film to improve immersion exposure throughput, then the water repellency of the wafer surface is improved, but the uniform spreading of developer over the wafer surface becomes more difficult
Solution Approach 1:
The invention applies a preliminary action by forming a water-repellent protective film on the resist film before the developing process. This film is specifically designed to control water interaction, preventing excessive water absorption that would cause developer non-uniformity, while still allowing the developer to spread evenly across the wafer surface during development.
2Measurement precision
If the minimum feature size of patterns is minimized to improve resolution, then the exposure resolution is improved, but the degree of defective development increases due to enhanced water repellency
Solution Approach 1:
The invention changes the surface energy parameters of the wafer by forming a water-repellent protective film with controlled hydrophobicity. This parameter modification allows the surface to maintain high water repellency for improved resolution while controlling the interaction with developer solution to prevent development defects, achieving both high resolution and reliable development.
3Productivity
If the wafer surface has high water repellency to improve immersion exposure performance, then the throughput is improved, but it is difficult to spread the developer uniformly particularly in the circumferential part of the surface
Solution Approach 1:
The water-repellent protective film acts as an intermediary layer between the wafer surface and the developer solution. This intermediate film mediates the interaction by providing controlled wettability that facilitates uniform developer spreading across the entire wafer surface, including the circumferential areas, while maintaining the water repellency needed for high immersion exposure throughput.
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 ensures highly uniform processing of the substrate surface, reducing development defects and improving wettability, allowing for effective dissolution of resist film patterns regardless of high water repellency.
Implementation Method 1
a diffusion-assisting liquid spouting nozzle for spouting a diffusion-assisting liquid not having any developing effect and capable of assisting the diffusion of the developer on the substrate
Implementation Method 2
a rotating mechanism for rotating the substrate holding device about a vertical axis
Implementation Method 3
spouting the developer onto the central part of the substrate being rotated in the normal direction by the rotating mechanism to spread the developer all over the surface of the substrate such that parts of the resist film is dissolved to produce a solution
Data Source
AI summary
A pretreatment process, carried out prior to a developing process, spouts pure water, namely, a diffusion-assisting liquid for assisting the spread of a developer over the surface of a wafer, through a cleaning liquid spouting nozzle onto a central part of the wafer to form a puddle of pure water. The developer is spouted onto the central part of the wafer for prewetting while the wafer is rotated at a high rotating speed to spread the developer over the surface of the wafer. The developer dissolves the resist film partly and produces a solution. The rotation of the wafer is reversed, for example, within 7 s in which the solution is being produced to reduce the water-repellency of the wafer by spreading the solution over the entire surface of the wafer. Then, the developer is spouted onto the rotating wafer to spread the developer on the surface of the wafer.