Wafer Edge Coating Pretreatment for Uniform Film Thickness
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Solution Overview
Problem
The existing methods for forming a coating film on the peripheral edge of disk-shaped substrates, such as semiconductor wafers, often result in non-uniform film thickness, leading to 'humps' that can cause cracking or residue issues during sintering or etching processes.
Innovation Solution
A substrate treatment method involving the application of a pretreatment solution to reduce the contact angle of the coating solution, forming a liquid film, and then applying the coating solution on this film while rotating the substrate, thereby reducing the occurrence of humps by ensuring uniform film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a coating solution is supplied to the peripheral edge part of the substrate, then a coating film is formed on the peripheral edge part, but the center side of the substrate is raised and film thickness increases causing non-uniform film thickness
Solution Approach 1:
A pretreatment solution is supplied to the peripheral edge part of the substrate before supplying the coating solution. This preliminary action modifies the surface properties of the peripheral edge part, reducing the contact angle and preventing the coating solution from accumulating and forming humps, thereby achieving uniform film thickness across the substrate.
Solution Approach 2:
The contact angle of the coating solution on the substrate surface is changed by applying a pretreatment solution. This parameter change reduces the wettability difference between the peripheral edge part and the center side, preventing excessive coating solution accumulation at the peripheral edge and ensuring uniform film thickness.
2Manufacturing precision
If the contact angle of the coating solution is reduced, then hump formation is reduced, but this requires additional pretreatment steps
Solution Approach 1:
The pretreatment solution is applied in advance to modify the surface properties of the peripheral edge part. This preliminary action creates optimal conditions for subsequent coating solution application, reducing contact angle and preventing hump formation without requiring complex real-time control mechanisms.
Solution Approach 2:
The pretreatment solution acts as an intermediary substance between the substrate and the coating solution. It modifies the substrate surface properties to achieve the desired contact angle reduction and uniform film thickness, simplifying the overall coating process control.
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 minimizes the formation of humps, preventing cracking and residue issues during subsequent processes, and ensures a more uniform coating film thickness.
Implementation Method 1
supplying, to an upper surface of the peripheral edge part of the substrate, a pretreatment solution reducing a contact angle of a coating solution for forming the coating film with respect to the upper surface while rotating the substrate in a horizontal plane
Implementation Method 2
a pretreatment solution reducing a contact angle of a coating solution for forming the coating film with respect to the upper surface
Data Source
Figure 1
Figure 2
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AI summary
A pretreatment solution is supplied to an upper surface of a peripheral edge part of a substrate on which a pattern is formed to form a liquid film of the pretreatment solution. A coating solution is supplied on the liquid film of the pretreatment solution to form the coating film. The pretreatment solution is a solution including a solvent of the coating solution or a solution reducing a contact angle of the coating solution with respect to an upper surface of the substrate. The coating solution is supplied on the liquid film of the pretreatment solution, thus the contact angle of the coating solution with respect to the upper surface of the substrate is reduced, and occurrence of a hump where a film thickness is larger than that of the other region can be reduced in forming the coating film.