Spin Coating Acceleration Profile for Resist Uniformity
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Solution Overview
Problem
In the photolithography process for semiconductor device manufacturing, the miniaturization of circuits leads to thinner resist films, requiring a reduction in the amount of resist solution used, but existing spin coating methods often result in streak-shaped coating mottles due to rapid diffusion, causing defocusing and failure to form desired resist patterns.
Innovation Solution
A coating treatment method involving a sequence of rotation speed changes: initially accelerating the substrate at a low speed, then increasing to a higher speed to smoothly diffuse the coating solution, and finally reducing to a lower speed to minimize scattering and ensure uniform application, even with a small coating amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the supply amount of the resist solution is reduced to form thinner resist films for circuit miniaturization, then the cost is reduced and the film thickness is decreased, but the resist solution rapidly diffuses outward forming streak-shaped coating mottles that cause defocusing and pattern formation failure
Solution Approach 1:
The patent applies dynamic rotation speed control during the coating process. The substrate rotation speed is changed in three stages: initially accelerated at a first acceleration, then accelerated at a second acceleration higher than the first, and finally accelerated at a third acceleration lower than the second. This dynamic adjustment of rotation speed allows the coating solution to be uniformly applied even with small coating amounts by controlling the diffusion rate at different phases of the coating process.
Solution Approach 2:
The patent changes the physical parameter of rotation acceleration in a specific sequence (first acceleration, then second acceleration higher than first, then third acceleration lower than second) to control the coating process. By varying the acceleration parameter dynamically, the system achieves uniform coating distribution and prevents streak formation while using reduced amounts of expensive resist solution.
2Productivity
If the resist film is thinned for further circuit miniaturization, then the productivity and circuit density are improved, but the coating becomes more difficult to control uniformly
Solution Approach 1:
The patent uses dynamic multi-stage acceleration control to achieve uniform thin film coating. By applying three different acceleration stages (first acceleration, second acceleration higher than first, third acceleration lower than second), the system can precisely control the coating process to produce uniform thin resist films required for high-density circuits.
Solution Approach 2:
The patent employs parameter changes in rotation acceleration to control thin film formation. The specific sequence of acceleration changes allows precise control over the coating process, enabling uniform application of thin resist films that are necessary for circuit miniaturization while maintaining coating quality.
3Ease of manufacture
If the resist solution is supplied to the center of a high-speed rotating substrate, then the coating process is simplified, but the resist solution rapidly diffuses outward causing streak-shaped coating mottles
Solution Approach 1:
The patent maintains the simple center-supply method but introduces dynamic acceleration control to prevent defects. By applying three stages of acceleration (first acceleration, second acceleration higher than first, third acceleration lower than second), the system controls the diffusion rate of the resist solution, preventing streak formation while maintaining process simplicity.
Solution Approach 2:
The patent uses parameter changes in rotation acceleration to resolve the contradiction between simple process and uniform coating. The three-stage acceleration sequence controls the fluid dynamics of the resist solution during supply, preventing rapid outward diffusion and streak formation while maintaining the simplicity of center supply method.
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 allows for uniform application of a thin coating film, reducing costs and preventing coating mottles, thereby ensuring accurate pattern formation on the substrate.
Implementation Method 1
since the rotation speed of the substrate is low immediately after the coating solution is discharged to the central portion of the substrate, a strong centrifugal force is not applied to the coating solution on the substrate
Data Source
AI summary
A coating treatment method includes: a first step of discharging a coating solution from a nozzle to a central portion of a substrate while acceleratingly rotating the substrate, to apply the coating solution over the substrate; a second step of then decelerating the rotation of the substrate and continuously rotating the substrate; and a third step of then accelerating the rotation of the substrate to dry the coating solution on the substrate. In the first step, the acceleration of the rotation of the substrate is changed in the order of a first acceleration, a second acceleration higher than the first acceleration, and a third acceleration lower than the second acceleration to acceleratingly rotate the substrate at all times.