Resist Coating Apparatus Dynamic Speed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing resist coating methods face challenges in achieving uniform film thickness with reduced resist solution supply, as rapid drying and deceleration shocks lead to uneven thickness distribution, particularly with the outer circumference being thinner than the central portion, making it difficult to adjust the film thickness effectively.
Innovation Solution
A resist coating method and apparatus that gradually reduce the rotational speed of the substrate after resist solution supply, with a smaller deceleration rate as the speed approaches the second rotational speed, followed by acceleration to spin off the residue, allowing for uniform film thickness with minimal resist solution consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the amount of resist solution dropped on the wafer is reduced, then the manufacturing cost is reduced, but the uniformity of film thickness becomes difficult to achieve
Solution Approach 1:
The patent applies dynamic rotational speed control during the coating process. The substrate rotation speed is dynamically adjusted in multiple stages: initially rotating at a first rotational speed during resist solution supply, then decelerating to a second rotational speed for thickness adjustment, and finally accelerating to a third rotational speed for residue removal. This dynamic speed variation enables uniform film thickness formation even with reduced resist solution amounts by controlling the spreading and drying rates at different phases of the coating process.
2Manufacturing precision
If the rotational speed is rapidly reduced to adjust film thickness, then the thickness uniformity is improved, but a deceleration shock causes the resist solution to return toward the center, increasing the supply amount
Solution Approach 1:
The patent employs periodic action through multi-stage rotational speed control. Instead of a single rapid deceleration, the rotation speed is controlled in distinct periodic phases: (1) supply phase at first rotational speed, (2) thickness adjustment phase at second rotational speed, and (3) residue removal phase at third rotational speed. This periodic control prevents deceleration shock by using gradual speed transitions and intermediate holding periods, thereby avoiding the inward return of resist solution while still achieving uniform thickness distribution.
3Loss of substance
If the amount of resist solution is small, then the cost is reduced, but the drying progresses rapidly before the solution spreads sufficiently, causing non-uniform thickness distribution
Solution Approach 1:
The patent applies preliminary action by pre-heating the substrate before resist solution supply. The substrate is heated to a predetermined temperature prior to coating, which pre-conditiones the substrate surface to control the drying rate. This preliminary heating ensures that when the reduced amount of resist solution is applied, the drying process proceeds at a controlled rate that allows sufficient time for the solution to spread uniformly across the substrate surface, preventing premature drying and thickness non-uniformity.
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 enables the reduction of resist solution supply while maintaining uniform film thickness across the substrate, minimizing excess solution consumption and ensuring precise thickness adjustment, even with reduced amounts of resist solution.
Implementation Method 1
a semiconductor wafer is rotated together with a spin chuck by rotational drive means with the semiconductor wafer vacuum-fixed on the spin chuck, and a resist nozzle positioned above the semiconductor wafer drops a resist solution onto the center of the wafer surface. The dropped resist solution spreads radially outward toward the circumference of the semiconductor wafer by centrifugal force.
Implementation Method 2
the semiconductor wafer is continuously rotated while decreasing the rotational speed to spin off and dry the resist solution spread over the wafer surface
Data Source
AI summary
A resist coating method supplies a resist solution to substantially the center of a target substrate to be processed while rotating the target substrate at a first rotational speed, then decelerates the rotation of the substrate to a second rotational speed lower than the first rotational speed, or until rotational halt, makes the deceleration smaller in the deceleration step as the rotational speed becomes closer to the second rotational speed or the rotational halt, and accelerates the rotation of the substrate to a third rotational speed higher than the second rotational speed to spin off a residue of the resist solution.