Wafer Resist Coating with Gap Airflow and Two-Speed Spin Control
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Solution Overview
Problem
In semiconductor manufacturing, the uniformity of resist film thickness on wafers with irregular patterns is compromised due to high viscosity and centrifugal forces, leading to non-uniform drying and increased throughput issues when rotating at low speeds.
Innovation Solution
A coating film forming method involving a substrate holder, air flow management using a ring plate to increase air flow velocity over the wafer, and controlled rotation speeds to optimize film thickness distribution by scattering the coating liquid from the peripheral portion, ensuring uniform drying and improved throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air flow velocity is increased to improve drying uniformity, then drying efficiency improves, but coating liquid distribution uniformity deteriorates
Solution Approach 1:
The patent applies preliminary action by performing air drying with high air flow velocity at a first rotation speed before spin coating at a second rotation speed. This preliminary high-velocity air flow effectively removes excess coating liquid and improves drying efficiency without causing scattering, because the low rotation speed during this phase prevents centrifugal scattering
Solution Approach 2:
The patent uses dynamics by adjusting rotation speed between two phases: low speed during high-velocity air flow for efficient drying, and higher speed during spin coating to prevent scattering. This dynamic control allows high drying efficiency while maintaining coating uniformity through proper sequencing
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 achieves high uniformity of resist film thickness across the wafer surface by enhancing air flow velocity and controlled rotation speeds, effectively addressing the non-uniformity issues and improving processing efficiency.
Implementation Method 1
forming an air flow on a front surface of the substrate by exhausting an atmosphere around the substrate
Implementation Method 2
forming the air flow in a gap formed by the covering member placed at the second position and the front surface of the substrate such that a flow velocity of the air flow becomes larger
Implementation Method 3
rotating the substrate at a second rotation number higher than a first rotation number of the substrate in the forming of the air flow in the gap to adjust a film thickness distribution of the coating film by scattering the coating liquid from a peripheral portion of the substrate
Data Source
AI summary
A coating film forming method includes holding a substrate by a substrate holder; forming an air flow on a front surface of the substrate; supplying a coating liquid configured to form a coating film on the front surface; forming, after moving a covering member from a first position to a second position relatively to the substrate, the air flow in a gap formed by the covering member placed at the second position and the front surface of the substrate being rotated at a first rotation number such that a flow velocity of the air flow becomes larger than that of the air flow obtained when the covering member is placed at the first position; and rotating the substrate at a second rotation number higher than the first rotation number to adjust a film thickness distribution of the coating film by scattering the coating liquid from a peripheral portion thereof.