Wafer Coating Film Formation for Annular Thickness Uniformity
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Solution Overview
Problem
In semiconductor device manufacturing, existing coating film forming methods struggle to achieve uniform film thickness distribution on wafers, particularly in the annular region, which can lead to inadequate coatability and film thickness variations.
Innovation Solution
A coating film forming method that involves supplying a coating liquid to the front surface of a substrate and rotating it to form a coating film. High-temperature gas is then applied to the rear surface of the substrate to adjust the film thickness distribution and dry the coating film, with specific rotation speeds used to optimize film thickness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature gas is supplied to the rear surface of the substrate during coating, then film thickness distribution is improved, but the coating process complexity increases
Solution Approach 1:
The high-temperature gas is supplied to the rear surface of the substrate before the coating liquid is applied to the front surface. This preliminary heating action prepares the substrate by creating temperature differential that prevents annular low-film-thickness regions, thereby improving film thickness distribution without requiring complex in-process adjustments
Solution Approach 2:
The high-temperature gas acts as an intermediary element that mediates between the substrate and the coating liquid. By heating the rear surface, it creates a temperature gradient across the substrate that influences coating liquid flow and distribution, achieving uniform film thickness without direct contact or complex mechanical intervention
2Manufacturing precision
If the substrate is rotated at different speeds for adjusting and drying, then film thickness uniformity is optimized, but the processing time increases
Solution Approach 1:
The substrate rotation is divided into distinct periodic phases: a first rotation speed phase for film thickness distribution adjustment, and a second rotation speed phase for drying. This periodic variation in rotation speed optimizes film uniformity at each stage while maintaining efficient overall processing
Solution Approach 2:
The rotation speed is dynamically adjusted between two distinct phases rather than maintaining a constant speed. The first rotation speed optimizes film distribution, then transitions to a second rotation speed for drying, allowing each phase to be optimized independently for both quality and efficiency
3Manufacturing precision
If high-temperature gas is supplied continuously, then film thickness distribution is maintained, but energy consumption increases
Solution Approach 1:
The high-temperature gas is supplied in advance to the rear surface before coating liquid application, establishing the necessary temperature gradient upfront. This preliminary action ensures proper film thickness distribution without requiring continuous gas supply during the entire coating and drying process, thereby reducing energy consumption
Solution Approach 2:
The high-temperature gas supply is concentrated in a specific time window before and during initial coating, then discontinued or reduced. This skipping approach achieves the critical film thickness distribution control without sustaining high energy consumption throughout the entire multi-stage process
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 effectively prevents the formation of annular low-film-thickness regions, ensuring high coatability and uniform film thickness distribution across the wafer, even with reduced resist usage.
Implementation Method 1
supplying high-temperature gas having a temperature higher than the substrate to an exposed region of a rear surface of the substrate
Implementation Method 2
coating a coating liquid by supplying the same to a front surface of a substrate and rotating the substrate to form a coating film
Implementation Method 3
drying, after the adjusting the film thickness distribution, the coating film by adjusting the film thickness of the coating film in an entire plane of the substrate
Data Source
AI summary
A coating film forming method includes coating a coating liquid by supplying the same to a front surface of a substrate and rotating the substrate to form a coating film, supplying a high-temperature gas having a temperature higher than the substrate to an exposed region of a rear surface of the substrate, adjusting film thickness distribution of the coating film in a plane of the substrate by rotating the substrate at a first rotation speed, and drying, after the adjusting the film thickness distribution, the coating film by adjusting the film thickness of the coating film in an entire plane of the substrate by rotating the substrate at a second rotation speed different from the first rotation speed. A period in which the drying of the coating film is performed includes a period in which the supplying of the high-temperature gas to the substrate is stopped.