Silicon Substrate Drying via Temperature-Gradient Water and Rotation
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Solution Overview
Problem
The existing substrate processing methods for silicon wafers often result in foreign matter remaining on the surface due to evaporation of DIW before it can be spun off during high-speed rotation, and they rely on expensive organic solvents like IPA to prevent water marks, which increases operational costs.
Innovation Solution
A method involving a rinsing step with water at a first temperature, followed by a second temperature water supply lower than the first, and a drying step where the substrate is rotated to spin off the water, preventing foreign matter retention and reducing the need for organic solvents by controlling evaporation and spreading the water across the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high speed rotation is applied to dry the wafer, then the wafer can be dried quickly, but foreign matter remains on the wafer surface due to evaporation of DIW before it can be spun off
Solution Approach 1:
The wafer is rotated at a first rotation speed before the drying process to spread DIW uniformly across the surface. This preliminary action ensures that foreign matter is suspended in the DIW and positioned near the circumferential edge before high-speed drying begins, preventing foreign matter from remaining on the surface after drying.
Solution Approach 2:
The invention uses dynamic adjustment of rotation speed with two distinct phases: a first rotation speed during the rinsing process to spread DIW and suspend foreign matter, and a second, higher rotation speed during drying to spin off DIW and foreign matter. This dynamic speed adjustment resolves the contradiction between drying speed and foreign matter removal.
2Manufacturing precision
If IPA is used to replace DIW and prevent water mark formation, then water marks are suppressed, but running cost increases due to the expensive organic solvent
Solution Approach 1:
The invention replaces expensive IPA with cheap DIW for the drying process. By controlling the rotation speed and using DIW with appropriate physical properties, the method achieves water mark suppression without incurring the high cost of organic solvents, thus reducing running costs while maintaining manufacturing precision.
3Productivity
If DIW is supplied at high temperature for efficient rinsing, then rinsing efficiency is improved, but evaporation occurs during drying leaving foreign matter on the surface
Solution Approach 1:
The wafer is rotated at a first rotation speed before the drying process to spread DIW uniformly across the surface. This preliminary action ensures that foreign matter is suspended in the DIW and positioned near the circumferential edge before high-speed drying begins, preventing foreign matter from remaining on the surface after drying.
Solution Approach 2:
The invention changes the rotation speed parameter from a first rotation speed during rinsing to a second, higher rotation speed during drying. This parameter change controls the evaporation process and ensures foreign matter is removed with the spun-off DIW rather than remaining on the surface.
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 prevents foreign matter from remaining on the substrate and suppresses water mark formation without using IPA, enhancing processing efficiency and reducing costs by managing evaporation and silicon elution during the drying process.
Implementation Method 1
The drying of the wafer by high speed rotation is considered to be mainly due to evaporation of the DIW from the surface of the wafer being rotated at high speed
Implementation Method 2
a drying step of rotating the silicon substrate after the second temperature water supplying step to spin off the water on the silicon substrate surface to a periphery of the silicon substrate
Data Source
AI summary
A substrate processing method includes a rinsing step of supplying water of a first temperature to a surface of a silicon substrate to apply a rinsing process using the water to the silicon substrate surface, a second temperature water supplying (coating) step of supplying water of a second temperature lower than the first temperature to the silicon substrate surface after the rinsing step, and a drying step of rotating the silicon substrate after the second temperature water supplying step to spin off the water on the silicon substrate surface to a periphery of the silicon substrate and thereby dry the silicon substrate.