Semiconductor Substrate Cleaning via Variable Speed Rotation
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Solution Overview
Problem
The challenge in semiconductor substrate cleaning is the accumulation of electrostatic charge during the rinsing process, which can damage components and integrated circuits, and existing methods either increase costs or compromise safety when attempting to mitigate this issue.
Innovation Solution
A method involving a three-step process: applying a first agent at high speed, immersing the substrate in a second agent while stationary, and performing a low-speed rinse with a third agent, all using deionized water, to effectively dissipate electrostatic charge and reduce particle contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed rinsing is used to clean the semiconductor substrate, then cleaning efficiency is improved, but electrostatic charge accumulates on the substrate
Solution Approach 1:
The rinsing process is divided into three distinct stages with different rotational speeds: high-speed rinsing (900-1500 rpm) for initial cleaning, low-speed rinsing (300-600 rpm) for charge dissipation, and stationary immersion for final cleaning. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between cleaning efficiency and charge accumulation.
Solution Approach 2:
The process uses periodic variation in rotational speed throughout the rinsing cycle. The substrate is rotated at high speed initially, then slowed to low speed, and finally held stationary. This periodic action enables the system to achieve both high cleaning efficiency during high-speed rotation and effective charge dissipation during low-speed and stationary phases.
2Manufacturing precision
If chemical reagents are used to clean the substrate, then contaminant removal is improved, but cost and safety issues arise
Solution Approach 1:
The invention replaces expensive and potentially hazardous chemical reagents with deionized water, which is inexpensive and safe. The water is used in a disposable manner through multiple rinsing stages, effectively removing contaminants without the cost and safety concerns associated with chemical cleaners.
Solution Approach 2:
The invention substitutes chemical cleaning mechanisms with mechanical cleaning through controlled rotation and fluid dynamics. The mechanical action of high-speed rotation combined with deionized water rinsing achieves contaminant removal comparable to or better than chemical methods, while eliminating the need for hazardous chemicals.
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 significantly reduces electrostatic charge and defect counts on semiconductor substrates, improving the yield and quality of integrated circuits without increasing costs or compromising safety.
Implementation Method 1
immersing the semiconductor substrate in a second agent while rotating the semiconductor substrate at a second rotational frequency, wherein the second rotational frequency is less than the first rotational frequency
Implementation Method 2
The cleaning methods include wet cleaning with a liquid medium and dry cleaning with vapor phase medium
Data Source
AI summary
A method for cleaning a semiconductor substrate is provided. The method includes the steps of: applying a first agent onto a top surface of the semiconductor substrate while the semiconductor substrate is rotated at a first rotational frequency; immersing the semiconductor substrate in a second agent while rotating the semiconductor substrate at a second rotational frequency; and rotating the semiconductor substrate at a third rotational frequency while a third agent is introduced onto the top surface of the semiconductor substrate. The first rotational frequency may be greater than the third rotational frequency and the third rotational frequency is greater than the second rotational frequency. In some embodiments, the second rotational frequency is zero and the semiconductor substrate is held stationary during the immersing step.