Marangoni Drying Apparatus for Semiconductor Substrate Particle Control
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Solution Overview
Problem
In post chemical mechanical polishing (CMP) cleaning, particles reattach to substrates during the drying process due to inadequate fluid flow, leading to residue and yield reduction.
Innovation Solution
An apparatus with a body that accommodates a semiconductor substrate, featuring a waterfall-like rinse fluid flow and solvent vapor application to create a Marangoni drying effect, reducing particle reattachment by optimizing fluid flow and surface tension gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large volume bath is used to submerge the substrate during cleaning, then the substrate can be thoroughly rinsed, but particles accumulate in the tank and reattach to the substrate
Solution Approach 1:
The invention extracts the harmful accumulated particles from the system by continuously removing and replacing the bath fluid, rather than attempting to clean particles out of a large static volume. The fluid is actively exchanged to prevent particle accumulation and reattachment.
Solution Approach 2:
The invention uses hydraulic principles to create controlled fluid flow patterns through the substrate passage, generating forces that prevent particle reattachment while using minimal fluid volume. The flow dynamics are engineered to maintain cleaning effectiveness without requiring a large bath.
2Ease of operation
If apparatuses are used to move the substrate through the tank, then substrate transport is achieved, but optimal fluid flow is prevented and particle reattachment increases
Solution Approach 1:
The invention merges the substrate transport function with the fluid flow path, allowing the substrate to be moved through the tank while simultaneously maintaining optimal fluid circulation. The substrate passage is designed to accommodate both movement and flow without interference.
Solution Approach 2:
The invention creates dynamic fluid flow conditions that adapt to substrate movement, using controlled circulation to maintain cleaning effectiveness throughout the transport process rather than relying on static flow patterns.
3Manufacturing precision
If Marangoni drying is used to prevent streaking and residue, then substrate surface quality is improved, but the process requires precise control of solvent vapor and fluid meniscus
Solution Approach 1:
The invention enables the Marangoni drying process to be self-regulating, where the natural surface tension gradients automatically drive the drying process without requiring complex external control mechanisms. The system uses the inherent physical properties of the fluids to maintain optimal drying conditions.
Solution Approach 2:
The invention controls the Marangoni drying process by managing key parameters such as solvent vapor concentration and fluid composition, allowing precise control of surface tension gradients to achieve high-quality drying while simplifying the overall control system.
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 apparatus effectively prevents particle reattachment, improving substrate cleanliness and yield by ensuring thorough rinsing and drying without streaks or residue, enhancing overall device performance.
Implementation Method 1
The solvent vapor is absorbed along the surface of the fluid. The concentration of the absorbed vapor is higher at the tip of the meniscus.
Implementation Method 2
The higher concentration of absorbed vapor causes surface tension to be lower at the tip of the meniscus than in the bulk of the bath fluid, causing bath fluid to flow from the drying meniscus toward the bulk bath fluid. Such a flow is known as a 'Marangoni' flow
Implementation Method 3
During Marangoni drying, a solvent miscible with the bath fluid (i.e., isopropyl alcohol (IPA) vapor) is introduced to a fluid meniscus which forms as the substrate is lifted from the bath or as the bath fluid is drained past the substrate
Data Source
AI summary
An apparatus for drying of wet substrates in a post CMP cleaning apparatus is provided. The apparatus provides a waterfall or shallow reservoir of rinsing solution, such as DIW, through which a substrate may be lifted. A solvent vapor may be provided at the rinsing solution interface on the substrate, such as in a Marangoni process. In certain embodiments, the volume of solution through which the substrate is lifted is reduced, which may provide for reduced or eliminated particle reattachment to the substrate.