Substrate Drying Nozzle Inclination and IPA Concentration Control
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Solution Overview
Problem
Current substrate drying methods for semiconductor devices, particularly after copper wiring formation, often result in defects like watermarks due to the hydrophobic nature of Low-k films and the complexity of maintaining effective IPA concentrations and temperatures, which complicates apparatus configuration and control.
Innovation Solution
A substrate drying apparatus and method that utilizes a rinse agent nozzle and a drying gas nozzle to control the IPA concentration and flow direction, ensuring the drying gas collides with the substrate downstream of the rinse agent, maintaining an IPA concentration less than 2 mol% in the center area and adjusting it for the outer periphery, while maintaining a constant rotation speed and moving speed to inhibit defects and enhance drying efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply amount of IPA is increased or the temperature of gas containing IPA is raised to increase IPA dissolved in the rinse agent, then the drying effectiveness is improved, but the apparatus configuration and control become complicated
Solution Approach 1:
The invention changes the parameter of IPA concentration in the drying gas flow supplied to the substrate. Specifically, the IPA concentration is set to 2 mol% or more, which is a specific parameter value that achieves effective drying without requiring complex apparatus configuration or control systems. This parameter optimization allows the system to achieve reliable drying results while maintaining simplicity in the drying apparatus design.
2Reliability
If the IPA concentration in the drying gas flow is increased to improve drying effectiveness, then the surface tension reduction is enhanced, but the defect occurrence may increase due to improper distribution
Solution Approach 1:
The invention applies local quality by differentiating the IPA concentration requirements for different regions of the substrate. The center area requires IPA concentration of 2 mol% or more to effectively reduce surface tension and prevent watermark defects, while the outer periphery area can tolerate lower IPA concentration. This spatial differentiation of IPA concentration requirements allows the system to achieve effective surface tension reduction where needed while avoiding defect occurrence in other regions, thus resolving the contradiction between drying effectiveness and defect prevention.
3Ease of manufacture
If the drying gas is supplied vertically to the substrate, then the drying process is simplified, but the drying gas flows into the already dried region reducing efficiency
Solution Approach 1:
The invention introduces asymmetry in the drying gas supply direction. Instead of supplying the drying gas vertically (symmetrically) to the substrate, the gas is supplied at an inclined angle. This asymmetric supply direction prevents the drying gas from flowing directly into the already dried region, thereby improving drying efficiency by ensuring that the gas acts primarily on the wet regions of the substrate. This directional adjustment resolves the contradiction between process simplicity and drying efficiency.
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 reduces the occurrence of defects, such as watermarks, by controlling the IPA concentration and flow dynamics, leading to improved drying efficiency and throughput without increasing processing time, even under stricter defect size evaluation standards.
Implementation Method 1
a gas flow for drying the substrate containing IPA (isopropyl alcohol) which reduces surface tension of the rinse agent is supplied to the inside of the liquid flow, and by moving a liquid flow nozzle and a gas flow nozzle from the center to the outer periphery of the rotating substrate, the rinse agent is moved to the outer periphery side due to centrifugal force and Marangoni force
Implementation Method 2
IPA (isopropyl alcohol) which reduces surface tension of the rinse agent
Implementation Method 3
the rinse agent is moved to the outer periphery side due to centrifugal force and Marangoni force
Implementation Method 4
the drying gas draws out the rinse agent to make the film of the rinse agent covering the substrate thin, which achieves reduction of a drying load
Data Source
AI summary
A substrate drying apparatus includes a drying gas nozzle configured so that, assuming that a surface WA of the substrate W is a projection plane, regarding the drying gas flow Gf in the nozzle moving direction Dr, a collision position Gfw with the substrate W is located downstream of a projected discharge position Gfv′, the projected discharge position Gfv′ being a discharge position from the drying gas nozzle projected on the projection plane. In a three-dimensional space, the drying gas flow Gf is inclined, such that an angle α formed by an axis Ga of the drying gas flow Gf and a vertical line Wp of the substrate W is in a range from a half contact angle θ/2 to an angle determined by deducting the half contact angle θ/2 from 90°, the half contact angle θ/2 being a half of the contact angle θ.