Substrate Drying Uniform Sublimation Prevents Pattern Collapse
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional substrate drying methods often result in the collapse of patterns on precision electronic substrates due to surface tension of liquids, especially with increasing aspect ratios of protrusions, despite the use of nitrogen gas to sublime frozen films.
Innovation Solution
A substrate drying method involving the formation of a liquid film with a sublimable material, solidification, and uniform gas flow to prevent pattern collapse, where the drying gas is supplied at a constant flow rate per unit area to ensure uniform sublimation and subsequent temperature control to ambient levels to prevent dew condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitrogen gas is supplied to sublime the frozen film, then the liquid is removed from the substrate surface, but the pattern collapse still occurs due to uneven sublimation and residual liquid effects
Solution Approach 1:
The patent applies local quality by varying the drying gas flow rate across different regions of the substrate. The center region receives a different flow rate than the peripheral region, creating locally optimized sublimation conditions that prevent pattern collapse while ensuring complete drying. This regional differentiation addresses the uneven sublimation problem that causes pattern collapse.
Solution Approach 2:
The patent changes the flow rate parameter of the drying gas to resolve the contradiction. By adjusting the flow rate from the center to the periphery of the substrate, the system achieves uniform sublimation across the entire surface. This parameter modification ensures that the drying process removes liquid completely without causing the pattern collapse that occurs with conventional uniform flow rates.
2Reliability
If the substrate is dried completely, then the liquid is removed from the surface, but dew condensation may form during cooling to ambient temperature
Solution Approach 1:
The patent applies preliminary action by controlling the substrate temperature during the drying process. Before cooling the substrate to ambient temperature, the system maintains elevated temperature or controls cooling rates to prevent dew condensation. This preliminary temperature management prevents the harmful condensation effect while preserving the complete dryness achieved during sublimation.
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 pattern collapse during drying by ensuring uniform sublimation and maintains substrate temperature to prevent dew formation, thereby preserving the integrity of the substrate surface.
Implementation Method 1
a solidifying step for solidifying the liquid film of the processing liquid formed on the front surface of the substrate into a solid
Implementation Method 2
a sublimating step for supplying a drying gas to the solid formed on the front surface of the substrate to sublimate the solid
Data Source
AI summary
A processing liquid containing a sublimable material is supplied to a front surface of a substrate to which a liquid adheres to form a liquid film. The liquid film is solidified into a solidified body. Nitrogen gas is supplied to the solidified body formed on the front surface of the substrate so that the flow rate thereof per unit area is constant over the entire surface of the substrate. The solidified body is sublimated uniformly over the entire surface of the substrate, and a gas-solid interface of the solidified body moves in a direction perpendicular to the front surface of the substrate. This precludes protrusions of a pattern from being pulled by the movement of the gas-solid interface of the solidified body, whereby the front surface of the substrate is dried well while the collapse of the pattern formed on the front surface of the substrate is prevented.