Supercritical CO2 Wet Etching to Prevent Wafer Pattern Collapse
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Solution Overview
Problem
The pattern on a semiconductor wafer collapses during the drying process after wet etching, which compromises the integrity of the semiconductor substrate.
Innovation Solution
A semiconductor manufacturing system utilizing a supercritical fluid mixture of carbon dioxide and a pH-adjusted fluid is used to etch the semiconductor substrate, followed by supercritical drying to minimize surface tension and prevent pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drying methods are used after wet etching, then the drying process is simple and fast, but the pattern on the semiconductor wafer collapses
Solution Approach 1:
The patent changes the physical parameters of the drying process by using supercritical carbon dioxide (temperature above 31.1°C and pressure above 73.0 atm) instead of conventional atmospheric drying. This parameter change allows the drying to occur without surface tension forces that cause pattern collapse, while maintaining process efficiency.
Solution Approach 2:
The patent utilizes the phase transition of carbon dioxide from supercritical state to gaseous state during the drying process. The supercritical CO2 penetrates the porous structure, then undergoes phase transition to gas, eliminating liquid surface tension that would otherwise collapse the patterns. This phase transition mechanism solves the contradiction between simple drying and pattern integrity.
2Manufacturing precision
If wet etching is performed to achieve high etching selectivity, then the etching precision is improved, but the pattern collapses during subsequent drying
Solution Approach 1:
The patent introduces supercritical carbon dioxide as an intermediary medium between the wet etching process and final drying. The supercritical CO2 acts as a mediator that replaces the liquid etchant and performs drying without surface tension, thus preserving the patterns created by wet etching while maintaining etching selectivity.
Solution Approach 2:
The patent changes the physical state parameters from liquid (conventional drying) to supercritical fluid to gas, which fundamentally alters the drying mechanism. This parameter change allows the system to achieve both high etching selectivity and pattern stability by eliminating the harmful surface tension effect during the transition from wet etching to dry state.
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 system effectively prevents pattern collapse during drying by using a supercritical fluid mixture that maintains high etching selectivity and reduces surface tension, ensuring the integrity of the semiconductor substrate.
Implementation Method 1
supercritical drying to minimize surface tension and prevent pattern collapse
Implementation Method 2
A semiconductor manufacturing system utilizing a supercritical fluid mixture of carbon dioxide and a pH-adjusted fluid is used to etch the semiconductor substrate
Data Source
AI summary
A semiconductor manufacturing system and a method are capable of restraining a pattern on a semiconductor substrate from collapsing while performing wet etching on the semiconductor substrate. As an example, a semiconductor manufacturing system includes a first fluid reservoir that retains a first fluid generated by adding, to a first liquid, an adjusting substance for adjusting a pH. The first fluid supplier supplies the first fluid to a mixer. A second fluid supplier causes a second fluid to turn into a supercritical fluid and supplies the supercritical fluid to the mixer. A first heating mechanism houses the mixer and heats the mixer. A second heating mechanism heats a chamber capable of housing a substrate. A fluid mixture supplier supplies the second heating mechanism with a fluid mixture into which the first fluid and the supercritical fluid are mixed in the mixer.