Substrate Support Baffle for Supercritical CO2 Drying
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Solution Overview
Problem
Current wet cleaning techniques face challenges in drying semiconductor substrates with high aspect ratio features, leading to deformation and stiction due to capillary forces, and particle deposition during phase transition processes, which can damage the substrate and degrade device performance.
Innovation Solution
A substrate support apparatus and method utilizing a circular base plate with spacers and a ring body, along with a baffle plate, positioned in a processing chamber with supercritical CO2 to prevent line stiction and particle deposition by using supercritical CO2's unique properties to bypass the liquid state and eliminate capillary forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet cleaning techniques are used to clean semiconductor substrates, then cleaning effectiveness is improved, but capillary forces cause line stiction and deformation of high aspect ratio structures
Solution Approach 1:
The patent changes the physical state parameter of the cleaning fluid from liquid to supercritical state. By operating above the critical point of CO2 (31.1°C, 73 atm), the fluid exhibits properties intermediate between liquid and gas, providing effective cleaning while eliminating surface tension and capillary forces that cause line stiction in traditional liquid cleaning processes
Solution Approach 2:
The patent utilizes the phase transition properties of CO2 between supercritical and gaseous states. The cleaning process uses supercritical CO2, which then undergoes a controlled phase transition to gas during the drying stage, allowing complete evaporation without liquid-gas interface formation, thereby preventing capillary-induced deformation of high aspect ratio structures
2Reliability
If traditional drying methods are used after wet cleaning, then the cleaning liquid is removed from the substrate, but particle generation and particle deposition occur during phase transition
Solution Approach 1:
The patent employs a controlled phase transition from supercritical to gaseous state of CO2 for drying. This supercritical drying process avoids the liquid-gas interface formation that causes particle deposition, while the controlled expansion and cooling prevent particle generation, achieving effective drying without the harmful side effects of traditional drying methods
Solution Approach 2:
The patent uses CO2 as an inert supercritical fluid that creates a controlled atmosphere during cleaning and drying. This inert environment prevents unwanted chemical reactions and particle generation, while the uniform expansion during phase transition avoids turbulent flows that could cause particle deposition on the substrate
3Reliability
If high pressure is applied during processing to achieve supercritical state, then cleaning and drying effectiveness is improved, but particle generation is increased
Solution Approach 1:
The patent precisely controls pressure and temperature parameters to maintain CO2 in the supercritical state only where and when needed. By carefully managing the pressure gradient and temperature distribution, the system achieves effective supercritical cleaning while avoiding excessive pressure that would generate particles, and enables controlled phase transition for particle-free drying
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 solution effectively prevents line stiction and particle deposition, ensuring the integrity of high aspect ratio semiconductor structures and improving device performance by using supercritical CO2 to remove residues and particles without surface tension, suitable for substrates with high aspect ratios and 3D/vertical NAND flash devices.
Implementation Method 1
Capillary forces of the cleaning liquid often cause deformation of materials in these structures which can create undesired stiction
Implementation Method 2
Features with narrow line width and high-aspect-ratios are especially susceptible to the difference in surface tension created between liquid-air and liquid-wall interfaces due to capillary pressure
Implementation Method 3
the substrate may be exposed to supercritical CO2
Implementation Method 4
Drying of the substrate that has high aspect ratio features or low-k materials which have voids or pores is very challenging subsequent to the application of a cleaning liquid
Data Source
AI summary
A substrate support apparatus is provided. The apparatus includes a circular base plate and one or more spacers disposed about a circumference of the base plate. The spacers may extend from a top surface of the base plate and a ring body may be coupled to the spacers. The ring body may be spaced from the base plate to define apertures between the base plate and the ring body. One or more support posts may be coupled to the base plate and extend therefrom. The support posts may be coupled to the base plate at positions radially inward from an inner surface of the ring body.