Ultrasonic Viscosity Control for Spin Coating Planarity
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Solution Overview
Problem
Spin coating processes in semiconductor manufacturing face challenges in achieving planarity and reducing film shrinkage and cure time while minimizing topographical variations and volatile solvent content.
Innovation Solution
The use of ultrasonic viscosity control during spin coating by applying ultrasound waves to reduce the viscosity of the coating material, comprising a nonvolatile film material and a volatile solvent, to enhance film planarity and reduce topographical variations without increasing the molar percentage of the volatile solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the molar percentage of volatile solvent in coating material is increased to reduce viscosity and improve planarity, then film planarity is improved, but film shrinkage and cure time increase
Solution Approach 1:
The patent applies ultrasonic waves to change the physical state of the coating material by temporarily reducing its viscosity through acoustic energy input. This allows the coating to spread more uniformly during spin coating without permanently altering the solvent composition, thereby improving planarity without increasing shrinkage or cure time
Solution Approach 2:
Ultrasonic vibration is applied to the coating material during spin coating to reduce viscosity and improve planarity. The mechanical vibration energy from ultrasonic waves temporarily disrupts the molecular structure of the coating material, allowing better flow and distribution without requiring additional volatile solvent
2Manufacturing precision
If ultrasonic waves are applied to reduce viscosity of coating material, then topographical variations are reduced and planarity is improved, but device complexity increases
Solution Approach 1:
The rotor chuck is designed to perform multiple functions: it holds the substrate, provides rotational motion for spin coating, and simultaneously serves as the transducer for generating ultrasonic waves. This integration reduces device complexity by combining what would otherwise be separate components into a single multi-functional element
Solution Approach 2:
The ultrasonic generation capability is merged with the rotor chuck structure itself. The rotor chuck contains a piezoelectric element that converts electrical energy to mechanical vibration, eliminating the need for separate ultrasonic transducers and reducing overall system complexity
3Area of stationary object
If high rotational speed is used to spread coating material, then coating coverage is improved, but topographical variations and loss of planarity increase
Solution Approach 1:
Ultrasonic vibration applied to the coating material reduces its viscosity and allows it to flow more uniformly during spin coating. This prevents the formation of topographical variations that would otherwise occur at high rotational speeds, enabling both good coverage and planarity to be achieved simultaneously
Solution Approach 2:
The viscosity of the coating material is dynamically changed during the spin coating process through ultrasonic application. This temporary viscosity reduction allows the coating to adapt to high rotational speeds without developing defects, enabling better control over topographical variations while maintaining adequate coverage
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 topographical variations and shortens the cure time while maintaining film planarity, improving the precision and efficiency of the spin coating process for semiconductor manufacturing.
Implementation Method 1
applying ultrasound waves to the coating material to reduce a viscosity of the coating material during the spin coating
Implementation Method 2
The substrate spun at a high rotational speed, and the coating material is spread over the entire surface of the substrate by centrifugal force
Data Source
AI summary
A spin coating method includes dispensing a coating material including a nonvolatile film material and a volatile solvent over a substrate, and spin coating the coating material over the substrate by spinning the substrate while applying ultrasound waves to the coating material to reduce a viscosity of the coating material during the spin coating.