Induction Susceptor Annealing for Uniform Rapid Thermal Cycling
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Solution Overview
Problem
Existing annealing technologies face challenges in achieving uniform and rapid heating and cooling across workpieces at high temperatures without damaging the material or equipment, particularly for semiconductor wafers, and there is a need for a system that can handle extreme environments with higher versatility and uniformity.
Innovation Solution
An apparatus utilizing a susceptor and induction coil with gas nozzles for rapid-cycle heating and cooling, achieving temperature cycles of 800-1100°C to 1400-2500°C in one second each, using inductive coupling for heating and convective gas dispersion for cooling, ensuring even temperature distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional heating and cooling methods are used for annealing, then the equipment can operate at high temperatures, but the heating and cooling are uneven across the workpiece and the cycle time is long
Solution Approach 1:
The heating system is segmented into multiple independent induction coils positioned around the susceptor, allowing each coil to be controlled independently to achieve uniform heating across different zones of the workpiece. The cooling system is similarly segmented with multiple gas nozzles that can be independently controlled to provide uniform cooling.
Solution Approach 2:
The apparatus employs periodic rapid cycling between heating and cooling phases, with each phase lasting only one second. This periodic action enables the system to achieve the desired temperature uniformity while dramatically reducing the total cycle time compared to conventional continuous heating and cooling methods.
2Productivity
If higher temperatures and energy levels are used for faster annealing, then the cycle time is reduced, but the material properties may be damaged or destroyed
Solution Approach 1:
The susceptor is designed with specific material properties and geometric features that enable it to absorb electromagnetic energy locally and convert it to heat, then distribute this heat uniformly to the workpiece. This local energy conversion followed by uniform distribution allows rapid heating without creating hot spots that would damage the material.
Solution Approach 2:
The susceptor acts as an intermediary between the induction coil and the workpiece. It receives electromagnetic energy from the coil, converts it to thermal energy, and then transfers this heat uniformly to the workpiece through thermal conduction. This intermediary role prevents direct electromagnetic exposure to the workpiece while ensuring uniform heat distribution that preserves material properties.
3Temperature
If conventional heating methods are used, then the equipment can heat the workpiece, but the heating is uneven and causes warping or damage
Solution Approach 1:
The heating system is divided into multiple independently controlled induction coil segments positioned around the susceptor. Each segment can be adjusted to provide the appropriate amount of heating to specific zones, ensuring uniform temperature distribution across the workpiece and preventing warping or distortion.
Solution Approach 2:
The induction heating system is designed to create equipotential heating zones on the susceptor surface, ensuring that all areas of the workpiece in contact with the susceptor experience the same temperature conditions. This equipotential approach eliminates temperature gradients that would cause warping or distortion.
4Manufacturing precision
If the susceptor and workpiece assembly is designed for rapid thermal cycling, then the annealing quality is improved, but the equipment complexity increases
Solution Approach 1:
The susceptor is designed to be self-cooling through its inherent thermal conduction properties and contact with the cooling gas. The system leverages the natural thermal properties of the susceptor material and the workpiece-susceptor thermal contact to achieve rapid cooling without requiring complex active cooling mechanisms, thus improving annealing quality while limiting complexity increases.
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 provides uniform and rapid temperature cycling, enhancing the quality and reliability of semiconductor wafers while extending the lifespan of the equipment by avoiding uneven heating and cooling, suitable for a range of materials and environments.
Implementation Method 1
Inductive coupling of the induction coil(s) to the susceptor is used for each heating operation
Implementation Method 2
thermal conduction of the susceptor to the seated wafer for each heating of the wafer
Implementation Method 3
Convective heat removal by cooling gas dispersion of the gas nozzle(s) is used as the primary method for each cooling operation
Data Source
AI summary
Apparatuses for rapid-cycle high-temperature heating and cooling are disclosed. The apparatuses can be used for elementary, binary, tertiary, and quaternary alloys of wide and ultra-wide band gap compound semiconductors. The apparatuses can be used for wafer annealing, and can include an induction coil, and at least one gas nozzle. A susceptor holds a workpiece with a first face of the workpiece exposed and a second face of the workpiece in thermal contact with a first surface of the susceptor. The first gas nozzle is arranged to disperse cooling gas to the susceptor and workpiece assembly. Each heating operation uses inductive coupling to the susceptor to heat the workpiece from 800° C.-1100° C. to 1400° C.-2500° C. in about one second (for one example). Each cooling operation uses cooling gas dispersion to cool the workpiece from 1400° C.-2500° C. to 800° C.-1100° C. in about one second (for another cooling example).