Induction Annealing Chamber for Uniform High-Temperature SiC Substrates
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Solution Overview
Problem
Conventional annealing methods for semiconductor substrates, particularly silicon carbide, are limited by low maximum temperatures, long processing times, uneven heating and cooling, and heater reliability issues, which hinder efficient and uniform annealing in high-volume manufacturing.
Innovation Solution
An annealing system with a process chamber featuring multiple angularly spaced zones, a rotating carrier, and strategically positioned induction heaters, along with a removable heat shield, enables precise and controlled heating and cooling of semiconductor substrates, using liquid-cooled induction heaters and thermally insulating materials to manage high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional batch annealing tools are used to anneal multiple substrates simultaneously, then manufacturing throughput is maintained, but the maximum substrate temperature is limited to below 1800°C due to heater constraints
Solution Approach 1:
The patent replaces conventional contact-based heating elements with induction heating technology. The induction heater generates an alternating magnetic field that induces eddy currents in the substrate, heating it directly without physical contact. This eliminates the mechanical and thermal limitations of conventional heaters, enabling substrate temperatures exceeding 1800°C while maintaining heater reliability since the induction coil operates at a lower temperature.
Solution Approach 2:
The patent introduces a removable cap with a heat shield as an intermediary component. The heat shield, made of thermally insulating material, is positioned between the hot substrate and the process chamber walls to protect the chamber from excessive heat while allowing the substrate to reach the required high temperatures for optimal annealing.
2Manufacturing precision
If conventional annealing processes are used with long ramp-up and cool-down periods, then uniform heating is achieved, but processing time increases to several hours
Solution Approach 1:
The induction heating system provides rapid and uniform heating through electromagnetic induction. The alternating magnetic field penetrates the substrate and generates heat throughout its volume simultaneously, achieving uniform temperature distribution much faster than conventional contact heating methods. This reduces the ramp-up time from several hours to a fraction of that time while maintaining annealing uniformity.
Solution Approach 2:
The induction heater operates with alternating current at high frequency, creating periodic magnetic fields that continuously induce eddy currents in the substrate. This periodic action ensures uniform heating throughout the substrate volume and enables precise temperature control during the annealing process, achieving both speed and uniformity.
3Productivity
If fast cool-down is implemented to freeze annealing properties, then processing time is reduced, but conventional annealing tools struggle to achieve rapid cooling
Solution Approach 1:
The patent inverts the heating mechanism for cooling. The same induction heater that rapidly heated the substrate can be used for rapid cooling by reversing its function. By controlling the induction heating power and chamber atmosphere, the system can achieve fast cool-down rates while maintaining precise control over the annealing properties, freezing the desired microstructure and electrical characteristics.
4Temperature
If conventional heaters are used to reach high annealing temperatures, then optimal annealing of SiC doped wafers is achieved, but heater surface properties deteriorate due to exfoliation and oxidation
Solution Approach 1:
The patent replaces conventional contact heaters with induction heating. The induction coil generates an alternating magnetic field that heats the substrate without physical contact. The coil itself operates at a much lower temperature since it transfers energy electromagnetically rather than through direct thermal contact, eliminating heater surface exfoliation and oxidation while enabling the substrate to reach the required 1800-1900°C for optimal SiC doped wafer annealing.
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 achieves rapid heating and cooling of semiconductor substrates to optimal temperatures, ensuring uniformity and reliability, thereby improving the efficiency and quality of annealing processes.
Implementation Method 1
The system incorporates one or more induction heaters, strategically placed within the process chamber to heat the substrate
Implementation Method 2
Annealing of semiconductor substrates is a thermal process used to alter the physical and electrical properties of materials
Implementation Method 3
This heat shield consists of at least one layer of thermally insulating material and is designed to protect the walls of the process chamber from radiant heat emanating from the substrate
Implementation Method 4
This heat shield consists of at least one layer of thermally insulating material
Data Source
AI summary
An annealing system for a semiconductor substrate includes a process chamber having a central axis and one or more process zones. A carrier positioned in the process chamber may be configured to support the substrate during processing. One or more induction heaters may be positioned in the process chamber to heat the substrate during processing. The system may also include a removable cap with a heat shield. The cap may be configured to be inserted and removed from the process chamber through an opening on the process chamber wall. When the cap is used it may be coupled to the process chamber such that its heat shield is disposed above the substrate positioned on the carrier.