01. What performance factors should be considered when designing heat treatment equipment?

The topic we will cover today is the “thermal performance of semiconductor heat treatment equipment.”

Heat treatment equipment used in semiconductor device manufacturing must be capable of maintaining, measuring, and controlling a uniform temperature across the entire wafer. This is especially important during temperature ramp-up and cool-down processes. If the peripheral region of the wafer becomes colder than the inner region, the resulting temperature non-uniformity can cause serious issues after heat treatment, such as wafer warpage, crystal defects, and thin-film slip.

In addition, the absorptivity of radiant heat can vary significantly depending on the thickness and optical properties of the thin film deposited on the wafer. As a result, temperature calibration may be required for different thin-film conditions. For patterned wafers, maintaining temperature uniformity across the entire wafer becomes even more difficult because the thickness and optical properties of the thin film vary locally.

The surface roughness of the wafer, as well as the structure and optical properties of the wafer backside, can also greatly affect the accuracy of wafer temperature measurement. Therefore, one of the greatest challenges for system designers is to maintain uniform wafer temperature while accurately measuring and controlling the temperature.

Equipment manufacturers generally need a system design that can address the following requirements:
Maintain the same temperature-time profile even when wafers are replaced.
Ensure uniform gas flow inside the chamber.
Maintain uniform temperature, with a temperature difference within 2°C across the entire wafer.
Accurately measure and control the temperature inside the heat treatment equipment.

02. Is it necessary to conduct physical tests for every design variable?

If an analysis model is established based on test data, the optimal internal design of the equipment can be reviewed through simulation results under various design parameter changes. CFD analysis can be used to evaluate results such as pressure distribution, velocity distribution, and temperature distribution inside the equipment.

03. How can we define and design “cooling performance”?

The easiest way to understand vacuum is by analogy with outer space. In space, no particles exist, and it is said that no physical phenomena such as fluid flow, pressure, friction, or resistance are present. In contrast, on Earth where we live, the atmosphere is composed of various particles and components, and equal atmospheric pressure acts on both the inside and outside of structures.

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