Deposition coating equipment is constantly exposed to high-temperature environments during processing. To prevent issues related to airtight sealing and thermal deformation, the thermal distribustion of the structure under these confitions must be verifies. In this example, we will explore methods for analyzing and verifying temperature distribution and thermal deformation in the PECVD device cover under operating conditions.
Today's topic is "thermo-structural evaluation" of deposition coating equipment.
PECVD High-Temperature Environment Example
Due to the nature of semiconductor processes, many devices are exposed to high-temperature environments ranging from 100 ℃ to 500 ℃.
Considering that a hot midsummer day typically reaches around 35 ℃, the operating temperatures of 100 ℃ to 500 ℃ at which this equipment runs may be difficult to imagine.
It is said that the famous Eiffel Tower in Paris, France, is 6 inch (15.24 cm) taller in summer than in winter.
At high temperatures, the volume of an object increases due to "thermal expansion".
So what happens to semiconductor equipment at high temperatures?
Thermal Expansion Phenomenon Example
The top lid of the deposition coating device covered in this topic is the cover of the PECVD used for deposition in semiconductor processes. In the case of plasma-based devices, they are exposed to extremely high-temperature environments of 300 ℃ to 500 ℃. Heat is transferred from the internal heat block (Head block) to the top lid cover structure via radiation, and internal cooling pipes maintain the structure at an appropriate temperature.
In semiconductor equipment exposed to temperatures exceeding 300 ℃ and containing various materials, temperature-related issues can become significantly more severe. For the deposition process, the interior is always exposed to high-temperature environments while maintaining vacuum-level airtightness.
If the rubber O-ring used for sealing melts due to high temperatures, or if thermal expansion occurs — causing the entire top lid to warp due to temperature differentials and creating gaps — internal airtightness cannot be maintained, rendering the equipment unable to function as intended. If the load induced by thermal expansion is excessive, there is also the risk of the structure itself being damaged.
What kinds of problems can arise at high temperatures? Simply put, just as ice cream or chocolate melts from heat, steel and plastic can also melt at extremely high temperatures. Alternatively, structures can undergo severe deformation due to thermal expansion. To prevent this, if you look at railways or roads around us, you can see that gaps are intentionally left at regular intervals. If everything were joined together without gaps, highly dangerous situations could occur such as railway tracks buckling or road surfaces breaking apart and heaving upward.
The physical phenomena of heat transfer can generally be quantified and expressed as conduction, convection, and radiation heat transfer. It is necessary to numerically verify how heat generated from the high-temperature heat block is transferred to the structure at each location and what temperature distribution occurs at each position, and to qualitatively assess whether the structure is safe in terms of thermal expansion deformation or permanent deformation caused by heat.
Let us then explore how temperature is transferred from the internal high-temperature heat block in semiconductor equipment structures, and whether the temperature distribution and structural safety are adequate. The example is a study that reviews safety in accordance with ASME, based on temperature distribution, thermal expansion, and stress distribution, taking into account the effects of radiant heat from the internal heat block and the internal cooling pipes on the top lid of the deposition coating device.