Rhenium MOCVD Heater Filaments:

Rhenium MOCVD heater filaments are one of our more advantageous products. The rhenium heater filaments are used in the MOCVD (Metal Organic Chemical Vapor Phase Deposition) process. In this process, semiconductor layers are created for LEDs, solar cells, and other opto-electronic components. In MOCVD systems, heating elements are heated to 2000°C. Rhenium has excellent high-temperature performance and a longer lifespan, so it is commonly used for MOCVD heaters.

We pay special attention to the element control for the homogeneous temperature distribution in MOCVD as it is an important prerequisite. Customers can benefit from a greater yield from each coating cycle and thus from increased productivity.

Metal Organic Chemical Vapor Deposition (MOCVD) is a chip epitaxial technology for preparing mixed semiconductor devices, metal and metal oxide, and metal nitride film materials. In the MOCVD system, crystal growth is mostly under normal or low pressure (10-100 Torr), and the substrate temperature is 500 to 1200℃. To achieve the growth of pure materials with steep interfaces and uniform films, MOCVD equipment must create the appropriate chemical reaction environment. The heating system is an important part of the MOCVD equipment. Whether it can heat the substrate quickly and uniformly directly affects the quality of film deposition, thickness consistency, and chip performance.

The working conditions of the MOCVD heater are very harsh. The conditions involve extended continuous operation, elevated temperatures, high heat flux, and repeated temperature change. The resistor piece is the core part of the heater. After a certain current is passed, the resistor piece generates heat and becomes the heat source of the entire device. The surface temperature of the graphite plate used to place the substrate reaches 1350K, the temperature of the resistance piece can be as high as 2000K, and the temperature of the resistance heater can surpass 2500℃ during the heating process. Therefore, the material being used must have a high melting point, high-temperature strength, and high chemical stability characteristics. Take the MOCVD equipment for growing GaN as an example, the optimal growth temperature is about 1000~1200℃. The temperature for the heating element of the heater is about 1500~2000℃. In the process of growing GaN, the epitaxial substrate is required to rapidly rise in temperature (the heating rate reaches 3-10°C/s) and drop in temperature.

According to the process requirements of the MOCVD equipment, the performance of the heating ring must meet:

1. Achieve uniform heating of the large-size graphite tray and the effective heating area ratio should cover the entire surface.
2. The temperature rise and fall rate is fast and the stability time is short.
3. The temperature rise and fall dynamics Keep the temperature uniform during the process.
4. For different gas flow environments, uniform heating can be achieved.
5. In the process of repeated heating and cooling, the structure is stable and reliable, and the service life is long.

According to the working characteristics of MOCVD, the selection of metal-resistance heating elements is the most reasonable. According to the actual temperature conditions that need to be met, only a few refractory metals such as tungsten and rhenium can meet the requirements of use.

Tungsten heating devices will become brittle after being recrystallized because of the high temperatures. This will cause them to easily break under impact or vibration. Rhenium has a higher recrystallization temperature than tungsten. Recrystallized rhenium is not a brittle material, but its strength is reduced. As a non-stressed heating device, it still has good working ability and has the best high-temperature stability. High creep strength. Therefore, rhenium is used to manufacture MOCVD heating devices. It is the best choice when considering performance and cost, no other material can replace it.