MOCVD overview

MOCVD (Metal Organic Chemical Vapor Deposition, metal organic chemical vapor deposition) technology, also known as OMVPE, MOVPE, etc., is a new technology for preparing compound semiconductor single film proposed by Rockwell in 1968. The MOCVD method is to decompose and react the metal organic compound diluted in the carrier gas and the hydride of the V or VI element on the heated epitaxial substrate, and the reaction product is deposited on the epitaxial substrate to form A kind of epitaxial film technology, the use of this technology can grow nano-level high-quality film, it is precisely because of this feature that MOCVD technology is widely used in the production and manufacturing of semiconductor devices [1]. This technology has now become the most flexible, lowest cost, and most efficient technology for the growth of multi-layer structures of high-quality devices of III-V and II-VI compound semiconductors. In recent decades, the IT industry has been driven by the advancement of semiconductor technology. The rapid development, especially the rapid development of new semiconductor optoelectronic devices and microwave devices, huge market demand and the continuous progress of MOCVD technology, make MOCVD the key core equipment for semiconductor manufacturing with huge demand, and it is also the most promising development in the optoelectronics industry. One of the dedicated equipment. This equipment integrates precision machinery, semiconductor materials, vacuum electronics, fluid mechanics, optics, chemistry, computers and other disciplines into one. It is a sophisticated optoelectronic special equipment with high automation, high price, and high technology integration [2]. At present, MOCVD equipment has been widely used in the epitaxial growth of GaN (gallium nitride) semiconductor materials and blue, green or ultraviolet light emitting diode chips, heterojunction bipolar transistors (HBT), high electron mobility transistors (HFET), solar energy In the manufacturing and research of semiconductor devices such as batteries, field effect tubes (FETs), and optical detectors, it can be seen that MOCVD has a pivotal position in the semiconductor industry.

Overview of Foreign Research

The manufacturing technology of MOCVD equipment is mastered by a few foreign companies, such as AIXTRON in Germany, Thomas Swan and EMF in the United Kingdom, Veeco in the United States, Nissia, Nippon Sanso and Nissin Electric in Japan, etc. Some companies use their own in the production process. Unique MOCVD equipment.

Brief introduction of MOCVD equipment principle:

MOCVD equipment mainly includes four parts: gas system, heating system, reaction chamber and detection and control system. The gas path system mainly realizes the transportation of the gas source, the precise control of the gas flow, the accurate and fast switching of the valve and the treatment of the exhaust gas; the heating system mainly heats the substrate where the reaction occurs, provides the temperature required for the reaction, and satisfies the heating Uniformity, fast heating and cooling speed, short temperature stabilization time, etc.; the reaction chamber is the core part of the entire equipment. After the reaction gas enters the reaction chamber through the transport system, gas phase chemical reactions occur in the reaction chamber and the heated substrate surface respectively It reacts with the surface chemically, and after several complicated steps such as diffusion, adsorption, reaction and desorption, a homogeneous or heterogeneous crystal film is uniformly epitaxially grown on the substrate; the detection and control system mainly detects the temperature field in the reaction chamber online , Film thickness and uniformity and other parameters, and control the gas path and heating system.

The heating system of MOCVD has two functions. One is to provide temperature control for the constant temperature water bath containing the organic source steel cylinder, and the other is to provide the temperature required for epitaxial growth in the reaction chamber. The main temperature control equipment in the reaction chamber is the graphite carrier. The heating electric furnace under the sheet table adjusts the temperature of the reaction chamber by changing the power of the heating electric furnace to meet the needs of epitaxial growth. The core of the heating system design is the design of the heating electric furnace. The MOCVD equipment generally needs a heating temperature of about 1500°C during the growth process, so the heating element of the heating electric furnace needs to be able to withstand a high temperature above 2000°C. The heating element material we choose must It can withstand this high temperature, and the properties of the material must be very stable at this high temperature, so as to ensure the long-term stable heating of the electric furnace. At present, the materials suitable for this situation mainly include rhenium, tungsten and tungsten rhenium alloy.