MOCVD, or metal organic chemical vapor deposition, is the key tool used for LED production. MOCVD is also used in III-V applications, such as RF and optoelectronics. It is sometimes called metal organic vapor phase epitaxy (MOVPE).
In MOCVD, pure gases are injected into a reactor. The tool deposits a thin layer of atoms onto the wafer. This, in turn, creates a crystalline, or epitaxial growth, of materials.
For LEDs, the basic building block for a GaN-based LED is the n-GaN/InGaN/p-GaN heterojunction structure. Each LED maker has a proprietary MOCVD recipe, which is a closely guarded secret.
Basically, MOCVD is a challenging art form. The first challenge is growing layers with good uniformity. The overall cost of ownership has to be inexpensive. To keep the LED industry competitive, the MOCVD cost-of-ownership (COO) must fall 50% every five years, according to the U.S. Department of Energy. Epitaxy growth costs must fall $0.3/μm·cm2 today to $0.1/μm·cm2 by 2016, according to experts. In addition, epitaxial throughputs must increase from 5 2-inch wafers an hour today to 10 2-inch wafers by 2016, they said. And wafer uniformity must fall from 1.7nm today to 0.5nm by 2016, they added.