03 Dec Reducing LED Chip Manufacturing Costs
Metalorganic chemical vapor deposition (MOCVD), also called Metalorganic vapor phase epitaxy (MOVPE) or organometallic vapor phase epitaxy (OMVPE), involves a complex chemical deposition method. MOCVD grows multiple layers of crystalline semiconductor materials, such as Gallium Arsenide (GaAs) or Indium Phosphide (InP), on a substrate.
Epitaxy is an important process in the manufacturing of chips for electronics and optoelectronics devices used for manufacturing of cell phones, aviation lights, solar cells, and traffic lights. In addition, MOCVD is critical for the development of devices used for optical storage, optical communications, and light-emitting diodes (LEDs).
LED Fabrication Requires Precision
Conventional LED chip manufacturing entails complex dynamics and long processing times of 6-12 hours. An ultra-pure pure (99.9999 %) gas mixture is injected into the chamber. As the precursor molecules passes over the heated substrate, it decompose (pyrolyze) and deposit the material’s atoms (i.e., GaAs) to the substrates and bond to the surface.
The epitaxial process requires necessitates precise control of the gas blending system, substrate temperature, scrubbing, and other considerations.
Reducing LED Manufacturing Costs
LED manufacturers are constantly on the lookout for innovative MOCVD systems that will increase throughput, deposit more material in a single run, and improve yield.
Better packaging can help reduce LED manufacturing costs. Currently, packaging accounts for 20% to 50% of production expenses. Improved thermal management can also lower the cost of fabricating LEDs.
Approximately 70% of the energy output converts to heat instead of light. Improved heat dissipation enhances reliability ensures a maximum lifetime for LEDs.
In LED fabrication, the MOCVD process represents one of the most important phases in determining LED performance.
Yield losses comprised the most costly aspect of LED manufacturing because of its connection to on device performance.
Automated Yield Management Systems
Integrated circuit manufacturers have sophisticated yield management systems (YMSs) for fabricating ICs. While similar in many ways, the differences between IC fabrication and LED manufacturing make the YMSs used in IC manufacturing ineffective for the LED process.
Devices that meet LED performance specifications may have loss rates as high as 50% (yield).
The U.S. Department of Energy (DOE) has provided funding for a project designed to improve automated yield management solutions for LED manufacturing.
The scope of the DOE’s YMSs project has a two-prong approach:
- Development of detection sensitivity tools for identifying defects in the process that limits yields and reliability.
- Creation of a sensitive inspection hardware and software that pinpoint defects, including micro scratches and cracks in the substrates or microscopic particles, which compromise the epitaxial process. The solution must accelerate data collection and the analysis of the wafer fabrication process.
The DOE initiative has an objective of achieving a 50% cost reduction on the LED inline inspection process by 2015.