Radiation-assisted MOCVD Heating for Improved Within-wafer Temperature Uniformity in LED Manufacturing

This Small Business Innovative Research (SBIR) Phase I project will demonstrate the feasibility of an innovative control technology for improved within-wafer temperature uniformity in Metal-Organic Chemical Vapor Deposition (MOCVD) process that is used in the fabrication of Multi-Quantum Well (MQW) LEDs. The proposed control technology has the strong potential to substantially reduce the need for “binning” in LED manufacturing. The deposition processes create significant variations in LED performance primarily as a result of temperature non-uniformity within the wafer. To mitigate this problem, LED manufacturers group the devices into “bins” with each bin spanning a range of color temperature, voltage or lumens. However, binning reduces yield, and produces devices with less desirable colors that hinders widespread acceptance of LED lighting. SC will address the problem by employing radiant heating from the top of the wafer with a heat flux profile shaped using a specially designed mask. The heater will be located beyond the susceptor edge and it will be controlled, together with the susceptor heaters, using an integrated control architecture. This approach will dramatically reduce within-wafer non-uniformity by 90% or more. In Phase I, we will design the radiant heating system including choice of heater and mask design. Additionally, we will formulate an integrated control system (open and closed-loop) which can rapidly ramp wafer temperature up and down through the process cycle while maintaining excellent within-wafer temperature uniformity. We will thus demonstrate feasibility of the concept on a bench-scale experiment with a heated plate. Commercial Applications and Other Benefits The proposed program for developing an innovative temperature control scheme for epitaxial deposition of GaN for LED manufacturing process has the potential to dramatically reduce the need for LED binning. The control concept demonstrated in Phase I on a bench-scale set-up will be productized in Phase II. This novel control technology will help maintain U.S. leadership in MOCVD equipment used for LED and other semiconductor applications. The increase in yield of LEDs with desirable color will help the LED market keep pace with DoE’s goals of accelerating the pace of adoption of LED lighting and reducing the price of LED lighting by a factor of ten over this decade.