The emerging GaN-on-Silicon technology for electronic and optoelectronic applications also has an impact on MOCVD reactor design as well as on the expected yield. To address these challenges we developed a Planetary Reactor for 5x200 mm GaN-on-Si applications. Advanced process control and yield improvement using metrology tools play a significant role to achieve the required production quality.

To assess the reactor performance we grew 5-fold InGaN LED structures with a total thickness of 5.9 µm on 200 mm (111) silicon wafer using a sequence of strain management AlGaN layers with Al-concentrations of ~67%, ~57% and ~32% followed by an in-situ deposited SiN mask. The GaN buffer had a total thickness of 6 µm with intermittent low temperature (LT) AlN strain management layers.

From in-situ curvature traces continuous buildup of compressive strain without signs of relaxation throughout the GaN buffer could be seen. Even during the 2 µm thick n-doped GaN layer no signs of tensile strain components are evident, as often seen in such layers. Apart from the outermost ~3 mm edge the layers were virtually crack free as determined by Candela measurements.

On wafer temperature measurements using pyrometer at different wavelength are developed to asses temperature distributions in the reactor. We found that the wafer surface shows a different temperature distribution than the wafer pocket due to wafer bowing issues.

White light interference maps yielded an average thickness across all wafers of 6.02 µm with a spread of +/- 25 nm. The on-wafer thickness standard deviation was 0.81% on average. Photoluminescence maps exhibited an average wavelength of 451 nm with on-wafer standard deviations of 2 nm without edge exclusion. The wafer-to-wafer wavelength spread was measured to 2.6 nm. These results show that the thermal management of the reactor allowed for uniform growth.

HR-XRD measurements at center, halfway and edge positions across the wafer were performed to assess the quality and composition of the structure. The GaN FWHM of the XRD traces were 412 arcsec and 682 arcsec for the (002) and (102) reflexes, respectively. Also clearly distinguishable are the three strain reduction AlGaN layers with their different compositions and the fringes of the MQW up to the 5th order which correspond to a uniform pair thickness of ~13 nm.

We will show additional results on uniformity, electrical properties and strain management. Special emphasis will be put on the interplay between in-situ metrology, shortening of development time and final yield improvement.

1. PRESENTATION: Next generation production MOVPE - on the role of in-situ metrology for process control and yield enhancement, Microsoft Office Document, 0MB

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