PVD AlNValue Proposition•NanocolumnarAlNPVD nucleation layers are used to replace existing nucleation layers–Produce higher brightness LEDs
•50-70% lower defect density (002 and 102)–Produce better wavelength uniformity (binning)
•Improves PSS LED uniformity also–Improve MOCVD throughput and repeatability–Lower cost, more scalable (silicon industry tech!)
•1 PVD tool boosts throughput on 6-10 MOCVD’s
MOCVD Time Savings of AlN
•PVD AlNbuffer allows bypass of several steps–Initial ramp to high temp–High temperature sapphire cleaning step–Ramp to nucleation temp–Nucleation layer growth
•1-2 hrs of total time
AlNTemplate Properties•Repeatable and uniform nucleation surface for GaNepitaxy
–<1nm RMS roughness
–AlNthickness of 10nm –5000nm
–(00.2) FWHM routinely below 20 arcsec
–Epi-ready (no additional processing required)
•GaNepitaxyon PVD AlNis high quality, repeatable, and less complex
–Kyma has used these templates for our bulk GaNgrowth for 10 years
AlN Template Surface
-AFM•RMS Roughness <1nm
•Nanocolumnsof AlNprovide a repeatable and uniform nucleation surface for GaN
•Nano-roughness assists defect density reduction, improves GaNnucleation uniformity, reduces strain
PVD AlNTechnology Summary•GaNdevice market >99% heteroepitaxybased
–Significant wafer bow during temperature changes
–Performance and reliability problems induced by high defect density
•GaN/InGaNdevices use 3 growth temps (500C, 800C, 1050C)
–Wafer uniformity is dreadful (<20% binning yield?)
–Even worse on patterned sapphire
•GaNnucleation issues
–GaNdirect nucleation has contentious IP landscape
–MOCVD AlN/AlGaNnucleation is expensive
•MOCVD is slow, expensive, low purity, and has poor scalability
–$3M tools only 4,000 2” wafers/month, 6-10 hour long run
•NanocolumnarAlNPVD nucleation layers are superior in all regards
–Produces better wavelength uniformity (binning)
–Produces high brightness LEDs (defect density appears to be lower)
–Lower cost and much more scalable–Improve throughput and repeatability
Secondary AlNBenefits•AlNPVD useful for all substrates–Sapphire, SiC, Silicon
•MOCVD processes for these all very different
–C-plane, R-plane, M-plane, A-plane
•Fewer MOCVD steps increases fabthroughput
–Simpler N+ etch-back contact since no undopedlayer needed
•Really helpful on patterned sapphire which has larger thickness variations from coalescence issues
•May enable use of wet-etch patterned sapphire
–Lower cost than dry-etch patterned sapphire
•PVD AlNeven better for HVPE GaN
–HVPE is gaining credence as a replacement for MOCVD GaN
–100x higher growth rate, higher purity, better transparency, lower cost, less toxic
–AMAT recent announcement of HVPE/MOCVD cluster tool
•http://www.semiconductor-today.com/news_items/2010/JAN/DOE_180110.htm–Direct nucleation in hot wall HVPE is challenging, PVD AlNbypasses this problem
•Hot wall tools change temp very slowly
•Large temp swings present quartz lifetime issues–Kyma’sHVPE GaNeffort has used PVD AlNfor 10 years
