CHARACTERIZATIONOF SEMICONDUCTORS WITH RESOLUTION DOWN TO LUM

NEAR-SURFACE DEFECTS IN SEMICONDUCTORS HAVE A PRIMARY INFLUENCE UPON DEVICE PROPERTIES, PARTICULARLY THE YIELD. IT WOULD BE VERY USEFUL TO BE ABLE TO MAP SPATIALLY THE DENSITY AND TYPE OF DEFECTS NEAR A SEMICONDUCTOR SURFACE EITHER AS A WAFER QUALITY CONTROL STEP OR TO SUPPORT DEVICE PHYSICAL EXPERIMENTS. CONVENTIONAL TECHNIQUES USED FOR THIS PURPOSE SUFFER FROM ONE OR MORE OF THE FOLLOWING LIMITATIONS: THEY ARE DESTRUCTIVE; THEY CAN ONLY IDENTIFY DEFECTS THAT INTERSECT THE SURFACE OR THEY HAVE INADEQUATE RESOLUTION. THIS PROPOSAL DISCUSSES A RESEARCH AND DEVELOPMENT PROGRAM LEADIG TO THE DEVELOPMENT AND TESTING OF A SCANNING PHOTOVOLTAGE (SPV) INSTRUMENT FOR THE NON-DESTRUCTIVE IDENTIFICATION AND MAPPING OF NEAR-SURFACE DEFECTS IN SEMICONDUCTORS. ARACOR HAS DEVELOPED AN SPV TECHNIQUE WHICH SHOWS PROMISE OF BEING USEFUL FOR THIS PURPOSE IN SEMI-INSULATING MATERIAL SUCH AS GAAS, SILICON-ON-SAPPHIRE AND INP. THE EXISTING TECHNIQUE IS INAPPROPRIATE, HOWEVER, FOR DEVELOPMENT INTO A USEFUL INSTRUMENT BECAUSE THE RESOLUTION LIMIT 10 M. IN THIS PROPOSAL, WE DESCRIBE PLANS FOR UPGRADING THIS TECHNIQUE IN TWO WAYS: (1) BY UTILIZING DIFFRACTION-LIMITED OPTICS AT A LASER WAVELENGTH OF 500NM, COMBINED WITH A MODIFIED STAGE WITH 0.5 M RANGE; (2) BY ADOPTING A MULTIPLE WAVELENGTH APPROACH IN COMBINATION WITH MINICOMPUTER DATA REDUCTION, WE WILL IMPROVE THE SENSITIVITY OF THE TECHNIQUE SO AS TO (A) DIFFERETIATE BETWEEN SURFACE AND BULK DEFECTS, AND (B) APPLY THE METHOD OF DOPED CONDUCTIVE SUBSTRATES.