Processing yields in electron-cyclotron-resonance ͑ECR͒ and other high-density plasma sources will be increasingly limited by plasma-induced damage. This work investigates the effects of plasma nonuniformities on charging damage to polysilicon-gate MOS capacitor test structures exposed to O 2 ECR plasmas. The nonuniformities were produced by independently biasing electrodes located above the wafer. The damage was characterized with ramp-voltage breakdown measurements.Comparison of calculated profiles of the potential difference across the gate-oxide layers of the MOS capacitors with whole wafer maps of the breakdown voltage measurements shows that maximum damage occurs where the oxide potential difference is largest but only in the presence of plasma nonuniformities. © 1995 American Institute of Physics.The purpose of this work is: ͑i͒ to investigate charging damage to polysilicon-gate metal-oxide-semiconductor ͑MOS͒ capacitor antenna test structures upon exposure to O 2 plasmas generated in an electron-cyclotron-resonance ͑ECR͒ plasma source; and ͑ii͒ to determine the effect of radial plasma nonuniformities on the charging damage. Previous work with ECR reactors 1-3 and other types of plasma systems 4 -7 has indicated that nonuniformities in the plasma parameters across the surface of the wafer during processing may play a role in the generation of charging damage. Our goal is to quantify the relationship between the plasma conditions and the degree of process-induced damage.We will show that charging damage occurs when sufficiently large potential differences exist across the gate-oxide layers of the test structures. Also, it will be shown that these potential differences can only occur in the presence of plasma nonuniformities. The plasma parameters were characterized in terms of averages and standard deviations of profiles measured radially across the wafer surface. Charging damage was determined from ramp-voltage oxidebreakdown measurements of the MOS test structures.The etching system employed here consists of a source region where high-density ECR plasma production is maintained, and a downstream processing region where the wafer is positioned. The source ͑ASTeX S-1500i, 1.5 kW 2.45 GHz͒ has a pair of magnets arranged in a magnetic-mirror configuration. The plasma parameters were measured with a Langmuir probe. 8 To modify the radial profiles of the plasma parameters, a dual-electrode assembly, oriented parallel to the wafer, consisting of a ring ͑10-cm diam͒ and a grid electrode ͑4.5 cm diam͒ which were independently biased, was mounted above the wafer stage. A diagram of the ECR system and dual-electrode assembly is shown in Fig. 1.Charging of MOS capacitors produces potential differences across the gate oxide that cause Fowler-Nordheim ͑FN͒ tunneling currents 9,10 to flow through the gate-oxide layer which degrades the quality of the oxide and leads to breakdown. Such charging can result from local differences in the ion and electron current fluxes to the individual gates of the test structures. 6 To a...
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