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Electrostatics in Advanced 300 mm Semiconductor Operations. Larry Levit, Ph.D. Chief Scientist ION Systems, Inc. Berkeley, California USA NARTE Certified ESD Engineer. Cleanrooms and Static Charge. Insulators Like Teflon Quartz SiO 2 Low Humidity Ions Swept Away by HEPAs.
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Electrostatics in Advanced 300 mm Semiconductor Operations Larry Levit, Ph.D. Chief Scientist ION Systems, Inc. Berkeley, California USA NARTE Certified ESD Engineer
Cleanrooms and Static Charge • Insulators Like • Teflon • Quartz • SiO2 • Low Humidity • Ions Swept Away by HEPAs
Particle attraction & bonding to charged surfaces • Damage to product • Robotic lockup
Electrostatics and Contamination
Wafer charged to 500V Without static charge Wafer charged to 4000V ESA (electrostatic attraction)
Problem: How To Dissipate Static Charge on an Insulator? Solution: Make the Air Conductive Air Ions neutralize surface charge by contact.
10-20 kV Intense Electric Field A Basic Corona Ionizer Positive HV makes Positive Ions Negative HV makes Negative Ions
Ceiling Emitter- neutralizes FOUP shells, windows and other insulators In-Tool Bars- neutralize end effectors, Teflon handling parts, wafers and FOUP insides In-Tool vs. Ceiling IonizersDifferent functions
Microcontamination Histogram Etch Tool Ch 2 • Ions On 11.6 ± 4.4 • Ions Off 25.3 ± 6.8
0.4 0.35 Ionization Off: 8.2 ± 3.6 Ionization On: 3.3 ± 0.9 0.3 0.25 Frequencey of Occurrence 0.2 ( per wafer) On Off 0.15 0.1 0.05 0 0 2 4 6 8 10 12 14 16 More Number of Defects Microcontamination Histogram For an Implant Tool