Patent Number: 6,297,510

Title: Ion implant dose control

Abstract: The true beam current corrected for neutrals in the beam impinging on thewafer during processing, is calculated by taking repeated measurements ofthe beam current during periods when the beam is clear of the wafer duringa process. During such periods of multiple beam current measurements, theresidual gas pressure declines in accordance with a pump down constantwhich is also determined. A quadratic expression relating measured beamcurrent and time can then be solved for a factor giving a value for thecorrected beam current. A corrected beam current is used to control thedosimetry of the apparatus to ensure the correct dose is uniformly appliedto the surface of a wafer.

Inventors: Farley; Marvin (Ipswich, MA)


International Classification:

Expiration Date: 10/02/2013