Dose cup located near bend in final energy filter of serial implanter for closed loop dose control

Abstract

An ion implantation system (600) having a dose cup (634) located near a final energy bend of a scanned or ribbon-like ion beam of a serial ion implanter for providing an accurate ion current measurement associated with the dose of a workpiece or wafer. The system comprises an ion implanter having an ion beam source for producing a ribbon-like ion beam (602). The system further comprises an AEF system configured to filter an energy of the ribbon-like ion beam by bending the beam at a final energy bend. The AEF system further comprises an AEF dose cup associated with the AEF system and configured to measure ion beam current, the cup located substantially immediately following the final energy bend. An end station (610) downstream of the AEF system is defined by a chamber wherein a workpiece is secured in place for movement relative to the ribbon-like ion beam for implantation of ions therein. The AEF dose cup is beneficially located up stream of the end station near the final energy bend mitigating pressure variations due to outgassing from implantation operations at the workpiece. Thus, the system provides accurate ion current measurement before such gases can produce substantial quantities of neutral particles in the ion beam, generally without the need for pressure compensation. Such dosimetry measurements may also be used to affect scan velocity to ensure uniform closed loop dose control in the presence of beam current changes from the ion source and outgassing from the workpiece.

Description

technical field [0001] The present invention relates to an ion implantation system, and more particularly to a system and method for ion dose measurement and compensation in the presence of photoresist outgassing, pressure, and ion source fluctuations in a continuous ion implanter. Background technique [0002] In the manufacture of semiconductor devices, ion implantation is used to incorporate impurities into semiconductors. Ion beam implanters use ion beams to process silicon wafers to create n- or p-type foreign material doping or to form passivation layers during integrated circuit fabrication. When used to dope semiconductors, ion beam implanters implant selected ionic species to produce the desired foreign material. Implantation of ions from source materials such as antimony, arsenic, or phosphorous forms an "n-type" foreign material wafer, while if a "p-type" foreign material wafer is desired, implants can be implanted using source materials such as boron, gallium, o...

AI Technical Summary

Problems solved by technology

Therefore, using such dose cup measurements to correct or compensate for dose rates encounters significant obstacles due to these variables

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