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...

Examples

Embodiment Construction

[0043] The invention will now be described with reference to the accompanying drawings, in which like reference characters indicate like parts throughout. The present invention provides a system and method for providing accurate ion current measurements correlated to the dose of a wafer for use with an ion implantation system. Such uses may include dosimetry, data logging, and feedback to the system for closed loop control of, for example, the speed of a wafer slow scan movement drive.

[0044] Dose control, especially in the presence of high pressure in the process chamber due to photoresist gas outgassing, requires a measure for determining the effective implant beam current when part of the ion beam is neutralized on its way to the wafer. This is traditionally achieved by measuring the pressure within the beam path and correcting the flow measured at the wafer in the end station by estimating the fraction that has become neutral based on the pressure and the known or empiri...

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...

Examples

Embodiment Construction

[0043] The invention will now be described with reference to the accompanying drawings, in which like reference characters indicate like parts throughout. The present invention provides a system and method for providing accurate ion current measurements correlated to the dose of a wafer for use with an ion implantation system. Such uses may include dosimetry, data logging, and feedback to the system for closed loop control of, for example, the speed of a wafer slow scan movement drive.

[0044] Dose control, especially in the presence of high pressure in the process chamber due to photoresist gas outgassing, requires a measure for determining the effective implant beam current when part of the ion beam is neutralized on its way to the wafer. This is traditionally achieved by measuring the pressure within the beam path and correcting the flow measured at the wafer in the end station by estimating the fraction that has become neutral based on the pressure and the known or empiri...

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