Axcelis Technologies, Inc.

Eaton Corporation

James D Bernstein

Peter Lawrence Kellerman

Brian S Freer

A Stuart Denholm

Peter M Kopalidis

Alec S Denholm

A method for use with a plasma immersion ion implantations systems wherein a substrate W having a patterned photoresist P thereon is implanted. The method includes ionizing a first gas in a chamber to produce electrically inactive ions and reacting the electrically active ions with the photoresist P to produce outgassing . The outgassed material is continuously evacuated until outgassing is substantially completed. The method further includes ionizing a second gas to produce electrically active ions and implanting a positively charged species of the electrically active ions into the substrate. Also disclosed is a method for curing the photoresist prior to ion implantation. A gas is ionized in the chamber to produce positively and electrons. The electrons are first attracted to a substrate in the chamber having patterned photoresist P thereon for hardening the photoresist. The positively charged ions are then implanted into substrate W wherein photoresist outgassing is substantially prevented.

Pretreatment process for plasma immersion ion implantation

A plasma immersion ion implantation method and system is provided for maintaining uniformity in implant energy distribution and for minimizing charge accumulation of an implanted substrate such as a wafer. A voltage modulator (,) applies a pulsed voltage signal (&minus;V,) to a platen (,) in a process chamber (,) containing a plasma, so that ions in the plasma are attracted by and implanted into a wafer residing on the platen. The voltage modulator (,) comprises: (i) a first switch (,) disposed between a power supply (,) and the platen for momentarily establishing a connection therebetween and supplying the pulsed voltage signal to the platen; (ii) a second switch (,) disposed between the platen (,) and ground for at least momentarily closing to discharge residual voltage (&minus;V,) from the platen after the first switch (,) opens and the connection between the power supply and the platen is broken; and (iii) a controller (,) for controlling sequential operation of the switches (,). By closing second switch (,) and grounding the platen, (a) only ions within a certain energy level range are implanted into the wafer, improving the implant energy distribution and (b) wafer charging due to implantation of positive ions is neutralized by allowing electrons in the plasma to flow toward the wafer between implant pulses. Upon opening, second switch (,) permits the platen to float to achieve the floating potential of the plasma thus minimizing voltage stresses on devices in the wafer. Alternatively, the platen may be positively biased to the plasma floating potential.

System for improving energy purity and implant consistency, and for minimizing charge accumulation of an implanted substrate

A method and system is provided for cleaning a contaminated surface of a vacuum chamber, comprising means for (i) generating an ion beam (,) having a reactive species (e.g., fluorine) component; (ii) directing the ion beam toward a contaminated surface (,); (iii) neutralizing the ion beam (,) by introducing, into the chamber proximate the contaminated surface, a neutralizing gas (,) (e.g., xenon) such that the ion beam (,) collides with molecules of the neutralizing gas, and, as a result of charge exchange reactions between the ion beam and the neutralizing gas molecules, creates a beam of energetic reactive neutral atoms of the reactive species; (iv) cleaning the surface (,) by allowing the beam of energetic reactive neutral atoms of the reactive species to react with contaminants to create reaction products; and (v) removing from the chamber any volatile reaction products that result. Alternatively, the method and system include means for (i) generating an energetic non-reactive (e.g., xenon) ion beam (,); (ii) directing the non-reactive ion beam toward a contaminated surface (,); (iii) introducing a cleaning gas (,) proximate the contaminated surface, comprised at least partially of a reactive species (e.g., fluorine) component; (iv) dissociating the cleaning gas using the ion beam (,) to create a supply of energetic reactive neutral atoms of the reactive species; (v) cleaning the surface (,) by allowing the energetic reactive neutral atoms of the reactive species to react with contaminants to create reaction products; and (vi) removing from the chamber any volatile reaction products that result.

System and method for cleaning contaminated surfaces in an ion implanter

A plasma-enhanced electron shower (62) for an ion implantation system (10) is provided, including a target (64) provided with a chamber (84) at least partially defined by a replaceable graphite liner (82). A filament assembly (67) attached to the target generates and directs a supply of primary electrons toward a surface (118) provided by the graphite liner, which is biased to a low negative voltage of up to -10V (approximately -6V) to insure that secondary electrons emitted therefrom as a result of impacting primary electrons have a uniform low energy. The filament assembly (67) includes a filament (68) for thermionically emitting primary electrons; a biased (-300V) filament electrode (70) for focusing the emitted primary electrons, and a grounded extraction aperture (72) for extracting the focused primary electrons toward the graphite surface (118). A gas nozzle (77) attached to the target (64) introduces into the chamber a supply of gas molecules to be ionized by the primary electrons. The direction of the nozzle is set with respect to the filament assembly (67) to maximize the ionization rate of the gas molecules.

Ion implanter electron shower having enhanced secondary electron emission

A plasma-enhanced electron shower (62) for an ion implantation system (10) is provided, including an extension tube (66) having a replaceable graphite inner liner (88). The inner liner is biased to a low negative potential (-6 V) to prevent low energy secondary electrons generated by the electron shower target from being shunted away from the wafer, keeping them available for wafer charge neutralization. The electrically biased inner surface is provided with serrations (126) comprising alternating wafer-facing surfaces (128) and target-facing surfaces (130). During operation of the electron shower (62), photoresist or other material which may sputter back from the wafer collects on the wafer-facing surfaces (128), rendering them non-conductive, while the target-facing surfaces (130) remain clean and therefore conductive. The conductive target-facing surfaces provide a shunt (low resistance) path to electrical ground for high energy electrons generated in the electron shower.

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Beverly, MA, United States of America

James D Bernstein