Plasma doping with enhanced charge neutralization

Abstract

A plasma doping apparatus includes a pulsed power supply that generates a pulsed waveform having a first period with a first power level and a second period with a second power level. A plasma source generates a pulsed plasma with the first power level during the first period and with the second power level during the second period. A bias voltage power supply generates a bias voltage waveform at an output that is electrically connected to a platen which supports a substrate. The bias voltage waveform having a first voltage during a first period and second voltage with a negative potential that attract ions in the plasma to the substrate for plasma doping during a second period. At least one of the first and second power levels of the RF waveform is chosen to at least partially neutralize charge accumulating on the substrate.

Description

[0001]The section headings used herein are for organizational purposes only and should not to be construed as limiting the subject matter described in the present application.BACKGROUND OF THE INVENTION[0002]Plasma processing has been widely used in the semiconductor and other industries for many decades. Plasma processing is used for tasks such as cleaning, etching, milling, and deposition. More recently, plasma processing has been used for doping. Plasma doping is sometimes referred to as PLAD or plasma immersion ion implantation (PIII). Plasma doping systems have been developed to meet the doping requirements of some modern electronic and optical devices.[0003]Plasma doping is fundamentally different from conventional beam-line ion implantation systems that accelerate ions with an electric field and then filter the ions according to their mass-to-charge ratio to select the desired ions for implantation. In contrast, plasma doping systems immerse the target in a plasma containing ...

AI Technical Summary

Benefits of technology

The present invention relates to a system and method for plasma doping, which is a process used in the semiconductor and other industries for doping materials with ions. The invention aims to improve the process control of plasma doping systems by reducing the non-uniformity of doping and the development of charge build-up on the substrate being plasma doped. The invention provides a waveform that can neutralize charge accumulation on the substrate and a method for applying a negative voltage to the substrate to attract ions for implantation. The invention also includes various alternatives, modifications, and equivalents for use in plasma doping systems.

Problems solved by technology

In general, the process control of plasma doping systems is not as good as conventional beam-line ion implantation systems.

This charge build-up can result in the development of a relatively high potential voltage on the substrate that can cause doping non-uniformities, arcing, and device damage.

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