ION IMPLANTATION BASED EMITTER PROFILE ENGINEERING VIA PROCESS MODIFICATIONS

摘要

A method of tailoring the dopant profile of a workpiece by modulating one or more operating parameters is disclosed. In one embodiment, the workpiece may be a solar cell and the desired dopant profile may include a heavily doped surface region and a highly doped region. These two regions can be generated by varying one or more of the parameters of the ion implanter. For example, the extraction voltage may be changed to affect the energy of the implanted ions. The ionization energy can be changed to affect the species of ions being generated from the source gas. In another embodiment, the source gasses that are ionized may be changed to affect the species being generated. After the implant has been performed, thermal processing is performed which minimizes the diffusion of the ions in the workpiece.

主权项

1. A method of creating a desired dopant profile in a workpiece, using an implant system comprising an ion source in communication with a gas source and an ionization power supply, and an extraction electrode in communication with an extraction power supply, comprising:
introducing a gas comprising a dopant from the gas source into the ion source; energizing the ion source using the ionization power supply to create ions from the gas; energizing the extraction electrode at a first extraction voltage using the extraction power supply so as to extract the ions from the ion source and direct the ions toward the workpiece with a first energy; implanting the ions at a first depth; energizing the extraction electrode at a second extraction voltage, lower than the first extraction voltage, using the extraction power supply so as to extract the ions from the ion source and direct the ions toward the workpiece with a second energy, lower than the first energy; implanting the ions at a second depth, the second depth less than the first depth; and performing a thermal cycle so as to allow the dopant to diffuse into the workpiece.