Timothy Miller

High-efficiency, high-productivity boron doping implantation by diboron tetrafluoride (B 2 F 4 ) gas on Applied Materials solar ion implanter

Ion implantation is known for its precise control and reproducibility of doping, enabling it to become one of the main approaches for high-efficiency cell manufacturing in the solar industry. Among the dopant materials, boron doping often represents the largest challenge to productivity as the efficiency of the traditional doping material, boron trifluoride (BF3), is always low. This paper presents a high-efficiency and high-productivity solution for boron doping on an Applied Materials solar ion implanter by using diboron tetrafluoride (B2F4) as a replacement gaseous boron source material for BF3. Both the B+ beam current and source life effects were evaluated. With optimized source parameters and beam tuning, the solar implanter with B2F4 has demonstrated significant improvements for both B+ beam current performance and source lifetime.

Solion ion source for high-efficiency, high-throughput solar cell manufacturing

In this paper, we introduce the Solion ion source for high-throughput solar cell doping. As the source power is increased to enable higher throughput, negative effects degrade the lifetime of the plasma chamber and the extraction electrodes. In order to improve efficiency, we have explored a wide range of electron energies and determined the conditions which best suit production. To extend the lifetime of the source we have developed an in situ cleaning method using only existing hardware. With these combinations, source life-times of >200 h for phosphorous and >100 h for boron ion beams have been achieved while maintaining 1100 cell-per-hour production.

Sidewall doping mechanism and doping profile tuning on 3D structure by plasma doping

In this paper the primary mechanisms for the plasma doping (PLAD) of 3D structures — direct implant, scattered implant, deposition & knock-in, and sputtering (etching) — are discussed. The TRI3DYN code was used to elucidate the roles these various doping mechanisms play. Through-fin SIMS profiles for an arsenic plasma doping process were calculated from the model and compared to experimental results. Further, by adjusting the competition and balance among these different doping mechanisms, we also demonstrate that the doping profile can be tuned on 3D fin structures for a boron plasma doping process.