Paper PS2+PV-MoM2
Plasma Etching and Texturing of Multi-Crystalline for Silicon Solar Cells using Remote-Type Pin-To-Plate Dielectric Barrier Discharge

Monday, November 9, 2009, 8:40 am, Room A8

During the preparation of the wafers for the multi-crystalline silicon (mc-Si) solar cells, the mechanical saw damage induced during the slicing of mc-Si ingots into wafers needs to be removed by etching in addition to the texturing of the silicon surface for the increased light scattering. For the etching and texturing of the mc-Si substrates, isotropic wet processing by using alkaline or acid solution is generally applied, however, wet treatments are environmentally undesirable due to the large amount of chemicals used.

In this study, an atmospheric pressure plasma called “remote-type pin-to-plate DBD” was used for the application to the etching of the saw damage removal and texturing process of mc-Si to increase the processing rate by increasing the plasma density without damaging the substrate surface. Especially, the effect of additive gases such as NF₃ and O₂ to the N₂-based atmospheric pressure plasma on the etching and texturing characteristics of mc-Si was investigated.

The results showed that the addition of NF₃ up to 1 slm increased the mc-Si etch rate continuously by increasing the F radicals in the gas mixture. Furthermore, the addition of a certain amount of O₂ (400sccm) to the mixture of N₂(40 slm) /NF₃(1slm) increased the mc-Si etch rate further by showing the two times higher etch rate of mc-Si (749.6 nm/scan, 1meter/scan). Especially, the addition of O₂ to the N₂/NF₃ improved the surface morphology by increasing surface texturing and, by the addition of 600sccm O₂, the reflectance less than 20% could be obtained.