Spacer formation in a solar cell using oxygen ion implantation

A solar cell comprising:

• a solar cell substrate having a front side and a back side opposite the front side, wherein the front side faces the sun during normal operation;
• a polysilicon layer disposed over the back side of the solar cell substrate;
• a P-type diffusion region disposed in the polysilicon layer;
• an N-type diffusion region disposed in the polysilicon layer;
• a separation region disposed in the polysilicon layer between the P-type diffusion region and the N-type diffusion region, the separation region having higher resistivity than either the P-type diffusion region or the N-type diffusion region, the separation region extending from a side of the P-type diffusion region to a side of the N-type diffusion region;
• a trench structure formed over the separation region and disposed between the P-type diffusion region and the N-type diffusion region;
• a first contact plug that is electrically connected to the P-type diffusion region;
• and
• a second contact plug that is electrically connected to the N-type diffusion region.

A solar cell comprising:

• a solar cell substrate having a front side and a back side opposite the front side, wherein the front side faces the sun during normal operation;
• a polysilicon layer disposed over the back side of the solar cell substrate;
• a P-type diffusion region disposed in the polysilicon layer;
• an N-type diffusion region disposed in the polysilicon layer;
• a separation region disposed in the polysilicon layer between the P-type diffusion region and the N-type diffusion region, the separation region having higher resistivity than either the P-type diffusion region or the N-type diffusion region, the separation region extending from a side of the P-type diffusion region to a side of the N-type diffusion region;
• a first metal grid disposed over the polysilicon layer and is electrically connected to the P-type diffusion region;
• a second metal grid disposed over the polysilicon layer and is electrically connected to the N-type diffusion region;
• a front side diffusion region disposed on the front side of the solar cell substrate;
• and
• an oxide layer disposed over the front side diffusion region.