Metallization method for silicon solar cells

A method of forming emitter contacts on a surface emitter of a silicon solar cell comprising a substrate of silicon material, the method comprising:

• (i) forming the surface emitter by performing an n-type diffusion of a surface of the substrate to form an emitter surface layer with a pn junction depth of at least 1.5 μm;
• (ii) etching back the surface of the substrate to achieve a dopant concentration at the surface of the substrate to less than 1020 atoms/cm3 and to increase a sheet resistance of the emitter surface layer to 100-160 Ω/square;
• (iii) depositing a surface dielectric layer or layers onto the etched back surface of the substrate;
• (iv) patterning the dielectric layer in localized areas to expose regions of a silicon surface of the substrate where contacts are to be formed;
• (v) doping the surface of the substrate in the exposed regions where contacts are to be formed whereby a dopant concentration at the surface of the exposed regions is greater than the dopant concentration at the surface of the substrate over a remainder of the surface of the substrate by a factor of at least two;
• and
• (vi) selectively plating the silicon surface of the substrate in the exposed regions where contacts are to be formed to make an electrical connection the emitter surface layer.