NOVELTY - The method comprises depositing a first set of nanoparticles comprising a first dopant on a first surface region of a front surface of a substrate, depositing a second set of nanoparticles comprising a second dopant on a third surface region of a rear surface of the substrate, heating the substrate in an inert ambient to a first temperature for a first time period to create a first densified film and a first diffused region having a first diffusion depth in the substrate beneath the first surface region, depositing a first metal paste on the rear surface of the substrate.    USE - The method is useful for forming a multi-doped junction on a substrate to form semiconductor devices such as computers, cellular phones and solar cells.    ADVANTAGE - The method is capable of efficiently and economically forming the multi-doped junction on the substrate by forming both the selective emitter and the back surface field in a simultaneous diffusion step thus achieving high bulk lifetime and good surface recombination current density in the electronic device, reducing the manufacturing cost of the electrical devices and improving the efficiencies of the electrical device.    DETAILED DESCRIPTION - The method comprises depositing a first set of nanoparticles comprising a first dopant on a first surface region of a front surface of a substrate, depositing a second set of nanoparticles comprising a second dopant on a third surface region of a rear surface of the substrate, heating the substrate in an inert ambient to a first temperature for a first time period to create a first densified film and a first diffused region having a first diffusion depth in the substrate beneath the first surface region, depositing a first metal paste on the rear surface of the substrate, exposing the substrate to a diffusion gas comprising phosphorus at a second temperature for a second time period to create a phosphosilicate glass (PSG) layer on a second surface region of the front surface and a second diffused region having a second diffusion depth in the substrate beneath the second surface region, where the first diffused region is proximate to the second diffused region, exposing the substrate to an oxidizing gas at a third temperature for a third time period to form a silicon dioxide layer between the PSG layer and the front surface and then increasing the first diffusion depth relative to the second diffusion depth, depositing a surface passivation layer on the front surface of the substrate, and depositing a second metal paste on the surface passivation layer. The first and second temperatures are 800 degrees C. The first time period is 15 seconds. The second time period is 15 minutes. The third temperature is 1000 degrees C. The third time period is 15-30 minutes. The step of heating the substrate further creates a second densified film and a third diffused region having a third diffusion depth in the substrate beneath the third surface region.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a solar cell.    Front-metal contact (502)    Silicon dioxide layer (506)    Front negative-type diffused region (508)    Silicon substrate (510)    Nanoparticle densified film. (512)