Conductive paste for semiconductor device and preparation method

A method for using a front-side conductive paste to form a front-side electrode for a crystalline silicon solar cell comprising:

• providing a crystalline silicon solar cell chip having a front side of silicon covered by an insulating film;
• screen printing the front-side conductive paste over the insulating film, the front-side conductive paste comprising, based on 100 parts by weight,
• 82.0-93.0 parts of a metal powder;
• 6.0-13.0 parts of an organic carrier;
• 1.0-5.0 parts of an oxide etching agent, wherein based on 100% by mole, the oxide etching agent comprises at least 10-40% of MgO, 0.1-5.0% of B2O3, 0.1-5% of PbO, and 5.0˜30.0% of Li2O;
• heating the crystalline silicon solar cell chip to melt the oxide etching agent to a liquid contacted with the metal powder to dissolve the metal powder therein while evaporate the organic carrier, the oxide etching agent liquid with dissolved metal powder further etching through the insulating film to form a sintering bond with the front side of silicon;
• and
• cooling the crystalline silicon solar cell chip to turn the oxide etching agent liquid to a high-resistivity solid layer with the dissolved metal powder being precipitated out to form fine metal nanoparticles around the sintering bond between the metal and the front side of silicon with a good ohmic contact and a strong metal-silicon adhesion characterized by a lateral tensile force greater than 4 Newtons per 1 mm width.