Conductive paste composition and semiconductor devices made therefrom
View Patent ↗A conductive paste composition contains a source of an electrically conductive metal, a lead-tellurium-based oxide, a discrete oxide of an adhesion promoting element, and an organic vehicle. An article such as a high-efficiency photovoltaic cell is formed by a process of deposition of the paste composition on a semiconductor substrate (e.g., by screen printing) and firing the paste to remove the organic vehicle and sinter the metal and lead-tellurium-based oxide.
1. An article comprising a substrate and an electrically conductive structure thereon, the article having been formed by a process comprising:
(a) providing a substrate having a first major surface;
(b) applying a paste composition onto a preselected portion of the first major surface, wherein the paste composition comprises in admixture:
an inorganic solids portion comprising:
i) a source of electrically conductive metal,
ii) a lead-tellurium-based oxide,
iii) a discrete additive that is: (A) an oxide of a metal element selected from the group consisting of Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and mixtures thereof, (B) a compound capable of forming such an oxide upon heating, or (C) a mixture of (A) and (B) thereof, and
an organic vehicle; and
(c) firing the substrate and paste composition thereon, whereby the electrically conductive structure is formed on the substrate, and wherein:
the inorganic solids portion forms 85 to 95 wt. % of the total paste composition;
the source of electrically conductive metal forms 95 to 99% by weight of the inorganic solids portion;
a combination of lead and tellurium cations represents at least 60% of the cations in the lead-tellurium-based oxide; and
a ratio of a cation percentage of lead to a cation percentage of tellurium in the lead tellurium based oxide ranges from 35:65 to 65:35.
2. The article of claim 1 , wherein the substrate is a silicon wafer.
3. The article of claim 1 , wherein the article comprises a semiconductor device.
4. The article of claim 3 , wherein the article comprises a photovoltaic cell.
5. The article of claim 1 , wherein the discrete additive is: (A) an oxide of a metal element selected from the group consisting of Ti, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and mixtures thereof, (B) a compound capable of forming such an oxide upon heating, or (C) a mixture of (A) and (B) thereof.