Conductive paste composition and semiconductor devices made therewith

Patent metadata

Field	Value
Publication number	US-9236161-B2
Application number	US-201314016506-A
Country	US
Kind code	B2
Filing date	Sep 3, 2013
Priority date	Sep 6, 2012
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

A conductive paste composition contains a source of an electrically conductive metal, a Ti—Te—Li oxide, 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 establish electrical contact between it and the device.

First claim

What is claimed is:

1. A paste composition comprising:
(a) a source of electrically conductive metal;
(b) a Ti—Te—Li oxide; and
(c) an organic vehicle in which the source of electrically conductive metal and the Ti—Te—Li oxide are dispersed,
and wherein the titanium, tellurium, and lithium cations together comprise at least 70% of the cations present in the oxide and the minimum content of titanium, tellurium, and lithium cations in the oxide is at least 2, 30, and 18 cation %, respectively, and wherein Bi 2 O 3 is present in the Ti—Te—Li oxide at an amount of 0-10 cation %, and the paste composition is lead free.

2. The paste composition of claim 1 , comprising 1.0 to 10 weight % of the Ti—Te—Li oxide.

3. The paste composition of claim 1 , wherein Ti, Te, and Li cations comprise 75 to 95 cation percent of the Ti—Te—Li oxide.

4. The paste composition of claim 1 , wherein the Ti—Te—Li oxide further incorporates at least one oxide selected from the group consisting of oxides of B, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Al, Cr, Mn, Fe, Co, Cu, Zn, Zr, Nb, Si, Mo, Hf, Ag, Ga, Ge, In, Sn, Sb, Se, Ru, P, Y, La and the other lanthanide elements, and mixtures thereof.

5. The paste composition of claim 1 , further comprising any one or more of:
(a) 0.1 to 25 cation % of B 2 O 3 ;
(b) 0.1 to 25 cation % of ZnO;
(c) 0.1 to 25 cation % of one or more of Na 2 O, K 2 O, Cs 2 O, Rb 2 O, or a combination thereof.

6. The paste composition of claim 1 , wherein the constituents of the Ti—Te—Li oxide are intimately mixed.

7. The paste composition of claim 1 , further comprising a discrete oxide additive that is at least one oxide selected from the group consisting of oxides of one or more of B, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Al, Cr, Mn, Fe, Co, Cu, Zn, Zr, Nb, Si, Mo, Hf, Ag, Ga, Ge, In, Sn, Sb, Se, Ru, Bi, P, Y, La and the other lanthanide elements, and mixtures thereof, or a substance that forms such an oxide upon heating.

8. The paste composition of claim 7 , wherein the discrete oxide additive comprises 0.01 to 5 wt. % of the paste composition.

9. The paste composition of claim 1 , wherein up to 10 anion % of the oxygen anions of the Ti—Te—Li oxide are replaced by halogen anions.

10. The paste composition of claim 9 , wherein up to 10 anion % of the oxygen anions are replaced by fluorine anions.

11. The paste composition of claim 1 , wherein the electrically conductive metal comprises Ag.

12. The paste composition of claim 1 , wherein the titanium, tellurium, and lithium cations together comprise at least 75% of the cations present in the oxide.

13. A process for forming an electrically conductive structure on a substrate, the process comprising:
(a) providing a substrate having a first major surface;
(b) applying the paste composition of claim 1 onto a preselected portion of the first major surface;
(c) firing the substrate and paste composition thereon, whereby the electrically conductive structure is formed on the substrate.

14. The process of claim 13 , wherein the substrate comprises an insulating layer present on at least the first major surface and the paste composition is applied onto the insulating layer of the first major surface, and wherein the insulating layer is at least one layer comprised of aluminum oxide, titanium oxide, silicon nitride, SiN x :H, silicon oxide, or silicon oxide/titanium oxide.

15. The process of claim 14 , wherein the insulating layer is comprised of silicon nitride or SiN x :H.

16. The process of claim 15 , wherein the insulating layer is penetrated and the electrically conductive metal is sintered during the firing, whereby an electrical contact is formed between the electrically conductive metal and the substrate.

17. An article comprising a substrate and an electrically conductive structure thereon, the article having been formed by the process of claim 13 .

18. The article of claim 17 , wherein the substrate is a silicon wafer.

19. The article of claim 17 , wherein the article comprises a semiconductor device.

20. The article of claim 19 , wherein the article comprises a photovoltaic cell.

Assignees

• Du Pont

Inventors

• Mikeska Kurt Richard
• Roach David Herbert
• Torardi Carmine
• Vernooy Paul Douglas

Classifications

• H10F77/211

  for photovoltaic cells · CPC title

• H10F77/206

  for devices having potential barriers · CPC title

• H01B1/22 Primary

  the conductive material comprising metals or alloys · CPC title

• B05D5/12

  to obtain a coating with specific electrical properties · CPC title

• H01B1/16 Primary

  the conductive material comprising metals or alloys · CPC title