Thick-film pastes containing lead-tellurium-boron-oxides, and their use in the manufacture of semiconductor devices

1. A thick-film paste composition for use in forming an electrical connection in a photovoltaic device comprising a semiconductor substrate having at least one insulating layer on a main surface thereof, the composition comprising:

a) 85 to 99.5% by weight of an electrically conductive metal or derivative thereof, based on total solids in the composition;

b) 0.5 to 15% by weight, based on total solids in the composition, of a lead-tellurium-boron-oxide, wherein the lead-tellurium-boron-oxide comprises 0.25 to 5 wt % B 2 O 3 ; and

c) an organic medium;

wherein the thick-film paste, when fired, is capable of penetrating the at least one insulating layer.

2. The thick-film paste of claim 1 , wherein the electrically conductive metal comprises silver.

3. The thick-film paste of claim 1 , wherein the mole ratio of lead to tellurium of the lead-tellurium-boron-oxide is between 5/95 and 95/5.

4. The thick-film paste of claim 1 , wherein the lead-tellurium-boron-oxide comprises:

25-75 wt % PbO,

10-70 wt % TeO 2 ,

and 0-20.0 wt % of components selected from the group of PbF 2 , SiO 2 , Bi 2 O 3 , BiF 3 , Li 2 O, SnO 2 , AgO 2 , ZnO, V 2 O 5 , Al 2 O 3 , Na 2 O, TiO 2 , CuO, ZrO 2 , and CeO 2 .

5. The thick-film paste of claim 4 , wherein the lead-tellurium-boron-oxide further comprises: 0.1-5 wt % TiO 2 .

6. The thick-film paste of claim 5 , wherein the organic medium further comprises one or more additives selected from the group consisting of solvents, stabilizers, surfactants, and thickeners.

7. The thick-film paste of claim 1 , wherein the electrically conductive metal is 90-95 wt % of the solids.

8. The thick-film paste of claim 1 , wherein the lead-tellurium-boron-oxide is at least partially crystalline.

9. The thick-film paste of claim 4 , further comprising an additive selected from the group consisting of: PbF 2 , SiO 2 , Na 2 O, K 2 O, Rb 2 O, Cs 2 O, Al 2 O 3 , MgO, CaO, SrO, BaO, V 2 O 5 , ZrO 2 , MoO 3 , Mn 2 O 3 , Ag 2 O, ZnO, Ga 2 O 3 , GeO 2 , In 2 O 3 , SnO 2 , Sb 2 O 3 , Bi 2 O 3 , BiF 3 , P 2 O 5 , CuO, NiO, Cr 2 O 3 , Fe 2 O 3 , CoO, Co 2 O 3 , and CeO 2 .

10. The thick film paste of claim 1 , wherein the lead-tellurium-boron-oxide further comprises oxides of one or more elements selected from the group consisting of: Si, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, V, Zr, Mo, Mn, Zn, B, P, Se, Sn, Ga, Ge, In, Sb, Bi, Ce, Cu, F, Ni, Cr, Fe, Co, and Ag.

11. A process comprising:

(a) providing a semiconductor substrate comprising one or more insulating films deposited onto at least one surface of the semiconductor substrate;

(b) applying a thick-film paste composition onto at least a portion of the insulating film to form a layered structure, wherein the thick-film paste composition comprises:

i) 85 to 99.5% by weight of an electrically conductive metal or derivative thereof, based on total solids in the composition;

ii) 0.5 to 15% by weight, based on total solids in the composition, of a lead-tellurium-boron-oxide, wherein the lead-tellurium-boron-oxide comprises 0.25 to 5 wt % B 2 O 3 ; and

iii) an organic medium; and

(c) firing the semiconductor substrate, insulating film, and thick-film paste, to form an electrode in contact with the insulating layer and in electrical contact with the semiconductor substrate.

12. The process of claim 11 , wherein the thick-film paste composition is applied pattern-wise onto the insulating film.

13. The process of claim 11 , wherein the firing is carried out in air or an oxygen-containing atmosphere.

14. The process of claim 11 , wherein the thick-film paste composition further comprises: 0.5 to 15% by weight based on solids of a lead-tellurium-lithium-titanium-oxide.

15. An article comprising:

(a) a semiconductor substrate;

(b) an insulating layer on the semiconductor substrate; and

(c) an electrode in contact with the insulating layer and in electrical contact with the semiconductor substrate, the electrode comprising an electrically conductive metal and lead-tellurium-boron-oxide, wherein the lead-tellurium-boron-oxide comprises 0.25 to 5 wt % B 2 O 3 .

16. The article of claim 15 , wherein the electrode further comprises lithium and titanium.

17. The article of claim 15 , wherein the article is a semiconductor device.

18. The article of claim 17 , wherein the semiconductor device is a solar cell.

19. The thick-film paste of claim 1 , further comprising: 0.5-15% by weight based on solids of a lead-tellurium-lithium-titanium-oxide.

20. The thick-film paste of claim 19 , wherein the lead-tellurium-lithium-titanium-oxide comprises:

25-80 wt % PbO,

10-65 wt % TeO 2 ,

0.1-5 wt % Li 2 O, and

0.1-5 wt % TiO 2 .

21. The thick-film paste of claim 1 , wherein the lead-tellurium-boron-oxide comprises 0.4-5 wt % B 2 O 3 .

22. The thick-film paste of claim 1 , wherein the lead-tellurium-boron-oxide comprises 0.4-2 wt % B 2 O 3 .

23. The process of claim 11 , wherein the lead-tellurium-boron-oxide comprises 0.4-5 wt % B 2 O 3 .

24. The process of claim 11 , wherein the lead-tellurium-boron-oxide comprises 0.4-2 wt % B 2 O 3 .

25. The article of claim 15 , wherein the lead-tellurium-boron-oxide comprises 0.4-5 wt % B 2 O 3 .

26. The article of claim 15 , wherein the lead-tellurium-boron-oxide comprises 0.4-2 wt % B 2 O 3 .