Method for structuring an oxide layer applied to a substrate material

1. A method for manufacturing a solar cell with a selective emitter layer, comprising the following steps:

providing a p-doped semiconductor wafer having a surface, with a front side comprising a light-facing side, and a rear side;

forming the selective emitter layer on the light-facing side by:

applying an oxide layer on the light-facing side of the p-doped wafer;

Structuring the oxide layer, using a screen printing process, wherein a squeegee paste containing an oxide-etching component is printed onto the oxide layer via a pattern stencil and the printed-on squeegee paste is removed again after a predetermined dwell time, to form structured areas;

introducing a selective high degree of n-doping in the structured areas;

removing the oxide layer;

introducing weak n-doping, including over a large part of the surface of the wafer between the structured areas; and

contacting of the light-facing side in areas of the selective high degree of n-doping.

2. The method according to claim 1 , wherein the n-doping is introduced by means of phosphorus doping.

3. The method according to claim 2 , wherein a phosphorus glass (POCl 3 ) formed during introducing the phosphorus doping is removed in a subsequent etching step.

4. The method according to claim 1 , wherein the front side is contacted with a silver squeegee paste.

5. Use of a squeegee paste comprising a binding agent and an oxide-etching component in a method for manufacturing a solar cell with a selective emitter layer on the light-facing side according to claim 1 .

6. A method for production of a solar cell with a selective emitter layer and a back-surface-field, comprising the following steps:

providing a p-doped semiconductor wafer having a surface, with a front side comprising a light-facing side and a rear side, and an edge;

forming the selective emitter layer on the light-facing side and the back-surface-field on the rear side by:

applying to the rear side of the wafer a diffusion source layer containing boron as a dopant;

treating the wafer in an oxygenous atmosphere at a temperature of 900° C. to 1200° C. to create an oxide layer and drive the dopant in;

Structuring the oxide layer on the light-facing side of the wafer, using a screen printing process, wherein a squeegee paste containing an oxide-etching component is printed onto the oxide layer via a pattern stencil and the printed-on squeegee paste is removed again after a predetermined dwell time, to form structured areas;

introducing a selective high degree of n-doping in the structured areas;

removing the diffusion source layer and the oxide layer;

introducing a weak n-doping, including over a large part of the surface of the wafer between the structured areas;

contacting the light-facing side in areas of the selective high degree of n-doping; and

applying a back contact to the rear side.

7. The method according to claim 6 , wherein a boron-dopant coating or a boron-dopant paste is applied to act as the diffusion source layer.

8. The method according to claim 6 , wherein the diffusion source layer and oxide layer are removed by etching with an HF solution.

9. The method according to claim 6 , wherein the n-doping, is introduced by means of phosphorus doping.

10. The method according to claim 9 , wherein a phosphorus glass (POCl 3 ) formed during introducing of the phosphorus doping is removed in a subsequent etching step.

11. The method according to claim 6 , wherein the front side is contacted with a silver squeegee paste.

12. The method according to claim 6 , wherein the rear side is contacted with a silver squeegee paste containing 1% to 3% by weight of aluminium.

13. The method according to claim 6 , wherein the rear side is contacted in such a way that the boron doping is overcompensated by a flat n+-doping between the areas covered by the back contact.

14. The method according claim 6 , wherein an anti-reflection layer is applied to the light-facing side and a passivation layer to the rear side.

15. Use of a squeegee paste comprising a binding agent and an oxide-etching component in a method for manufacturing a solar cell with a selective emitter layer on the light-facing side and a back surface field on the rear side according to claim 6 .

16. The method according to claim 1 or 6 , wherein the oxide-etching component consists of hydrofluoric acid (HF) and/or ammonium fluoride (NH 4 F) and/or ammonium hydrogen fluoride (NH 4 HF 2 ).

17. The method according to claim 1 or 6 , wherein the oxide-etching component constitutes a proportion of 10% to 20% by volume of the squeegee paste.

18. The method according to claim 1 or 6 , wherein the dwell time ranges from 30 seconds to 2 minutes.

19. The method according to claim 1 or 6 , wherein the semiconductor wafer is a silicon wafer.

20. The method according to claim 1 or 6 , wherein the light-facing side is contacted using the screen printing process.

21. The method according to claim 1 or 6 , wherein the n-doping is depleted at the edge of the wafer after introducing the weak n-doping.

22. The method according claim 21 , wherein the depleting of the n-doping at the edge of the wafer is carried out by etching of the edge.

23. The use according to claim 5 or 15 , wherein the binding agent comprises wallpaper paste.

24. The use according to claim 5 or 15 , wherein the binding agent consists of an epoxy resin.

25. The use according to claim 5 or 15 , wherein the squeegee paste has a viscosity of between 10 and 500 Pa-s.

26. The use according to claim 5 or 15 , wherein the oxide-etching component comprises hydrofluoric acid (HF) and/or ammonium fluoride (NH 4 F) and/or ammonium hydrogen fluoride (NH4HF2) as the oxide-etching component.

27. The use according to claim 5 or 15 , wherein the oxide-etching component constitutes a proportion of 10% to 20% by volume of the squeegee paste.

28. The use according to claim 5 or 15 , wherein the squeegee paste has a viscosity of between 50 and 200 Pa-s.