Method for producing through-contacts in semi-conductor wafers via production of through-plated holes
The invention relates to a method for producing vertical through-contacts (micro-vias) in semi-conductor wafers in order to produce semi-conductor components, i.e. contacts on the front side of the wafer through the semi-conductor wafer to the rear side of the wafer. The invention also relates to a method which comprises the following steps: blind holes on the contact connection points are laser drilled from the rear side of the wafer into the semi-conductor substrate, the wafer is cleaned, the semi-conductor substrate is plasma etched in a material selected manner until the active layer stack of the wafer is reached, the active layer stack of the wafer is plasma etched in a material selective manner until the contacts, which are to be connected to the rear side of the wafer, are reached, a plating base is applied to the rear side of the wafer and into the blind holes and gold is applied by electrodeposition onto the metallizied rear side of the wafer and the blind holes.
1. A method for the production of vertical through-plated holes for the fabrication of contacts extending from a front side of a semiconductor wafer, through the semiconductor wafer to a rear side of the wafer, comprising:
Coating the rear side of the wafer with indium tin oxide (ITO);
Laser drilling of partial pocket holes at the contacting sites from the rear side of the wafer into the semiconductor substrate such that an active layer stack arranged on the front side of the wafer is not reached;
Cleaning of the wafer;
Material-selective plasma etching of the partial pocket holes in the semiconductor substrate through to the active layer stack of the wafer;
Material-selective plasma etching of the active layer stack of the wafer until contacts that are to be connected to the rear side are reached and entire pocket holes are formed;
Removing the indium tin oxide coating from the rear side of the wafer;
Applying a plating base to the rear side of the wafer and to the inside of the entire pocket holes; and
Applying gold by plating the metallized rear side of the wafer and the entire pocket holes.
2. The method of claim 1 , wherein before drilling the partial pocket holes with the laser, a protective varnish is applied to the front side of the wafer, said protective varnish being again removed following the gold application.
3. The method of claim 1 , wherein cleaning occurs with wet chemistry by means of buffered hydrofluoric acid.
4. The method of claim 1 , wherein finally, a dewetting layer is applied to the rear side of the wafer in the region of the entry openings of the through-holes.
5. The method of claim 4 , wherein titanium is used for the dewetting layer.
6. The method of claim 4 , wherein the dewetting layer is applied by sputtering.
7. The method of claim 4 , wherein the application of the dewetting layer takes place with the use of a shadow mask.
8. The method of claim 1 , wherein a UV laser is used for laser-drilling.
9. The method of claim 1 , wherein the plating base is applied by oblique vapor deposition.
10. The method of claim 1 , the plating base is applied by sputtering.
11. The method of claim 1 , wherein the plating base is applied by chemical bath deposition.
12. The method of claim 1 , wherein for laser-drilling, a laser is used, said laser having a beam that is smaller than the cross-sectional area of the partial pocket hole that is to be produced, whereby the beam is moved across the area of the partial pocket hole.
13. The method of claim 1 , wherein plasma-etching of the semiconductor substrate takes place by ICP etching.
14. The method of claim 1 , wherein plasma-etching of the active layer stack takes place by RIE etching.