Monolithic printhead with self-aligned groove and relative manufacturing process
View Patent ↗A monolithic thermal ink jet printhead ( 40 ) comprising a groove ( 45 ), a plurality of chambers ( 74 ) and nozzles ( 56 ) is manufactured by means of steps of: ( 203, 205 ) partially etching the groove ( 45 ) by means of a “dry” process and a “wet” process; ( 210 ) depositing a plurality of sacrificial layers ( 54 ); ( 212 ) obtaining a plurality of casts ( 156 ); ( 216 ) completing the etching of the groove ( 45 ) by means of an electrochemical process; and ( 220 ) removing the casts ( 156 ) and the sacrificial layers ( 54 ) in such a way as to obtain a plurality of nozzles ( 56 ) and chambers ( 74 ).
1. Thermal ink jet printhead comprising nozzles, chambers in turn comprising resistors, and a groove, made in a substrate, suitable for fluidly ducting ink to said chambers, an N-well layer positioned for forming a portion of the groove, wherein said groove comprises a first portion produced by means of a dry etching, and a second portion produced by means of an electrochemical etching.
2. Printhead according to claim 1 , wherein said substrate is made of silicon.
3. Printhead according to claim 2 , wherein said nozzles and said resistors are disposed in columns parallel to one and the same geometric reference.
4. Printhead according to claim 3 , wherein said first portion of said groove has a substantially rectangular shape having a greater side parallel to said geometric reference.
5. Printhead according to claim 3 , wherein said second portion of said groove has a substantially rectangular shape having a greater side parallel to said geometric reference.
6. Printhead according to claim 3 , wherein said first portion of said groove also comprises a wet etching having a substantially rectangular shape and a greater side parallel to a crystallographic axis of said silicon which constitutes said substrate, and that said crystallographic axis cannot be parallel to said geometric reference.
7. Printhead according to claim 1 , further comprising a P+ layer positioned adjacent to the substrate and within the groove between the N-well layer.
8. Printhead according to claim 1 , further comprising an anti- cavitation layer of electrically conducting material.
9. Printhead according to claim 8 , wherein said anti-cavitation layer of electrically conducting material forms a single equipotential surface through said head.
10. Printhead according to claim 8 wherein said anti-cavitation layer is made of tantalum.
11. Printhead according to claim 10 , wherein said anti-cavitation layer of tantalum is between 0.4 and 0.6 μm thick.
12. Printhead according to claim 8 , wherein said anti-cavitation layer is covered by a layer of gold.
13. Printhead according to claim 12 , wherein said layer of gold is between 100 and 200 Å thick.
14. Printhead according to claim 8 , further comprising a first metal or a second metal and that said first metal or said second metal forms one or more electric contacts with said anti-cavitation layer.
15. A thermal ink jet printhead, comprising:
at least one nozzle connected to an ink chamber;
a substrate, the substrate having a lower face, an upper face, and a groove for supplying ink, the groove extending into the substrate from the lower face and towards the upper face, the groove comprising a top portion; and
an N-well layer positioned laterally for surrounding at least a portion of the groove.
16. The printhead of claim 15 , wherein the N-well layer is positioned laterally for surrounding the top portion of the groove.
17. The printhead according to claim 16 , further comprising a silicon P+ layer contacting the upper face of the substrate and overlying the top portion of the groove in the substrate, the silicon P+ layer being positioned within the N-well layer.
18. The printhead according to claim 17 , in which the silicon P+ layer is electrochemically etched so as to connect the groove to the chamber for supplying ink thereto.
19. The printhead according to claim 15 , wherein the substrate comprises P-type silicon.
20. The printhead according to claim 15 , further comprising an insulating layer lateral to the groove and positioned on the upper face of the substrate.
21. The printhead of claim 20 , further comprising an anti-cavitation layer overlying the insulating layer.
22. The printhead of claim 20 further comprising a resistor overlying the insulating layer and another insulating layer overlying the resistor.
23. The printhead according claim 15 , wherein the N-well layer further includes walls which form a portion of the groove.