Technique for efficiently patterning an underbump metallization layer using a dry etch process
By patterning the underbump metallization layer stack on the basis of a dry etch process, significant advantages may be achieved compared to conventional techniques involving a highly complex wet chemical etch process. In particular embodiments, a titanium tungsten layer or any other appropriate last layer of an underbump metallization layer stack may be etched on the basis of a plasma etch process using a fluorine-based chemistry and oxygen as a physical component. Moreover, appropriate cleaning processes may be performed for removing particles and residues prior to and after the plasma-based patterning process.
1. A method, comprising:
patterning a first layer of an underbump metallization layer stack by an electrochemical etch process in the presence of a plurality of bumps formed on said underbump metallization layer stack to expose at least a portion of a second layer of said underbump metallization layer;
cleaning said exposed portion of said underbump metallization layer to remove at least one byproduct of said electrochemical etch process by performing a first sweep operation while maintaining a current flow used during said electrochemical etch process and performing a second sweep operation with said current flow discontinued; and
patterning said second layer of said underbump metallization layer stack by a dry etch process after said cleaning.
2. The method of claim 1 , wherein cleaning said second layer comprises removing particles from said second layer.
3. The method of claim 1 , wherein said cleaning further comprises performing a wet clean process after said second sweep operation.
4. The method of claim 1 , wherein patterning said second layer comprises establishing a plasma ambient comprising a chemically reactive component and a physical component for bombarding said second layer.
5. The method of claim 1 , further comprising performing a plasma cleaning process after patterning said second layer for removing carbon residues from a passivation layer underlying said underbump metallization layer stack.
6. The method of claim 1 , further comprising performing a final wet chemical cleaning process for removing byproducts of the preceding dry etching process.
7. The method of claim 1 , wherein said second layer is comprised of titanium and tungsten.
8. The method of claim 1 , wherein said second layer comprises at least one of titanium, tantalum, tungsten, alloys thereof, nitrogen compounds thereof, silicon compounds thereof and nitrogen/silicon compounds thereof.
9. The method of claim 1 , wherein said first layer comprises at least one of copper and chromium.
10. The method of claim 1 , further comprising optically detecting an endpoint of said dry etch process.
11. The method of claim 4 , wherein said plasma ambient comprises fluorine and oxygen as a chemically reactive and a physical component, respectively.
12. The method of claim 5 , wherein said plasma cleaning process is performed in situ with said dry etch process for patterning said second layer.
13. The method of claim 5 , further comprising optically detecting an endpoint of said plasma cleaning process.
14. The method of claim 10 , further comprising determining an appropriate monitor wavelength of at least one volatile component formed by etching into an underlying passivation layer.
15. A method, comprising:
providing a substrate having formed thereon an underbump metallization layer stack with at least a first layer and a second layer and a plurality of bumps formed above said underbump metallization layer stack;
patterning said first layer of said underbump metallization layer stack to expose at least a portion of said second layer;
cleaning said exposed portion of second layer to remove at least one byproduct of said patterning by performing a first sweep operation while maintaining a current flow used during said patterning of said first layer and performing a second sweep operation with said current flow discontinued; and
dry etching said exposed second layer while using said bumps as an etch mask.
16. The method of claim 15 , wherein patterning said first layer comprises etching said first layer by an electrochemical etch process.
17. The method of claim 15 , wherein cleaning said second layer comprises removing particles from said second layer.
18. The method of claim 15 , wherein said cleaning further comprises performing a wet clean process after said second sweep operation.
19. The method of claim 15 , wherein patterning said second layer comprises establishing a plasma ambient comprising a chemically reactive component and a physical component for bombarding said second layer.
20. The method of claim 15 , further comprising performing a plasma cleaning process after dry etching said second layer for removing carbon residues from a passivation layer underlying said underbump metallization layer stack.
21. The method of claim 15 , further comprising performing a final wet chemical cleaning process for removing byproducts of the preceding dry etching process.
22. The method of claim 15 , wherein said second layer is comprised of titanium and tungsten.
23. The method of claim 15 , wherein said second layer comprises at least one of titanium, tantalum, tungsten, alloys thereof, nitrogen compounds thereof, silicon compounds thereof and nitrogen/silicon compounds thereof.
24. The method of claim 15 , wherein said first layer comprises at least one of copper and chromium.
25. The method of claim 15 , further comprising optically detecting an endpoint during dry etching said second layer.
26. The method of claim 19 , wherein said plasma ambient comprises fluorine and oxygen as a chemically reactive and a physical component, respectively.
27. The method of claim 20 , wherein said plasma cleaning process is performed in situ with dry etch of said second layer.
28. The method of claim 27 , further comprising optically detecting an endpoint of said plasma cleaning process.
29. The method of claim 25 , further comprising determining an appropriate monitor wavelength of at least one volatile component formed by etching into an underlying passivation layer.