Methods and apparatuses for cleaning electroplating substrate holders
Disclosed herein are methods of cleaning a lipseal and/or cup bottom of an electroplating device by removing metal deposits accumulated in prior electroplating operations. The methods may include orienting a nozzle such that it is pointed substantially at the inner circular edge of the lipseal and/or cup bottom, and dispensing a stream of cleaning solution from the nozzle such that the stream contacts the inner circular edge of the lipseal and/or cup bottom while they are being rotated, removing metal deposits. In some embodiments, the stream has a velocity component against the rotational direction of the lipseal and/or cup bottom. In some embodiments, the deposits may include a tin/silver alloy. Also disclosed herein are cleaning apparatuses for mounting in electroplating devices and for removing electroplated metal deposits from their lipseals and/or cup bottoms. In some embodiments, the cleaning apparatuses may include a jet nozzle.
1. A method of cleaning a lipseal and/or cup bottom of an electroplating device by removing metal deposits accumulated on an inner circular edge of the lipseal and/or cup bottom in prior electroplating operations, the method comprising:
orienting a first nozzle relative to the lipseal and/or cup bottom such that the first nozzle is pointed substantially at the inner circular edge of the lipseal and/or cup bottom, wherein the first nozzle is a jet nozzle having a base and a tip, the jet nozzle having a larger interior diameter at the base than at the tip, wherein the interior diameter of the jet nozzle tapers from the base to the tip, wherein the inner circular edge is the innermost surface of the lipseal and/or cup bottom that is exposed to an electrolyte during electroplating of a wafer;
rotating the lipseal and cup bottom in a first rotational direction; and
dispensing a stream of the cleaning solution having a fluid velocity between about 5 and 40 meters/second from the first nozzle such that the stream of the cleaning solution contacts the inner circular edge of the lipseal and/or cup bottom while they are rotating in the first rotational direction, removing metal deposits from the lipseal and/or cup bottom, wherein the dispensed stream of the cleaning solution has a velocity component opposing the first rotational direction.
2. The method of claim 1 , wherein the fluid velocity of the stream of the cleaning solution is between about 10 and 25 meters/second.
3. The method of claim 1 , wherein the fluid pressure within the first nozzle while dispensing the stream of the cleaning solution is between about 20 and 100 PSI.
4. The method of claim 1 , further comprising raising and/or lowering the lipseal and cup bottom while dispensing the stream of the cleaning solution so as to vary the cleaning solution's area of contact with the inner circular edge of the lipseal and/or cup bottom.
5. The method of claim 1 , further comprising varying the orientation of the first nozzle while dispensing the stream of the cleaning solution so as to vary the cleaning solution's angle of impact with the inner circular edge of the lipseal and/or cup bottom.
6. The method of claim 1 , wherein the metal deposits comprise a tin/silver alloy.
7. The method of claim 1 , wherein the cleaning solution is substantially distilled and deionized water.
8. The method of claim 1 , wherein the cleaning solution comprises distilled and deionized water, a surface tension reducing agent selected from polyethylene glycol and polypropylene glycol, and is substantially free of acid.
9. The method of claim 1 , wherein the first nozzle is oriented relative to the inner circular edge of the lipseal and/or cup bottom at a normal angle between 0 and 45 degrees.
10. The method of claim 9 , wherein the first nozzle is oriented relative to the horizontal plane of the lipseal and/or cup bottom at a horizontal angle between about −30 and +10 degrees.
11. The method of claim 10 , wherein the first nozzle tip is oriented at a distance of between about 2 and 50 mm from nearest point of the inner circular edge of the lipseal and cup bottom.
12. The method of claim 10 , wherein the flow rate of the stream of the cleaning solution dispensed from the first nozzle is between about 250 and 750 ml/min.
13. The method of claim 1 , further comprising generating megasonic waves in the cleaning solution within the first nozzle as the cleaning solution is dispensed from the first nozzle.
14. A method of electroplating a metal onto a plurality of semiconductor substrates using an electroplating apparatus having a lipseal and cup bottom, wherein the metal is a tin-silver alloy, the method comprising:
electroplating the metal onto a first set of one or more substrates;
determining whether to perform a cleaning operation which removes metal deposits accumulated on the lipseal and/or cup bottom while electroplating the first set of substrates, wherein the determining comprises an assessment of whether there is sufficient build-up of metal deposits on the lipseal and/or cup bottom to warrant cleaning;
if it is determined that the cleaning operation is warranted, performing the cleaning operation which removes the metal deposits according to the cleaning method of claim 1 ; and
after determining whether a cleaning operation is warranted and if the cleaning operation is warranted after performing the cleaning operation, electroplating the metal onto a second set of one or more substrates.
15. The electroplating method of claim 14 , wherein it is determined that a cleaning operation is warranted if more than a predetermined number of substrates have been electroplated since the last cleaning operation.
16. The electroplating method of claim 15 , wherein the predetermined number of substrates is selected dependent on the ratio of patterned to unpatterned surface area of the substrates electroplated since the last cleaning operation.
17. The electroplating method of claim 16 , wherein the predetermined number of substrates is selected depending on the ratio of patterned to unpatterned surface area of the substrates electroplated since the last cleaning operation, and also the radial distribution of patterned surface area and/or the radial distribution of unpatterned surface area of the substrates electroplated since the last cleaning operation.
18. The electroplating method of claim 14 , wherein it is determined that a cleaning operation is warranted if more than a predetermined quantity of electric charge has been transferred to the substrate via electroplating since the last cleaning operation.
19. The electroplating method of claim 18 , wherein the predetermined quantity of electric charge is selected depending upon the radial distribution of patterned surface area and/or the radial distribution of unpatterned surface area of the substrates electroplated since the last cleaning operation.
20. The method of claim 1 , wherein the first nozzle dispenses a substantially collimated stream of the cleaning solution from an orifice in the first nozzle, the orifice having a diameter of 0.02-0.04 inches.
21. The method of claim 20 , wherein the substantially collimated stream of the cleaning solution has a diameter of 0.02-0.04 inches upon exiting the first nozzle.
22. The method of claim 1 , wherein the first nozzle is affixed to a nozzle arm, wherein the electroplating device further includes a nozzle arm actuator mechanically coupled to the nozzle arm, wherein the nozzle arm actuator is configured to move the nozzle arm and the first nozzle between a cleaning position and a retracted position.
23. The method of claim 22 , further comprising moving the nozzle arm and the first nozzle to the retracted position from the cleaning position after dispensing the stream of cleaning solution.
24. The method of claim 23 , further comprising placing a semiconductor substrate on the lipseal without contacting the semiconductor substrate with the first nozzle or nozzle arm while the first nozzle is in the retracted position.
25. The method of claim 1 , further comprising removing the metal deposits using a second nozzle.
26. The method of claim 1 , wherein the cleaning solution comprises an acid.
27. The method of claim 1 , wherein the cleaning solution comprises methanesulfonic acid.