Wafer shielding for prevention of lipseal plate-out

Patent metadata

Field	Value
Publication number	US-12241173-B2
Application number	US-202017754345-A
Country	US
Kind code	B2
Filing date	Sep 30, 2020
Priority date	Oct 4, 2019
Publication date	Mar 4, 2025
Grant date	Mar 4, 2025

Abstract

Undesired deposition of metals on a lipseal (lipseal plate-out) during electrodeposition of metals on semiconductor substrates is minimized or eliminated by minimizing or eliminating ionic current directed at a lipseal. For example, electrodeposition can be conducted such as to avoid contact of a lipseal with a cathodically biased conductive material on the semiconductor substrate during the course of electroplating. This can be accomplished by shielding a small selected zone proximate the lipseal to suppress electrodeposition of metal proximate the lipseal, and to avoid contact of metal with a lipseal. In some embodiments shielding is accomplished by sequentially using lipseals of different inner diameters during electroplating of metals into through-resist features, where a lipseal having a smaller diameter is used during a first electroplating step and serves as a shield blocking electrodeposition in a selected zone. In a second electroplating step, a lipseal of a larger inner diameter is used.

First claim

What is claimed is:

1. A method of electrodepositing a metal onto a semiconductor substrate having a plurality of through-mask recessed features, while preventing or reducing deposition of the metal on a lipseal of an electroplating apparatus, the method comprising:
(a) electrodepositing a first metal into the through-mask recessed features of the semiconductor substrate in a first electroplating cell using a first lipseal; and
(b) electrodepositing a second metal into the through-mask recessed features after (a), in a second electroplating cell using a second lipseal having a larger inner diameter than the first lipseal, wherein the semiconductor substrate comprises a selected zone shielded from exposure to an electrolyte by the first lipseal but not by the second lipseal, such that the first metal is not electrodeposited in the selected zone and such that the second metal is allowed to be electrodeposited in the selected zone.

2. The method of claim 1 , wherein electrodeposition of the second metal in the selected zone in (b) does not result in electrodeposition above a plane of the mask.

3. The method of claim 1 , wherein electrodeposition of the second metal in the selected zone in (b) does not result in contact of the electrodeposited second metal with the second lipseal.

4. The method of claim 1 , wherein (b) results in electrodeposition of the second metal above a plane of the mask outside of the selected zone.

5. The method of claim 1 , wherein (b) results in electrodeposition of the second metal above a plane of the mask outside of the selected zone, and in electrodeposition below the plane of the mask in the selected zone.

6. The method of claim 1 , wherein the first metal is copper and the second metal is a combination of tin and silver.

7. The method of claim 1 , wherein the first metal is a combination of tin and silver, and the second metal is a combination of tin and silver.

8. The method of claim 1 , wherein the width of the selected zone is between about 0.05-1 mm.

9. The method of claim 1 , wherein the width of the selected zone is about 0.25 mm.

10. The method of claim 1 , wherein the mask is photoresist and the second lipseal is in direct contact with the photoresist during the course of electroplating.

11. The method of claim 1 , wherein the through-mask recessed features have widths of between about 10-50 μm.

12. The method of claim 1 , wherein the mask has a thickness of between about 10-100 μm.

13. The method of claim 1 , wherein the first and second lipseals are made from an elastomeric material, wherein a width of the selected zone is equal to a difference between an inner radius of the second lipseal and an inner radius of the first lipseal, and wherein the selected zone has an annular shape.

14. A system for electroplating a metal onto the semiconductor substrate, the system comprising:
(a) a first electroplating apparatus configured for electrodepositing a first metal onto the semiconductor substrate, the first electroplating apparatus comprising a substrate holder having a first lipseal; and
(b) a second electroplating apparatus configured for electrodepositing a second metal onto the semiconductor substrate, the second electroplating apparatus comprising a substrate holder having a second lipseal, wherein the second lipseal has a greater inner diameter than the first lipseal.

15. The system of claim 14 , wherein a difference between an inner radius of the second lipseal and an inner radius of the first lipseal is less than about 1 mm.

16. The system of claim 14 , wherein a difference between an inner radius of the second lipseal and an inner radius of the first lipseal is between about 0.05-1 mm.

17. The system of claim 14 , wherein a difference between an inner radius of the second lipseal and an inner radius of the first lipseal is about 0.25 mm.

18. The system of claim 14 , wherein the first and the second lipseals comprise elastomeric material.

19. The system of claim 14 , wherein the first and second metals are different, and wherein the first electroplating apparatus comprises a copper anode, and the second electroplating apparatus comprises a tin anode.

20. The system of claim 14 , wherein the first metal and the second metal are both a combination of tin and silver, and wherein the first electroplating apparatus and the second electroplating apparatus both comprise tin anodes.

21. The system of claim 14 , further comprising a mechanism configured for transferring the semiconductor substrate from the first electroplating apparatus to the second electroplating apparatus.

22. The system of claim 14 , wherein at least one of the first and second electroplating apparatuses is configured for electrodeposition of a combination of tin and silver, and includes a membrane separating an anode chamber and a cathode chamber, wherein the membrane substantially prevents silver ions from moving across the membrane.

23. The system of claim 22 , wherein the first electroplating apparatus is configured for electrodeposition of copper, and the second apparatus is configured for electrodeposition of a combination of tin and silver.

24. The system of claim 14 , further comprising a controller comprising program instructions for causing:
(i) electroplating of a first metal in the first electroplating apparatus to partially fill through-mask recessed features on the semiconductor substrate;
(ii) transfer of the semiconductor substrate to the second electroplating apparatus; and
(iii) electroplating of a second metal in the second electroplating apparatus over the first metal, such that the second lipseal does not come into contact with the electroplated second metal during the course of electroplating, and such that at least some of the through-mask recessed features are filled above a plane of the mask.

25. A method of electrodepositing a metal onto a semiconductor substrate having a plurality of through-mask recessed features, while preventing or reducing deposition of a metal on a lipseal of an electroplating apparatus, the method comprising:
(a) electrodepositing a metal into the recessed through-mask features of the semiconductor substrate in an electroplating cell using a flexible lipseal wherein the flexible lipseal is configured in a first position, such that the metal is not electrodeposited in a selected zone shielded by the first position of the lipseal, wherein the selected zone is located at a periphery of the substrate; and
(b) configuring the flexible lipseal to a second position to remove the shielding of the selected zone, and electrodepositing the metal into the recessed through-mask features after (a), while the lipseal is in the second position, wherein the electrodeposition in the selected zone does not result in electrodeposition above the plane of the mask and does not result in a contact of the electrodeposited metal with the lipseal, while electrodeposition elsewhere on the semiconductor substrate results in electrodeposition above the plane of the mask.

Assignees

• Lam Res Corp

Inventors

• Kearns Gregory J
• Chua Lee Peng
• Blickensderfer Jacob Kurtis
• Mayer Steven T

Classifications

• H10P14/47

  Electrolytic deposition, i.e. electroplating; Electroless plating · CPC title

• H10W72/0198

  batch processes · CPC title

• H10W72/0112

  Apparatus for manufacturing bump connectors · CPC title

• H10W72/227

  Multiple bumps having different sizes · CPC title

• H10W72/252

  comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu · CPC title