Process and arrangement for the selective metallization of 3D structures

• US 20040087127A1
• Filed: 08/29/2003
• Published: 05/06/2004
• Est. Priority Date: 09/02/2002
• Status: Active Grant

• Current Assignee: Polaris Innovations Limited (Wi-LAN Inc.)
• Original Assignee: Qimonda AG (Infineon Technologies AG)
• Inventors: Uhlendorf, Ingo
• Granted Patent: US 7,211,504 B2
• Time in Patent Office: Days
• US Class Current: 438/597
• CPC Class Codes: C25D 17/001 Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
• CPC Class Codes: C25D 17/06 Suspending or supporting devices for articles to be coated
• CPC Class Codes: C25D 3/48 of gold
• CPC Class Codes: C25D 5/06 Brush or pad plating
• CPC Class Codes: C25D 7/123 Semiconductors first coated with a seed layer or a conductive layer
• CPC Class Codes: H01L 2224/0231 Manufacturing methods of the redistribution layers
• CPC Class Codes: H01L 2224/02331 Multilayer structure
• CPC Class Codes: H01L 2224/02381 Side view
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/05147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05655 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/11825 Plating, e.g. electroplating, electroless plating
• CPC Class Codes: H01L 2224/13008 Bump connector integrally formed with a redistribution layer on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/13564 Only on the bonding interface of the bump connector
• CPC Class Codes: H01L 2224/13566 Both on and outside the bonding interface of the bump connector
• CPC Class Codes: H01L 2224/13583 Three-layer coating
• CPC Class Codes: H01L 2224/13644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/13647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/13655 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/16227 : the bump connector connecting to a bond pad of the item
• CPC Class Codes: H01L 24/11 : Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/13 : of an individual bump connector
• CPC Class Codes: H01L 24/16 : of an individual bump connector
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01068 : Erbium [Er]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys

Abstract

A process is provided for the selective metallization of 3D structures, particularly for the selective gold-plating of 3D contact structures on wafers, such as contact bumps, which are electrically connected to a bond pad on the wafer via a three-dimensional, mechanically flexible structure in the form of a redistribution layer, for subsequent electrical connection to a carrier element, e.g., a printed circuit board. The process is intended to considerably simplify the process sequence. The metallization of the previously prepared 3D structures on the wafer is carried out electrochemically, under current or potential control, by the structures being partially immersed in an electrolyte with a fixed surface. The electrolyte can be covered with a membrane which is permeable to the corresponding ions, or alternatively a gel electrolyte may be used.

Claims

1. Process for the selective metallization of 3D structures comprising raised portions of circuits on a wafer for subsequent electrical connection to a carrier element, comprising providing an electrolyte with a fixed surface, contacting said raised circuit portions with said fixed surface of said electrolyte and applying current between said raised circuit portions and said electrolyte to electrochemically metallize said raised circuit portions.

2. Process according to claim 1, wherein contacting said raised circuit portions comprises immersing said raised circuit portions to a depth which is sufficient for a surface portion of the 3D structure, which is to be metallized, to be completely wetted.

3. Process according to claim 1 wherein providing the electrolyte comprises providing a gel electrolyte.

4. Process according to claim 3 wherein providing gel electrolyte comprises providing an electrolyte gel formed using inorganic materials.

5. Process according to claim 4 wherein providing the gel electrolyte comprises providing a silica gel.

6. Process according to claim 3 wherein providing the gel electrolyte comprises providing an electrolyte gel formed using organic materials.

7. Process according to claim 6 wherein providing the gel electrolyte comprises providing an electrolyte gel formed using one or more organic materials selected from the group comprising polyacrylic acid, polyvinylphosphoric acid, polyethyleneamine, polyvinylamine, PEO (polyelectrolyte), polyvinylidene fluoride hexafluoropropylene, polyamidoacrylic acid and carboxymethylcellulose.

8. Process according to claim 1 wherein providing the electrolyte comprises providing an electrolyte covered with a membrane which is permeable to the ions of the electrolyte.

9. Apparatus for electrochemically metallizing raised contact bumps on a wafer comprising a vessel for holding an electrolyte, an electrolyte in said vessel having a fixed surface, an anode electrically connected to the electrolyte, a vertically adjustable holder arranged to hold a wafer with said raised contact bumps in a downwardly facing arrangement above said electrolyte, said holder being arranged for vertical movement to cause said contact bumps to contact said fixed surface of said electrolyte, said holder having electrical contacts to contact said wafer as a cathode and a circuit for supplying electrical current between said anode and said wafer thereby to electrochemically metallize said contact bumps.

10. Apparatus as specified in claim 9 wherein the holder comprises at least two receiving devices which are arranged at a distance from each other, each having at least one bearing element for receiving the wafer, said bearing elements being arranged so that the wafer can be placed onto the bearing element with its active side having said contact bumps facing downwards.

11. Apparatus as specified in claim 10 wherein the bearing element has a channel with a bearing edge.

12. Apparatus as specified in claim 11 wherein the bearing element, in the edge region of the wafer, has a protected area inside the channel.

13. Apparatus as specified in claim 12 wherein wherein the electrical contacts are in the protected area.

14. Apparatus as specified in claim 9 wherein there is further provided apparatus for monitoring vertical movement of the holder.

15. Apparatus as specified in claim 9 wherein there is provided an arrangement for monitoring current in the circuit and wherein the vertically adjustable holder, with the wafer suspended in it is arranged to move into the electrolyte located in the vessel at least until electrical current is detected by the monitoring arrangement.

16. Apparatus as specified in claim 15 wherein the vertically adjustable holder is arranged to move a selected additional distance into the electrolyte after current is detected.