# US 2018/0026002 A1 · Under Bump Metallurgy (UBM) And Methods Of Forming Same

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- Number: US 2018/0026002 A1
- Document ID: US20180026002A1
- Status: Published application
- Kind: A1
- Application number: 15/722,578
- Filed: 2017-10-02
- Published: 2018-01-25
- Earliest claimed: 2015-06-30
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Wei-Yu Chen; Hsien-Wei Chen; An-Jhih Su; Cheng-Hsien Hsieh
- Web page: https://patentgrep.com/patent/US20180026002A1

## CPC

- H10W 20/063: {by forming conductive members before forming protective insulating material}
- H10W 72/20: Bump connectors, e.g. solder bumps or copper pillars; Dummy bumps; Thermal bumps
- H10W 90/701: {characterised by the relative positions of pads or connectors relative to package parts}
- H10W 70/05: of insulating or insulated package substrates, or of interposers, or of redistribution layers (manufacture or treatment of leadframes H10W70/04)
- H10W 70/655: Fan-out layouts
- H10W 70/69: Insulating materials thereof
- H10W 72/01225: {in solid form, e.g. by using a powder or by stud bumping}
- H10W 72/019: {of bond pads}
- H10W 72/01935: {by plating, e.g. electroless plating or electroplating}
- H10W 72/01951: {Changing the shapes of bond pads}
- H10W 72/01955: {by using masks}
- H10W 72/232: {Plan-view shape, i.e. in top view}
- H10W 72/234: {Cross-sectional shape, i.e. in side view}
- H10W 72/241: {Dispositions, e.g. layouts}
- H10W 72/242: {relative to the surface, e.g. recessed, protruding}
- H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu}
- H10W 72/29: Bond pads specially adapted therefor
- H10W 72/874: {On different surfaces}
- H10W 72/922: {Bond pads being integral with underlying chip-level interconnections}
- H10W 72/9223: {with redistribution layers [RDL]}
- H10W 72/923: {Bond pads having multiple stacked layers}
- H10W 72/931: {Shapes of bond pads}
- H10W 72/932: {Plan-view shape, i.e. in top view}
- H10W 72/9413: {on encapsulations}
- H10W 72/9415: {relative to the surface, e.g. recessed, protruding}
- H10W 72/942: {relative to underlying supporting features, e.g. bond pads, RDLs or vias}
- H10W 72/981: {Auxiliary members, e.g. spacers}
- H10W 72/983: {Reinforcing structures, e.g. collars}
- H10W 72/987: {Flow barriers}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A device package includes a die, fan-out redistribution layers (RDLs) over the die, and an under bump metallurgy (UBM) over the fan-out RDLs. The UBM comprises a conductive pad portion and a trench encircling the conductive pad portion. The device package further includes a connector disposed on the conductive pad portion of the UBM. The fan-out RDLs electrically connect the connector and the UBM to the die.

## Claims

### Claim 1

A method for forming a device package, the method comprising:
forming a seed layer over a die;
forming a conductive line on the seed layer;
forming a first mask layer over the conductive line and the seed layer;
patterning openings in the first mask layer, wherein the openings comprise:
a first opening for a conductive pad portion of an under bump metallurgy (UBM); and
a second opening for a retaining wall portion of the UBM, wherein the second opening forms a ring around the first opening, and wherein a portion of the first mask layer remains disposed between the first opening and the second opening;
forming the UBM in the first opening and the second opening, the UBM comprising the conductive pad portion contacting a surface of the conductive line, the UBM further comprising the retaining wall portion having a bottom-most portion physically contacting the conductive line;
removing the first mask layer; and
mounting a solder ball to the conductive pad portion of the UBM.

### Claim 2 (depends on 1)

The method of claim 1, wherein forming the UBM comprises filling the first opening and the second opening with conductive material.

### Claim 3 (depends on 2)

The method of claim 2, wherein filling the first opening and the second opening with conductive material comprises providing nucleation sites for a plating process, wherein the nucleation sites are provided by at least one of the conductive line or the seed layer.

### Claim 4 (depends on 1)

The method of claim 1, wherein forming the conductive line comprises:
before forming the first mask layer, forming a second mask layer over the seed layer;
patterning a third opening in the second mask layer, wherein the third opening exposes the seed layer; and
filling the third opening with a conductive material to form the conductive line.

### Claim 5 (depends on 1)

The method of claim 1, further comprising etching portions of the seed layer.

### Claim 6 (depends on 5)

The method of claim 5, wherein the seed layer is not etched until after forming the UBM.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
forming a polymer layer over the UBM; and
patterning the polymer layer to expose at least a portion of the UBM.

### Claim 8 (depends on 7)

The method of claim 7, wherein, after patterning the polymer layer, the conductive pad portion is free from the polymer layer and the polymer layer overlies outermost sidewalls of the retaining wall.

### Claim 9

A method for forming a device package, the method comprising:
patterning openings in a mask layer to expose a conductive line, wherein the openings comprise:
a central opening for a conductive pad portion of an under bump metallurgy (UBM); and
a peripheral opening for a retaining wall portion of the UBM, wherein the peripheral opening forms a ring around the central opening; and
filling the central opening and the peripheral opening with conductive material to form the UBM, wherein the conductive pad portion of the UBM contacts a surface of the conductive line, and wherein the retaining wall portion of the UBM has a bottom-most portion physically contacting the conductive line.

### Claim 10 (depends on 9)

The method of claim 9, wherein the conductive pad portion of the UBM physically contacts the surface of the conductive line.

### Claim 11 (depends on 9)

The method of claim 9, wherein a portion of the mask layer separates the first opening from the second opening.

### Claim 12 (depends on 11)

The method of claim 11, wherein a dimension of the portion of the mask layer is between to micrometers and 20 micrometers.

### Claim 13 (depends on 9)

The method of claim 9, wherein filling the central opening and the peripheral opening with conductive material comprises a plating process using the mask layer as a plating mask.

### Claim 14 (depends on 11)

The method of claim 11, wherein filling the central opening and the peripheral opening with conductive material comprises providing nucleation sites for a plating process, wherein the nucleation sites are provided by at least one of the conductive line or the seed layer.

### Claim 15 (depends on 9)

The method of claim 9, wherein a dimension of the retaining wall portion of the UBM is between 10 micrometers and 20 micrometers.

### Claim 16 (depends on 9)

The method of claim 9, further comprising:
removing the mask layer to form a trench between the conductive pad portion of the UBM and the retaining wall portion of the UBM; and
forming a connector over the conductive pad portion of the UBM, wherein no portion of the connector is disposed in the trench.

### Claim 17

A method for forming a device package, the method comprising:
forming a redistribution layer (RDL) over a die;
forming a polymer layer over the RDL, the polymer layer having an opening exposing a portion of the RDL;
depositing a seed layer over the polymer layer and the RDL, and over sidewalls of the opening;
forming a conductive line on the seed layer;
forming a first mask layer having a first opening and a second opening over the conductive line and the seed layer; and
forming an under bump metallurgy (UBM) in the first opening and the second opening, the UBM comprising a conductive pad portion within the first opening, the conductive pad portion contacting a surface of the conductive line, the UBM further comprising a retaining wall portion within the second opening, the retaining wall portion having a bottom-most portion physically contacting the conductive line.

### Claim 18 (depends on 17)

The method of claim 17, wherein the second opening forms a ring around the first opening and is separated from the first opening by a distance between to micrometers and 20 micrometers.

### Claim 19 (depends on 17)

The method of claim 17, further comprising:
removing the first mask layer to form a trench between the conductive pad portion of the UBM and the retaining wall portion of the UBM; and
forming a connector over the conductive pad portion of the UBM.

### Claim 20 (depends on 10)

The method of claim 10, wherein no portion of the connector is disposed in the trench and no portion of the connector is disposed on the retaining wall portion of the UBM.