# US 5,347,086 A · Coaxial die and substrate bumps

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- Number: US 5,347,086 A
- Document ID: US5347086A
- Status: Granted
- Kind: A
- Application number: 07/856,501
- Filed: 1992-03-24
- Granted: 1994-09-13
- Earliest claimed: 1992-03-24
- Assignees: Microelectronics and Computer Technology Corporation
- Inventors: Curtis N. Potter; David A. Gibson; Uttam S. Ghoshal
- Web page: https://patentgrep.com/patent/US5347086A

## CPC

- H10W 72/20: Bump connectors, e.g. solder bumps or copper pillars; Dummy bumps; Thermal bumps
- H10W 44/20: at high-frequency [HF] or radio frequency [RF]
- H10W 44/212: {Coaxial feed-throughs in substrates}
- H10W 72/251: {Materials}
- H10W 72/923: {Bond pads having multiple stacked layers}
- H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A coaxial bump for connecting a die to a substrate includes a center post and a ground ring surrounding and shielding the center post. The center post may be a center conductor line, and the ground ring may be generally torus-shaped, nearly closed or completely closed. The coaxial bump provides very low crosstalk in chip-to-substrate interconnections and provides a constant impedance with negligible inductive discontinuity.

## Claims

### Claim 1

A coaxial bump for connecting a die to a substrate, said coaxial bump comprising:
a center conductor line; and
a ground ring spaced from and surrounding said center conductor line wherein said ground ring provides said center conductor line with electromagnetic shielding from adjacent signal bumps thereby permitting only a very low level of crosstalk between said center conductor line and said adjacent signal bumps.

### Claim 2 (depends on 1)

A coaxial bump as recited in claim 1, wherein said ground ring is at least generally torus-shaped.

### Claim 3 (depends on 2)

A coaxial bump as recited in claim 2, wherein said ground ring completely surrounds said center conductor line.

### Claim 4 (depends on 3)

A coaxial bump as recited in claim 3, wherein said bump contains no flux within said ground ring.

### Claim 5

A coaxial bump comprising:
a dielectric layer;
a passivation layer;
a ground layer disposed between said dielectric layer and said passivation layer;
an inner bump center conductor extending through and electrically isolated from said ground layer; and
an outer bump shield mounted atop and electrically connected to said ground layer.

### Claim 6 (depends on 5)

A coaxial bump as recited in claim 5, wherein said dielectric is selected from the group consisting of silicon dioxide and polyimide.

### Claim 7 (depends on 5)

A coaxial bump as recited in claim 5, wherein said ground layer is selected from the group consisting of niobium, copper and aluminum.

### Claim 8 (depends on 5)

A coaxial bump as recited in claim 5, further comprising a feed within said dielectric layer connected to said inner bump center conductor and electrically isolated from said ground layer.

### Claim 9 (depends on 8)

A coaxial bump as recited in claim 8, further comprising exposed, top stripline pads.

### Claim 10 (depends on 9)

A coaxial bump as recited in claim 9, wherein said exposed, top stripline pads are metallized with a barrier metal.

### Claim 11 (depends on 10)

A coaxial bump as recited in claim 10, wherein said barrier metal is palladium.

### Claim 12 (depends on 9)

A coaxial bump as recited in claim 9, wherein said entire coaxial bump is formed on a wafer.

### Claim 13 (depends on 12)

A coaxial bump as recited in claim 12, wherein said wafer has a surface which is coated with gold so as to provide a plating interconnect.

### Claim 14

A coaxial bump for connecting a die to a substrate, said bump comprising:
a center conductor line; and
a ground ring with at least one gap therein, said ground ring spaced from and partially surrounding said center conductor line wherein said ground ring provides said center conductor line with electromagnetic shielding from adjacent signal bumps thereby reducing crosstalk between said center conductor line and said adjacent signal bumps.

### Claim 15 (depends on 14)

A coaxial bump as recited in claim 14, wherein said at least one gap does not significantly decrease the electromagnetic shielding capability of said ground ring.

### Claim 16 (depends on 15)

A coaxial bump as recited in claim 15, wherein said at least one gap permits gas pressure release.

### Claim 17 (depends on 15)

A coaxial bump as recited in claim 15, wherein said die is flip-chip bonded to said substrate.

### Claim 18 (depends on 15)

A coaxial bump as recited in claim 15, wherein said center conductor line is at least partially formed with aluminum.