# US 2021/0242141 A1 · Physical Unclonable Functions in Integrated Circuit Chip Packaging for Security

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- Number: US 2021/0242141 A1
- Document ID: US20210242141A1
- Status: Published application
- Kind: A1
- Application number: 17/225,941
- Filed: 2021-04-08
- Published: 2021-08-05
- Earliest claimed: 2017-11-09
- Assignees: Lexmark International, Inc.
- Applicants: Lexmark International, Inc.
- Inventors: Stephen P. Bush; Gary A. Denton; James Paul Drummond; Kelly Ann Killeen; Carl E. Sullivan
- Web page: https://patentgrep.com/patent/US20210242141A1

## CPC

- H10W 42/40: protecting against tampering, e.g. unauthorised inspection or reverse engineering
- G09C 1/00: Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a predetermined system (cryptographic typewriters G09C3/00)
- H04L 9/3278: {using physically unclonable functions [PUF]}
- H10W 42/284: {shielding resins}
- H10W 42/287: {materials for magnetic shielding, e.g. ferromagnetic materials}
- H10W 46/00: Marks applied to devices, e.g. for alignment or identification
- H10W 74/111: {the semiconductor body being completely enclosed}
- H10W 74/121: {by multiple encapsulations, e.g. by a thin protective coating and a thick encapsulation}
- H10W 74/40: characterised by their materials
- H10W 74/473: {containing a filler}
- H10W 46/401: {for identification or tracking}
- H10W 46/607: {Located on parts of packages, e.g. on encapsulations or on package substrates}
- H10W 70/421: {Shapes or dispositions}
- H10W 72/50: Bond wires
- H10W 72/59: Bond pads specially adapted therefor
- H10W 72/90: Bond pads, in general
- H10W 90/756: {between a chip and a stacked lead frame, conducting package substrate or heat sink}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- G09C: CIPHERING OR DECIPHERING APPARATUS FOR CRYPTOGRAPHIC OR OTHER PURPOSES INVOLVING THE NEED FOR SECRECY
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

In the invention described, magnetic field characteristics of randomly placed magnetized particles are exploited by using the magnetic field fluctuations produced by the particles as measured by a sensor. The magnetized particles generate a complex magnetic field near the surface of an integrated circuit chip that can be used as a “fingerprint.” The positioning and orientation of the magnetized particles is an uncontrolled process, and thus the interaction between the sensor and the particles is complex. The randomness of the magnetic field magnitude and direction near the surface of the material containing the magnetic particles can be used to obtain a unique identifier for an item such as an integrated circuit chip carrying the PUF.

## Claims

### Claim 1

A system comprising:
a substrate;
a plurality of pre-magnetized particles that have random orientations of magnetization and are randomly dispersed in the substrate;
an external magneto-resistive sensor, wherein a magnetic field profile is measured along a defined non-linear path by relative movement of the sensor and the substrate; and an integrated circuit chip.

### Claim 2 (depends on 1)

The system of claim 1, further comprising a non-volatile memory on the integrated circuit chip, wherein the non-volatile memory contains magnetic field profile data measured from the pre-magnetized particles.

### Claim 3 (depends on 1)

The system of claim 1, wherein the pre-magnetized particles contain neodymium and iron and boron.

### Claim 4 (depends on 1)

The system of claim 1, wherein the pre-magnetized particles contain samarium and cobalt.

### Claim 5 (depends on 1)

The system of claim 1, wherein the average particle size diameter of the pre-magnetized particles is greater than 0.1 mm.

### Claim 6 (depends on 1)

The system of claim 1, wherein the average particle size diameter of the pre-magnetized particles is greater than 0.001 mm.