Sensor and heater for stimulus-initiated fracture of a substrate

• US 10,224,297 B2
• Filed: 07/26/2016
• Issued: 03/05/2019
• Est. Priority Date: 07/26/2016
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Chua, Christopher L., Lu, Jeng Ping, Whiting, Gregory, Limb, Scott J., Lujan, Rene A., Wang, Qian
• Primary Examiner(s): Luu, Thanh
• Application Number:
  US15/220,221
• Publication Number:
  US 20180033742A1
• Time in Patent Office: 952 Days
• CPC Class Codes: H01L 23/15 Ceramic or glass substrates H01L23/142, H01L23/145, H01L23/147 take precedence
• CPC Class Codes: H01L 23/345 Arrangements for heating thermal treatment apparatus H01L21/00
• CPC Class Codes: H01L 23/5256 comprising fuses, i.e. connections having their state changed from conductive to non-conductive
• CPC Class Codes: H01L 23/57 Protection from inspection, reverse engineering or tampering
• CPC Class Codes: H01L 23/576 using active circuits
• CPC Class Codes: H01L 23/64 Impedance arrangements
• CPC Class Codes: H01L 29/74 Thyristor-type devices, e.g. having four-zone regenerative action two-terminal thyristors H01L29/87
• CPC Class Codes: H01L 31/022408 for devices characterised by at least one potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/022475 composed of indium tin oxide [ITO]
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H03K 19/17768 for security

Abstract

A self-destructing device includes a stressed substrate with a heater thermally coupled to the stressed substrate. The device includes a power source and trigger circuitry comprising a sensor and a switch. The sensor generates a trigger signal when exposed to a trigger stimulus. The switch couples the power source to the heater in response to the trigger signal When energized by the power source, the heater generates heat sufficient to initiate self-destruction of the stressed substrate.

Claims

1. A device, comprising:

a stress-engineered substrate;

a heater thermally coupled to the stress-engineered substrate, the heater comprising a fuse portion;

a power source; and

trigger circuitry, comprising;

a sensor configured to generate a trigger signal when exposed to a trigger stimulus; and

a switch configured to electrically couple the power source to the heater when activated by the trigger signal, wherein, when electrically coupled to the power source for a predetermined period of time, the fuse portion of the heater is configured to heat up and break, and wherein the stress-engineered substrate is configured to fracture during a cool-down phase after the fuse portion break.

2. The device of claim 1, wherein the sensor is a photodiode and the photodiode comprises:

a first electrode layer disposed over a substrate and extending over the substrate to form a first lead of the photodiode;

a first doped layer disposed over the first electrode layer;

a second oppositely doped layer disposed over the first doped layer, the first and second doped layers forming at least a portion of an active region of the photodiode; and

a second electrode layer disposed over the second doped layer, the second doped layer and the second electrode layer extending over the substrate to form a second lead of the photodiode.

3. The device of claim 2, wherein the first and second leads electrically connect the active region of the photodiode to a periphery of the device and are configured to be connected to external leads that communicate with one or more external electronic devices.

4. The device of claim 1, further comprising an adhesion promoting surface disposed between the substrate and the sensor.

5. The device of claim 4, wherein the adhesion promoting surface is a barrier layer comprising one or more of silicon dioxide (SiO2), silicon nitride (SiN), and silicon oxynitride (SiON).

6. The device of claim 1, wherein the stress-engineered substrate includes at least one tensile stress layer having a residual tensile stress and at least one compressive stress layer having a residual compressive stress and being mechanically coupled to the at least one tensile stress layer such that the at least one tensile stress layer and the at least one compressive stress layer are self-equilibrating.

7. The device of claim 1, wherein the stress-engineered substrate comprises chemically tempered glass.

8. The device of claim 1, wherein the switch is a thyristor.

9. The device of claim 1, wherein one or more electronic devices are disposed on the stress-engineered substrate such that fracture of the stress-engineered substrate fractures the electronic devices.

10. The device of claim 1, wherein an impedance of the heater is substantially equally to an impedance of the power source.

11. The device of claim 1, wherein the sensor is configured to sense at least one of radiation, electromagnetic radiation, radio frequency radiation, infrared radiation, ultraviolet radiation, x-ray radiation, visible light, laser light, vibration, a chemical, vapor, gas, sound, temperature, time, moisture, and an environmental condition.

12. A method, comprising:

generating a trigger signal in response to exposure to a trigger stimulus;

in response to the trigger signal, activating a switch that couples a power source to a heater in thermal contact with a stress-engineered substrate, the heater comprising a fuse portion;

the fuse portion of the heater heating up and breaking after being coupled to power source for a predetermined period of time; and

the stress-engineered substrate fracturing during a cool-down phase after the fuse portion of the heater breaks.

13. The method of claim 12, wherein the trigger stimulus is caused by a tampering event.

14. The method of claim 12, wherein:

the trigger stimulus is light; and

further comprising aiming a source of the light toward a sensor sensitive to the light.

15. The method of claim 12, wherein generating the trigger signal comprises generating the trigger signal in response to a tampering event, wherein the trigger stimulus comprises at least one of sunlight, room light, a chemical, and x-rays.