SEGMENTED FOCAL PLANE ARRAY ARCHITECTURE

• US 20140184807A1
• Filed: 12/13/2013
• Published: 07/03/2014
• Est. Priority Date: 04/23/2010
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Simolon, Brian, Kurth, Eric A., Nussmeier, Mark, Hgasten, Nicholas, Hoelter, Theodore R., Strandemar, Katrin, Boulanger, Pierre, Sharp, Barbara
• Granted Patent: US 9,918,023 B2
• Time in Patent Office: Days
• US Class Current: 348/164
• CPC Class Codes: H01L 27/14634 Assemblies, i.e. Hybrid structures
• CPC Class Codes: H01L 27/1469 Assemblies, i.e. hybrid integration
• CPC Class Codes: H04N 23/57 Mechanical or electrical details of cameras or camera modules specially adapted for being embedded in other devices
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

Various techniques are provided for implementing a segmented focal plane array (FPA) of infrared sensors. In one example, a system includes a segmented FPA. The segmented FPA includes a top die having an array of infrared sensors (e.g., bolometers). The top die may also include a portion of a read-out integrated circuit (ROIC). The segmented FPA also includes a bottom die having at least a portion of the ROIC. The top and the bottom dies are electrically coupled via inter-die connections. Advantageously, the segmented FPA may be fabricated with a higher yield and a smaller footprint compared with conventional FPA architectures. Moreover, the segmented FPA may be fabricated using different semiconductor processes for each die.

Claims

1. A system comprising:

a segmented focal plane array (FPA) comprising;

a first die comprising an array of active bolometers adapted to receive infrared (IR) radiation from a scene;

a second die stacked relative to the first die and comprising at least a portion of a read-out integrated circuit (ROIC); and

a plurality of inter-die connections adapted to pass signals between the first die and the second die, wherein the passed signals are used to generate output values corresponding to the IR radiation received at the active bolometers.

2. The system of claim 1, wherein:

the first die comprises one or more thermally shorted bolometers and accompanying circuitry adapted to adjust bias signals associated with the active bolometers to compensate for temperature variations of the first die;

the FPA comprises a cap adapted to seal at least a portion of the first die; and

the first die and the cap form a vacuum package assembly (VPA).

3. The system of claim 1, wherein:

the passed signals comprise a detected signal provided by at least one of the active bolometers in response to the radiation and passed from the first die to the second die through at least one of the inter-die connections; and

the portion of the ROIC of the second die comprises;

an integrator adapted to provide an analog signal in response to the detected signal, and

an analog-to-digital converter (ADC) adapted to provide at least one of the output values in response to the analog signal.

4. The system of claim 1, wherein the first die comprises at least another portion of the ROIC.

5. The system of claim 4, wherein:

the first die portion of the ROIC comprises an integrator adapted to provide an analog signal in response to a detected signal provided by at least one of the active bolometers in response to the radiation;

the passed signals comprise the analog signal passed from the first die to the second die through at least one of the inter-die connections; and

the second die portion of the ROIC comprises an analog-to-digital converter (ADC) adapted to provide at least one of the output values in response to the analog signal.

6. The system of claim 4, wherein:

the first die portion of the ROIC comprises;

an integrator adapted to provide an analog signal in response to a detected signal provided by at least one of the active bolometers in response to the radiation,

a sample-and-hold circuit adapted to capture a voltage in response to the analog signal, and

a comparator;

the second die portion of the ROIC comprises a ramp generator;

the passed signals comprise a ramp signal provided by the ramp generator and passed from the second die to the first die through at least one of the inter-die connections; and

the comparator is adapted to receive the captured voltage from the sample-and-hold circuit and select at least one of the output values based on the captured voltage and the ramp signal.

7. The system of claim 1, wherein:

the passed signals comprise a regulated voltage;

the second die further comprises a low-dropout regulator (LDO) adapted to provide the regulated voltage to the first die through at least one of the inter-die connections; and

the inter-die connections comprise through-silicon vias (TSVs) and/or micro-bumps.

8. The system of claim 1, wherein the first die and the second die are fabricated using different semiconductor fabrication processes.

9. A method comprising:

fabricating a first die comprising an array of active bolometers adapted to receive infrared (IR) radiation from a scene;

fabricating a second die comprising at least a portion of a read-out integrated circuit (ROIC);

forming a plurality of inter-die connections adapted to pass signals between the first die and the second die, wherein the passed signals are used to generate output values corresponding to the IR radiation received at the active bolometers;

stacking the first and second dies relative to each other; and

wherein the first die, the second die, and the inter-die connections are part of a segmented focal plane array (FPA).

10. The method of claim 9, further comprising sealing at least a portion of the first die by a cap, wherein:

the first die and the cap form a vacuum package assembly (VPA); and

the first die comprises one or more thermally shorted bolometers and accompanying circuitry adapted to adjust bias signals associated with the active bolometers to compensate for temperature variations of the first die.

11. The method of claim 9, wherein:

the passed signals comprise a detected signal provided by at least one of the active bolometers in response to the radiation and passed from the first die to the second die through at least one of the inter-die connections; and

the portion of the ROIC of the second die comprises;

an integrator adapted to provide an analog signal in response to the detected signal, and

an analog-to-digital converter (ADC) adapted to provide at least one of the output values in response to the analog signal.

12. The method of claim 9, wherein the first die comprises at least another portion of the ROIC.

13. The method of claim 12, wherein:

the first die portion of the ROIC comprises an integrator adapted to provide an analog signal in response to a detected signal provided by at least one of the active bolometers in response to the radiation;

the passed signals comprise the analog signal passed from the first die to the second die through at least one of the inter-die connections; and

the second die portion of the ROIC comprises an analog-to-digital converter (ADC) adapted to provide at least one of the output values in response to the analog signal.

14. The method of claim 12, wherein:

the first die portion of the ROIC comprises;

an integrator adapted to provide an analog signal in response to a detected signal provided by at least one of the active bolometers in response to the radiation,

a sample-and-hold circuit adapted to capture a voltage in response to the analog signal, and

a comparator;

the second die portion of the ROIC comprises a ramp generator;

the passed signals comprise a ramp signal provided by the ramp generator and passed from the second die to the first die through at least one of the inter-die connections; and

the comparator is adapted to receive the captured voltage from the sample-and-hold circuit and select at least one of the output values based on the captured voltage and the ramp signal.

15. The method of claim 9, wherein:

the passed signals comprise a regulated voltage;

the second die further comprises a low-dropout regulator (LDO) adapted to provide the regulated voltage to the first die through at least one of the inter-die connections; and

the inter-die connections comprise through-silicon vias (TSVs) and/or micro-bumps.

16. The method of claim 9, wherein:

the fabricating the first die is performed using a first semiconductor fabrication process; and

the fabricating the second die is performed using a second different semiconductor fabrication process.

17. A method comprising:

receiving infrared (IR) radiation from a scene at a segmented focal plane array (FPA) comprising;

a first die comprising an array of active bolometers,

a second die stacked relative to the first die and comprising at least a portion of a read-out integrated circuit (ROIC), and

a plurality of inter-die connections between the first die and the second die;

passing signals between the first die and the second die through the inter-die connections; and

generating output values corresponding to the IR radiation received at the active bolometers, wherein the passed signals are used to perform the generating.

18. The method of claim 17, wherein:

the FPA comprises a cap adapted to seal at least a portion of the first die;

the first die and the cap form a vacuum package assembly (VPA); and

the generating comprises operating one or more thermally shorted bolometers of the first die and accompanying circuitry of the first die to adjust bias signals associated with the active bolometers to compensate for temperature variations of the first die.

19. The method of claim 17, wherein:

the passing comprises passing a detected signal provided by at least one of the active bolometers in response to the radiation from the first die to the second die through at least one of the inter-die connections; and

the generating comprises;

integrating, by the second die portion of the ROIC, the detected signal to provide an analog signal, and

providing, by the second die portion of the ROIC, at least one of the output values in response to the analog signal.

20. The method of claim 17, wherein the first die comprises at least another portion of the ROIC.

21. The method of claim 20, wherein:

the generating comprises;

providing, by at least one of the active bolometers in response to the radiation, a detected signal,

integrating, by a first die portion of the ROIC, the detected signal to provide an analog signal, and

providing, by the second die portion of the ROIC, at least one of the output values in response to the analog signal; and

the passing comprises passing the analog signal from the first die to the second die.

22. The method of claim 20, wherein:

the generating comprises;

providing, by at least one of the active bolometers in response to the radiation, a detected signal,

integrating, by a first die portion of the ROIC, the detected signal to provide an analog signal,

capturing, by the first die portion of the ROIC, a voltage in response to the analog signal, and

selecting, by the first die portion of the ROIC, at least one of the output values based on the captured voltage and a ramp signal; and

the passing comprises passing the ramp signal from the second die to the first die.

23. The method of claim 17, wherein:

the generating comprises providing a regulated voltage from a low-dropout regulator (LDO) of the second die;

the passing comprises passing the regulated voltage from the second die to the first die through at least one of the inter-die connections;

the inter-die connections comprise through-silicon vias (TSVs) and/or micro-bumps.

24. The method of claim 17, wherein the first die and the second die are fabricated using different semiconductor fabrication processes.