Far infrared photoconductor array

• US 7,180,077 B1
• Filed: 02/18/2005
• Issued: 02/20/2007
• Est. Priority Date: 02/20/2004
• Status: Expired due to Fees

• Current Assignee: Technoscience Corporation
• Original Assignee: Techoscience Corporation
• Inventors: Farhoomand, Jam
• Primary Examiner(s): Porta; David
• Assistant Examiner(s): TANINGCO, MARCUS H
• Application Number:
  US11/062,178
• Time in Patent Office: 732 Days
• Field of Search: 250/384.4
• US Class Current: 250/338.4
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/1463 Pixel isolation structures
• CPC Class Codes: H01L 27/14634 Assemblies, i.e. Hybrid structures
• CPC Class Codes: H01L 27/1467 of the hybrid type
• CPC Class Codes: H01L 27/1469 Assemblies, i.e. hybrid integration
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/351 Thermal stress

Abstract

Fabrication of far infrared photoconductor arrays, especially for low background astronomy, is particularly challenging due to arrays'"'"' relatively large pixel size, susceptibility to stray radiation, and the requirement for low bias levels. A hybrid-far infrared photoconductor array as presented, provides a system and method for the development of large-format far IR arrays. The hybrid-far infrared array is provided with a blocking layer, situated in between a detecting layer and a readout layer, which allows detection of far infrared signals without complications based on readout glow. In particular, the readout glow, detector heating, and thermal mismatch between the readout and the detecting layer are addressed by careful selection of the materials for the blocking layer. The blocking layer is provided with an array of conductive vias passing through the bulk of the blocking layer in order to efficiently transmit electrical signals between the detecting layer and the readout layer.

Claims

1. An apparatus for detecting far infrared radiation comprising:

a detecting layer, formed on a first substrate, for receiving far infrared radiation and converting the radiation into a first electrical signal;

a readout layer, formed on a second substrate, for receiving the first electrical signal, converting the first electrical signal to a second electrical signal suitable for processing by a micro-processing device, and generating background radiation capable of detrimentally affecting an efficiency of the detecting layer; and

a blocking layer, formed by a third substrate situated in between the first substrate and the second substrate, for transmitting the first electrical signal from the detecting layer to the readout layer, providing a heat sink for both the detecting layer and the readout layer, and blocking the background radiation of the readout layer from reaching the detecting layer, and wherein the third substrate is constructed from a material that is opaque to far infrared radiation.

2. The apparatus of claim 1, wherein the blocking layer further comprises:

a first array of conductive pads on a top surface of the third substrate and a second array of conductive pads on the bottom surface of the third substrate; and

an array of conductive vias passing through the third substrate, in electrical contact with the first and second array of conductive pads, and substantially aligned with the first and second array of conductive pads.

3. The apparatus of claim 1, wherein the third substrate is constructed from an electrically insulating material.

4. The apparatus of claim 1, wherein the third substrate is constructed from a material that is opaque to far infrared radiation.

5. The apparatus of claim 1, wherein the third substrate is constructed from a thermally conductive material.

6. The apparatus of claim 2, wherein the blocking layer further comprises:

one or more blocking pads imbedded within the third substrate, aligned substantially perpendicular to a long axis of the array of conductive vias, for blocking the background radiation of the readout layer from reaching the detecting layer.

7. The apparatus of claim 6, wherein the one or more blocking pads are staggered throughout the third substrate, forcing the background radiation to travel in a meandering path.

8. The apparatus of claim 2 further comprising:

a first array of bump bonds providing electrical connection between the first array of conductive pads and an array of detection pads, the array of detection pads located on a bottom surface of the detecting layer; and

a second array of bump bonds providing electrical connection between the second array of conductive pads and an array of readout pads, the array of readout pads located on a top surface of the readout layer.

9. The apparatus of claim 8, wherein the first and second array of bump bonds are constructed from a conductive epoxy or indium.

25. The apparatus of claim 8, wherein the first array of bump bonds is constructed from a conductive epoxy and the second array of bump bonds is constructed from indium.

10. An apparatus for detecting far infrared radiation comprising:

a receiving means, formed on a first substrate, for receiving a far infrared signal, the receiving means capable of converting the far infrared signal into a first electrical signal;

a reading means, formed on a second substrate, for reading the first electrical signal, the reading means capable of converting the first electrical signal into a second electrical signal suitable for electronics processing; and

a transmitting means, formed by a third substrate, for transmitting the first electrical signal to the reading means, the transmitting means capable of shielding the detecting means from receiving background radiation emitted from the reading means, and wherein the third substrate is constructed from a material that is opaque to far infrared radiation.

11. The apparatus of claim 10, wherein the third substrate is constructed from an electrically insulating material with a top and a bottom surface.

12. The apparatus of claim 10, wherein the first substrate is constructed from a material, having a first thermal expansion coefficient, and a top and a bottom surface.

13. The apparatus of claim 12, wherein the second substrate is constructed from a material, having a second thermal expansion coefficient, and a top and a bottom surface.

14. The apparatus of claim 13, wherein the third substrate is constructed from a material, having a third thermal expansion coefficient, and a top and a bottom surface.

15. The apparatus of claim 14, wherein the third thermal expansion coefficient is a value in between the first and second thermal expansion coefficients.

16. The apparatus of claim 13, wherein the transmitting means further comprises:

a conducting means, passing through the third substrate, for conducting electrical signals from the bottom surface of the receiving means to the top surface of the reading means.

17. The apparatus of claim 16, wherein the transmitting means further comprises a blocking means, embedded within the third substrate, substantially near the conducting means, for shielding the receiving means from receiving background radiation generated from the reading means.

18. The apparatus of claim 16, wherein the conducting means is an array of conductive vias substantially aligned perpendicular to the bottom surface of the receiving means and the top surface of the reading means.

19. A method for manufacturing a sensor for sensing far infrared radiation, the method comprising the steps of:

establishing a support substrate, with a top and a bottom surface, for transmitting electrical signals and blocking background radiation, and wherein the support substrate is constructed from a material that is opaque to far infrared radiation;

depositing a second substrate on the top surface of the support substrate for receiving far infrared radiation and converting the received far infrared radiation into a first electrical signal; and

depositing a third substrate on the bottom surface of the support substrate for receiving the first electrical signal and converting the first electrical signal to a second electrical signal suitable for processing by a micro-processing device.

20. The method of claim 19, wherein the support substrate prevents background radiation generated by the second layer from reaching the first layer.

21. The method of claim 19, wherein the support substrate transmits the first electrical signal from the first layer to the second layer.

22. The method of claim 19, further comprising:

boring an array of conductive vias through the support substrate, such that the array of conductive vias is in electrical contact with the first and second layers and substantially aligned perpendicular with the first and second layers.

23. The method of claim 22, further comprising:

imbedding a plurality of conductive pads within the support substrate, substantially perpendicular to the array of conductive vias, such that the background radiation generated by the second layer is forced to proceed through a meandering path when traveling towards the first layer.

24. The method of claim 19, wherein the third substrate comprises a capacitive transimpedance amplifier.

26. An apparatus for detecting far infrared radiation comprising:

a detecting layer, formed on a first substrate, for receiving far infrared radiation and converting the radiation into a first electrical signal;

a readout layer, formed on a second substrate, for receiving the first electrical signal, converting the first electrical signal to a second electrical signal suitable for processing by a micro-processing device, and generating background radiation capable of detrimentally affecting an efficiency of the detecting layer; and

a blocking layer, formed by a third substrate situated in between the first substrate and the second substrate, for transmitting the first electrical signal from the detecting layer to the readout layer, providing a heat sink for both the detecting layer and the readout layer, and blocking the background radiation of the readout layer from reaching the detecting layer, and wherein the third substrate comprises one or more embedded blocking pads positioned to cut off a linear path for the background radiation of the readout layer to reach the detecting layer.

27. An apparatus for detecting far infrared radiation comprising:

a receiving means, formed on a first substrate, for receiving a far infrared signal, the receiving means capable of converting the far infrared signal into a first electrical signal;

a reading means, formed on a second substrate, for reading the first electrical signal, the reading means capable of converting the first electrical signal into a second electrical signal suitable for electronics processing; and

a transmitting means, formed by a third substrate, for transmitting the first electrical signal to the reading means, the transmitting means capable of cutting off a linear path for background radiation emitted from the reading means to reach the receiving means.

28. A method for manufacturing a sensor for sensing far infrared radiation, the method comprising the steps of:

establishing a support substrate, with a top and a bottom surface, for transmitting electrical signals and blocking background radiation;

depositing a second substrate on the top surface of the support substrate for receiving far infrared radiation and converting the received far infrared radiation into a first electrical signal; and

depositing a third substrate on the bottom surface of the support substrate for receiving the first electrical signal and converting the first electrical signal to a second electrical signal suitable for processing by a micro-processing device, and

wherein the support substrate comprises one or more embedded blocking pads positioned to cut off a linear path for background radiation emitted from the third substrate to reach the second substrate.