Image sensor for detecting wide spectrum and method of manufacturing the same

• US 7,723,686 B2
• Filed: 08/14/2008
• Issued: 05/25/2010
• Est. Priority Date: 08/14/2008
• Status: Active Grant

• Current Assignee: Hanvision Co., Ltd., Lumiense Photonics, Inc.
• Original Assignee: Hanvision Co., Ltd., Lumiense Photonics, Inc.
• Inventors: Hannebauer, Robert
• Primary Examiner(s): Hannaher; Constantine
• Application Number:
  US12/191,447
• Publication Number:
  US 20100038540A1
• Time in Patent Office: 649 Days
• Field of Search: 250/349, 250/339.01
• US Class Current: 250/349
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01J 5/04 Casings
• CPC Class Codes: G01J 5/045 Sealings; Vacuum enclosures; Encapsulated packages; Wafer bonding structures; Getter arrangements getter arrangements per se H01L23/26 and H01L21/3221
• CPC Class Codes: G01J 5/06 Arrangements for eliminating effects of disturbing radiation; Arrangements for compensating changes in sensitivity for adjusting of solid angle of collected radiation G01J5/07; means for wavelength selection G01J5/0801
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 27/14647 Multicolour imagers having a stacked pixel-element structure, e.g. npn, npnpn or MQW elements
• CPC Class Codes: H01L 27/14652 Multispectral infrared imagers, having a stacked pixel-element structure, e.g. npn, npnpn or MQW structures
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• 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

An image sensor for detecting a wide spectrum includes a plurality of infrared ray receiving layers which individually receive infrared rays having different wavelengths for each pixel, the plurality of infrared ray receiving layers stacked to each other. The image sensor, which is an integrated image sensor where at least two micro bolometers are stacked, acquires spectrum information about visible rays and near-infrared rays as well as two or more infrared rays applied on an object, without mechanical/thermal/optical distortion, and provides the spectrum information to a silicon-based semiconductor such as a photodiode, thereby improving photoelectric conversion efficiency.

Claims

1. An image sensor for detecting a wide spectrum comprising:

a multi-layer micro bolometer structure including a multi-layer micro bolometer and two shield layers, wherein the multi-layer micro bolometer include a first detector including an absorber for absorbing light and converting the light into heat and a resistor whose resistance varies according to a change in temperature of the absorber, a first thermal sink separated by an empty space from the lower surface of the first detector, and a second detector having the same structure as a structure of the first detector and separated by an empty space from the lower surface of the first thermal sink, the two shield layers respectively positioned over and below the multi-layer micro bolometer and made of a silicon layer and an oxide layer, and the multi-layer micro bolometer is repeatedly formed one or more times in such a manner that each multi-layer micro bolometer is divided by a shield layer, thereby forming a multi-layer structure; and

a transistor layer applied on the multi-layer micro bolometer structure, electrically connected to the first detector and the second detector, and processing signals detected by the first detector and the second detector.

2. The image sensor of claim 1, wherein the first detector and the second detector contact the lower and upper surfaces of the first thermal sink, respectively, by electrostatic attraction force generated by applying a potential difference at regular time intervals to the first thermal sink, the first detector, and the second detector.

3. The image sensor of claim 1, wherein a first oxide layer is formed on one of the shield layer, a second oxide layer is formed on the first detector, a third oxide layer is formed on the first thermal sink, and a fourth oxide layer is formed on the second detector, and

the empty spaces are formed by partially removing the first through fourth oxide layers.

4. The image sensor of claim 1, further comprising:

a single-layer micro bolometer including a third detector separated by an empty space from the multi-layer micro bolometer and having the same structure as the structure of the first detector, and a second thermal sink separated by an empty space from the third detector,

wherein the transistor layer is electrically connected to the third detector and processes signals detected by the third detector.

5. The image sensor of claim 4, wherein the first detector and the second detector contact the lower and upper surfaces of the first thermal sink, respectively, by electrostatic attraction force generated by applying a potential difference at regular time intervals to the first thermal sink, the first detector and the second detector, and

the third detector contacts the second thermal sink by electrostatic attraction force generated by applying a potential difference at regular time intervals to the second thermal sink and the third detector.

6. The image sensor of claim 4, wherein a first oxide layer is formed on one of the shield layer, a second oxide layer is formed on the first detector, a third oxide layer is formed on the first thermal sink, a fourth oxide layer is formed on the second detector, a fifth oxide layer is formed on the second thermal sink, and a sixth oxide layer is formed on the third detector, and

the empty spaces are formed by partially removing the first through sixth oxide layers.

7. The image sensor of claim 1, wherein the absorber has a multi-layer structure including at least one of a nitride (Si₃N₄) layer, an oxide layer, or a dielectric layer, and has wavelength selectivity.

8. The image sensor of claim 1, wherein the resistor is a single-crystalline silicon thin layer with a serpentine structure having a narrow, curved shape.

9. The image sensor of claim 1, wherein the two shield layers each includes a silicon layer and an oxide layer and is grounded.

10. The image sensor of claim 1, wherein the transistor layer has a MOS semiconductor structure.

11. The image sensor of claim 10, wherein the MOS semiconductor structure is a transistor manufactured using a bulk semiconductor process.

12. The image sensor of claim 10, wherein the MOS semiconductor is a bipolar junction transistor (BJT) insolated by dielectric or a flip-fet transistor isolated by dielectric.

13. The image sensor of claim 10, wherein the MOS semiconductor structure is a transistor having four terminals of a source, a drain, a top-side gate, and a back-side gate.

14. The image sensor of claim 1, wherein by forming a photo diode layer on the multi-layer micro bolometer structure, a ultraviolet ray, a visible ray, a near- infrared ray, or a combination of spectrums of the ultraviolet ray, the visible ray, and the near-infrared ray is detected.

15. A method of manufacturing an image sensor, comprising:

forming a buffer oxide layer and a dielectric layer sequentially on an upper surface of a handle wafer, thus preparing a working substrate;

forming a first oxide layer, a first absorber, a first resistor, a second oxide layer, a first thermal sink, a third oxide layer, a second absorber, a second resistor, and a fourth oxide layer, sequentially, on the dielectric layer which is a top layer of the working substrate, thus forming a multi-layer micro bolometer, wherein the multi-layer micro bolometer is repeatedly formed one or more times to form a multi-layer bolometer structure;

forming a silicon-on-insulator (SOI) thin layer on the multi-layer micro bolometer structure;

forming a transistor circuit on the SOI thin layer;

electrically connecting the transistor circuit to the first resistor and the second resistor; and

forming a metal layer including a bump on the transistor circuit.

16. The method of claim 15, further comprising forming a second thermal sink, a fifth oxide layer, a third absorber, a third resistor, and a sixth oxide layer on the dielectric layer which is the top layer of the working substrate, between the preparing of the working substrate and the forming of the multi-layer micro bolometer structure, thus forming a single-layer micro bolometer on the multi-layer bolometer structure, wherein the transistor circuit is connected to the third resistor.