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Radiation detectors including thermal-type displaceable element with increased responsiveness

Imported: 23 Feb '17 | Published: 22 Oct '02

Junji Suzuki, Tohru Ishizuya

USPTO - Utility Patents

Abstract

Radiation detector arrays are provided that include one or more thermal-type displaceable elements having reduced thickness without compromising mechanical strength or sensitivity of the displaceable elements to incident radiation. An exemplary displaceable element includes first and second membrane layers made of materials having different coefficients of thermal expansion. The layers are supported relative to a substrate by a leg. The displaceable element can also serve as an absorbing member for the incident radiation to be detected. Each element can also include a reflector of signal light. When the displaceable element incident radiation (such as infrared radiation) to be detected, it undergoes heating which bends the element. Displacement of the element is detected as a change in signal light or as a change in capacitance. If the displaceable member includes a signal-light reflector, the reflector includes a planar portion including “dropped” edges serving to strengthen the planar portion and allow the thickness of the planar portion to be reduced.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS.

1(

a)-(

b) are schematic plan and sectional views, respectively, of a pixel of a radiation detector according to Representative Embodiment 1. FIG.

1(

b) is an elevational section along the line X

1-X

2 of FIG.

1(

a).

FIGS.

2(

a)-(

d) show, in respective schematic vertical sections, the results of respective steps in a method for fabricating the radiation detector of Representative Embodiment 1.

FIGS.

3(

a)-

3(

b) schematically illustrate, in respective elevational sections, the results of an experiment showing the decrease in thickness of the reflector

6 that can be achieved according to the invention.

FIG. 4 is a schematic elevational view of an imaging apparatus with which various embodiments of radiation detectors according to the invention can be used.

FIGS.

5(

a)-

5(

l) are respective schematic elevational sections of various possible layer and edge configurations of the reflector used in a detector according to the invention.

FIG. 6 is a schematic plan view of a pixel of a light-readout-type radiation detector according to Representative Embodiment 2.

FIG. 7 is a schematic elevational section along the line X

11-X

12 in FIG.

6.

FIG. 8 is a schematic elevational section along the line X

13-X

14 of FIG.

6.

FIG. 9 is a schematic elevational section along the line X

15-X

16 of FIG.

6.

FIG. 10 is a schematic elevational section along the line Y

11-Y

12 of FIG.

6.

FIG. 11 is a schematic elevational section along the line Y

13-Y

14 of FIG.

6.

FIG. 12 is a schematic elevational section along the line Y

15-Y

16 of FIG.

6.

FIGS. 13-18 are schematic plan views each showing the result of a respective step in a method for fabricating a radiation detector according to Representative Embodiment 2.

FIG. 19 is a schematic plan view of a pixel of a light-readout-type radiation detector according to Representative Embodiment 3.

FIG. 20 is a schematic elevational section along the line X

21-X

22 of FIG.

19.

FIG. 21 is a schematic plan view showing a pixel of a light-readout-type radiation detector according to Representative Embodiment 4.

FIG. 22 is a schematic elevational section along the line X

31-X

32 of FIG.

21.

FIG. 23 is a schematic elevational section along the line X

33-X

34 of FIG.

21.

FIG. 24 is a schematic elevational section along the line X

35-X

36 of FIG.

21.

FIG. 25 is a schematic elevational section along the line Y

31-Y

32 of FIG.

21.

FIG. 26 is a schematic elevational section along the line Y

33-Y

34 of FIG.

21.

FIG. 27 is a schematic elevational section along the line X

35-X

36 of FIG.

21.

FIGS. 28-31 are schematic plan views each showing the result of a respective step in a method for fabricating a radiation detector according to Representative Embodiment 4.

FIG.

32(

a) is schematic plan view of a pixel of a light-readout-type radiation detector according to Representative Embodiment 5.

FIG.

32(

b) is a schematic elevational section along the line A-A′ of FIG.

32(

a).

FIG. 33 is a schematic plan view of a pixel of a light-readout-type radiation detector according to Representative Embodiment 6.

FIG. 34 is a schematic elevational section along the line B-B′ of FIG.

33.

FIG. 35 is a schematic elevational section along the line C-C′ of FIG.

33.

FIG. 36 is a schematic elevational section of a pixel of a light-readout-type radiation detector according to Representative Embodiment 7.

FIG. 37 is a schematic elevational section of a pixel of a light-readout-type radiation detector according to Representative Embodiment 8.

FIG.

38(

a) is schematic plan view of a pixel of a capacitor-type radiation detector according to Representative Embodiment 9.

FIG.

38(

b) is a schematic elevational section along the line D-D′ of FIG.

38(

a).

FIG. 39 is a schematic elevational section of a pixel of capacitor-type radiation detector according to Representative Embodiment 10.

Claims

1. In a radiation detector, a detection element comprising a displaceable member comprising a planar portion comprising at least one membrane layer, the planar portion being supported relative to a substrate of the radiation detector such that the planar portion is displaced from the substrate, the planar portion having a periphery and being edged by a dropping portion on at least a portion of the periphery of the planar portion.

2. The radiation detector of claim 1, wherein the dropping portion is perpendicular to the planar portion.

3. The radiation detector of claim 1, wherein the planar portion includes a reflector of signal light.

4. The radiation detector of claim 1, wherein the displaceable member includes a region that absorbs radiation to be detected by the detector.

5. The radiation detector of claim 4, wherein the radiation-absorbing region absorbs infrared radiation.

6. In a radiation detector, a detection element comprising a displaceable member comprising a planar portion comprising at least first and second superposed membrane layers, the planar portion being supported relative to a substrate of the radiation detector such that the planar portion is displaced from the substrate, at least one of the membrane layers being configured to cover at least a portion of a peripheral edge of the other membrane layer.

7. The radiation detector of claim 3, wherein:

8. In a radiation detector, a detection element comprising a displaceable member supported relative to a substrate of the radiation detector, the displaceable member being mounted to a leg that is mounted to the substrate, the leg comprising a layer including a horizontal portion and a dropping portion extending around at least a portion of a peripheral edge of the horizontal portion.

9. A radiation detector, comprising:

10. The radiation detector of claim 9, wherein the displacement readout member provides a readout corresponding to a condition of signal light reflecting from the displacement readout member.

11. The radiation detector of claim 9, wherein the displacement readout member provides a readout corresponding to a condition of electrical capacitance as a function of displacement of the displacement readout member.

12. A thermal-type displaceable element for a radiation detector, the displaceable element comprising:

13. The displaceable element of claim 12, wherein the displaceable structure includes a reflector of signal light.

14. The displaceable element of claim 12, wherein the independently displaceable members include respective regions that absorb incident light to be detected.

15. The displaceable element of claim 14, wherein the regions absorb incident infrared light.

16. The displaceable element of claim 12, wherein:

17. A radiation detector, comprising:

18. The radiation detector of claim 1, wherein the displaceable member further comprises a radiation-absorbing region that absorbs incident radiation and exhibits heating in response to an amount of absorbed incident radiation, the heating causing a corresponding change in displacement of the displaceable member relative to the substrate, and the radiation-absorbing region reflecting a portion of the incident radiation; and

19. The radiation detector of claim 18, wherein the displaceable structure includes the radiation-reflector having a constant positional relationship with the radiation-absorbing region, notwithstanding any displacement of the displaceable structure.

20. The radiation detector of claim 19, wherein the displaceable structure includes a readout-light reflector configured to reflect readout light incident on the readout-light reflector.

21. The radiation detector of claim 19, wherein the substrate includes a fixed electrode and the displaceable structure includes a movable electrode facing the fixed electrode; and

22. The radiation detector of claim 18, wherein the substrate includes a fixed electrode and the displaceable portion includes a movable electrode facing the fixed electrode; and

23. The radiation detector of claim 18, wherein the substrate includes a fixed electrode and the displaceable structure includes a movable electrode facing the fixed electrode; and