Radiation sensor

• US 8,461,533 B2
• Filed: 09/21/2011
• Issued: 06/11/2013
• Est. Priority Date: 11/25/2010
• Status: Active Grant

• Current Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Inventors: Findlay, Ewan
• Primary Examiner(s): Kim, Kiho
• Application Number:
  US13/238,551
• Publication Number:
  US 20120132809A1
• Time in Patent Office: 629 Days
• Field of Search: 250330-335, 2503361-3362, 250/337, 2503381-3385, 25033901-33915, 250/340, 2503411-3418, 250342-353
• US Class Current: 250/353
• CPC Class Codes: G01J 1/0209 Monolithic
• CPC Class Codes: G01J 1/0219 Electrical interface; User interface
• CPC Class Codes: G01J 1/0228 Control of working procedures; Failure detection; Spectral bandwidth calculation
• CPC Class Codes: G01J 1/0233 Handheld
• CPC Class Codes: G01J 1/0247 using a charging unit
• CPC Class Codes: G01J 1/0266 Field-of-view determination; Aiming or pointing of a photometer; Adjusting alignment; Encoding angular position; Size of the measurement area; Position tracking; Photodetection involving different fields of view for a single detector
• CPC Class Codes: G01J 1/0271 Housings; Attachments or accessories for photometers
• CPC Class Codes: G01J 1/0411 using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction
• CPC Class Codes: G01J 1/0492 using at least two different filters
• CPC Class Codes: G01J 1/06 Restricting the angle of incident light
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 1/44 Electric circuits for command of an exposure part G03B7/02
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: H01L 2224/48091 Arched
• 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 31/02019 for devices characterised by at least one potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/02024 : Position sensitive and lateral effect photodetectors; Quadrant photodiodes
• CPC Class Codes: H01L 31/0203 : Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/02162 : for filtering or shielding light, e.g. multicolour filters for photodetectors
• CPC Class Codes: H01L 31/02327 : the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216
• CPC Class Codes: H01L 31/107 : the potential barrier working in avalanche mode, e.g. avalanche photodiodes

Abstract

A radiation sensor includes first and second pixels with a radiation absorption filter positioned over the first pixel and an interference filter positioned over both the first and second pixels. The combined spectral response of the absorption filter and the first pixel has a first pixel pass-band and a first pixel stop-band. The spectral response of the interference filter has an interference filter pass-band which is substantially within the first pixel pass-band for radiation incident on the interference filter at a first angle of incidence, and substantially within the first pixel stop-band for radiation incident on the interference filter at a second angle of incidence greater than the first angle of incidence.

Claims

1. A radiation sensor comprising:

first and second pixels;

a radiation absorption filter positioned over the first pixel but not the second pixel, wherein a combined spectral response of the radiation absorption filter and the first pixel has a first pixel pass-band and a first pixel stop-band; and

an interference filter positioned over the first and second pixels, wherein a spectral response of the interference filter has an interference filter pass-band which is substantially within the first pixel pass-band for radiation incident on the interference filter at a first angle of incidence, and substantially within the first pixel stop-band for radiation incident on the interference filter at a second angle of incidence greater than the first angle of incidence.

2. The radiation sensor of claim 1 wherein the interference filter pass-band has a full-width-half-maximum bandwidth which is less than a full-width-half-maximum bandwidth of the first pixel pass-band.

3. The radiation sensor of claim 1 wherein the interference filter pass-band has a full-width-half-maximum bandwidth which is less than a full-width-half-maximum bandwidth of the first pixel stop-band.

4. The radiation sensor of claim 1 wherein the interference filter pass-band has a full-width-half-maximum bandwidth which is less than a full-width-half-maximum bandwidth of the first pixel pass-band and the full-width-half-maximum bandwidth of the interference filter pass-band is less than a full-width-half-maximum bandwidth of the first pixel stop-band.

5. The radiation sensor of claim 1 wherein the interference filter pass-band has a full-width-half-maximum bandwidth which is less than a 10 dB bandwidth of the first pixel pass-band.

6. The radiation sensor of claim 1 wherein the interference filter pass-band has a full-width-half-maximum bandwidth which is less than a 10 dB bandwidth of the first pixel stop-band.

7. The radiation sensor of claim 1 wherein the interference filter pass-band has a full-width-half-maximum bandwidth which is less than a 10 dB bandwidth of the first pixel pass-band and the full-width-half-maximum bandwidth of the interference filter pass-band is less than a 10 dB bandwidth of the first pixel stop-band.

8. The radiation sensor of claim 1 wherein the radiation absorption filter is a high-pass filter configured to transmit radiation having a wavelength above a predetermined threshold.

9. The radiation sensor of claim 1 wherein the first and second angles of incidence are less than 90°

.

10. The radiation sensor of claim 1 further comprising a lens substantially positioned over the first and second pixels.

11. The radiation sensor of claim 10 wherein the lens is a Fresnel lens.

12. The radiation sensor of claim 10 wherein the lens comprises one of a plurality of lenslets or a diffractive optical element positioned over the first and second pixels.

13. The radiation sensor of claim 10 wherein the lens is positioned between the interference filter and the first and second pixels.

14. The radiation sensor of claim 1 wherein the interference filter comprises a pair of opposing planar reflectors.

15. The radiation sensor of claim 14 wherein at least one of the planar reflectors is only partially reflective.

16. The radiation sensor of claim 1 wherein the interference filter is provided on a substrate.

17. The radiation sensor of claim 16 wherein the interference filter is formed from a coating applied to the substrate.

18. The radiation sensor of claim 1 wherein the radiation absorption filter comprises an organic resist applied to a sensing surface of the first pixel.

19. The radiation sensor of claim 1 wherein the first pixel stop-band substantially comprises wavelengths between 513 nm and 608 nm.

20. The radiation sensor of claim 1 wherein the first pixel pass-band comprises wavelengths exceeding 700 nm.

21. The radiation sensor of claim 1 wherein the interference filter comprises a second interference filter pass-band, the interference filter being configured such that the second interference filter pass-band is substantially within the first pixel stop-band for radiation incident on the interference filter at the first angle of incidence.

22. A combined proximity and ambient light sensor comprising:

first and second pixels;

a radiation absorption filter positioned over the first pixel but not the second pixel, wherein a combined spectral response of the radiation absorption filter and the first pixel has a first pixel pass-band and a first pixel stop-band; and

an interference filter positioned over the first and second pixels, wherein a spectral response of the interference filter has an interference filter pass-band which is substantially within the first pixel pass-band for radiation incident on the interference filter at a first angle of incidence, and substantially within the first pixel stop-band for radiation incident on the interference filter at a second angle of incidence greater than the first angle of incidence.

23. The combined proximity and ambient light sensor of claim 22 further comprising a radiation source.

24. The combined proximity and ambient light sensor of claim 23 wherein the radiation source is one of a light emitting diode or a semi-conductor laser diode.

25. The combined proximity and ambient light sensor of claim 23 wherein the radiation source has an emission spectrum having a full-width-half-maximum line-width which is greater than a full-width-half-maximum line-width of the interference filter pass-band.

26. The combined proximity and ambient light sensor of claim 22 wherein the first pixel is used for proximity sensing.

27. The combined proximity and ambient light sensor of claim 26 wherein the second pixel is used for ambient light sensing.

28. The combined proximity and ambient light sensor of claim 27 wherein the first pixel is used in combination with the second pixel for ambient light sensing.

29. A method of manufacturing a radiation sensor including first and second pixels, the method comprising:

positioning a radiation absorption filter over the first pixel; and

positioning an interference filter over the first and second pixels,

wherein a combined spectral response of the radiation absorption filter and the first pixel has a first pixel pass-band and a first pixel stop-band and

wherein positioning the interference filter comprises providing the interference filter with an interference filter pass-band which is substantially within the first pixel pass-band for radiation incident on the interference filter at a first angle of incidence, and substantially within the first pixel stop-band for radiation incident on the interference filter at a second angle of incidence greater than the first angle of incidence.

30. The method of claim 29 wherein positioning the radiation absorption filter comprises depositing the radiation absorption filter on a sensing surface of the first pixel by lithography.

31. The method of claim 29 wherein positioning the interference filter comprises integrally forming the interference filter with the first and second pixels.

32. The method of claim 29 wherein positioning the interference filter comprises forming the interference filter by applying a coating to a substrate mounted above the first and second pixels.

33. The method of claim 29 further comprising:

providing a plurality of first and second pixels;

positioning a radiation absorption filter over each of the first pixels; and

positioning an interference filter over the first and second pixels.

34. The method of claim 29 wherein the first and second pixels are provided as part of a pixel array.