Ultraviolet sensor having filter

Patent metadata

Field	Value
Publication number	US-10132679-B2
Application number	US-201414580406-A
Country	US
Kind code	B2
Filing date	Dec 23, 2014
Priority date	May 23, 2014
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

Techniques are provided to furnish a light sensor that includes a filter positioned over a photodetector to filter visible and infrared wavelengths to permit the sensing of ultraviolet (UV) wavelengths. In one or more implementations, the light sensor comprises a semiconductor device (e.g., a die) that includes a substrate. A photodetector (e.g., photodiode, phototransistor, etc.) is formed in the substrate proximate to the surface of the substrate. In one or more implementations, the substrate comprises a silicon on insulator substrate (SOI). A filter (e.g., absorption filter, interference filter, flat pass filter, McKinlay-Diffey Erythema Action Spectrum-based filter, UVA/UVB filter, and so forth) is disposed over the photodetector. The filter is configured to filter infrared light and visible light from light received by the light sensor to at least substantially block infrared light and visible light from reaching the photodetector. The thickness of the SOI substrate can be tailored to modify received UV/visible wavelength ratios.

First claim

What is claimed is:

1. A light sensor comprising:
a substrate having two insulating layers and a surface;
a photodetector formed in the substrate and disposed between the two insulating layers, the photodetector configured to detect light and to provide a signal in response thereto, the photodetector including a first photodetector and a second photodetector;
a filter formed via a magnetron sputtering deposition technique proximate the surface of the substrate, the filter comprising a plurality of dielectric layers in a stacked configuration, defining:
a first filter configured to block light outside of an ultraviolet spectrum of wavelengths in the range of approximately one hundred (100) nanometers to approximately four hundred (400) nanometers, including visible light, and to allow Ultraviolet A light and Ultraviolet B light to pass to the photodetector including the first photodetector and the second photodetector; and
a second filter configured to block light outside of the Ultraviolet A spectrum from the second photodetector, and to allow Ultraviolet A light to pass to the second photodetector.

2. The light sensor as recited in claim 1 , wherein the substrate is a silicon on insulator (SOI) substrate.

3. The light sensor as recited in claim 1 , wherein the filter includes hafnium oxide.

4. The light sensor as recited in claim 1 , wherein the filter includes a weighting factor to provide a McKinlay-Diffey Erythema Action Spectrum as an output of the photodetector.

5. The light sensor as recited in claim 1 , wherein the filter is configured as an intermediate McKinlay-Diffey Erythema Action Spectrum filter that controls an amount of passage of at least one of ultraviolet A light and ultraviolet B light.

6. The light sensor as recited in claim 1 , wherein at least a portion of the substrate is configured as at least one of a vertical junction or a horizontal junction.

7. The light sensor as recited in claim 1 , further comprising a filter configured to block all light from the photodetector to provide a dark current value from the photodetector.

8. The light sensor as recited in claim 7 , further comprising circuitry configured to subtract the dark current from another signal provided from the photodetector when at least a portion of light is passed to the photodetector.

9. The light sensor as recited in claim 1 , wherein a signal output from the first photodetector subtracted by a signal output from the second photodetector provides an indication of detected ultraviolet B light.

10. A process comprising:
forming a photodetector in a substrate having two insulating layers, the photodetector disposed between the two insulating layers and configured to detect light and to provide a signal in response thereto, the photodetector including a first photodetector and a second photodetector;
forming a filter via a magnetron sputtering deposition technique proximate to and on a surface of the substrate, the filter comprising a plurality of dielectric layers in a stacked configuration, defining:
a first filter configured to block light outside of an ultraviolet spectrum of wavelengths in the range of approximately one hundred (100) nanometers to approximately four hundred (400) nanometers, including visible light, and to allow Ultraviolet A light and Ultraviolet B light to pass to the photodetector including the first photodetector and the second photodetector; and
a second filter configured to block light outside of the Ultraviolet A spectrum from the second photodetector, and to allow Ultraviolet A light to pass to the second photodetector.

11. The process as recited in claim 10 , wherein forming a filter on the surface of the substrate includes coating a portion of a wafer with a photoresist, the wafer comprising the substrate.

12. The process as recited in claim 11 , further including depositing a filter material onto the surface.

13. The process as recited in claim 12 , further including performing a lift off technique to remove the photoresist.

14. The process of claim 10 , further including singulating an ultraviolet sensor from a wafer comprising the substrate.

15. The process of claim 14 , further including packaging the ultraviolet sensor to form an ultraviolet sensor package.

16. The process of claim 10 , further including modifying at least a portion of the substrate via laser annealing to provide a dopant profile.

17. The process of claim 10 , further including modifying at least a portion of the substrate via Epi growth to provide a dopant profile.

18. The process of claim 10 , further including providing circuitry to subtract a dark current value from the signal provided by the photodetector.

Assignees

• Maxim Integrated Products

Inventors

• Emadi Arvin
• Kerness Nicole D
• Pei Cheng-Wei
• Jones Joy T
• Samoilov Arkadii V
• Zeng Ke-Cai

Classifications

• H01L31/02162

  Electricity · mapped topic

• G01J1/0488

  with spectral filtering · CPC title

• G01J1/429 Primary

  applied to measurement of ultraviolet light (using counting tubes G01T) · CPC title

• H10F77/331

  for filtering or shielding light, e.g. multicolour filters for photodetectors · CPC title

• H10F30/21 Primary

  the devices being sensitive to infrared, visible or ultraviolet radiation · CPC title