Semiconductor imaging apparatus and method
A semiconductor imaging apparatus including a light detection device in a silicon substrate, an optical filter arranged to filter light incident on the light detection device and including a gap for allowing unfiltered light to reach the silicon substrate, an isolation structure for stopping light generated charge carriers in the silicon substrate from reaching the light detection device, and a photodiode for detecting the charge carriers.
1. A semiconductor imaging apparatus comprising:
a plurality of light detection devices in a silicon substrate;
an optical filter arranged to filter light incident on said light detection devices and comprising gaps for allowing unfiltered light to reach said silicon substrate between neighbouring light detection devices;
an isolation structure for stopping light generated charge carriers in said silicon substrate from reaching said light detection devices; and
a plurality of photodiodes for detecting said charge carriers in said silicon substrate, wherein said isolation structure comprises a buried oxide layer and deep trench isolation, DTI, wherein said DTI separates said light detection devices from said photodiodes, and wherein said photodiodes are connected to a buried layer in said silicon substrate below said buried oxide layer, so that said photodiodes can detect charge carriers generated in said silicon substrate below said buried oxide layer.
2. A semiconductor imaging apparatus according to claim 1 , wherein said isolation structure comprises a plurality of isolation wells surrounding respective light detection devices of said plurality of light detection devices.
3. A semiconductor imaging apparatus according to claim 2 , wherein said optical filter covers said light detection devices and said isolation wells.
4. A semiconductor imaging apparatus according to claim 2 , wherein said gaps in said optical filter are arranged to allow unfiltered light to reach said silicon substrate adjacent to said isolation wells.
5. A semiconductor imaging apparatus according to claim 1 , wherein each light detection device is a single photon avalanche diode, SPAD.
6. A semiconductor imaging apparatus according to claim 1 , wherein each light detection device is another photodiode, or an avalanche photodiode, APD.
7. A semiconductor imaging apparatus according to claim 1 , further comprising a backend stack comprising a plurality of metal layers located between said silicon substrate and said optical filter.
8. A semiconductor imaging apparatus according to claim 7 , wherein said light detection devices are electrically connected to a first metal layer of said plurality of metal layers.
9. A semiconductor imaging apparatus according to claim 8 , wherein said photodiodes are electrically connected to said first metal layer.
10. A semiconductor imaging apparatus according to claim 1 , wherein said optical filter is an infrared, IR, filter.
11. A semiconductor imaging apparatus according to claim 1 , wherein said optical filter is a bandpass filter having a central wavelength in the range of 850 nm to 940 nm.
12. A semiconductor imaging apparatus according to claim 1 , further comprising an emitter for illuminating an object to be imaged by the imaging apparatus.
13. An imaging method for a semiconductor imaging apparatus according to claim 1 , said method comprising:
performing time-of-flight measurements, TOF, with said light detection devices; and
simultaneously with said TOF measurements, performing visible light photodiode sensing with said photodiodes.
14. A semiconductor imaging apparatus comprising:
a plurality of light detection devices in a silicon substrate;
an optical filter arranged to filter light incident on said light detection devices and comprising gaps for allowing unfiltered light to reach said silicon substrate between neighbouring light detection devices; and
an isolation structure for stopping light generated charge carriers in said silicon substrate from reaching said light detection devices, wherein said isolation structure comprises a plurality of isolation wells surrounding respective light detection devices of said plurality of light detection devices and wherein each isolation well is a photodiode for detecting said charge carriers in said silicon substrate,
wherein said semiconductor imaging apparatus is arranged to perform time of flight, TOF, measurements based on output from said light detection devices, and wherein said semiconductor imaging apparatus is arranged to perform visible, VIS, light imaging based on output from said photodiodes.