Shallow junction photodiode for detecting short wavelength light
The present invention is a photodiode or photodiode array having improved ruggedness for a shallow junction photodiode which is typically used in the detection of short wavelengths of light. In one embodiment, the photodiode has a relatively deep, lightly-doped P zone underneath a P+ layer. By moving the shallow junction to a deeper junction in a range of 2-5 μm below the photodiode surface, the improved device has improved ruggedness, is less prone to degradation, and has an improved linear current.
1. A photodiode having a top surface defined by at least one SiO 2 layer comprising:
a low resistivity substrate;
a high resistivity silicon layer positioned atop the low resistivity substrate and below the top surface of the photodiode;
a first P doped zone within the high resistivity silicon layer, wherein the first P doped zone has a thickness of 2-5 μm;
a first P+ doped zone positioned between the top of the first P doped zone and the top of the photodiode.
2. The photodiode of claim 1 wherein the low resistivity substrate has a thickness in a range of 150 μm to 350 μm.
3. The photodiode of claim 1 wherein the low resistivity substrate is doped n+.
4. The photodiode of claim 1 wherein the high resistivity silicon layer has a thickness in a range of 10 μm to 100 μm.
5. The photodiode of claim 1 wherein the high resistivity silicon layer is doped n.
6. The photodiode of claim 1 wherein the first P+ doped zone and a portion of the first P doped zone is surrounded by P+ doped ring.
7. The photodiode of claim 1 further comprising a first N+ region extending throughout the thickness of the high resistivity silicon layer.
8. The photodiode of claim 7 further comprising a second N+ region extending throughout the thickness of the high resistivity silicon layer, wherein the second N+ region is separated from the first N+ region by a third region and wherein the first P doped zone and first P+ doped zone is located in the third region.
9. The photodiode of claim 8 further comprising a third N+ region extending throughout the thickness of the high resistivity silicon layer, wherein the third N+ region is separated from the second N+ region by a fourth region.
10. The photodiode of claim 1 further comprising a second P doped zone within said fourth region in the high resistivity silicon layer, wherein the second P doped zone has a thickness of 2-5 μm.
11. The photodiode of claim 2 further comprising a second P+ doped zone positioned between the top of the second P doped zone and the top of the photodiode in the fourth region.
12. The photodiode of claim 1 wherein all of the first P+ doped zone and a portion of the first P doped zone is surrounded by P+ doped ring.
13. The photodiode of claim 1 wherein all of the second P+ doped zone and a portion of the second P doped zone is surrounded by P+ doped ring.
14. The photodiode of claim 1 further comprising an anode and a cathode on the top surface of the photodiode.
15. The photodiode of claim 1 further comprising an anode on the top surface of the photodiode and a cathode on a backside of the photodiode.
16. The photodiode of claim 1 further comprising an anode on the top surface of the photodiode, a cathode on the top surface of the photodiode, and a cathode on a backside of the photodiode.