Photodetector including a Geiger mode avalanche photodiode and an integrated resistor and related manufacturing method

Patent metadata

Field	Value
Publication number	US-10797196-B2
Application number	US-201916386163-A
Country	US
Kind code	B2
Filing date	Apr 16, 2019
Priority date	Apr 17, 2018
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A photodetector includes a Geiger mode avalanche photodiode, which includes a body of semiconductor material, which is delimited by a front surface. The avalanche photodiode further includes: a cathode region having a first type of conductivity, which forms the front surface; and an anode region having a second type of conductivity, which extends in the cathode region starting from the front surface. The photodetector further includes: a dielectric region, arranged on the front surface; a quenching resistor, which extends on the dielectric region, is electrically connected to the anode region, and is laterally spaced apart with respect to the anode region; and an optical-isolation region, which extends through the dielectric region and laterally delimits a portion of the dielectric region, the anode region extending underneath the portion of the dielectric region, the optical-isolation region being moreover interposed between the portion of the dielectric region and the quenching resistor.

First claim

The invention claimed is:

1. A photodetector comprising:
a body of semiconductor material having a front surface;
a Geiger mode avalanche photodiode formed in the body and including:
a cathode region having a first type of conductivity and positioned at the front surface; and
an anode region having a second type of conductivity, which extends in the cathode region starting from the front surface;

a dielectric region arranged on the front surface and above the anode region;
a quenching resistor which extends on the dielectric region, is electrically connected to the anode region, and is laterally spaced apart from the anode region; and
an optical-isolation region which extends through the dielectric region and laterally delimits a portion of the dielectric region, the anode region extending underneath said portion of the dielectric region, the optical-isolation region being moreover interposed between said portion of the dielectric region and the quenching resistor.

2. The photodetector according to claim 1 , wherein the optical-isolation region moreover extends through part of the semiconductor body and laterally envelops at least part of the anode region, the optical-isolation region being moreover interposed between the anode region and the quenching resistor.

3. The photodetector according to claim 1 , further comprising a cavity, which extends through at least part of the semiconductor body, at least in part underneath the quenching resistor.

4. The photodetector according to claim 1 , wherein the quenching resistor is made of polysilicon.

5. The photodetector according to claim 1 , wherein the quenching resistor has an elongated shape.

6. The photodetector according to claim 1 , wherein the optical-isolation region extends in a trench and comprises a conductive region and an insulating region, which surrounds at least part of the conductive region and coats a bottom and side walls of the trench.

7. The photodetector according to claim 1 , further comprising a front region of dielectric material, which extends on the dielectric region and on the quenching resistor; and wherein said optical-isolation region extends in part through said front region.

8. The photodetector according to claim 1 , further comprising an intermediate semiconductor region having the second type of conductivity, which is interposed between the anode region and the dielectric region; and wherein the quenching resistor is electrically coupled to the anode region through the intermediate semiconductor region.

9. The photodetector according to claim 1 , wherein said first type of conductivity is a conductivity of an N type, and wherein said second type of conductivity is a conductivity of a P type.

10. The photodetector according to claim 1 , further comprising a cathode metallization, arranged underneath the semiconductor body, and an anode metallization, which contacts the quenching resistor; and wherein the anode region and the cathode region form a diode; and wherein said diode and the quenching resistor are connected in series between the anode and cathode metallizations.

11. A method for analyzing a sample, comprising:
getting infrared radiation generated by the quenching resistor of the photodetector according to claim 1 to impinge upon the sample; and
detecting radiation coming from the sample using the Geiger mode avalanche photodiode of said photodetector according to claim 1 .

12. An array of devices, comprising:
a die of semiconductor material having a front surface; and
a plurality of photodetectors, each photodetector including:
a Geiger mode avalanche photodiode formed in the die and including:
a cathode region having a first type of conductivity and positioned at the front surface; and
an anode region having a second type of conductivity, which extends in the cathode region starting from the front surface;

a dielectric region arranged on the front surface and above the anode region;
a quenching resistor which extends on the dielectric region, is electrically connected to the anode region, and is laterally spaced apart from the anode region; and
an optical-isolation region which extends through the dielectric region and laterally delimits a portion of the dielectric region, the anode region extending underneath said portion of the dielectric region, the optical-isolation region being moreover interposed between said portion of the dielectric region and the quenching resistor.

13. A method for manufacturing a photodetector, comprising:
forming a Geiger mode avalanche photodiode in a body of semiconductor material, which is delimited by a front surface, said forming the Geiger mode avalanche photodiode including:
forming a cathode region, having a first type of conductivity, at the front surface; and
forming an anode region having a second type of conductivity, which extends in the cathode region starting from the front surface;

forming a dielectric region on the front surface; and
forming, on the dielectric region, a quenching resistor which is electrically connected to the anode region and is laterally spaced apart from the anode region; and
forming, through the dielectric region, an optical-isolation region which laterally delimits a portion of the dielectric region, the anode region extending underneath said portion of the dielectric region, the optical-isolation region being moreover interposed between said portion of the dielectric region and the quenching resistor.

14. The manufacturing method according to claim 13 , wherein forming the optical-isolation region comprises forming the optical-isolation region to extend through part of the semiconductor body and laterally surround at least part of the anode region, the optical-isolation region being moreover interposed between the anode region and the quenching resistor.

15. The manufacturing method according to claim 13 , further comprising forming, underneath at least part of the quenching resistor, a cavity which extends through at least part of the semiconductor body.

16. The manufacturing method according to claim 13 , further comprising forming a front region of dielectric material on the dielectric region and on the quenching resistor; and wherein forming the optical-isolation region is such that the optical-isolation region extends in part through said front region.

17. The manufacturing method according to claim 16 , wherein forming the dielectric region comprises forming a bottom dielectric layer on the front surface and subsequently forming the quenching resistor; and wherein forming the front region comprises:
after forming the quenching resistor, forming an initial dielectric layer, on said bottom dielectric layer and on the quenching resistor;
selectively removing portions of the initial dielectric layer and of said bottom dielectric layer so as to form a trench; and
forming a final dielectric layer on the initial dielectric layer and on the optical-isolation region after forming the optical-isolation region within the trench.

18. The manufacturing method according to claim 13 , wherein the anode region and the cathode region form a diode, said method further comprising:
forming a cathode metallization underneath the semiconductor body;
forming an anode metallization, which contacts the quenching resistor; and
connecting in series said diode and the quenching resistor between the anode and cathode metallizations.

19. The manufacturing method according to claim 13 , further comprising forming, between the anode region and the dielectric region,

Assignees

• St Microelectronics Srl

Inventors

• Mazzillo Massimo Cataldo
• Cinnera Martino Valeria

Classifications

• H10F77/334

  for shielding light, e.g. light blocking layers or cold shields for infrared detectors · CPC title

• H10F77/147

  Shapes of bodies · CPC title

• H10F77/60

  Arrangements for cooling, heating, ventilating or compensating for temperature fluctuations · CPC title

• H10F71/128

  Annealing · CPC title

• H10F39/107

  having multiple elements covered by H10F30/00 in a repetitive configuration, e.g. radiation detectors comprising photodiode arrays · CPC title