# US 12,015,097 B2 · Germanium-based planar photodiode with a compressed lateral peripheral zone

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- Number: US 12,015,097 B2
- Document ID: US12015097B2
- Status: Granted
- Kind: B2
- Application number: 18/483,594
- Filed: 2023-10-10
- Published: 2024-04-18
- Granted: 2024-06-18
- Earliest claimed: 2022-10-14
- Assignees: Commissariat A L'energie Atomique Et Aux Energies Alternatives
- Applicants: Commissariat A L'energie Atomique Et Aux Energies Alternatives
- Inventors: Abdelkader Aliane; Hacile Kaya; Zouhir Mehrez
- Web page: https://patentgrep.com/patent/US12015097B2

## CPC

- H10F 30/2218: {the devices comprising active layers made of only Group IV-VI materials}
- H10F 30/2235: {the devices comprising Group IV amorphous materials}
- H10F 30/223: the potential barrier being a PIN barrier
- H10F 71/121: {The active layers comprising only Group IV materials}
- H10F 71/1215: {comprising at least two Group IV elements, e.g. SiGe}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

The invention relates to a planar photodiode 1 including a detection portion 10 made of a germanium-based material M0, and a peripheral lateral portion 3 including several materials stacked on top of one another, including a material M1 having a coefficient of thermal expansion lower than that of the material M0, and a material M2 having a coefficient of thermal expansion higher than or equal to that of the material M0. The intermediate region 13 includes a portion P1 surrounded by the material M1 and having tensile stresses. It also includes a portion P2 surrounded by the material M2 and having compressive stresses. This portion P2 surrounds a n doped box 12.

## Claims

### Claim 1

A planar photodiode, including:
a detection portion of a main semiconductor layer, made of at least one germanium-based crystalline semiconductor material M0, having first and second faces parallel to a main plane, and including: a p-type doped first region, flush with the first face; a n-type doped second region, flush with the second face; and an intermediate region, extending between the first and second doped regions, and surrounding the second doped region in the main plane while being flush with the second face;
a peripheral lateral portion, intended to be electrically polarized, made of at least one first electrically-conductive material M1, extending, along a vertical axis orthogonal to the main plane, until coming into contact with the first doped region, and extending in contact with the detection portion while surrounding the intermediate region in the main plane;
the first material M1 having a coefficient of thermal expansion CTE1 lower than that of the material M0, extending from the first face,
the intermediate region including a first portion P1, surrounded by the first material M1 in the main plane, having mechanical tensile stresses;
wherein the peripheral lateral portion includes several distinct electrically-conductive materials, stacked on top of one another along the vertical axis, including:
at least one second material M2, extending between the first material M1 and the second face, having a coefficient of thermal expansion CTE2 higher than or equal to that of the material M0,
the intermediate region including a second portion P2 flush with the second face F2, surrounded by the second material M2 in the main plane, formed by a peripheral lateral area Z2p having mechanical compressive stresses, which surrounds a central area Z2c in the main plane having mechanical tensile stresses and where the second doped region is located.

### Claim 2 (depends on 1)

The planar photodiode according to claim 1, wherein the first material M1 extends, along the thickness axis of the photodiode, starting from the first face F1 over a distance comprised between 50% and 80% of the thickness of the detection portion, and the second material M2 extends, along the thickness axis of the photodiode, starting from the first material M1 up to the second face F2 over a distance comprised between 20% and 50% of the thickness of the detection portion.

### Claim 3 (depends on 1)

The planar photodiode according to claim 1, wherein the material M1 is based on p-type doped silicon, and the material M2 is selected from among a metallic material and a p-type doped germanium-based semiconductor material.

### Claim 4 (depends on 1)

The planar photodiode according to claim 1, including an interlayer thin portion, made of at least one metallic material, and located between the p-type doped silicon-based material M1 and the metallic material M2.

### Claim 5 (depends on 1)

The planar photodiode according to claim 1, wherein the first material M1 is made based on p-type doped silicon and the second material M2 is made of a metallic material, the detection portion including a p-type doped lateral region extending over the entire height of the peripheral lateral portion and in contact with the latter.

### Claim 6 (depends on 1)

The planar photodiode according to claim 1, wherein the first material M1 is made based on p-type doped silicon, the detection portion including a lateral area made based on germanium silicon, extending over the entire height of the peripheral lateral portion and in contact with the latter.

### Claim 7 (depends on 1)

The planar photodiode according to claim 1, including an upper insulating layer, made of a dielectric material, extending over the second face in contact with the intermediate region and at the peripheral lateral area Z2p.

### Claim 8 (depends on 1)

A method for manufacturing at least one planar photodiode according to claim 1, including the following steps:
making the main semiconductor layer;
making at least one trench to form the detection portion;
depositing the first material M1 at a deposition temperature T1 higher than room temperature, so as to fill the trench, then returning to room temperature;
making at least one indentation by partial etching of the first material M1;
depositing the second material M2 at a deposition temperature T2 higher than room temperature, so as to fill the indentation, then returning to room temperature, thereby obtaining the central area Z2c and the peripheral lateral area Z2p.

### Claim 9 (depends on 8)

The manufacturing method according to claim 8, including a step of making the second doped region located in the central area Z2c.

### Claim 10 (depends on 8)

The manufacturing method according to claim 8, wherein the main semiconductor layer is made starting from a support layer having a coefficient of thermal expansion lower than the coefficient CTE0 of the material M0.