RU2790061C1 - Method for manufacturing a two-spectrum photosensitive element based on a schottky barrier - Google Patents

Abstract

FIELD: dual-spectrum photosensitive devices.

SUBSTANCE: method is used to manufacture dual-spectrum photosensitive devices designed for independent registration of radiation in the near ultraviolet (UV) and mid-infrared (IR) ranges of the spectrum. A method for manufacturing a two-spectrum photosensitive element based on a Schottky barrier includes deposition of AuGe on the reverse side of the substrate, fast thermal annealing, deposition of Ti-Au on the reverse side of the substrate, deposition of barrier Au on the epitaxial layer, etching of barrier Au using mesa technology, formation of a mask photoresist for "explosion", "explosion" of Au with photoresist, while after the Ti-Au deposition operation, the following operations are carried out: formation of a photoresist mask on the reverse side of the substrate for Au-Ti-AuGe etching to the substrate, deposition of barrier Au on the reverse side of the substrate, etching of barrier Au using mesa technology.

EFFECT: manufacturing dual-spectrum photosensitive devices.

1 cl, 1 dwg

Description

The claimed method of manufacturing a two-spectrum photosensitive element relates to the field of technologies for the production of semiconductor devices designed to detect and record radiation in the near ultraviolet (UV) and mid-infrared (IR) spectral range.

The method for manufacturing the device includes the formation of n-type Schottky photodiodes on the GaP epitaxial structure with different barrier heights for independent detection of near UV and mid-IR radiation. The creation of the device includes the formation of photosensitive elements, Schottky diodes, on the epitaxial structure. A Schottky diode with a barrier height of 1.3 V, designed to detect near UV radiation, is formed on an epitaxial layer with a concentration of n = 10 ¹⁶ cm ^-3 , and a Schottky diode with a barrier height of 0.3 V, designed to detect mid-IR radiation, is formed on a substrate with a concentration n = 2×10 ¹⁹ cm ^-3 .

Devices obtained by this method are dual-spectrum photodetectors capable of simultaneously receiving optical radiation with different wavelengths, near UV and mid-IR.

The claimed method makes it possible to manufacture devices capable of operating in two spectral ranges - near UV and mid-IR, which are two-spectrum photodetectors: some of the elements are formed on the GaP epitaxial layer using a mesa technology with an available photomask, and operate in the near ultraviolet range, as threshold devices (sensitivity is provided due to its own absorption), the other part of the elements is formed on the GaP substrate, using a new photomask using mesa technology with preliminary etching (the photomask is applied to the ohmic contact substrate), operating in the mid-infrared range as high-power optical signal detectors (sensitivity is provided by absorption on free charge carriers and separation of "hot" carriers at the Schottky barrier with a lower barrier height).

Closest to the claimed method and taken as a prototype is a method for manufacturing a two-spectrum photodetector element, the invention of a two-spectrum photodetector [patent RU 2708553, H01L 27/14], in which the creation of a photosensitive element designed to detect high-power optical signals of the middle IR due to absorption on free charge carriers and the separation of "hot" carriers on a Schottky barrier with a lower barrier height, was obtained by forming a Schottky diode to the near-surface region with an increased concentration of charge carriers n = 10 ¹⁹ cm ^-3 , by the ion implantation method, on the epitaxial layer.

The prototype manufacturing method includes the following technological operations:

1. Formation of a photoresist mask for ion implantation into the epitaxial layer;

2. Ion implantation;

3. Photoresist removal;

4. Dielectric deposition on both sides;

5. Annealing of the implanted layer;

6. Removal of the dielectric from both sides;

7. AuGe deposition on the reverse side of the substrate;

8. Rapid thermal annealing (RHT);

9. Ti-Au deposition on the reverse side of the substrate;

10. Deposition of barrier Au on the epitaxial layer;

11. Barrier Au etching + mesa technology;

12. Formation of a photoresist mask under the "explosion";

13. Deposition of contact Au on the epitaxial layer;

14. "Explosion" of Au with a photoresist.

In the claimed method, the technical result is achieved by the fact that in order to create a photosensitive element designed to detect high-power optical mid-IR signals due to absorption on free charge carriers and separation of "hot" carriers on a Schottky barrier with a lower barrier height, the substrate itself was used, the concentration charge carriers in which (n = 2×10 ¹⁹ cm ^-3 ) is higher than in the epitaxial layer (n = 10 ¹⁶ cm ^-3 ). This is realized by the following technological operations:

1. AuGe deposition on the reverse side of the substrate;

2. Rapid thermal annealing (RHT);

3. Ti4-Au deposition on the reverse side of the substrate;

4. Formation of a photoresist mask on the reverse side for Au-Ti-AuGe etching to the substrate;

5. Deposition of barrier Au on the reverse side of the substrate;

6. Barrier Au etching + mesa technology;

7. Deposition of barrier Au on the epitaxial layer;

8. Barrier Au etching + mesa technology;

9. Formation of the photoresist mask under the "explosion";

10. Deposition of contact Au on the epitaxial side;

11. "Explosion" of Au with a photoresist.

The method for manufacturing a two-spectrum photosensitive element includes the formation of Schottky photodiodes on the GaP epitaxial structure of the n-type for independent registration of the near UV and mid-IR spectrum. Crystal formation includes: creation on the substrate of an epitaxial GaP structure with a charge carrier concentration n = 2×10 ¹⁹ cm ^-3 of an ohmic contact (AuGe-GaP), contact metallization (Au-Ti), a Schottky diode (Au-GaP); creation of a Schottky diode (Au-GaP) on the GaP epitaxial layer with a charge carrier concentration n = 10 ¹⁶ cm ^-3 , a contact to the Schottky diode (Au).

The manufacturing method is illustrated by the figure of Fig.1. Structure of a two-spectral photosensitive element.

A device with photosensitive elements in the form of Schottky diodes manufactured according to the claimed method is a single-layer epitaxial structure based on gallium phosphide (GaP) and includes:

1 - single-crystal GaP substrate (n = 2×10 ¹⁹ cm ^-3 );

2 - GaP epitaxial layer (n = 10 ¹⁶ cm ^-3 );

3 - ohmic contact to the gold-germanium (Au-Ge) substrate;

4 - gold with titanium sublayer (Au-Ti);

5 - thick gold (d _(Au) = 3000 Å) to the substrate, acting as a barrier and contact;

6 - thin barrier gold (d _(Au) = 100 Å) and thick contact gold (d _(Au) = 3000 Å) to the epitaxial layer.

Two variations of photosensitive elements based on the Au-GaP Schottky barrier of the same type of conductivity are sensitive in two different spectral ranges: near UV and mid-IR.

The claimed method of manufacturing differs from the method of the prototype in that the Schottky diode, with a low barrier height, for registration of average IR radiation is formed to the substrate of the GaP epitaxial structure with a high concentration of charge carriers n = 2×10 ¹⁹ cm ^-3 , while in the prototype method to create the same Schottky diode, ion implantation into the epitaxial layer was made in order to create on the surface of the epitaxial layer a region with an increased concentration of charge carriers n = 10 ¹⁹ cm ^-3 compared with the initial concentration of the epitaxial layer n = 10 ¹⁶ cm ^-3 .

The advantage of the proposed method for manufacturing a two-spectrum photosensitive element is that the use of a GaP substrate with an initial high concentration of charge carriers n = 2×10 ¹⁹ cm ^-3 in the formation of a Schottky diode with a low barrier height for recording average IR radiation is more stable than the use of ion implantation with subsequent annealing, to achieve the same goal.

Claims (1)

A method for manufacturing a two-spectrum photosensitive element based on a Schottky barrier, including deposition of AuGe on the reverse side of the substrate, fast thermal annealing (RTA), deposition of Ti-Au on the reverse side of the substrate, deposition of barrier Au on the epitaxial layer, etching of barrier Au using mesa technology, formation of a photoresist mask for “explosion”, “explosion” of Au with photoresist; characterized in that after the Ti-Au deposition operation, the following operations are carried out: formation of a photoresist mask on the reverse side of the substrate for etching Au-Ti-AuGe to the substrate, deposition of barrier Au on the reverse side of the substrate, etching of barrier Au using mesa technology.

Images