CN113270505B - A photodetector structure and preparation method thereof - Google Patents

Abstract

The invention relates to the field of semiconductor production, in particular to a photoelectric detector structure and a preparation method thereof. A photodetector structure comprising: the silicon oxide layer comprises a substrate, a first silicon oxide layer, a second silicon oxide layer, an aluminum oxide layer and a P-I-N stacked layer, wherein the thickness of the second silicon oxide layer is 10 nm-1 mu m. The preparation method comprises the following steps: forming a germanium buffer layer on a substrate; forming an intrinsic semiconductor layer; forming a P-type semiconductor layer; forming an alumina layer, forming or not forming a second silicon dioxide layer, obtaining a substrate A, wherein the thickness of the second silicon dioxide layer is 10 nm-1 mu m; forming a first silicon oxide layer on another substrate, and if the substrate A does not form a second silicon oxide layer, continuing to form the second silicon oxide layer to obtain a substrate B; bonding the substrate A and the substrate B; removing the substrate and the germanium buffer layer in the substrate A; an N-type semiconductor layer is formed. The thicker double-layer silicon oxide structure is arranged below the PIN stacking structure, so that the optical reflection inside the device is enhanced, an optical resonant cavity is formed inside the device, and the effect of the optical resonant cavity is enhanced.

Description

A photodetector structure and preparation method thereof

Technical Field

The present invention relates to the field of semiconductor production, and in particular to a photoelectric detector structure and a preparation method thereof.

Background technique

High-performance photodetectors are core devices that connect optical devices and electronic devices. Their excellent photoelectric performance provides a solid foundation for the efficient conversion and transmission of photoelectric signals and the accurate reading of information, and provides core equipment support for optoelectronic integrated chip technology solutions.

Most of the traditional PIN detector structures have no optical resonance enhancement effect, and their responsiveness needs to be improved. There are also a few detectors with resonant cavity structures, but they usually use Bragg reflectors with fine and complex structures, and the manufacturing process is also very complicated.

To this end, the present invention is proposed.

Summary of the invention

The main purpose of the present invention is to provide a photodetector structure, which has a thicker double-layer silicon oxide structure under the PIN stack structure, which is beneficial to enhancing the optical reflection inside the device, forming an optical resonant cavity inside the device, and enhancing its optical resonant cavity effect; under the same incident light conditions, the photodetector with this structure has higher responsiveness and stronger photoelectric conversion capability than traditional detectors.

Another object of the present invention is to provide a method for preparing the above-mentioned photodetector structure. This method first separately manufactures two substrates and then bonds them to integrate the multi-layer structure into one, which has the advantages of fewer material defects and simple process.

A photodetector structure, comprising:

Substrate,

The first silicon oxide layer,

a second silicon oxide layer, wherein the thickness of the second silicon oxide layer is 10 nm to 1 μm,

Aluminum oxide layer,

P-I-N stacked layers.

A method for preparing a photodetector structure, comprising:

Forming substrate A:

forming a germanium buffer layer on the substrate;

forming an intrinsic semiconductor layer;

forming a P-type semiconductor layer;

Forming an aluminum oxide layer,

Forming or not forming a second silicon oxide layer to obtain a substrate A, wherein the thickness of the second silicon oxide layer is 10 nm to 1 μm;

Forming substrate B: forming a first silicon oxide layer on another substrate, and if the second silicon oxide layer is not formed on substrate A, continuing to form the second silicon oxide layer to obtain substrate B;

Bond:

Bonding the substrate A and the substrate B;

removing the substrate and the germanium buffer layer in the substrate A;

An N-type semiconductor layer is formed on the surface of the intrinsic semiconductor layer, or N-type ions are implanted into a shallow layer of the intrinsic semiconductor layer to form the N-type semiconductor layer.

Compared with the prior art, the present invention achieves the following technical effects:

(1) A thicker double-layer silicon oxide structure is provided under the PIN stack structure, which is beneficial to enhancing the optical reflection inside the device, forming an optical resonant cavity inside the device, and enhancing its optical resonant cavity effect; under the same incident light conditions, the photodetector with this structure has a higher responsiveness and a stronger photoelectric conversion capability than traditional detectors.

(2) The defect problem of the PIN stacking structure can be reduced and the device reliability can be improved by first making the P layer and the I layer, then bonding them, and finally making the N layer.

(3) High-quality germanium can be obtained based on the epitaxial germanium buffer layer, thereby improving device reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the invention.

FIG1 is a schematic diagram of the structure of a photoelectric detector provided by the present invention;

2 to 6 are schematic diagrams of structures formed in different steps in making the structure shown in FIG. 1 .

Detailed ways

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may further design regions/layers with different shapes, sizes, and relative positions according to actual needs.

In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, the layer/element may be directly on the other layer/element or an intervening layer/element may exist between them. In addition, if a layer/element is "on" another layer/element in one orientation, the layer/element may be "below" the other layer/element when the orientation is reversed.

The photodetector structure shown in FIG1 has a thicker double-layer silicon oxide structure disposed below the PIN stack structure, which is beneficial for enhancing the optical reflection inside the device, forming an optical resonant cavity inside the device, and enhancing its optical resonant cavity effect.

The detector consists of the following stacked from bottom to top:

Substrate 201,

The first silicon oxide layer 202,

The second silicon oxide layer 106 has a thickness of 10 nm to 1 μm.

Aluminum oxide layer 105,

P-I-N stacked layers.

Among them, the substrate is mainly a silicon-based substrate (but the present invention is not particularly limited to this and is also applicable to substrates of other semiconductor materials), but there are no specific requirements on the crystal orientation, the presence or absence of a buried oxide layer, etc. It can be any substrate known to those skilled in the art for carrying semiconductor integrated circuit components, such as silicon-on-insulator (SOI), bulk silicon, silicon germanium, etc.

The thickness of the first silicon oxide layer 202 is preferably 10 nm to 1 μm, and the thickness of the aluminum oxide layer 105 is not particularly limited.

The thickness of the second silicon oxide layer 106 is one of the keys to forming a resonant cavity, and the thickness is required to reach 10 nm to 1 μm. Thus, under the same incident light condition, the photodetector shown in FIG. 1 has a higher responsiveness and a stronger photoelectric conversion capability than a traditional detector.

The P-I-N stacked layer mainly refers to a vertical stacked structure, including a P-type doped semiconductor layer, an intrinsic semiconductor layer and an N-type doped semiconductor layer, all of which use germanium, as shown in FIG. 1 , respectively a P-type germanium layer 104, an intrinsic germanium layer 103 and an N-type germanium layer 107.

The P-I-N stacked layer is also connected to electrodes, usually the P layer and the N layer are connected to electrodes respectively.

The photodetector may be any detector for any purpose, such as a photoelectron emission device, a photomultiplier tube, a photoconductive device, etc.

The preparation method of the above-mentioned photodetector is critical to its quality. The following method can be used to obtain a high-quality, defect-free, and highly responsive device, including the preparation of a sacrificial substrate, a supporting substrate, and bonding.

Prepare substrate A (i.e. sacrificial substrate) as shown in FIG2:

In the first step, a germanium buffer layer 102 is formed on the substrate 101. The substrate used in this step is mainly a silicon-based substrate (but the present invention is not particularly limited to this, and is also applicable to substrates of other semiconductor materials), but there are no specific requirements for the crystal orientation, the presence or absence of a buried oxide layer, etc., and it can be any substrate known to those skilled in the art for carrying semiconductor integrated circuit components, such as silicon-on-insulator (SOI), bulk silicon, germanium silicon, etc.

In the second step, taking germanium as an example, an intrinsic semiconductor layer 103 is formed. The formation means is arbitrary, such as typical APCVD, UHVCVD, LPCVD, RTCVD, PECVD, MBE or epitaxial growth, etc., preferably RPCVD.

The third step is to form a P-type germanium layer 104. The forming method is also arbitrary, such as typical APCVD, UHVCVD, LPCVD, RTCVD, PECVD, MBE or epitaxial growth, preferably RPCVD. Synchronous doping or distributed doping, the P-type doping ions can be boron, gallium, etc.

The fourth step is to form an aluminum oxide layer 105. Aluminum oxide can reduce interface defects and enhance adhesion.

The fifth step is to form a second silicon oxide layer 106, and the thickness of the second silicon oxide layer is 10nm to 1μm; the deposition means include but are not limited to APCVD, UHVCVD, LPCVD, RTCVD, PECVD, etc. (except for the oxide layer formed by thermal oxidation, including silicon oxide whose silicon source is tetraethyl orthosilicate (TEOS)).

Prepare substrate B (i.e., supporting substrate) as shown in FIG3:

A first silicon oxide layer 202 is formed on another substrate 201. The first silicon oxide layer 202 is a thermal oxide layer. The substrate is mainly a silicon-based substrate (but the present invention is not particularly limited to this and is also applicable to substrates of other semiconductor materials). However, there are no specific requirements on the crystal orientation, the presence or absence of a buried oxide layer, etc. It can be any substrate known to those skilled in the art for carrying semiconductor integrated circuit components, such as silicon-on-insulator (SOI), bulk silicon, silicon germanium, etc.

Bond:

In the first step, the substrate A described in FIG. 2 and the substrate B described in FIG. 3 are bonded, so that the first silicon oxide layer 202 and the second silicon oxide layer 106 are in contact, and a structure as shown in FIG. 4 is obtained; before bonding, the surface silicon oxide layer is subjected to surface smoothing treatment, such as CMP.

In the second step, the substrate 101 and the germanium buffer layer 102 are removed to obtain a structure as shown in FIG. 5 ; the removal method is not limited, such as a combination of one or more methods including grinding and polishing, wet etching, dry etching, and CMP.

In the third step, an N-type germanium layer 107 is formed on the surface of the intrinsic layer, as shown in FIG. 1 , or an N-type ion implantation is performed on the shallow surface of the intrinsic layer to form an N-type germanium layer. The N-type ions may be phosphorus, arsenic, etc.

Finally, the electrode and detector structure are formed, as shown in FIG6 .

Alternatively, the present invention can also form a second silicon oxide layer on the substrate B, and the specific method is as follows:

Making substrate A:

In the first step, a germanium buffer layer is formed on the substrate.

The second step is to form an intrinsic germanium layer.

The third step is to form a P-type germanium layer.

The fourth step is to form an aluminum oxide layer.

Making substrate B (i.e. supporting substrate):

In the first step, a first silicon oxide layer is formed on another substrate, where the first silicon oxide layer is a thermal oxide layer.

In the second step, a second silicon oxide layer is formed, and the thickness of the second silicon oxide layer is 10 nm to 1 μm. The formation method adopts methods other than thermal oxidation, and the deposition means include but are not limited to APCVD, UHVCVD, LPCVD, RTCVD, PECVD, etc. (the oxide layer formed in addition to the thermal oxidation form includes silicon oxide whose silicon source is tetraethyl orthosilicate (TEOS)).

Bond:

In the first step, substrate A and substrate B are bonded; before bonding, surface smoothing treatment such as CMP is performed.

The second step is to remove the silicon substrate and the germanium buffer layer of the substrate A; the removal method is not limited, such as polishing, wet etching, dry etching, CMP or a combination of one or more methods.

The third step is to form an N-type germanium layer on the surface of the intrinsic layer, or to perform N-type ion implantation on the shallow layer of the intrinsic layer to form an N-type germanium layer. The N-type ions may be phosphorus, arsenic, etc.

Finally, the electrode and detector structure are formed, as shown in FIG6 .

The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, a person skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims (8)

1. A photodetector structure comprising, stacked in order from bottom to top:

The substrate is provided with a plurality of holes,

A first silicon oxide layer, the first silicon oxide layer being a thermal oxide layer;

the thickness of the second silicon dioxide layer is 10 nm-1 mu m, and the second silicon dioxide layer is a TEOS silicon oxide layer; the first silicon oxide layer and the second silicon oxide layer which are adjacently stacked are used for enhancing the internal optical reflection of the photoelectric detector and enhancing the optical resonant cavity effect;

The layer of aluminum oxide is formed from a layer of aluminum oxide,

P-I-N stack layers.

2. The photodetector structure of claim 1 wherein the P-I-N stack layer comprises, stacked from bottom to top: a P-type doped germanium layer, a germanium intrinsic layer, and an N-type doped germanium layer.

3. The photodetector structure of claim 1 or 2 wherein the P-I-N stack is connected to an electrode.

4. A method of fabricating a photodetector structure, comprising:

Forming a substrate A:

Forming a germanium buffer layer on a substrate;

forming an intrinsic semiconductor layer;

Forming a P-type semiconductor layer;

An aluminum oxide layer is formed and is formed,

Forming or not forming a second silicon dioxide layer to obtain a substrate A, wherein the thickness of the second silicon dioxide layer is 10 nm-1 mu m;

Forming a substrate B: forming a first silicon oxide layer on another substrate, and if the substrate A does not form the second silicon oxide layer, continuing to form the second silicon oxide layer to obtain a substrate B; the first silicon oxide layer is a thermal oxide layer; the second silicon dioxide layer is a TEOS silicon dioxide layer;

Bonding:

Bonding the substrate A and the substrate B; the first silicon oxide layer and the second silicon oxide layer which are adjacently stacked are used for enhancing the internal optical reflection of the photoelectric detector and enhancing the optical resonant cavity effect;

removing the substrate and the germanium buffer layer in the substrate A;

and forming an N-type semiconductor layer on the surface of the intrinsic semiconductor layer, or performing N-type ion implantation on a shallow surface layer of the intrinsic semiconductor layer to form the N-type semiconductor layer.

5. The method of manufacturing according to claim 4, further comprising, after forming the N-type semiconductor layer: and manufacturing an electrode.

6. The method of claim 4, wherein the semiconductor used for the P-type semiconductor layer, the intrinsic semiconductor layer, and the N-type semiconductor layer is germanium.

7. The method of manufacturing according to claim 4, wherein the substrate and the germanium buffer layer in the substrate a are removed by at least one of polishing, wet etching, dry etching, and chemical mechanical polishing.

8. The method according to claim 4, wherein the substrate having a silicon oxide surface is further subjected to a CMP treatment before the bonding.