CN109103283B - Transverse germanium detector structure and preparation method - Google Patents

Abstract

The invention comprises a transverse germanium detector structure and a preparation method thereof, wherein the transverse germanium detector structure is a transverse photodiode and comprises a silicon substrate; a silicon oxide layer is deposited on the upper surface of the silicon substrate; the silicon oxide layer includes a top layer silicon; the germanium layer is formed on the upper surface of the top silicon and comprises a germanium layer main body, a first extending part and a second extending part, wherein the first extending part and the second extending part extend from the germanium layer main body to two sides respectively; and the silicon nitride waveguide is formed above the germanium layer and is of a conical structure. Has the advantages that: through reforming transform germanium layer structure, effectively strengthen the coupling efficiency that silicon nitride waveguide couples to the germanium detector, can realize the effective integration of optical multiplexer and optical demultiplexer and germanium detector, can also be applied to the photoelectric detection field of high optical power and high bandwidth.

Description

A kind of lateral germanium detector structure and preparation method

technical field

The invention relates to the technical field of optical devices, in particular to a lateral germanium detector structure and a preparation method.

Background technique

Optical multiplexer (mux) and optical demultiplexer (demux) are one of the very important optical devices in optoelectronic chips at present. Considering the stability of optical multiplexer or optical demultiplexer, for example, it is affected by temperature and process. The optical multiplexer and the optical demultiplexer are caused by the shift of the center wavelength and the deformation of the spectral curve due to the conditions. We need to select suitable materials to prepare the optical multiplexer and the optical demultiplexer. Since the influence of the refractive index of silicon nitride (SiN) and silicon oxynitride (SiON) with temperature changes is much smaller than that of silicon (Si) materials, SiN or SiON are selected as materials for optical multiplexers and optical demultiplexers. In the application, the end of the optical multiplexer and the optical demultiplexer will be connected with the detector (PD) to realize photoelectric conversion. In ordinary optical module products, the optical multiplexer, the optical demultiplexer and the detector are in separate two The connection is realized by optical fiber (fiber) on each chip, which further increases the size and area of the product and increases the complexity of the back-end optical process. Germanium (Ge) detector, the light is coupled into the Ge detector by the Si waveguide, the Ge detector structure is usually a vertical PIN structure, and this detector structure is not suitable for the application scenario of this patent, followed by the traditional CMOS process. Ge detectors have relatively small saturation photocurrents, so they cannot be used for high optical power detection.

SUMMARY OF THE INVENTION

In view of the above problems existing in the prior art, a lateral germanium detector structure and a preparation method are now provided.

The specific technical solutions are as follows:

A lateral germanium detector structure, wherein the lateral germanium detector structure is a lateral photodiode, specifically comprising:

a silicon substrate;

A silicon oxide layer is deposited on the upper surface of the silicon substrate; the silicon oxide layer includes:

a top layer of silicon;

A germanium layer is formed on the upper surface of the top layer silicon, the germanium layer includes a germanium layer main body, and a first extension portion and a second extension portion extending from the germanium layer main body to two sides respectively. An extension portion and the second extension portion respectively form a first doped region and a second doped region, and a first doped region is respectively formed on the upper surface of the first doped region and the second doped region an electrode and a second electrode, the first electrode and the second electrode respectively extend upward from the silicon oxide layer;

A silicon nitride waveguide is formed above the germanium layer, the silicon nitride waveguide has a tapered structure, the silicon nitride waveguide has a first end and a second end, and the first end is smaller than the At the second end, the silicon nitride waveguide is used for receiving an optical signal and coupling the optical signal to the germanium layer, and the germanium layer is used for receiving the optical signal and converting the optical signal into electric signal.

Preferably, the germanium layer body, the first extension portion and the second extension portion form the germanium layer of an integrally formed T-shaped structure.

Preferably, the germanium layer body, the first extension part and the second extension part fully cover the top layer silicon.

Preferably, N+ ions are doped in the first doping region to form an N+ first implanting region;

N++ ions are doped into the N+ first implanted region to form an N++ first implanted region.

Preferably, the second doping region is doped with P+ ions to form a P+ second implanting region;

P++ ions are doped into the P+ second implantation region to form a P++ second implantation region.

Preferably, the thickness of the silicon nitride waveguide is at least 0.2um;

The width of the first end is 0.1-0.5um;

The width of the second end is 0.5-1.5um.

Preferably, the preset distance between the silicon nitride waveguide and the germanium layer is 0-0.2um.

A method for preparing a lateral germanium detector structure, characterized in that it is used in any one of the lateral germanium detector structures, wherein the lateral germanium detector structure is a lateral photodiode, comprising:

A silicon substrate is provided, and a silicon oxide layer and a top layer of silicon are sequentially formed on the silicon substrate;

The preparation method specifically includes:

Step S1, depositing a silicon oxide layer on the top silicon layer, opening a process window on the silicon oxide layer, forming a germanium layer in the process window, the germanium layer comprising a germanium layer main body, and the a first extension part and a second extension part respectively extending to both sides of the germanium layer body;

Step S2, doping the first extension portion and the second extension portion respectively to form a first doping region and a second doping region;

Step S3, depositing a silicon oxide layer on the germanium layer, forming a silicon nitride waveguide on the silicon oxide layer, the silicon nitride waveguide has a tapered structure, and the silicon nitride waveguide has a first end and a second end, the first end is smaller than the second end;

Step S4, depositing a silicon oxide layer on the silicon nitride waveguide, opening a first contact hole and a second contact hole on the silicon oxide layer, the first contact hole and the second contact hole respectively located on the upper surfaces of the first doped region and the second doped region;

Step S5 , filling the first contact hole and the second contact hole with metal respectively to form a first electrode and a second electrode, the first electrode and the second electrode respectively extend upwardly out of the hole. the silicon oxide layer.

Preferably, the germanium layer body, the first extension portion and the second extension portion form the germanium layer of an integrally formed T-shaped structure.

Preferably, the germanium layer body, the first extension part and the second extension part fully cover the top layer silicon.

The beneficial effect of the technical solution of the present invention is that the lateral germanium detector structure is a lateral photodiode structure, and by transforming the germanium layer structure and doping the two sides of the germanium layer respectively, the coupling of the silicon nitride waveguide to the germanium detector is effectively enhanced. The coupling efficiency can realize the effective integration of the optical multiplexer, the optical demultiplexer and the germanium detector. Compared with the traditional germanium detector, the silicon nitride coupled germanium detector can also be applied to high optical power and high bandwidth optoelectronics. in the detection field.

Description of drawings

Embodiments of the present invention are described more fully with reference to the accompanying drawings. However, the accompanying drawings are for illustration and illustration only, and are not intended to limit the scope of the present invention.

FIG. 1 is a schematic diagram of the overall structure of a preferred embodiment of the lateral germanium detector structure in the present invention;

FIG. 2 is a top plan view of a preferred embodiment of the lateral germanium detector structure in the present invention;

3 is a schematic diagram of the overall structure of another preferred embodiment of the lateral germanium detector structure in the present invention;

FIG. 4 is a flow chart of a method for fabricating a lateral germanium detector structure in the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

The present invention includes a lateral germanium detector structure, wherein the lateral germanium detector structure is a lateral photodiode, and specifically includes:

a silicon substrate 1;

A silicon oxide layer 2 is deposited on the upper surface of the silicon substrate 1; the silicon oxide layer 2 includes:

a top layer of silicon 20;

A germanium layer 21 is formed on the upper surface of the top layer silicon 20. The germanium layer 21 includes a germanium layer main body 21, and a first extension portion 210 and a second extension portion 211 extending from the germanium layer main body 21 to two sides respectively. A first doped region 212 and a second doped region 213 are respectively formed on the extension portion 210 and the second extension portion 211 , and a first electrode is respectively formed on the upper surfaces of the first doped region 212 and the second doped region 213 214 and a second electrode 214, the first electrode 214 and the second electrode 215 respectively extend upward from the silicon oxide layer 2;

A silicon nitride waveguide 22 is formed above the germanium layer 21. The silicon nitride waveguide 22 has a tapered structure. The silicon nitride waveguide 22 has a first end 220 and a second end 221. The first end 220 is smaller than the second end 220. At the end 221, the silicon nitride waveguide 22 is used for receiving the optical signal and coupling the optical signal to the germanium layer 21, and the germanium layer 21 is used for receiving the optical signal and converting the optical signal into an electrical signal.

Through the technical solution of the above-mentioned lateral germanium detector structure, as shown in FIGS. 1 and 2 , the lateral germanium detector structure is a lateral photodiode structure, a silicon oxide layer 2 is deposited on the upper surface of the silicon substrate 1 , and the silicon oxide layer 2 includes a top layer The silicon 20, the germanium layer 21 and the silicon nitride waveguide 22, wherein the germanium layer 21 includes a germanium layer main body 21, and a first extension portion 210 and a second extension portion 211 extending from the germanium layer main body 21 to both sides respectively. The main body 21 , the first extension portion 210 and the second extension portion 211 form an integrally formed T-shaped germanium layer 21 , and a first doped region 212 and a first doped region are respectively formed in the first extension portion 210 and the second extension portion 211 . Two doped regions 213, a first electrode 214 and a second electrode 215 are respectively formed on the upper surfaces of the first doped region 212 and the second doped region 213, and the first electrode 214 and the second electrode 215 extend upward respectively Silicon oxide layer 2; Specifically, N+ ions are doped into the first doping region 212 to form an N+ first implant region 212a, and N+ ions are doped in the N+ first implant region 212a to form an N++ first implant region 212b; Doping P+ ions in the second doping region 213 to form a P+ second implanting region 213a, and doping P++ ions in the P+ second implanting region 213a to form a P++ second implanting region 213b;

Further, the silicon nitride waveguide 22 is formed above the germanium layer 21, wherein the predetermined distance between the silicon nitride waveguide 22 and the germanium layer 21 is set to 0-0.2um, and the silicon nitride waveguide 22 has a tapered structure, The thickness t of the silicon nitride waveguide 22 is set to at least 0.2um, the width of the first end 220 of the silicon nitride waveguide 22 is set to 0.1-0.5um, and the width of the second end 221 of the silicon nitride waveguide 22 is set to 0.5-1.5 um, the silicon nitride waveguide 22 is used to receive the optical signal, and the optical signal is coupled to the germanium layer 21, and the germanium layer 21 is used to receive the optical signal and convert the optical signal into an electrical signal;

Further, by modifying the structure of the germanium layer and doping the two sides of the germanium layer respectively, the coupling efficiency of the silicon nitride waveguide to the germanium detector can be effectively enhanced, and the optical multiplexer, the optical demultiplexer and the germanium detection can be realized. Compared with the traditional germanium detector, the silicon nitride coupled germanium detector can also be applied to the field of photodetection with high optical power and high bandwidth.

In a preferred embodiment, as shown in FIG. 3 , the germanium layer body 21 , the first extension part 210 and the second extension part 211 fully cover the top layer silicon 20 , and the first extension part 210 and the second extension part A first doped region 212 and a second doped region 213 are formed on the portion 211 respectively, and a first electrode 214 and a second electrode 215 are respectively formed on the upper surfaces of the first doped region 212 and the second doped region 213 , the first electrode 214 and the second electrode 215 extend upward from the silicon oxide layer 2 respectively; specifically, doping N+ ions in the first doping region 212 to form an N+ first implanting region 212a, and in the N+ first implanting region 212a Doping N++ ions to form the first N++ implantation region 212b; doping the second doping region 213 with P+ ions to form the P+ second implantation region 213a, and doping the P+ second implantation region 213a with P++ ions to form P++ In the second implantation region 213b, by modifying the structure of the germanium layer 21, the coupling efficiency of the silicon nitride waveguide to the germanium detector is enhanced, and the effective integration of the optical multiplexer, the optical demultiplexer and the germanium detector can be realized, and compared with that of the germanium detector. The traditional germanium detector and silicon nitride coupled germanium detector can also be used in the field of photodetection with high optical power and high bandwidth.

The present invention also includes a method for preparing a lateral germanium detector structure, which is applied to any one of the lateral germanium detector structures, wherein the lateral germanium detector structure is a lateral photodiode, comprising:

A silicon substrate 1 is provided, and a silicon oxide layer 2 and a top layer silicon 20 are sequentially formed on the silicon substrate 1;

The preparation method specifically includes:

Step S1, depositing a silicon oxide layer 2 on the top layer silicon 20, opening a process window (not shown in the figure) on the silicon oxide layer 2, and forming a germanium layer in the process window (not shown in the figure) 21. The germanium layer 21 includes a germanium layer main body 21, and a first extension portion 210 and a second extension portion 211 extending from the germanium layer main body 21 to two sides respectively;

Step S2, doping the first extension portion 210 and the second extension portion 211 respectively to form a first doping region 212 and a second doping region 213;

Step S3, depositing a silicon oxide layer 2 on the germanium layer 21, forming a silicon nitride waveguide 22 on the silicon oxide layer 2, the silicon nitride waveguide 22 has a first end 220 and a second end 221, the first end 220 is smaller than the second end 221;

Step S4, depositing a silicon oxide layer 2 on the silicon nitride waveguide 22, and opening a first contact hole (not shown in the figure) and a second contact hole (not shown in the figure) on the silicon oxide layer 2 ), the first contact hole (not shown in the figure) and the second contact hole (not shown in the figure) are respectively located on the upper surfaces of the first doped region 212 and the second doped region 213;

Step S5, respectively filling the first contact hole (not shown in the figure) and the second contact hole (not shown in the figure) with metal to form a first electrode 212 and a second electrode 213, the first The electrode 212 and the second electrode 213 extend upward from the silicon oxide layer 2 respectively.

Specifically, the preparation method of the lateral germanium detector structure is suitable for the silicon nitride coupled germanium detector structure, the silicon nitride coupled germanium detector structure is a lateral photodiode structure, and the preparation process is simple, as shown in FIG. Substrate 1, a silicon oxide layer 2 and a top layer silicon 20 are sequentially formed on the silicon substrate 1, wherein the silicon oxide layer 2 is silicon dioxide; a silicon oxide layer 2 is deposited on the top layer silicon 20, and on the silicon oxide layer 2 A process window (not shown in the figure) is opened, and a germanium layer 21 is formed in the process window (not shown in the figure). The extended first extension portion 210 and the second extension portion 211; the first extension portion 210 and the second extension portion 211 are respectively doped to form a first doped region 212 and a second doped region 213;

Specifically, the germanium layer body 21 , the first extension portion 210 and the second extension portion 211 form an integrally formed germanium layer 21 with a T-shaped structure, as shown in FIG. 1 ; the germanium layer body 21 , the first extension portion 210 and the second extension portion 211 The extension portion 211 fully covers the top layer silicon 20, as shown in FIG. 3; wherein, the first doping region 212 is doped with N+ ions to form the N+ first implanting region 212a, and the N+ first implanting region 212a is doped with N++ ions , to form the N++ first implantation region 212b; dope the second doping region 213 with P+ ions to form the P+ second implantation region 213a, and dope the P+ second implantation region 213a with P++ ions to form the P++ second implantation region 213b;

Further, a silicon oxide layer 2 is deposited on the germanium layer 21, and a silicon nitride waveguide 22 is formed on the silicon oxide layer 2. The silicon nitride waveguide 22 has a tapered structure, and the silicon nitride waveguide 22 has a first end 220 and a The second end 221, the first end 220 is smaller than the second end 221, by setting the silicon nitride waveguide 22 into a tapered structure, the coupling efficiency of the silicon nitride waveguide 22 to the germanium detector is further enhanced;

Further, a silicon oxide layer 2 is deposited on the silicon nitride waveguide 22, and a first contact hole (not shown in the figure) and a second contact hole (not shown in the figure) are opened on the silicon oxide layer 2 ), the first contact hole (not shown in the figure) and the second contact hole (not shown in the figure) are located on the upper surfaces of the first doped region 212 and the second doped region 213 respectively; The hole (not shown in the figure) and the second contact hole (not shown in the figure) are filled with metal respectively to form a first electrode 212 and a second electrode 213, the first electrode 212 and the second electrode 213 The silicon oxide layers 2 are respectively extended upward.

The beneficial effect of the technical solution of the present invention is that the lateral germanium detector structure is a lateral photodiode structure, and by transforming the germanium layer structure and doping the two sides of the germanium layer respectively, the coupling of the silicon nitride waveguide to the germanium detector is effectively enhanced. The coupling efficiency can realize the effective integration of the optical multiplexer, the optical demultiplexer and the germanium detector. Compared with the traditional germanium detector, the silicon nitride coupled germanium detector can also be applied to high optical power and high bandwidth optoelectronics. in the detection field.

The above are only preferred embodiments of the present invention, and are not intended to limit the embodiments and protection scope of the present invention. For those skilled in the art, they should be aware of the equivalent replacement and Solutions obtained by obvious changes shall all be included in the protection scope of the present invention.

Claims (10)

1. The utility model provides a horizontal germanium detector structure which characterized in that, horizontal germanium detector structure is horizontal photodiode, specifically includes:

a silicon substrate;

a silicon oxide layer deposited on the upper surface of the silicon substrate; the silicon oxide layer comprises thereon:

a top layer of silicon;

the germanium layer comprises a germanium layer main body, a first extension part and a second extension part, wherein the first extension part and the second extension part extend from the germanium layer main body to two sides respectively;

a silicon nitride waveguide formed over the germanium layer, the silicon nitride waveguide having a tapered configuration, the silicon nitride waveguide having a first end and a second end, the first end being smaller than the second end, the silicon nitride waveguide being configured to receive an optical signal and couple the optical signal to the germanium layer, the germanium layer being configured to receive the optical signal and convert the optical signal to an electrical signal.

2. The lateral germanium detector structure of claim 1, wherein said germanium layer body, said first extension and said second extension form an integrally formed T-shaped structure of said germanium layer.

3. The lateral germanium detector structure of claim 1, wherein said germanium layer body, said first extension, and said second extension entirely cover said top layer of silicon.

4. The lateral germanium detector structure of claim 1, wherein said first doped region is doped with N + ions to form an N + first implanted region;

and doping N + + ions in the N + first injection region to form an N + + first injection region.

5. The lateral germanium detector structure of claim 1, wherein said second doped region is doped with P + ions to form a P + second implanted region;

and doping P + + ions in the P + second injection region to form a P + + second injection region.

6. The lateral germanium detector structure of claim 1, wherein said silicon nitride waveguide has a thickness of at least 0.2 um;

the width of the first end is 0.1-0.5 um;

the width of second end is 0.5-1.5 um.

7. The lateral germanium detector structure of claim 1, wherein the predetermined distance between the silicon nitride waveguide and the germanium layer is 0-0.2 um.

8. A method of manufacturing a lateral germanium detector structure for use in a lateral germanium detector structure according to any of claims 1-7, said lateral germanium detector structure being a lateral photodiode comprising:

providing a silicon substrate, and sequentially forming a silicon oxide layer and a top silicon layer on the silicon substrate;

the preparation method specifically comprises the following steps:

step S1, depositing a silicon oxide layer on the top silicon, opening a process window on the silicon oxide layer, and forming a germanium layer in the process window, wherein the germanium layer includes a germanium layer main body, and a first extension portion and a second extension portion that extend from the germanium layer main body to two sides, respectively;

step S2, doping the first extension portion and the second extension portion respectively to form a first doped region and a second doped region;

step S3, depositing a silicon oxide layer on the germanium layer, and forming a silicon nitride waveguide on the silicon oxide layer, where the silicon nitride waveguide has a tapered structure and has a first end and a second end, and the first end is smaller than the second end;

step S4, depositing a silicon oxide layer on the silicon nitride waveguide, forming a first contact hole and a second contact hole on the silicon oxide layer, where the first contact hole and the second contact hole are respectively located on the upper surfaces of the first doped region and the second doped region;

step S5, filling metal into the first contact hole and the second contact hole respectively to form a first electrode and a second electrode, wherein the first electrode and the second electrode extend upward to form the silicon oxide layer respectively.

9. The method of making a lateral germanium detector structure according to claim 8, wherein said germanium layer body, said first extension and said second extension form an integrally formed T-shaped structure of said germanium layer.

10. The method of claim 8, wherein the germanium layer body, the first extension, and the second extension entirely cover the top silicon.

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