High-power waveguide integrated photoelectric detector and preparation method thereof

Abstract

The high-power waveguide integrated photoelectric detector comprises an SOI substrate, a waveguide layer, a waveguide layer bottom electrode area, a Ge absorption area, a top electrode layer, a medium protection layer, a bottom metal electrode and a bottom metal electrode, and the waveguide layer comprises an end face incident waveguide I, an end face incident waveguide II, an edge incident waveguide, a light splitting device I, a light splitting device II, a groove I and a groove II. The invention further discloses a preparation method of the high-power waveguide integrated photoelectric detector. The invention has the advantages that: through the two light splitting devices, besides incident waveguides at two ends, an edge incident waveguide is added, so that part of light is coupled into the middle section of the Ge absorption region, the optical power density at the two ends of the Ge absorption region is reduced, the optical power density at the middle section of the Ge absorption region is increased, the optical field distribution in the Ge absorption region is more uniform, and the carrier shielding effect is reduced.

Description

Technical Field

[0001] This invention relates to the fields of optical chips, high-speed photodetectors, and silicon photonics, particularly in applications such as high-speed optical communication and optical interconnection of data centers / AI clusters. Specifically, it relates to a high-power waveguide integrated photodetector and its fabrication method. Background Technology

[0002] Waveguide photodetectors can achieve both high responsivity and bandwidth; generally, detectors with bandwidth greater than 50 GHz are waveguide-type. However, traditional waveguide detectors suffer from the problem of concentrated optical power density in the first 5 μm region at both ends of the waveguide. The optical field intensity in the middle section of the Ge waveguide is very low, resulting in a significant carrier shielding effect. As the photocurrent increases, the bandwidth performance drops rapidly. Maintaining high bandwidth performance under high photocurrent is a challenge. Summary of the Invention

[0003] The first objective of this invention is to propose a high-power waveguide integrated photodetector. By using two beam splitters, in addition to the incident waveguides at both ends, an additional side incident waveguide is added in the middle section of the Ge waveguide. This enables efficient utilization of the middle section of the Ge waveguide, reduces the optical power density at both ends of the Ge waveguide, and weakens the carrier shielding effect. It also allows the device to maintain high bandwidth performance even under high photocurrent.

[0004] The technical solution adopted is as follows: A high-power waveguide integrated photodetector, comprising an SOI substrate, The waveguide layer is located on the top silicon layer of the SOI substrate; it includes end-face incident waveguide I, end-face incident waveguide II, edge incident waveguide, beam splitter I, beam splitter II, groove I and groove II; The bottom electrode region of the waveguide layer is located on the top silicon layer of the SOI substrate; The Ge absorption region is located above the waveguide layer and between groove I and groove II; the middle section of the Ge absorption region is coupled to the side incident waveguide. The top electrode layer is located above the Ge absorption region; A dielectric protective layer that covers the entire device; The bottom metal electrode is located above the dielectric protective layer and is connected to the bottom electrode region of the waveguide layer through the bottom metal contact layer. The top metal electrode is located above the dielectric protective layer and is connected to the top electrode layer through the top metal contact layer.

[0005] Further optimization involves connecting one end of the beam splitter I to the input, and the other end being divided into two ports, which are respectively coupled to the input of the end-face incident waveguide I and the beam splitter II.

[0006] Further optimization involves dividing the other end of the beam splitter II into two ports, which are respectively coupled to the side incident waveguide and the end-face incident waveguide II.

[0007] Further optimization involves connecting beam splitter II and beam splitter I via a waveguide.

[0008] Further optimization is that the thickness of the Ge absorption region is 100-500 nm and the width is 100-3000 nm.

[0009] Further preferably, groove II is located on the side where the bottom electrode area is located, and the depth of groove II is less than that of groove I. Groove II being a shallow groove allows for lower resistance and better contact.

[0010] Further preferred, the bottom electrode region of the waveguide layer covers the bottom of the Ge absorption region.

[0011] Further optimization involves a distance greater than 1µm between the bottom metal contact layer and the Ge absorption region, which improves the detector's responsivity.

[0012] Further optimization involves using a bottom metal electrode with a width greater than 1µm, which simplifies the manufacturing process.

[0013] The second objective of this invention is to provide a method for fabricating a high-power waveguide integrated photodetector, comprising the following steps: S1. Prepare an SOI substrate and etch a waveguide layer on the top silicon layer of the SOI substrate. S2. Ion implantation is performed on the bottom electrode region of the waveguide layer on the top silicon layer of the SOI substrate to form the bottom electrode contact region. The ion implantation type is P / N type impurity. S3, a silica mask layer for epitaxial deposition; S4. Etch a selective epitaxial window at the location of the absorption region, and remove all the silicon dioxide within this window; S5. Selectively epitaxially extend Ge within the window to form a Ge absorption region; S6. Deposit polycrystalline silicon or amorphous silicon on the Ge absorption region to form a polycrystalline silicon layer; then perform ion implantation on it to form a top electrode layer; the ion implantation type is P / N type impurity; the doping type of the top electrode layer is opposite to the doping type of the bottom electrode region of the waveguide layer. S7. Etch away the polysilicon or amorphous silicon outside the polysilicon layer; S8, Deposition medium protective layer; S9. Make holes separately to create the bottom metal contact layer and the top metal contact layer; S10. Prepare the bottom metal electrode and the top metal electrode.

[0014] The advantages of this invention compared to the prior art are as follows: 1. The high-power waveguide integrated photodetector of the present invention adds a groove on each side of the Ge absorption region to further confine the light, thereby improving the final responsivity.

[0015] 2. The high-power waveguide integrated photodetector of the present invention uses two beam splitters to add a side incident waveguide in addition to the incident waveguides at both ends, so that part of the light is coupled into the middle section of the Ge absorption region, reducing the optical power density at both ends of the Ge absorption region and increasing the optical power density in the middle section of the Ge absorption region, making the optical field distribution in the Ge absorption region more uniform and reducing the carrier shielding effect. Attached Figure Description

[0016] Figure 1 This is a top view of a high-power waveguide integrated photodetector according to an embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of an electrodeless circuit; Figure 3 This is a cross-sectional view of a high-power waveguide integrated photodetector according to an embodiment of the present invention; Among them, 100-SOI substrate, 101-bottom silicon material layer, 102-middle silicon dioxide layer, 103-top silicon layer, 111-side incident waveguide, 112a-groove I, 112b-groove II, 113-bottom electrode region of waveguide layer, 120-Ge absorption region, 131-top electrode layer, 140-top metal contact layer, 141-bottom metal contact layer, 170-dielectric protection layer, 151-bottom metal electrode, 150-bottom metal electrode, 160-silicon dioxide mask layer, 201-beam splitter I, 202-waveguide, 203-end face incident waveguide I, 204-beam splitter II, 206-end face incident waveguide II. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figures 1-3 The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Example 1

[0018] like Figure 3 As shown, this embodiment is a high-power waveguide integrated photodetector. The waveguide detector design includes an SOI substrate 100, a waveguide layer, a bottom electrode region 113 of the waveguide layer, a Ge absorption region 120, a top electrode layer 131, a dielectric protective layer 170, a bottom metal electrode 151, and a bottom metal electrode 150.

[0019] like Figure 3 As shown, the waveguide layer, top electrode layer 131 and Ge absorption region 120 are all made of semiconductor materials. The top electrode layer 131 and the bottom electrode region 113 of the waveguide layer are formed by doping to form P and N electrodes, and the doping polarities of the top electrode layer 131 and the bottom electrode region 113 of the waveguide layer must be opposite.

[0020] like Figure 3 As shown, the waveguide layer is located above the top silicon layer 103 of the SOI substrate 100. Generally, the SOI substrate 100 includes a top silicon layer 103, an intermediate silicon dioxide layer 102, and a bottom silicon material layer 101, and the waveguide layer is the top silicon layer of the SOI substrate 100.

[0021] The waveguide layer includes end-face incident waveguide I 203, end-face incident waveguide II 206, side incident waveguide 111, beam splitter I 201, beam splitter II 204, groove I 112a, and groove II 112b.

[0022] like Figure 3 As shown, the side-incident waveguide 111 couples the middle section of the Ge absorption region 120, making the light distribution more uniform within the waveguide of the Ge absorption region 120 and reducing the carrier shielding effect. Grooves I 112a and II 112b are located on the left and right sides of the Ge absorption region 120, further confining the light and thus improving the final responsivity. Preferably, in this embodiment, the depth of groove I 112a is greater than the depth of groove II 112b, and preferably, the depth of groove I 112a is less than 0.2 μm, and the depth of groove II 112b is less than 0.1 μm.

[0023] The Ge absorption region 120 is located on the waveguide layer. The mask material used for the epitaxy of the Ge absorption region 120 is silicon dioxide, forming a silicon dioxide mask layer 160.

[0024] Typically, the thickness of the Ge absorption region 120 is 100 to 500 nm, and the width is 100 nm to 3000 nm. The bottom electrode region 113 of the waveguide layer must completely cover the bottom of the Ge absorption region 120. The width of the bottom electrode region 113 of the waveguide layer is greater than 3 μm; the distance between the bottom metal contact layer 141 and the Ge absorption region 120 is greater than 1 μm. The width of the bottom metal electrode 151 is greater than 1 μm.

[0025] like Figure 2As shown, in this embodiment of the high-power waveguide integrated photodetector, one end of the beam splitter I 201 is connected to the input, and the other end is divided into two ports, which are respectively coupled to the input of the end-face incident waveguide I 203 and the beam splitter II 204; the other end of the beam splitter II 204 is divided into two ports, which are respectively coupled to the side incident waveguide 111 and the end-face incident waveguide II 206; the beam splitter II 204 and the beam splitter I 201 are connected through waveguide 202.

[0026] The top electrode layer 131 is located above the Ge absorption region 120. The top electrode layer 131 is formed by ion implantation, and the ion doping type is N / P type (opposite to the doping type of the bottom electrode region 113 of the waveguide layer).

[0027] The dielectric protective layer 170 covers the entire device; the material of the dielectric protective layer 170 is silicon dioxide.

[0028] Bottom metal electrode 151, located above dielectric protective layer 170, is connected to bottom electrode region 113 of waveguide layer via bottom metal contact layer 141; bottom metal electrode 150, located above dielectric protective layer 170, is connected to top electrode layer 131 via top metal contact layer 140. Bottom metal contact layer 141 and top metal contact layer 140 are metal contact layers, typically tungsten; bottom metal electrode 150 and bottom metal electrode 151 are metal wires, typically Cu / Al.

[0029] Based on a 0.13µm CMOS process, the minimum achievable etching linewidth is 100nm. This embodiment proposes a method for fabricating a high-power waveguide integrated photodetector, including the following steps: S1. Prepare SOI substrate 100, and etch waveguide layer on top silicon 103 of SOI substrate 100. S2. Ion implantation is performed on the bottom electrode region 113 of the waveguide layer on the top silicon 103 of the SOI substrate 100 to form the bottom electrode contact region. The ion implantation type is P / N type impurity. S3, Deposited epitaxial silicon dioxide mask layer 160; S4. Etch a selective epitaxial window at the location of the absorption region, and remove all the silicon dioxide within this window; S5. Selectively epitaxially extend Ge within the window to form a Ge absorption region 120; S6. Polycrystalline silicon or amorphous silicon is deposited on the Ge absorption region 120 to form a polycrystalline silicon layer 130; then ion implantation is performed on it to form a top electrode layer 131; the ion implantation type is P / N type impurity; the doping type of the top electrode layer 131 is opposite to the doping type of the bottom electrode region 113 of the waveguide layer. S7. Etch away the polysilicon or amorphous silicon outside the polysilicon layer 130; S8, Deposition medium protective layer 170; S9. Make holes to form the bottom metal contact layer 141 and the top metal contact layer 140 respectively; S10, Prepare the bottom metal electrode 151 and the top metal electrode 150.

[0030] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-power waveguide integrated photodetector, characterized in that, Including SOI substrate (100). Waveguide layer, located on top silicon of SOI substrate (100); includes end face incident waveguide I (203), end face incident waveguide II (206), side incident waveguide (111), beam splitter I (201), beam splitter II (204), groove I (112a) and groove II (112b). The bottom electrode region (113) of the waveguide layer is located on the top silicon layer of the SOI substrate (100); The Ge absorption region (120) is located above the waveguide layer (103) and between groove I (112a) and groove II (112b); the side incident waveguide (111) couples the middle section of the Ge absorption region (120); The top electrode layer (131) is located above the Ge absorption region (120); A dielectric protective layer (170) covers the entire device; The bottom metal electrode (151) is located above the dielectric protective layer (170) and is connected to the bottom electrode region (113) of the waveguide layer through the bottom metal contact layer (141). The top metal electrode (150) is located above the dielectric protective layer (170) and is connected to the top electrode layer (131) through the top metal contact layer (140).

2. The high-power waveguide integrated photodetector according to claim 1, characterized in that, One end of the beam splitter I (201) is connected to the input, and the other end is divided into two ports, which are respectively coupled to the input of the end-face incident waveguide I (203) and the beam splitter II (204).

3. The high-power waveguide integrated photodetector according to claim 2, characterized in that, The other end of the beam splitter II (204) is divided into two ports, which are coupled to the side incident waveguide (111) and the end face incident waveguide II (206), respectively.

4. The high-power waveguide integrated photodetector according to claim 2, characterized in that, The beam splitter II (204) and the beam splitter I (201) are connected by a waveguide (202).

5. The high-power waveguide integrated photodetector according to claim 1, characterized in that, The thickness of the Ge absorption region (120) is 100-500 nm and the width is 100-3000 nm.

6. The high-power waveguide integrated photodetector according to claim 1, characterized in that, Groove II (112b) is located on the side where the bottom electrode area (113) is located, and the depth of groove II (112b) is less than that of groove I (112a).

7. The high-power waveguide integrated photodetector according to claim 1, characterized in that, The bottom of the waveguide layer bottom electrode region (113) covers the bottom of the Ge absorption region (120).

8. The high-power waveguide integrated photodetector according to claim 1, characterized in that, The distance between the bottom metal contact layer (141) and the Ge absorption region (120) is greater than 1 μm.

9. The high-power waveguide integrated photodetector according to claim 8, characterized in that, The width of the bottom metal electrode (151) is greater than 1 μm.

10. The method for fabricating a high-power waveguide integrated photodetector according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Prepare an SOI substrate (100). Etch a waveguide layer on the top silicon layer (103) of the SOI substrate (100). S2. Ion implantation is performed on the bottom electrode region (113) of the waveguide layer on the top silicon (103) of the SOI substrate (100) to form the bottom electrode contact region. The ion implantation type is P / N type impurity. S3, Deposited epitaxial silica mask layer (160); S4. Etch a selective epitaxial window at the location of the absorption region, and remove all the silicon dioxide within this window; S5. Selectively epitaxially extend Ge within the window to form a Ge absorption region (120). S6. Deposit polycrystalline silicon or amorphous silicon on the Ge absorption region (120) to form a polycrystalline silicon layer (130); then perform ion implantation on it to form a top electrode layer (131); the ion implantation type is P / N type impurity; the doping type of the top electrode layer (131) is opposite to the doping type of the bottom electrode region (113) of the waveguide layer. S7. Etch away the polysilicon or amorphous silicon outside the polysilicon layer (130); S8, Deposition medium protective layer (170); S9. Make holes to form the bottom metal contact layer (141) and the top metal contact layer (140) respectively. S10. Prepare the bottom metal electrode (151) and the top metal electrode (150).

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