CN102916071A - Photodiode and manufacturing method thereof - Google Patents

Abstract

The embodiment of the invention discloses a photodiode and a manufacturing method thereof, relating to the field of opto-electrical technology, wherein the photodiode is capable of reducing the energy loss. The photodiode comprises a substrate positioned on a bottom layer, a lower cladding layer boss covering the substrate, an incident wave core guiding layer covering the lower cladding layer boss, an upper cladding layer covering the incident wave core guiding layer, an optical matching layer positioned above the upper cladding layer and an avalanche photodiode positioned above the middle part of the back end of the optical matching layer, wherein the width of the lower cladding layer boss at the tail end in the incident wave direction is wider than that of the beginning end in the incident wave direction, both sides of the lower cladding layer boss at the tail end in the incident wave direction are parallel, and both sides of the lower cladding layer boss at the beginning end in the incident wave direction are parallel; and the optical matching layer comprises an optical matching layer front end and an optical matching layer back end, wherein the optical matching layer front end comprises at least one air seam extended along the incident wave direction, and the optical matching layer front end is divided into characteristic units partitioned by the air seams. The embodiment of the invention is applied to manufacturing the photodiode.

Description

A kind of photodiode and preparation method thereof

Technical field

The present invention relates to field of photoelectric technology, relate in particular to a kind of photodiode and preparation method thereof.

Background technology

Fast development along with optoelectronic integrated technology, demand that can the highly sensitive photo-detector of single chip integrated high speed is also more and more urgent, because evanescent wave coupled mode avalanche photodide (Avalanche Photo Diode, be called for short APD) be applied in the evanescent wave coupled mode photo-detector, and incoming signal polarisation of light attitude is random, and polarized non-sensitive is the General Requirements of detector, so the evanescent wave coupled mode avalanche photodide of the high speed high-quantum efficiency of design polarized non-sensitive just seems particularly important.The optical coupling absorption process of evanescent wave coupled mode avalanche photodide (APD) is: the first step, light are coupled to the light matching layer from fibre-optic waveguide first; Second step, again when light during by the top light matching layer rear end that the APD structure arranged, light is absorbed by the absorbed layer of APD and is converted into the signal of telecommunication.In order in the first step of optical coupling absorption process, to obtain effective optical coupling, the incident waveguide that its light matching layer front end and light matching layer front end cover generally is comprised of the waveguide of two sections width gradual changes, and the energy of light signal will gradually be transferred in the light matching layer from fibre-optic waveguide and go like this.

But in existing technology, on the one hand, because the grading structure of the incident waveguide that light matching layer front end and light matching layer front end cover, and the scattering loss of waveguide limit wall and the absorption loss of charge carrier, light can lose quite a few energy in this structure; On the other hand, because the high problem of polarization sensitivity in the optical coupling process, so that light is not high in the coupling absorption efficiency of the coupling unit of light matching layer rear end and avalanche photodide, absorption length is longer.

Summary of the invention

Embodiments of the invention provide a kind of photodiode and preparation method thereof, can fall low-energy loss.

For achieving the above object, embodiments of the invention adopt following technical scheme:

First aspect provides a kind of photodiode, includes that ejected wave is led, light matching layer and avalanche photodide, comprising:

Described photodiode also comprises the substrate that is positioned at bottom;

Described incident waveguide comprises: the under-clad layer that covers described substrate, described under-clad layer comprises the strip under-clad layer boss that is positioned at described under-clad layer upper center, described under-clad layer boss is wider than width at described incident wave direction top at the width of the end of incident wave direction, and described under-clad layer boss is parallel at the dual-side of the end of described incident wave direction, and described under-clad layer boss is parallel at the dual-side at the top of described incident wave direction;

Cover the incident waveguide core layer of described under-clad layer boss;

Cover the top covering of described incident waveguide core layer;

Described smooth matching layer is positioned at described top covering top, and described smooth matching layer comprises:

Light matching layer front end and light matching layer rear end, wherein said smooth matching layer front end include at least one air seam that extends along described incident wave direction, and described air seam is divided into the feature unit that the interval arranges with described smooth matching layer front end;

Described avalanche photodide is positioned at top, middle part, described smooth matching layer rear end.

Described photodiode also comprises the first contact electrode that is positioned at described avalanche photodide top and is positioned at the second contact electrode of the light matching layer top of described avalanche photodide both sides.

In the possible implementation of the first, according to first aspect, specific implementation is: the seam of described air seam is wide to be 50nm～250nm, and described air is sewn on described smooth matching layer front end for equidistantly symmetrical.

In the possible implementation of the second, in conjunction with first aspect, specific implementation is: the width of described smooth matching layer front end and described incident wave perpendicular direction be equal to or less than described incident waveguide and described incident wave perpendicular direction width.

In the third possible implementation, in conjunction with first aspect, specific implementation is: the width of described smooth matching layer front end and described avalanche photodide are with wide.

In the 4th kind of possible implementation, in conjunction with first aspect, specific implementation is: when the span of the thickness of described smooth matching layer satisfies at the Wave guide unit take described smooth matching layer rear end as sandwich layer with Wave guide unit take the absorbed layer of described avalanche photodide as sandwich layer in phase matched, the coupling coefficient κ value that described smooth matching layer thickness is corresponding is in maximum (max (κ TE, κ TM))-0.1dB;

Wherein: $\mathrm{\&kappa;}=\frac{{\mathrm{\&omega;\&epsiv;}}_0\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}(N^2-{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HDA00002048635100012.png,HDA00002048635100041.png"\; state="\{\{state\}\}">N</figure-callout>}}_2^2){\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">E</figure-callout>}}_1^{*}\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100041.png"\; state="\{\{state\}\}">E</figure-callout>}}_2\mathrm{dx}}{\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}{\mathrm{\&mu;}}_z\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">E</figure-callout>}}_1^{*}\&times;{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">H</figure-callout>}}_1+{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">E</figure-callout>}}_1\&times;{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">H</figure-callout>}}_1^{*})\mathrm{dx}},$

Described ω is light frequency, described ε ₀Be permittivity of vacuum, described N represents the space refraction index profile that described Wave guide unit and the described Wave guide unit take the described absorbed layer of described avalanche photodide as sandwich layer take described smooth matching layer rear end as sandwich layer forms, described N ₂For take the described absorbed layer of described avalanche photodide as space refraction index profile corresponding to the described Wave guide unit of sandwich layer, described μ _zExpression direction of propagation unit vector, described E ₁, E ₂Be respectively described Wave guide unit and electric-field intensity distribution take the described absorbed layer of described avalanche photodide as the basic mode pattern of the described Wave guide unit of sandwich layer take described smooth matching layer rear end as sandwich layer, described H ₁Be the magnetic field distribution take described smooth matching layer rear end as the basic mode pattern of the described Wave guide unit of sandwich layer, described kTE is the coupling function of transverse electric mode, and described kTM is the coupling function of transverse magnetic mode.

In the 5th kind of possible implementation, in conjunction with the 4th kind of possible implementation, specific implementation is: the thickness of described smooth matching layer is 0.38 μ m～0.45 μ m.

In the 6th kind of possible implementation, in conjunction with the 5th kind of possible implementation, specific implementation is: the width of described feature unit is 1.1 μ m～1.2 μ m.

In the 7th kind of possible implementation, in conjunction with the 4th kind of possible implementation, specific implementation is: described smooth matching layer front end length L and the Wave guide unit take described smooth matching layer front end as sandwich layer and the coupling length L of the transverse magnetic wave TM mould take described incident waveguide core layer as the Wave guide unit of sandwich layer _cSatisfy: Δ L=L _c-L≤1 μ m;

Wherein:

δ is poor for effective propagation constant of the described Wave guide unit take described smooth matching layer front end as sandwich layer and the described Wave guide unit take described incident waveguide core layer as sandwich layer.

In the 8th kind of possible implementation, in conjunction with first aspect, specific implementation is: described substrate is that indium phosphide, described under-clad layer are that indium phosphide, described incident waveguide core layer are the gallium arsenide phosphide indium, and described top covering is indium phosphide.

In the 9th kind of possible implementation, in conjunction with first aspect, specific implementation is: described smooth matching layer is silicon doping gallium arsenide phosphide indium, and the doping content of described gallium arsenide phosphide indium is (3.0 ± 0.5) * 10 ¹⁸/ cm ³

Second aspect provides a kind of manufacture method of photodiode, comprising:

Make substrate;

The multilayer material layer of on described substrate, growing successively, described multilayer material layer is used for making described each layer of photodiode structure;

End above described multilayer material layer forms the first protective layer of corresponding avalanche photodide top layer size, forms the described avalanche photodide that is positioned at light matching layer material layer top by etching, and peels off described the first protective layer;

Above described smooth matching layer material layer and described avalanche photodide top layer, form the second protective layer of corresponding described smooth matching layer size, form the described smooth matching layer that is positioned at top covering material layer top by etching, and peel off described the second protective layer;

Above described top covering material layer, described smooth matching layer and described avalanche photodide top layer, form the 3rd protective layer of corresponding described top covering size, form top covering, incident waveguide core layer and under-clad layer by etching;

Make to cover the electronic corrosion-resistant of described the 3rd protective layer and described under-clad layer, by electron beam exposure be etched on the light matching layer of described the 3rd protective layer below and form the air seam;

Described the 3rd protective layer above described avalanche photodide forms via hole, by described via hole the top layer of described avalanche photodide is carried out diffusing, doping, and forms the first contact electrode above doped region;

Above the 3rd protective layer of described avalanche photodide both sides, form via hole to expose described smooth matching layer, form the second contact electrode in the via hole above described smooth matching layer.

The manufacture method of a kind of photodiode that embodiments of the invention provide, the strip structure is made in the incident waveguide of light matching layer front end and light matching layer front end below, and stitch at light matching layer front end etching at least one air, reduce waveguide limit wall to scattering loss and the absorption loss of charge carrier and the polarization sensitivity in the optical coupling process of light wave, thereby can reduce the energy loss of photodiode.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, the below will do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art, apparently, accompanying drawing in the following describes only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.

The plan structure schematic diagram of a kind of photodiode that Fig. 1 provides for the embodiment of the invention;

The structural representation of the S-S ' section of the photodiode shown in Figure 1 that Fig. 2 provides for the embodiment of the invention;

The avalanche photodide of the photodiode shown in Figure 1 that Fig. 3 provides for the embodiment of the invention is at the structural representation of S-S ' section;

The cross-sectional view of the another kind of avalanche photodide that Fig. 4 provides for the embodiment of the invention;

The end face structure schematic diagram of the light matching layer front end of the photodiode that Fig. 5 provides for the embodiment of the invention;

A kind of photodiode that Fig. 6 provides for the embodiment of the invention corresponding the H mode TE mould of theoretical optimization model and transverse magnetic wave TM mould respectively when phase matched coupling coefficient about the simulation curve figure of light matching layer thickness;

A kind of photodiode that Fig. 7 provides for the embodiment of the invention corresponding the H mode TE mould of theoretical optimization model and transverse magnetic wave TM mould respectively at the width of the phase matched time matching layer front-end architecture feature unit simulation curve figure about light matching layer thickness;

A kind of photodiode that Fig. 8 provides for the embodiment of the invention corresponding the H mode TE mould of theoretical optimization model and transverse magnetic wave TM mould respectively when phase matched the thickness of avalanche photodide absorbed layer about the simulation curve figure of light matching layer thickness;

The manufacture method schematic flow sheet of a kind of photodiode that Fig. 9 provides for the embodiment of the invention;

The schematic diagram of the H mode TE mould of the theoretical optimization model of a kind of photodiode that Figure 10 provides for the embodiment of the invention and the photo-quantum efficiency of transverse magnetic wave TM mould;

Structure one schematic diagram of photodiode in manufacturing process that Figure 11 provides for embodiments of the invention;

Structure two schematic diagrames of photodiode in manufacturing process that Figure 12 provides for embodiments of the invention;

Structure three schematic diagrames of photodiode in manufacturing process that Figure 13 provides for embodiments of the invention;

Structure four schematic diagrames of photodiode in manufacturing process that Figure 14 provides for embodiments of the invention;

Structure five schematic diagrames of photodiode in manufacturing process that Figure 15 provides for embodiments of the invention;

Structure six schematic diagrames of photodiode in manufacturing process that Figure 16 provides for embodiments of the invention;

Structure seven schematic diagrames of photodiode in manufacturing process that Figure 17 provides for embodiments of the invention;

Structure eight schematic diagrames of photodiode in manufacturing process that Figure 18 provides for embodiments of the invention;

Structure nine schematic diagrames of photodiode in manufacturing process that Figure 19 provides for embodiments of the invention;

Structure ten schematic diagrames of photodiode in manufacturing process that Figure 20 provides for embodiments of the invention;

Structure ten one schematic diagrames of photodiode in manufacturing process that Figure 21 provides for embodiments of the invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that obtains under the creative work prerequisite.

Embodiments of the invention disclose a kind of photodiode, as shown in Figure 1, 2, comprising: substrate 1, incident waveguide 2, light matching layer 3 and avalanche photodide 4.

Incident waveguide 2 comprises: under-clad layer 21, incident waveguide core layer 22 and top covering 23.

Under-clad layer 21 covers substrate 1, under-clad layer 21 comprises the strip under-clad layer boss (as shown in Figure 5) that is positioned at under-clad layer 21 upper center, this under-clad layer boss is wider than the width at incident wave direction top at the width of the end of incident wave direction, and the dual-side of the end of the incident wave direction of under-clad layer boss is parallel, and the dual-side at the top of the incident wave direction of under-clad layer boss is parallel; Wherein optional, under-clad layer 21 thickness are 1.0 μ m.

Incident waveguide core layer 22 covers the under-clad layer boss; Wherein optional, incident waveguide core layer 22 thickness are 0.6 μ m.

Top covering 23 covers incident waveguide core layer 22; Wherein optional, top covering 23 thickness are 0.3 μ m.

Light matching layer 3 is positioned at top covering 23 tops, and light matching layer 3 comprises:

Light matching layer front end 31 and light matching layer rear end 32, as shown in Figure 5, wherein light matching layer front end 31 includes at least one air seam 31a that extends along the incident wave direction, and air seam 31a is divided into the feature unit 31b that the interval arranges with light matching layer front end 31.

The width of light matching layer front end 31 and avalanche photodide 4 are with wide, and be wherein preferred, and the width of light matching layer front end 31 is 4 μ m.

In addition, the span of the thickness of light matching layer 3 satisfies at the Wave guide unit C take light matching layer rear end 32 as sandwich layer and Wave guide unit D take the absorbed layer 45 of avalanche photodide 4 as sandwich layer in phase matched when (the sandwich layer effective refractive index that is Wave guide unit C and Wave guide unit D equates), the coupling coefficient κ value that light matching layer 3 thickness are corresponding is in maximum (max (κ TE, κ TM))-0.1dB;

Wherein: $\mathrm{\&kappa;}=\frac{{\mathrm{\&omega;\&epsiv;}}_0\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}(N^2-{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HDA00002048635100012.png,HDA00002048635100041.png"\; state="\{\{state\}\}">N</figure-callout>}}_2^2){\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">E</figure-callout>}}_1^{*}\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100041.png"\; state="\{\{state\}\}">E</figure-callout>}}_2\mathrm{dx}}{\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}{\mathrm{\&mu;}}_z\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">E</figure-callout>}}_1^{*}\&times;{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">H</figure-callout>}}_1+{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">E</figure-callout>}}_1\&times;{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA00002048635100012.png,HDA00002048635100031.png"\; state="\{\{state\}\}">H</figure-callout>}}_1^{*})\mathrm{dx}},$

ω is light frequency, ε ₀Be permittivity of vacuum, N represents the space refraction index profile that Wave guide unit C and Wave guide unit D form, N ₂For with space refraction index profile corresponding to Wave guide unit D, μ _zExpression direction of propagation unit vector, E ₁, E ₂Be respectively the electric-field intensity distribution of the basic mode pattern of Wave guide unit C and Wave guide unit D, H ₁Magnetic field distribution for the basic mode pattern of Wave guide unit C; KTE is the coupling function of transverse electric mode; KTM is the coupling function of transverse magnetic mode; Concrete, with reference to the simulation curve figure based on light matching layer 3 thickness corresponding to the κ value of theoretical optimization model shown in Figure 6, the Thickness scope of light matching layer 3 is 0.38 μ m～0.45 μ m, when the κ value at maximum (max (κ TE, κ TM))-0.1dB is with interior and Δ k=kTE-kTM is enough little, and the polarization sensitivity of the optical coupling process between Wave guide unit C and the Wave guide unit D is enough little so.

The coupling length L of the transverse magnetic wave TM mould of light matching layer front end 31 length L and the Wave guide unit B take light matching layer front end 31 as sandwich layer and the Wave guide unit A take incident waveguide core layer 22 as sandwich layer _cSatisfy: Δ L=Lc-L≤1 μ m; With Wave guide unit B with the coupling length L of the transverse magnetic wave TM mould of Wave guide unit A _cFor:

Wherein, when satisfying Wave guide unit B and Wave guide unit A phase matched, i.e. effective propagation constant residual quantity

The time, namely The length of when Wave guide unit A passes to Wave guide unit B and reach maximum among Wave guide unit B, propagating for light energy; Preferably, the length of light matching layer front end 31 is 16.5 μ m.

In addition, the width of the feature unit 31b that forms between the air of the etching seam 31a on the light matching layer 3, concrete can be with reference to the width of feature unit 31b based on the theoretical optimization model shown in Figure 7 simulation curve figure about light matching layer thickness, the width of feature unit 31b is 1.1 μ m～1.2 μ m.On the one hand, when the width of feature unit 31b when reducing, the polarization sensitivity of H mode TE and transverse magnetic wave TM is reducing, on the other hand, when the width of feature unit 31b when reducing, the thickness of light matching layer 3 is in continuous increase, range of values of thickness (0.38 μ m～0.45 μ m) according to the determined preferred light matching layer 3 of simulation curve figure of front, get one-tenth-value thickness 1/10 larger in the scope 0.43 μ m～0.45 μ m, could keep high coupling efficiency and low polarization sensitivity between Wave guide unit C and the Wave guide unit D.

Avalanche photodide 4 is positioned at top, 32 middle parts, light matching layer rear end.

Photodiode also comprises the first contact electrode e that is positioned at avalanche photodide 4 tops and is positioned at the second contact electrode g of light matching layer 3 tops of avalanche photodide both sides.

Wherein, because the realizability of the function of photodiode device, the incident wave line of propagation must be specific, namely along incident wave to sandwich layer, the light matching layer propagates to the direction of avalanche photodide.

Wherein, with reference to shown in Figure 3, the structure of avalanche photodide 4 comprises:

N-type doping transition zone 41 is positioned at bottom, and the preferred thickness of N-type doping transition zone 41 is 0.03 μ m;

Dynode layer 42 covers N-type doping transition zone 41, and the preferred thickness of dynode layer 42 is 0.1035 μ m;

Charge layer 43 covers dynode layer 4, and the preferred thickness of charge layer 43 is 0.05 μ m;

Absorbed layer 45 covers charge layer 4;

Then preferred, the simulation curve figure based on the thick thickness about the light matching layer of the absorbed layer of the avalanche photodide of theoretical optimization model as shown in Figure 8, according to the range of values of thickness of the determined preferred light matching layer 3 in front, absorbed layer 45 optional thickness are 0.14 μ m～0.16 μ m;

Eigen I nP layer 47 covers absorbed layer 45, and eigen I nP layer 47 optional thickness are 1.0 μ m;

P type heavy doping diffusion region 48 is positioned at the top, middle part of eigen I nP layer 47;

Wherein the length of P type heavy doping diffusion region 48 and width are less than eigen I nP layer 47;

The first contact electrode layer e covers P type heavy doping diffusion region 48;

Wherein, with N-type doping transition zone 41 same layers, the second contact electrode layer g is positioned at the top of the light matching layer 22 of avalanche photodide 4 both sides.

Further, consider the complexity of the layer structure that forms avalanche photodide, between charge layer 43 and the absorbed layer 45 and insert respectively one deck between absorbed layer 45 and the eigen I nP layer 47 and can be with transition zone, with reference to shown in Figure 4, i.e. lower graded bedding 44 between charge layer 43 and absorbed layer 45, upper graded bedding 46 between absorbed layer 45 and eigen I nP layer 47, the preferred thickness of wherein descending graded bedding 44 is 0.05 μ m, upper graded bedding 46 optional thickness are 0.05 μ m, owing to can weaken charge carrier in the build-up effect at heterojunction edge with transition zone, therefore can improve the speed of response of device.

The photodiode that embodiments of the invention provide, the strip structure is made in the incident waveguide of light matching layer front end and light matching layer front end below, and stitch at light matching layer front end etching at least one air, reduce waveguide limit wall to scattering loss and the absorption loss of charge carrier and the polarization sensitivity in the optical coupling process of light wave, thereby can reduce the energy loss of photodiode.

Embodiments of the invention have specifically described a kind of manufacture method of photodiode, and as shown in Figure 9, the method comprises the steps:

101, make substrate 1.

102, the multilayer material layer of growing successively on substrate 1, multilayer material layer are used for making each layer of photodiode structure.

Wherein, with reference to shown in Figure 11, the multilayer material layer comprises from top to bottom: under-clad layer material layer 210, incident waveguide core material layer 220 and top covering material layer 230; Light matching layer material layer 30, N-type doping buffer layer material layer 410, dynode layer material layer 420, charge layer material layer 430, absorbed layer material layer 450, eigen I nP layer of material 470.

Wherein, substrate 1 material is indium phosphide, and multilayer material layer layers of material is: under-clad layer material layer 210 is the gallium arsenide phosphide indium for indium phosphide, incident waveguide core material layer 220, and top covering material layer 230 is indium phosphide.Light matching layer material layer 30 is silicon doping gallium arsenide phosphide indium, and the doping content of this gallium arsenide phosphide indium is (3.0 ± 0.5) * 10 ¹⁸/ cm ³The material of N-type doping buffer layer material layer 410 is silicon Si doping indium arsenide aluminium InAlAs, the doping content preferred 3 * 10 of indium arsenide aluminium InAlAs ¹⁸/ cm ³The material of dynode layer material layer 420 is quantum well structures (the wherein forbidden band wavelength of Q1.03 gallium arsenide phosphide phosphide material) of gallium arsenide phosphide indium InGaAsP (Q1.03)/indium arsenide aluminium InAlAs (11.5nm/11.5nm).The material of charge layer material layer 430 is beryllium Be doping indium arsenide aluminium InAlAs, the doping content preferred 8 * 10 of indium arsenide aluminium InAlAs ¹⁷/ cm ³The material of absorbed layer material layer 450 is gallium arsenide phosphide indium InGaAsP, and eigen I nP layer of material 470 is indium phosphide.

Optionally, can can be with transition zone at the one deck of growing respectively between charge layer material layer 430 and the absorbed layer material layer 450 and between absorbed layer material layer 450 and the eigen I nP layer of material 470, i.e. lower graded bedding material layer 440 between charge layer material layer 430 and absorbed layer material layer 450, upper graded bedding material layer 460 between absorbed layer material layer 450 and eigen I nP layer of material 470, wherein descend graded bedding material layer 440 to comprise gallium arsenide phosphide indium InGaAsP layer (Q1.05)/gallium arsenide phosphide indium InGaAsP layer (Q1.2), upper graded bedding material layer 460 comprises gallium arsenide phosphide indium InGaAsP layer (Q1.20)/gallium arsenide phosphide indium InGaAsP layer (Q1.05), and above structure is not shown specifically can be with reference to shown in Figure 4.

103, the end above the multilayer material layer forms the first protective layer a of corresponding avalanche photodide 4 top layer sizes, forms by etching to be positioned at the avalanche photodide 4 of light matching layer material layer 30 tops, and peels off the first protective layer a.

With reference to shown in Figure 11, for in the photodiode manufacturing process shown in Figure 1 at the structural representation in SS ' cross section, at first, by plasma activated chemical vapour deposition (Plasma Enhanced Chemical Vapor Deposition, abbreviation PECVD) protective layer of growth one deck 200nm, this protective layer can be silicon dioxide, then apply the table top figure of photoresist definition avalanche photodide 4 in predetermined zone, because the mesa structure of avalanche photodide 4 is less, and comparatively responsive to size, therefore can form by anisotropic RIE dry etching the first protective layer a of corresponding avalanche photodide 4 top layer sizes, then continue to adopt dry etching to obtain each layer structure of avalanche photodide 4, remake a simple wet etching and process (etching time is very short), improve the oblique angle of each layer limit wall of avalanche photodide 4 and roughness to reduce the dark current of avalanche photodide 4; Then remove the first protective layer a with peeling off, obtain structure as shown in figure 12.Here, dry etching speed needs carefully calibration, guarantees that reactive ion etching (Reactive Ion Etching is called for short RIE) stops before etching into light matching layer material layer 30.

104, above light matching layer material layer 30 and avalanche photodide 4 top layers, form the second protective layer b of corresponding 4 smooth matching layer sizes, be positioned at 3 smooth matching layers of top covering material layer 230 tops by etching formation, and peel off described the second protective layer b.

With reference to Figure 13 and shown in Figure 14, in the photodiode manufacturing process shown in Figure 1 at the structural representation in SS ' cross section, this step can adopt and step 103 similarly method process, specifically with reference to step 103, repeat no more here.

105, above top covering material layer 230, light matching layer 3 and avalanche photodide 4 top layers, form the 3rd protective layer c that one deck is made of silicon dioxide, corrode downwards by etching and form top covering 23, incident waveguide core layer 22 and under-clad layer 21.

With reference to Figure 15 and shown in Figure 16; for in the photodiode manufacturing process shown in Figure 1 at the structural representation in MM ' cross section; at first; protective layer by plasma activated chemical vapour deposition (PECVD) growth one deck 200nm; this protective layer can be silicon dioxide; then apply the table top figure of photoresist definition top covering 23 in predetermined zone; form the 3rd protective layer c of corresponding top covering 23 sizes by dry etching, then continue to adopt dry etching to obtain each layer structure of incident waveguide 22.Here, dry etching speed needs carefully calibration, guarantees to stop when reactive ion etching (RIE) etches the under-clad layer boss shape of under-clad layer 21.

106, make to cover the electronic corrosion-resistant d of the 3rd protective layer c and under-clad layer 21, by electron beam exposure be etched on the light matching layer 3 of the 3rd protective layer c below and form air seam 31a.

With reference to Figure 17 and shown in Figure 180; for in the photodiode manufacturing process shown in Figure 1 at the structural representation in NN ' cross section; at first; at the 3rd protective layer c growth one deck electronic corrosion-resistant d; form the air crack structure by electron beam exposure at electronic corrosion-resistant d; the air crack structure is transferred on the 3rd diaphragm c of light matching layer 3 tops by dry etching again; then utilize the 3rd protective layer c to make mask; etch the air crack structure on the light matching layer 3 by being dry-etched in, form the light matching layer 3 with air seam 31a.

107, the 3rd protective layer c above avalanche photodide 4 forms via hole, by via hole the top layer of avalanche photodide 4 is carried out diffusing, doping, and forms the first contact electrode e above doped region.

With reference to Figure 19 and shown in Figure 20; for in the photodiode manufacturing process shown in Figure 1 at the structural representation in SS ' cross section; at top covering 23; form one deck photoresist f on light matching layer 3 and the 3rd protective layer c top; through overexposure; develop and remove the photoresist of the 3rd protective layer c top on the avalanche photodide 4; and by the upper via hole that forms of the 3rd protective layer c that is dry-etched in avalanche photodide 4 tops; peel off remaining photoresist; then in diffusion furnace; take zinc methide as diffusion material the eigen I nP layer 47 of avalanche photodide 4 top layers is carried out diffusing, doping by via hole and form P type heavily doped diffusion layer 48; and the scope of diffusion temperature is 450-550 ℃, optionally makes the carrier concentration in the P type heavily doped diffusion layer 48 that diffuses to form reach 3 * 10 ¹⁸/ cm ³

With reference to shown in Figure 21; for in the photodiode manufacturing process shown in Figure 1 at the structural representation in SS ' cross section; at top covering 23; form one deck photoresist f on light matching layer 3 and the 3rd protective layer c top; remove the photoresist f of avalanche photodide 4 tops through exposure imaging; then above photoresist and avalanche photodide 4 by electron beam evaporation plating form metal film wherein metal membrane material can be Ti (10nm)/Pt (30nm)/Au (100nm)/Ti (100nm); utilize at last the metal film on divesting technology removal photoresist and the photoresist; form the first contact electrode e, and rapid thermal annealing.

108, above the 3rd protective layer c of avalanche photodide 4 both sides, form via hole to expose light matching layer 3, form the second contact electrode g in the via hole above light matching layer 3.

The method that forms the first contact electrode e in this step and the step 107 is similar, specifically with reference to step 107, repeats no more here.

Analog result by the theoretical optimization model can obtain photodiode that embodiments of the invention provide and reach 80% corresponding absorption length when above in quantum efficiency and only have 14 microns, with reference to shown in Figure 10 based on the H mode TE mould of theoretical optimization model and the photo-quantum efficiency schematic diagram of transverse magnetic wave TM mould, it is polarization correlated that the shortening absorption length is conducive to improve the frequency characteristic reduction like this, the polarization correlated degree that can arrive less than or equal to 0.1db of the photodiode that embodiments of the invention provide.

The manufacture method of a kind of photodiode that embodiments of the invention provide, the strip structure is made in the incident waveguide of light matching layer front end and light matching layer front end below, and stitch at light matching layer front end etching at least one air, reduce waveguide limit wall to scattering loss and the absorption loss of charge carrier and the polarization sensitivity in the optical coupling process of light wave, thereby can reduce the energy loss of photodiode.

The above; be the specific embodiment of the present invention only, but protection scope of the present invention is not limited to this, anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; can expect easily changing or replacing, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of described claim.

Claims (11)

1. photodiode includes that ejected wave is led, light matching layer and avalanche photodide, it is characterized in that,

Described photodiode also comprises the substrate that is positioned at bottom;

Described incident waveguide comprises: the under-clad layer that covers described substrate, described under-clad layer comprises the strip under-clad layer boss that is positioned at described under-clad layer upper center, described under-clad layer boss is wider than width at described incident wave direction top at the width of the end of incident wave direction, and described under-clad layer boss is parallel at the dual-side of the end of described incident wave direction, and described under-clad layer boss is parallel at the dual-side at the top of described incident wave direction;

Cover the incident waveguide core layer of described under-clad layer boss;

Cover the top covering of described incident waveguide core layer;

Described smooth matching layer is positioned at described top covering top, and described smooth matching layer comprises:

Light matching layer front end and light matching layer rear end, wherein said smooth matching layer front end include at least one air seam that extends along described incident wave direction, and described air seam is divided into the feature unit that the interval arranges with described smooth matching layer front end;

Described avalanche photodide is positioned at top, middle part, described smooth matching layer rear end;

Described photodiode also comprises the first contact electrode that is positioned at described avalanche photodide top and is positioned at the second contact electrode of the light matching layer top of described avalanche photodide both sides.

2. photodiode according to claim 1 is characterized in that, the seam of described air seam is wide to be 50nm～250nm, and described air is sewn on described smooth matching layer front end for equidistantly symmetrical.

3. photodiode according to claim 1 is characterized in that, the width of described smooth matching layer front end and described incident wave perpendicular direction be equal to or less than described incident waveguide and described incident wave perpendicular direction width.

4. photodiode according to claim 1 is characterized in that,

The width of described smooth matching layer front end and described avalanche photodide are with wide.

5. photodiode according to claim 1 is characterized in that,

When the span of the thickness of described smooth matching layer satisfies at the Wave guide unit take described smooth matching layer rear end as sandwich layer with Wave guide unit take the absorbed layer of described avalanche photodide as sandwich layer in phase matched, the coupling coefficient κ value that described smooth matching layer thickness is corresponding is in maximum (max (κ TE, κ TM))-0.1dB;

Wherein: $\mathrm{\&kappa;}=\frac{{\mathrm{\&omega;\&epsiv;}}_0\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}(N^2-N_2^2)E_1^{*}\&CenterDot;E_2\mathrm{dx}}{\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}{\mathrm{\&mu;}}_z\&CenterDot;(E_1^{*}\&times;H_1+E_1\&times;H_1^{*})\mathrm{dx}},$

Described ω is light frequency, described ε ₀Be permittivity of vacuum, described N represents the space refraction index profile that described Wave guide unit and the described Wave guide unit take the described absorbed layer of described avalanche photodide as sandwich layer take described smooth matching layer rear end as sandwich layer forms, described N ₂For take the described absorbed layer of described avalanche photodide as space refraction index profile corresponding to the described Wave guide unit of sandwich layer, described μ z represents direction of propagation unit vector, described E ₁, E ₂Be respectively described Wave guide unit and electric-field intensity distribution take the described absorbed layer of described avalanche photodide as the basic mode pattern of the described Wave guide unit of sandwich layer take described smooth matching layer rear end as sandwich layer, described H ₁Be the magnetic field distribution take described smooth matching layer rear end as the basic mode pattern of the described Wave guide unit of sandwich layer, described kTE is the coupling function of transverse electric mode, and described kTM is the coupling function of transverse magnetic mode.

6. photodiode according to claim 5 is characterized in that, the thickness of described smooth matching layer is 0.38 μ m～0.45 μ m.

7. photodiode according to claim 6 is characterized in that, the width of described feature unit is 1.1 μ m～1.2 μ m.

8. photodiode according to claim 5 is characterized in that, described smooth matching layer front end length L and the Wave guide unit take described smooth matching layer front end as sandwich layer and the coupling length L of the transverse magnetic wave TM mould take described incident waveguide core layer as the Wave guide unit of sandwich layer _cSatisfy: Δ L=L _c-L≤1 μ m;

Wherein:

δ is poor for effective propagation constant of the described Wave guide unit take described smooth matching layer front end as sandwich layer and the described Wave guide unit take described incident waveguide core layer as sandwich layer.

9. manufacture method according to claim 1 is characterized in that, described substrate is that indium phosphide, described under-clad layer are that indium phosphide, described incident waveguide core layer are the gallium arsenide phosphide indium, and described top covering is indium phosphide.

10. manufacture method according to claim 1 is characterized in that,

Described smooth matching layer is silicon doping gallium arsenide phosphide indium, and the doping content of described gallium arsenide phosphide indium is (3.0 ± 0.5) * 10 ¹⁸/ cm ³

11. the manufacture method of a photodiode is characterized in that, comprising:

Make substrate;

The multilayer material layer of on described substrate, growing successively, described multilayer material layer is used for making described each layer of photodiode structure;

End above described multilayer material layer forms the first protective layer of corresponding avalanche photodide top layer size, forms the described avalanche photodide that is positioned at light matching layer material layer top by etching, and peels off described the first protective layer;

Above described smooth matching layer material layer and described avalanche photodide top layer, form the second protective layer of corresponding described smooth matching layer size, form the described smooth matching layer that is positioned at top covering material layer top by etching, and peel off described the second protective layer;

Above described top covering material layer, described smooth matching layer and described avalanche photodide top layer, form the 3rd protective layer of corresponding described top covering size, form top covering, incident waveguide core layer and under-clad layer by etching;

Make to cover the electronic corrosion-resistant of described the 3rd protective layer and described under-clad layer, by electron beam exposure be etched on the light matching layer of described the 3rd protective layer below and form the air seam;

Described the 3rd protective layer above described avalanche photodide forms via hole, by described via hole the top layer of described avalanche photodide is carried out diffusing, doping, and forms the first contact electrode above doped region;

Above the 3rd protective layer of described avalanche photodide both sides, form via hole to expose described smooth matching layer, form the second contact electrode in the via hole above described smooth matching layer.

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