Utility model content
The shortcoming of prior art in view of the above, the purpose of this utility model is to provide a kind of silicon-based modulator, for solving in prior art the problem of the photoelectricity modulation efficiency improving silicon-based modulator.
For achieving the above object and other relevant objects, the utility model provides a kind of silica-based photomodulator, and described silicon-based modulator at least comprises:
Ridge waveguide, described ridge waveguide comprises flat part and being positioned in the middle of described flat part, and higher than the raised line of described flat part;
Described ridge waveguide comprises the first light doping section and the second light doping section, described first light doping section comprises longitudinally the first light doping section and at least one horizontal first light doping section, described longitudinal direction first light doping section is formed in the middle of raised line, and along the bearing of trend of described raised line, described transverse direction first light doping section is formed on described raised line and described flat part, and crossing with described raised line; The doping type of described second light doping section and described first light doping section is contrary, and in the raised line be formed at outside described first light doping section and flat part, to be formed horizontal and vertical PN junction with described first light doping section.Preferably, the width of described longitudinal direction first light doping section is 100nm ~ 250nm.
Preferably, the width of described transverse direction first light doping section is 300nm ~ 1000nm.
Preferably, in described ridge waveguide, the height in described dull and stereotyped district is 50nm ~ 200nm, and the height of described raised line is 220nm ~ 340nm, and the width of described raised line is 300nm ~ 700nm.
Preferably, in described flat part, also comprise the first heavily doped region and the second heavily doped region, described first heavily doped region be formed at described second light doping section two outside, described second heavily doped region is formed at the outside of wherein the first heavily doped region; Described transverse direction first light doping section is multiple long strip type regions side by side, and described in each, laterally the first light doping section is connected to described second heavily doped region through described first heavily doped region; Described first heavily doped region is identical with the doping type of described second light doping section; Described second heavily doped region is identical with the doping type of described first light doping section; Be formed with metal electrode in described first heavily doped region and the second heavily doped region, described in the metal electrode be in the first heavily doped region link together, described in be in the second heavily doped region metal electrode link together.
Preferably, described in adjacent two, laterally the spacing of the first light doping section is 300nm ~ 700nm.
Preferably, a metal electrode is formed in the first heavily doped region between every two adjacent described transverse direction first light doping sections.
Preferably, described transverse direction first light doping section and described first heavily doped region, also there is undoped region between described first heavily doped region and the second heavily doped region.
Preferably, the width of described undoped region is 1 μm.
Preferably, the distance of described first heavily doped region and described raised line is 1 μm ~ 2 μm.
Preferably, the width of described first heavily doped region be close to the second heavily doped region is 1 μm ~ 10 μm, and the width of the first heavily doped region described in another and described second heavily doped region is 1 μm ~ 50 μm.
Preferably, the doping type of described first light doping section is P type.
Preferably, in described first light doping section, doping content is 1 × 10
17cm
-3to 5 × 10
18cm
-3, in described second light doping section, doping content is 1 × 10
17cm
-3to 5 × 10
18cm
-3, in described first heavily doped region, doping content is 1 × 10
19cm
-3to 5 × 10
20cm
-3, in described second heavily doped region, doping content is 1 × 10
19cm
-3to 5 × 10
20cm
-3.
As mentioned above, silica-based photomodulator of the present utility model, has following beneficial effect:
The silica-based photomodulator provided in the technical solution of the utility model utilizes multiple transverse direction first light doping section and the second light doping section to form multiple PN junction structure in the direction of propagation, mould field of ridge waveguide simultaneously, utilize longitudinally the first light doping section and the second light doping section in the raised line of ridge waveguide, form two back-to-back PN junction structures, operation can form two depletion regions, add the area of depletion region in mould field, thus improve the modulation efficiency of silica-based photomodulator.
Embodiment
Inventor finds, under making certain voltage situation, there is more displacement (namely silicon-based modulator has higher modulation efficiency) in spectrum, the interfacial position of PN junction is very important, be on the one hand due to the electronics of same concentrations and the change of hole refractive index inconsistent, be the intensity of mould field in different positions uneven in ridge waveguide on the other hand.Particularly important for the modulation efficiency improving modulator, be also the emphasis paid close attention in the industry.
And traditional PN junction design comprises three kinds, form PN junction in level, the perpendicular direction of propagation, direct sum module field respectively.For horizontal PN junction, manufacture craft is comparatively complicated; For vertical PN junction, need very large alignment precision, although depletion region can be made to be positioned at mould field maximum by optimization, the width of depletion region generally only has about 100nm, overall width is generally to the ridge waveguide of 500nm, still has very multi-mode field and do not overlap with depletion region; And for the PN junction in the direction of propagation, mould field, although there is larger process allowance, periodically arrangement makes it have ignored the mould field of cycle inner single doping content waveguide.Therefore the surface of contact of depletion region and mould field is improved, particularly important for the modulation efficiency improving modulator.
By particular specific embodiment, embodiment of the present utility model is described below, person skilled in the art scholar the content disclosed by this instructions can understand other advantages of the present utility model and effect easily.
Refer to Fig. 1 to Fig. 2.Notice, structure, ratio, size etc. that this instructions institute accompanying drawings illustrates, content all only in order to coordinate instructions to disclose, understand for person skilled in the art scholar and read, and be not used to limit the enforceable qualifications of the utility model, therefore the not technical essential meaning of tool, the adjustment of the modification of any structure, the change of proportionate relationship or size, do not affecting under effect that the utility model can produce and the object that can reach, still all should drop on technology contents that the utility model discloses and obtain in the scope that can contain.Simultaneously, quote in this instructions as " on ", D score, "left", "right", " centre " and " one " etc. term, also only for ease of understanding of describing, and be not used to limit the enforceable scope of the utility model, the change of its relativeness or adjustment, under changing technology contents without essence, when being also considered as the enforceable category of the utility model.
As shown in Figure 1, the utility model provides a kind of silicon-based modulator, and described silicon-based modulator at least comprises:
Ridge waveguide 400, described ridge waveguide 400 comprises flat part 50 and is positioned in the middle of described flat part 50, and higher than the raised line 70 of described flat part 50.
In the present embodiment, described ridge waveguide 400 is formed in (not shown) in the top layer silicon of SOI substrate, is also surrounded by other low-index material around described ridge waveguide 400.Being specifically as follows, is the oxygen buried layer of SOI substrate below described ridge waveguide 400, is silicon dioxide covering above described ridge waveguide 400.
In ridge waveguide 400 in the present embodiment, the material due to described ridge waveguide 400 is silicon, below or the material of surrounding described ridge waveguide 400 be above silicon dioxide.The refractive index of silicon refractive index ratio silicon dioxide is large, so, when work, need the electromagnetic wave (light) of transmission just to propagate along the bearing of trend of raised line 70 in described ridge waveguide 400.Determine the size of each several part in described ridge waveguide, according to the size that maxwell equation group, boundary condition also have optical waveguide concrete, the concrete condition that can solve electromagnetic wave (light) electromagnetic field can propagated in described ridge waveguide 400 (comprises Electric and magnetic fields intensity, direction, speed, decay etc.).
Concrete, in the present embodiment, the height H 1 of flat part 50 is 50nm ~ 200nm, and height (height of the described raised line 70) H2 of described ridge waveguide 400 is 220nm ~ 340nm, the width L1 of described raised line 70 is 300nm ~ 700nm, and described duct width L2 is 450nm ~ 600nm.
In addition, in described ridge waveguide 400, multiple doped region is also formed.Described doped region is by repeatedly ion implantation formation.Concrete, described ridge waveguide 400 comprises the first light doping section, light doping section 111,112 and second 211,212, described first light doping section comprises longitudinally the first light doping section 111 and at least one horizontal first light doping section 112, described longitudinal direction first light doping section 111 is formed in the middle of raised line 70, and along the bearing of trend of described raised line 70, described transverse direction first light doping section 112 is formed on described raised line 70 and described flat part 50, and crossing with described raised line 70; The doping type of described second light doping section 211 and described first light doping section 111,112 is contrary, and in the raised line 70 be formed at outside described first light doping section 111,112 and flat part 50, to be formed horizontal and vertical PN junction with described first light doping section 111,112.
In the present embodiment, the principle of described silicon-based modulator is: the voltage change at PN junction two ends can cause the change of the width of depletion region of PN junction, and the change of the width of depletion region of PN junction can cause the index distribution of waveguide to change, the index distribution of waveguide changes can cause wherein electromagnetic mould field change, and then cause the electromagnetic wave propagated to change, thus achieve the function of the electrooptical modulation of modulator.
Wherein, electromagnetic mould field refers in described ridge waveguide 400, the space distribution of electromagnetic wave (light) electromagnetic intensity of propagation.
In the present embodiment, multiple transverse direction first light doping section 112 and the second light doping section 211,212 form multiple PN junction structure in the direction of propagation, mould field of ridge waveguide 400 simultaneously, improve the modulation efficiency of silica-based photomodulator.
In the present embodiment, longitudinally the first light doping section 111 and the second light doping section 211,212 form two back-to-back PN junction structures in ridge waveguide 400, and operation can form two depletion regions.In work, the area of the depletion region of two PN junction structures, by being greater than the depletion region area of common PN junction design, improves modulation efficiency.
In addition, two PN junctions that longitudinally the first light doping section 111 and the second light doping section 211,212 are formed reach the problem solving ion implantation alignment error, improve the modulation efficiency of silica-based photomodulator.Concrete, in the present embodiment, the doping type of described first light doping section 111,112 is P type, namely described longitudinal direction first light doping section 111 defines with described second light doping section 211,212 structure that doped forms is NPN in raised line 70, include two PN junctions, operationally can form two depletion regions.Like this, if ion implantation is aimed to the left, the PN junction on right side is relatively near the place of optimal value; If ion implantation is to the right, the PN junction in left side can make up.So utilize two PN junctions to reach the problem solving ion implantation alignment error.
The first heavily doped region 123, heavily doped region 221,222 and second is also comprised in described flat part 50, wherein, described first heavily doped region 221,222 be formed at respectively described second light doping section 211,212 two outside, wherein the outside of one first heavily doped region 222 is formed with the second heavily doped region 123; Described transverse direction first light doping section 112 is at least one long strip type region side by side, and described in each, laterally the first light doping section 112 is connected to described second heavily doped region 123 through described first heavily doped region 222; Described first heavily doped region 221,222 is identical with the doping type of described second light doping section 211,212, is N-type.Doping type, the 3rd light doping section 112 of described second heavily doped region 123 are identical with the doping type of described first light doping section 111, are P type.
Undoped region 100 is also comprised in described flat part 50, be formed at described transverse direction first light doping section and described first heavily doped region, between described first heavily doped region and the second heavily doped region, act as isolating laterally the first light doping section 112 and the first heavily doped region 221,222, and isolation the first heavily doped region 222 and the second heavily doped region 123.
In addition, as shown in Figure 2, through hole (sign) is also formed in described first heavily doped region 123, heavily doped region 221,222 and second, metal electrode 300 is filled with in described through hole, the described metal electrode 300 be in the first heavily doped region 221,222 links together, described in be in the second heavily doped region 123 metal electrode 300 link together.
Heavy doping in described first heavily doped region 123, heavily doped region 221,222 and second, to form Ohmic contact with described metal electrode 300 wherein.What described transverse direction first light doping section 112 and described second heavily doped region 123 connected act as the second heavily doped region 123 that longitudinally the first light doping section 111 is identical with doping type in the middle of connecting, and makes electric current can flow into longitudinally the first light doping section 111 from the metal electrode 300 of the second heavily doped region 123 along horizontal first light doping section 112.
Namely as described in Fig. 1 to 2, each doped region situation is from left to right specially:
First heavily doped region 221 is N heavily doped region, doping content 1 × 10
19cm
-3to 5 × 10
20cm
-3, through hole is placed in this region, and for connection metal electrode 300, the metal electrode 300 of one's respective area is connected with the metal electrode 300 of the first heavily doped region 222.Second light doping section 211 is N light doping section, doping content 1 × 10
17cm
-3to 5 × 10
18cm
-3, this region is without through hole.
First light doping section 111 is P light doping section, and doping content is 1 × 10
17cm
-3to 5 × 10
18cm
-3, this region is without through hole.
Second light doping section 212 is N light doping section, doping content 1 × 10
17cm
-3to 5 × 10
18cm
-3, this region is without through hole.
First heavily doped region 222 is N heavily doped region, and doping content is 1 × 10
19cm
-3to 5 × 10
20cm
-3, there is through hole in this region, and for connection metal electrode 300, the metal electrode 300 of one's respective area is connected with the metal electrode 300 of the first heavily doped region 221.
Undoped region 100, act as isolating laterally the first light doping section 112 and the first heavily doped region 221,222, and isolation the first heavily doped region 222 and the second heavily doped region 123.
Second heavily doped region 123 is P heavily doped region, and doping content is 1 × 10
19cm
-3to 5 × 10
20cm
-3, there is through hole in this region, for connection metal electrode 300.
Concrete, in the present embodiment, described longitudinal direction first light doping section 111 becomes rotational symmetry with described second light doping section 211,212 with the center line of the described raised line parallel with the bearing of trend of described raised line 70.Described first light doping section 111, in centre, needs wider, and reason is that two interphases of described first light doping section 111 and described second light doping section 211,212 all will form depletion region, too near, and two depletion regions can be overlapping.In addition due to the limitation of prior art processes, longitudinal 300nm ~ 700nm.The width W 3 of the first light doping section 111 can be greater than 150nm.The width K1 of described transverse direction first light doping section 111 is 300nm ~ 1000nm.
Described in adjacent two, laterally the spacing K2 of the first light doping section is 300nm ~ 700nm.The width K3 (or W6) of described undoped region is 1 μm.
In the present embodiment, spacing W2, the W4 on two borders that described first heavily doped region 221,222 is relative with described raised line 70 are 1 μm ~ 2 μm.This is because metal electrode 300 is formed in the first heavily doped region 123, heavily doped region 221,222 and second, thus the first heavily doped region 221,222 will from away from the middle of ridge waveguide some, not so the electric field of metal electrode 300 can destroy the light field in optical waveguide.
In the present embodiment, the width W 5 of described first heavily doped region 222 be close to described second heavily doped region 123 is 1 μm ~ 10 μm, described in another, the width W 1 of the first heavily doped region 221 is 1 μm ~ 50 μm, and the width W 7 of described second heavily doped region 123 is 1 μm ~ 50 μm.This is because there is electrode the first heavily doped region 221 and the second heavily doped region 123, so the first heavily doped region 221 and the second heavily doped region 123 need wider, to optimize metal electrode 300, ensures the low-loss transmission of electric signal.
In addition, when the electric signal of driven modulator work is low frequency, wavelength wants large more than modulator size, therefore can use lump electrode.But when signal frequency is more than 10GHz, be microwave signal, because microwave signal wavelength is close to electrode length, so must need to use traveling wave electrode.In the present embodiment, the thickness arranging described metal electrode 300 is 0.5 μm ~ 3 μm, and the spacing between two metal electrodes 300 is 2 μm ~ 20 μm, and the width of metal electrode 300 is 5 μm ~ 500 μm.
In sum, the silica-based photomodulator provided in the technical solution of the utility model utilizes multiple transverse direction first light doping section and the second light doping section to form multiple PN junction structure in the direction of propagation, mould field of ridge waveguide simultaneously, utilize longitudinally the first light doping section and the second light doping section in the raised line of ridge waveguide, form two back-to-back PN junction structures, operation can form two depletion regions, add the area of depletion region in mould field, thus improve the modulation efficiency of silica-based photomodulator.
So the utility model effectively overcomes various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present utility model and effect thereof only, but not for limiting the utility model.Any person skilled in the art scholar all without prejudice under spirit of the present utility model and category, can modify above-described embodiment or changes.Therefore, such as have in art and usually know that the knowledgeable modifies or changes not departing from all equivalences completed under the spirit and technological thought that the utility model discloses, must be contained by claim of the present utility model.