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 silica-based photomodulator, the problem that PN junction is less to process allowance on the ridge waveguide solving silica-based photomodulator in prior art.
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 is positioned at the raised line in the middle of described flat part, and described raised line is higher than described flat part;
Be formed with the first light doping section and the second light doping section in described ridge waveguide, described first light doping section is formed in the middle of described raised line, and extends along the bearing of trend of described raised line; The raised line that described second light doping section is formed at described first both sides, light doping section neutralizes in the flat part be connected with described raised line both sides;
The doping type of described first light doping section and described second light doping section is contrary.
Preferably, the width of described first light doping section is 100nm ~ 250nm.
Preferably, described first light doping section becomes rotational symmetry with described second light doping section with the center line of the described raised line parallel with the bearing of trend of described raised line.
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, the first heavily doped region, the second heavily doped region and the 3rd light doping section is also comprised in described flat part;
Wherein, described first heavily doped region be formed at respectively described second light doping section two outside, wherein the outside of one first heavily doped region is formed with described second heavily doped region;
Described 3rd light doping section is at least one long strip type region side by side, and one end of the 3rd light doping section described in each connects described first light doping section, and the other end connects described second heavily doped region;
Described first heavily doped region is identical with the doping type of described second light doping section; Doping type, the 3rd light doping section of described second heavily doped region are identical with the doping type of described first light doping section;
Also be formed with through hole in described first heavily doped region and the second heavily doped region, in described through hole, be filled with metal electrode, 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, a metal electrode is formed with between every two adjacent described 3rd light doping sections.
Preferably, the spacing on two borders that described first heavily doped region is relative with described raised line is 1 μm ~ 2 μm.
Preferably, the width of described first heavily doped region be close to described second heavily doped region is 1 μm ~ 10 μm, and the width of the first heavily doped region described in another is 1 μm ~ 50 μm, and the width of 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, the silica-based photomodulator provided in the technical solution of the utility model, has following beneficial effect:
Two back-to-back PN junctions are formed by the first light doping section and the second light doping section in the raised line of ridge waveguide, two depletion regions can be formed when silica-based photomodulator work, 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, and solves the problem of ion implantation alignment error like this; Further, the area of the depletion region of two PN, by being greater than the depletion region area of a PN junction design, improves the modulation efficiency of silica-based photomodulator.
Embodiment
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.
In the technical scheme that the utility model provides, in ridge waveguide, form two back-to-back PN, operation can form two depletion regions.In work, the area of the depletion region of two PN will be greater than the depletion region area of common PN junction design, forms the problem that two PN junctions solve ion implantation alignment error, improve the modulation efficiency of silica-based photomodulator so utilize in ridge waveguide.
Concrete the utility model provides a kind of silica-based photomodulator, comprises ridge waveguide 400 as shown in Figure 1, the raised line 70 that described ridge waveguide 400 comprises flat part 50 and is positioned in the middle of described flat part 50, and described raised line 70 is higher than 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, also has other low-index material to surround 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.Concrete, in the present embodiment, the height H 1 of flat part 50 is 50nm ~ 200nm, the height (height of described raised line 70) of described ridge waveguide 400 for H2 be 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, be formed with the first light doping section 111 and the second light doping section 211,212 in described ridge waveguide, described first light doping section 111 is formed at the centre of described raised line 70, and extends along the bearing of trend of described raised line 70; The raised line 70 that described second light doping section 211,212 is formed at described first both sides, light doping section 111 neutralizes in the flat part 50 be connected with described raised line 70 both sides; The doping type of described first light doping section 111 and described second light doping section 211,212 is contrary.
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 change of waveguide can cause the communication mode of this waveguide support to change, and then cause the effective refractive index of mould field 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 described ridge waveguide 400, the intensity of some local described electromagnetic mould field is large, and the intensity of some local described electromagnetic mould field is weak.Concrete, in the present embodiment, in described ridge waveguide 400, in the centre of described raised line 70, the intensity of described mould field is maximum.
Preferably, in the present embodiment, need the depletion region of PN junction in the maximum place of electromagnetic mould field strength, like this, the change of the depletion region of PN junction electromagneticly to have the greatest impact to propagated.
In the present embodiment, the doping type of described first light doping section 111 is P type, namely described first light doping section 111 defines with described second light doping section 211,212 structure that doped forms is NPN in raised line 70, includes 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.Further, by optimizing, in work, the area of the depletion region of two PN junctions is by being greater than the depletion region area of common PN junction design, improves modulation efficiency.
In addition, the first heavily doped region 123, heavily doped region 221,222, second and the 3rd light doping section 112 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 described second heavily doped region 123; Described 3rd light doping section 112 is at least one long strip type region side by side, and one end of the 3rd light doping section 112 described in each connects described first light doping section 111, and the other end connects described second heavily doped region 123; 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.
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.Because different electrode metals and heavily doped region form Ohmic contact, are different to the requirement of doping content.Doping contents different in described first heavily doped region 221,222 and described second heavily doped region 123 is for different electrode metals.
Acting as of described 3rd light doping section 112 connects second heavily doped region 123 identical with doping type, the first middle light doping section 111, makes electric current can flow into the first light doping section 111 from the metal electrode 300 of the second heavily doped region 123 along the 3rd 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.
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 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, the width W 3 of the first light doping section 111 is minimum should >150nm.
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, so the first heavily doped region 221,222 will from away from the middle of ridge waveguide some, otherwise the electric field of metal electrode 300 likely 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 6 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.
Because the 3rd light doping section 112 can through the second light doping section 211 and the first heavily doped region 221 in the process of arrival second heavily doped region 123, therefore likely can in these formation depletion regions, region, but because the mould field strength in these regions is very little, form depletion region in these regions and can not improve modulation efficiency, the loss of electric current can be caused on the contrary.Concrete, the width arranging described 3rd light doping section 112 is g, and spacing is l, then each Cycle Length can represent with g+l, and described 3rd light doping section 112 proportion is a=g/ (g+l).In the present embodiment, the scope of described g is 50nm ~ 1000nm, and the scope of described l is 50nm ~ 1000nm, and the scope of described a is 0 ~ 1.
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 utility model forms two back-to-back PN junction structures in ridge waveguide, can form two depletion regions during work, reaches the problem solving ion implantation alignment error, improves 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.