The utility model content
The utility model is intended to solve at least the technical problem that exists in prior art, has proposed to special innovation a kind of power device that improves the diffusion zone pattern.
In order to realize above-mentioned purpose of the present utility model, according to first aspect of the present utility model, the utility model provides a kind of power device that improves the diffusion zone pattern, comprises substrate and the upper epitaxial loayer that forms thereof, and described epitaxial loayer and described substrate are the N-type doping; Be formed with buried regions in described epitaxial loayer, the upper surface of described buried regions and the upper surface of epitaxial loayer are positioned at same plane, and described buried regions is the doping of P type; Be formed with the source region in described buried regions, the upper surface in described source region and the upper surface of described epitaxial loayer are positioned at same plane, and described source region is N-type doping class; Be formed with the prediffusion district in described epitaxial loayer, described prediffusion district is connected with described buried regions, and the upper surface in described prediffusion district and the upper surface of described epitaxial loayer be positioned at same plane, and described prediffusion district is the doping of P type; Be formed with gate dielectric layer and grid on the upper surface of described epitaxial loayer, described gate dielectric layer and grid cover on the part in buried regions and described source region; Be formed with dielectric layer and front metal layer on described grid and epitaxial loayer; Be formed with the back side diffusion district under described substrate; And be formed with metal layer on back under described back side diffusion district.
the utility model employing prediffusion district, buried regions is expanded gently to epitaxial loayer, the utility model has improved the pattern of trench edges diffusion zone, particularly prepare the situation of P-type conduction raceway groove in the N-type epitaxial loayer, the district improves the P type carrier concentration of channel surface due to employing prediffusion, be conducive to the diffusion of diffusion region P type doping, finally make the pattern of p type diffusion region extend gently to the N-type epitaxial loayer, thereby optimized the Electric Field Distribution of device under HTHP, thereby reduce the levels of leakage of device under HTHP, can significantly improve power MOSFET, the thermal reliability of IGBT constant power device.Be fit to requirements of one's work under high temperature, high-power environment.
In a kind of preferred embodiment of the present utility model, include the conducting channel district that is connected with described source region in described buried regions and inject the diffusion region, described conducting channel district is positioned between source region and described prediffusion district and the upper surface in conducting channel district and the upper surface of described epitaxial loayer are positioned at same plane, described injection diffusion region is positioned at the below in source region, and described conducting channel district and described injection diffusion region are the doping of P type.
In another kind of preferred embodiment of the present utility model, described conducting channel district is connected with described prediffusion district.
Conducting channel of the present utility model district is connected with the prediffusion district, improved the carrier concentration of conducting channel area edge, reduced doping particle resistance extending transversely in buried regions, thereby the doping particle in it can be to laterally mild expansion of epitaxial loayer in forming process to make buried regions, improved the pattern of trench edges diffusion zone, optimize the Electric Field Distribution of device under HTHP, reduced the levels of leakage of device under HTHP.
In a kind of preferred embodiment of the present utility model, the degree of depth in described conducting channel district is less than the degree of depth sum in described injection diffusion region and source region.
In another kind of preferred embodiment of the present utility model, described conducting channel district is light dope, and described injection diffusion region is heavy doping.
The utility model is by the degree of depth of controlling the conducting channel district and the degree of depth sum of injecting diffusion region and source region, and by buried regions is carried out inhomogeneous doping, can reduce the conducting resistance of device, improves the withstand voltage level of device.
In a kind of preferred embodiment of the present utility model, described prediffusion district diminishes gradually along the width of epitaxial loayer depth direction.
In another kind of preferred embodiment of the present utility model, described prediffusion district is wedge along the section of the epitaxial loayer degree of depth.
The utility model is at the upper surface place of epitaxial loayer, this prediffusion district is wider, along with deeply inner to epitaxial loayer, the width in prediffusion district diminishes gradually, thereby make the prediffusion district higher the closer to the carrier concentration of epi-layer surface, the closer to epi-layer surface, in buried regions, the resistance extending transversely of doping particle reduces more obvious.
In a kind of preferred embodiment of the present utility model, the degree of depth in described prediffusion district is 0-5000A, and the concentration in described prediffusion district is E10-E13.
In another kind of preferred embodiment of the present utility model, described dielectric layer is formed by silicon dioxide and boron-phosphorosilicate glass.
The utility model dielectric layer can improve the functional reliability of device, is fit to the needs under high temperature, high-power environment.
Additional aspect of the present utility model and advantage part in the following description provide, and part will become obviously from the following description, or recognize by practice of the present utility model.
Embodiment
The below describes embodiment of the present utility model in detail, and the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or the element with identical or similar functions from start to finish.Be exemplary below by the embodiment that is described with reference to the drawings, only be used for explaining the utility model, and can not be interpreted as restriction of the present utility model.
in description of the present utility model, it will be appreciated that, term " vertically ", " laterally ", " on ", D score, " front ", " afterwards ", " left side ", " right side ", " vertically ", " level ", " top ", " end " " interior ", orientation or the position relationship of indications such as " outward " are based on orientation shown in the drawings or position relationship, only the utility model and simplified characterization for convenience of description, rather than device or the element of indication or hint indication must have specific orientation, with specific orientation structure and operation, therefore can not be interpreted as restriction of the present utility model.
In description of the present utility model, unless otherwise prescribed and limit, need to prove, term " installation ", " being connected ", " connection " should be done broad understanding, for example, can be mechanical connection or electrical connection, can be also the connection of two element internals, can be directly to be connected, and also can indirectly be connected by intermediary, for the ordinary skill in the art, can understand as the case may be the concrete meaning of above-mentioned term.
Fig. 1 is the structural representation of a kind of preferred implementation of the utility model power device of improving the diffusion zone pattern, is only each regional size that provided of signal in figure, and concrete size can design according to the requirement of device parameters.As seen from the figure, this power device that improves the diffusion zone pattern comprises substrate 1, this substrate 1 can be any backing material of preparation power MOSFET or IGBT, can be specifically but be not limited to SOI, silicon, germanium, GaAs, in the present embodiment, the preferred silicon that adopts, this substrate 1 is light dope, and its doping type is N-type, is formed with epitaxial loayer 2 on this substrate 1, the doping type of this epitaxial loayer 2 is identical with the doping type of substrate 1, and the doping type of this epitaxial loayer 2 is N-type.Be formed with buried regions in epitaxial loayer 2, the doping type of buried regions is opposite with the doping type of epitaxial loayer 2, and namely this buried regions is P type doping, and this buried regions comprises conducting channel district 4 and inject diffusion region 5, and epitaxial loayer 2 partly exposes with respect to buried regions.In a kind of preferred implementation of the present utility model, this buried regions is Uniform Doped, and in another preferred implementation of the present utility model, this buried regions is non-uniform doping, and the conducting channel district 4 of buried regions is light dope, injects diffusion region 5 and is heavy doping.Be formed with source region 6 in buried regions, the doping type in source region 6 is identical with the doping type of epitaxial loayer 2, namely this source region 6 is exposed to the upper surface of epitaxial loayer 2, this source region 6 is heavy doping, the doping type in source region 6 is identical with the doping type of epitaxial loayer 2, and namely the doping type in source region 6 is opposite with the doping type of buried regions, in the present embodiment, the doping type in this source region 6 is N-type, and the buried regions between source region 6 and epitaxial loayer 2 is conducting channel district 4.
Particularly, be formed with prediffusion district 3 in epitaxial loayer 2, this prediffusion district 3 is connected with buried regions, and the upper surface in prediffusion district 3 and the upper surface of epitaxial loayer 2 be positioned at same plane, and the doping type in this prediffusion district 3 is identical with the doping type of buried regions, the doping type that is prediffusion district 3 is opposite with the doping type of epitaxial loayer 2, concrete, adulterate for the P type in this prediffusion district 3, and its upper surface from epitaxial loayer 2 is deep into epitaxial loayer 2 inside, its thickness is 0-5000A, and its concentration is E10-E13.Need to prove, in embodiment of the present utility model, prediffusion district 3 can form prior to buried regions, also can be later than buried regions and form.
Particularly, conducting channel district 4 and inject diffusion region 5 and be formed between epitaxial loayer 2 and source region 6, and injection diffusion region 5 is positioned under source region 6.So, this prediffusion district 3 is positioned at the epitaxial loayer 2 that is connected with conducting channel district 4, and this prediffusion district 3 can be connected with conducting channel district 4, also can not be connected with conducting channel district 4.As shown in Figure 1, the degree of depth in described conducting channel district 4 is less than the degree of depth sum in described injection diffusion region 5 and source region 6.
Due to the surface the closer to buried regions, the resistance extending transversely of doping particle is larger, in the present embodiment, prediffusion district 3 diminishes gradually along the width of epitaxial loayer 2 depth directions, and namely at the upper surface place of epitaxial loayer 2, this prediffusion district 3 is wider, along with deeply inner to epitaxial loayer 2, the width in prediffusion district 3 narrows down gradually, and under preferable case, prediffusion district 3 is wedge along the section of epitaxial loayer depth direction.Due to the upper surface place at epitaxial loayer 2, this prediffusion district 3 is wider, and along with deeply inner to epitaxial loayer, the width in prediffusion district 3 narrows down gradually, thereby make prediffusion district 3 higher the closer to the carrier concentration on epitaxial loayer 2 surfaces, in buried regions, the resistance extending transversely of doping particle reduces more obvious.By adopting identical with buried regions doping type prediffusion district 3, improved the carrier concentration of conducting channel area edge, reduced doping particle resistance extending transversely in buried regions, thereby the doping particle in it can be to laterally mild expansion of epitaxial loayer in forming process to make buried regions, improved the pattern of trench edges diffusion zone, optimize the Electric Field Distribution of device under HTHP, reduced the levels of leakage of device under HTHP.Can also be formed with isolated area epitaxial loayer 2 is interior, be used for the isolation between power device, this isolated area and prediffusion district 3 lay respectively at the both sides of buried regions, and it can be connected with buried regions, also can not be connected with buried regions.This isolated area can be oxygen district, field or deep trench isolation district, and in the present embodiment, preferred the oxygen district of adopting isolates.
in the present embodiment, be formed with gate dielectric layer 7 on the part in buried regions and source region 6, in the other preferred implementation of the utility model, conducting channel district 4 and between epitaxial loayer 2 and the part in source region 6 on be formed with gate dielectric layer 7, in the other preferred implementation of the utility model, also can be only form gate dielectric layer 7 on conducting channel district 4, be formed with grid 8 on this gate medium 7, be coated with one deck dielectric layer on grid 8 and on not by the epitaxial loayer 2 of grid 8 and gate dielectric layer 7 coverings, has the contact hole that connects to the source region on this dielectric layer, be filled with front metal layer 11 in this contact hole, this front metal layer 11 is connected with source region 6 by contact hole.Gate dielectric layer 7 can be any gate dielectric material that preparation is used in transistor, can for but be not limited to high K dielectric, silicon dioxide, in the present embodiment, preferably adopt silicon dioxide.Grid 8 can for but be not limited to polysilicon gate or metal gates, in the present embodiment, preferably adopt polysilicon gate.Dielectric layer can for but be not limited to oxide, the nitride of silicon, the nitrogen oxide of silicon, the boron-phosphorosilicate glass of silicon, in the present embodiment, preferably adopt layer of silicon dioxide layer 9 and one deck boron-phosphorosilicate glass layer 10 jointly to form.Be formed with back side diffusion district 12 under substrate 1, back side diffusion district 12 is heavy doping, doping type can be identical with the doping type of substrate 1, also can be opposite with the doping type of substrate 1, when the doping type in back side diffusion district 12 identical with the doping type of substrate 1, when being the N-type doping, be the MOSFET device; When the doping type in back side diffusion district 12 opposite with the doping type of substrate 1, when being the doping of P type, be the IGBT device, be formed with metal layer on back 13 under diffusion region 12 overleaf, in a kind of preferred implementation of the present utility model, this metal layer on back 13 comprises three-layer metal, is followed successively by titanium, nickel, gold or titanium, nickel, silver.
The utility model has also proposed a kind of manufacture method of improving the power device of diffusion zone pattern, and Fig. 2-Fig. 8 is the processing step schematic diagram that improves the power device of diffusion zone pattern shown in Fig. 1, and described method comprises the steps:
S11: substrate 1 is provided and forms epitaxial loayer 2 on substrate 1, this epitaxial loayer 2 is identical with the doping type of substrate 1;
S21: form gate dielectric layer 7 on epitaxial loayer 2;
S31: the interior formation prediffusion of epitaxial loayer 2 district 3 under gate dielectric layer 7, this prediffusion district 3 is opposite with the doping type of substrate 1;
S41: form grid 8 on gate dielectric layer 7;
S51: at the interior formation buried regions of epitaxial loayer 2, the doping type of buried regions is opposite with the doping type of epitaxial loayer 2, the doping type that is buried regions is identical with the doping type in prediffusion district 3, buried regions comprises conducting channel district 4 and injects diffusion region 5, wherein, prediffusion district 3 is between epitaxial loayer 2 and buried regions, and epitaxial loayer partly exposes with respect to buried regions.
S61: be formed with source region 6 in buried regions, this source region 6 is heavy doping, and the doping type of its doping type is identical with the doping type of epitaxial loayer 2, wherein, conducting channel district 4 and inject diffusion region 5 and be formed between epitaxial loayer 2 and source region 6, and injection diffusion region 5 is positioned under source region 6.
S71: form dielectric layer on grid 8 and source region 6, have on dielectric layer and connect to the source region 6 contact hole;
S81: form front metal layer 11 on dielectric layer, this front metal layer 11 is connected with source region 6 by contact hole;
S91: form back side diffusion district 12 under substrate 1, this back side diffusion district 12 is heavy doping;
S101: be formed with metal layer on back 13 under diffusion region 12 overleaf.
in step S11: as shown in Figure 2, substrate 1 is provided, this substrate 1 can be any backing material of preparation power MOSFET or IGBT, can be specifically but be not limited to SOI, silicon, germanium, GaAs, in the present embodiment, the preferred silicon that adopts, this substrate 1 is light dope, be formed with epitaxial loayer 2 on this substrate 1, this epitaxial loayer 2 is identical with the doping type of substrate 1, namely can be N-type, form this epitaxial loayer 2 method can for but be not limited to chemical vapor deposition, can also be formed with isolated area epitaxial loayer 2 is interior, this isolated area can be oxygen district, field or deep trench isolation district, in the present embodiment, oxygen district, preferred employing field isolates.
In step S21: as shown in Figure 3, form gate dielectric layer 7 on epitaxial loayer 1, this gate dielectric layer 7 can be any gate dielectric material that uses in the preparation transistor, can for but be not limited to high K dielectric, silicon dioxide, in the present embodiment, preferably adopt silicon dioxide, form gate dielectric layer concrete grammar can for but be not limited to chemical vapor deposition.In an embodiment of the present utility model, also can form grid 8 in this step, perhaps, in other embodiment of the present utility model, also can form in step S4.
In step S31, as shown in Figure 4, the interior formation prediffusion of epitaxial loayer 2 district 3 under gate dielectric layer 7, the doping type in this prediffusion district 3 is opposite with the doping type of epitaxial loayer 2, i.e. this prediffusion district 3 is the doping of P type, and the upper surface of the upper surface in prediffusion district 3 and epitaxial loayer 2 is positioned at same plane, its upper surface from epitaxial loayer 2 is deep into epitaxial loayer inside, its degree of depth is 0-5000A, its concentration is E10-E13, and the concrete grammar that forms the prediffusion district is photoetching, carries out Implantation in the situation that mask is sheltered, and diffusion, the method for annealing.
In step S41, as shown in Figure 5, form grid 8 on gate dielectric layer 7, this grid 8 can for but be not limited to polysilicon gate or metal gates, in the present embodiment, preferably adopt polysilicon gate, form grid concrete grammar can for but be not limited to chemical vapor deposition.
in step S51, as shown in Figure 6, at the interior formation buried regions of epitaxial loayer 2, this buried regions is connected with prediffusion district 3, the doping type in this prediffusion district 3 is identical with the doping type of buried regions, buried regions is the doping of P type, this buried regions comprises conducting channel district 4 and injects diffusion region 5, in a kind of preferred implementation of the present utility model, this buried regions is Uniform Doped, in another preferred implementation of the present utility model, this buried regions is non-uniform doping, the conducting channel district 4 of buried regions is light dope, inject diffusion region 5 and be heavy doping, the step that forms the buried regions of this non-uniform doping is: at first, light dope is all carried out in the zone that forms buried regions in epitaxial loayer, doping type is the P type, then, carry out heavy doping in the injection diffusion region 5 of buried regions, doping type is the P type.The method that forms buried regions is specially photoetching, carries out Implantation in the situation that mask is sheltered, and diffusion, the method for annealing.
In step S61, as shown in Figure 7, be formed with source region 6 in buried regions, this source region 6 is exposed to the upper surface of epitaxial loayer 2, this source region 6 is heavy doping, and its doping type is N-type, and the concrete grammar that forms source region 6 is photoetching, in the situation that sheltering, mask carries out Implantation, and diffusion, the method for annealing.
In step S71, as shown in Figure 8, form dielectric layer at grid 8 and on not by the epitaxial loayer 2 of grid 8 and gate dielectric layer 7 coverings, has the contact hole that connects to the source region on this dielectric layer, this dielectric layer can for but be not limited to oxide, the nitride of silicon, the nitrogen oxide of silicon, the boron-phosphorosilicate glass of silicon, in the present embodiment, preferably adopt silicon dioxide layer 9 and boron-phosphorosilicate glass layer 10.In step S81, form front metal layer 11 on dielectric layer, this front metal layer 11 is connected with source region 6 by contact hole.In the present embodiment, can also form passivation layer on front metal layer 11, the material of this passivation layer is specifically as follows but is not limited to silicon dioxide.
in step S91 and step S101, form back side diffusion district 12 under substrate 1, this back side diffusion district 12 is heavy doping, its doping type can be identical with the doping type of substrate 1, also can be opposite with the doping type of substrate 1, when the doping type of the doping type in back side diffusion district 12 and substrate 1 is identical, be the MOSFET device, when the doping type of the doping type in back side diffusion district 12 and substrate 1 is opposite, be the IGBT device, the concrete grammar in formation back side diffusion district is photoetching, in the situation that sheltering, mask carries out Implantation, and diffusion, the method of annealing.Be formed with metal layer on back 1 under diffusion region 12 overleaf, this metal layer on back 13 comprises three-layer metal, is followed successively by titanium, nickel, gold or titanium, nickel, silver.After carrying out for the 8th step, namely obtain device architecture shown in Figure 1.
In the present embodiment, step S21 and step S41 can carry out between step S61 and step S71, namely can be first in the interior formation prediffusion of epitaxial loayer 2 district 3, the doping type in this prediffusion district 3 is opposite with the doping type of substrate 1, is the P type; Then at the interior formation buried regions of epitaxial loayer 2, this buried regions is connected with prediffusion district 3, and the doping type of buried regions is opposite with the doping type of substrate, is the P type; Be formed with subsequently source region 6 in buried regions, this source region 6 is heavy doping, and its doping type is identical with the doping type of substrate 1, is N-type; Again, form gate dielectric layer 7 on epitaxial loayer 2, form grid 8 on gate dielectric layer 7.
In the other preferred implementation of the utility model, before also step S41 can being moved on to step S31, after namely forming gate dielectric layer 7 and grid 8, then form prediffusion district 3.
In the other preferred implementation of the utility model, can also step S31 and step S51 between exchange, namely first form buried regions in epitaxial loayer 2, afterwards in the interior formation prediffusion of epitaxial loayer 2 district 3.
According to manufacture method of the present utility model, in a kind of preferred implementation of the present utility model, the preparation method who improves the IGBT of diffusion zone pattern is: at first, form N-shaped epitaxial loayer 2 by epitaxial growth method on lightly doped N-shaped silicon substrate 1, in present embodiment, to make DRAM cell as example on the N-shaped substrate, for the device for preparing on the p-type substrate, get final product according to opposite doping type doping.Then, utilize CVD (Chemical Vapor Deposition) method deposit silicon dioxide as gate dielectric layer 7 according to predetermined device architecture on the N-shaped epitaxial loayer, utilize subsequently the polysilicon of CVD (Chemical Vapor Deposition) method deposit N-shaped impurity doping, form the grid 8 of device by chemical etching technique; Subsequently, photoetching on the N-shaped epitaxial loayer, inject p-type impurity, and diffuse to form P-type thin layer through high-temperature heat treatment, namely the prediffusion layer 3, and in the present embodiment, B11 or BF2 can be adopted in the injection source, and implantation dosage is in the E12 magnitude, and the input energy is 10~50Kev; Again, adopt successively ion injection method to inject respectively P-from the both sides of grid and inject P+ according to predetermined structure, and injecting diffusion region 5 through high-temperature heat treatment formation P-conducting channel district 4 and P+; Then, inject N+ impurity, form source region 6; Surface deposition dielectric layer at power device, comprise silicon dioxide layer 9 and boron-phosphorosilicate glass layer 10, and according to the predetermined structure photoetching, etch metal contact hole, subsequently, at the surface deposition metal level of power device, and form front metal layer 11 according to predetermined structure photoetching and etching; Then, with the device thinning back side, carry out Implantation p-type impurity in the situation that mask is sheltered, and diffusion, annealing forms back side diffusion district 12; At last, overleaf under diffusion region 12 deposit titanium, nickel, gold be formed with metal layer on back 13.Present embodiment improves the p-type doping content of channel surface by adopting p-type prediffusion district 3, and the horizontal proliferation of more favourable and P-buried regions finally makes the P-buried regions to the horizontal expansion of N-shaped epitaxial loayer, has improved the diffusion pattern.
In manufacture method of the present utility model, make the device of making have good thermal stability by the diffusion region, can significantly improve the thermal reliability of MOSFET, IGBT constant power device, and manufacture process and existing power device technique are fully compatible, have the distinguishing features such as simple in structure, easily manufactured, improved production efficiency and rate of finished products.
In the description of this specification, the description of reference term " embodiment ", " some embodiment ", " example ", " concrete example " or " some examples " etc. means to be contained at least one embodiment of the present utility model or example in conjunction with specific features, structure, material or the characteristics of this embodiment or example description.In this manual, the schematic statement of above-mentioned term not necessarily referred to identical embodiment or example.And the specific features of description, structure, material or characteristics can be with suitable mode combinations in any one or more embodiment or example.
Although illustrated and described embodiment of the present utility model, those having ordinary skill in the art will appreciate that: in the situation that do not break away from principle of the present utility model and aim can be carried out multiple variation, modification, replacement and modification to these embodiment, scope of the present utility model is limited by claim and equivalent thereof.