CN103794721A - Phase change memory unit and method for manufacturing phase change memory unit - Google Patents
Phase change memory unit and method for manufacturing phase change memory unit Download PDFInfo
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- CN103794721A CN103794721A CN201410057134.7A CN201410057134A CN103794721A CN 103794721 A CN103794721 A CN 103794721A CN 201410057134 A CN201410057134 A CN 201410057134A CN 103794721 A CN103794721 A CN 103794721A
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- insulating layer
- change memory
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Abstract
The invention provides a phase change memory unit and a method for manufacturing the phase change memory unit. The phase change memory unit comprises a substrate, a lower electrode, a lower heat insulating layer, a phase change material layer, an upper heat insulating layer and an upper electrode, wherein the upper electrode is electrically connected with a phase change material film, the lower heat insulating layer is provided with a periodic structure which is mainly composed of a plurality of units in the shape of a quadrangular frustum pyramid and particularly silicon dioxide quadrangular frustum pyramids, the phase change material layer is arranged on the periodic structure continuously in a covering mode, and then a plurality of groove structures are formed. The phase change memory unit is easy to manufacture, low in cost, high in memory density, and capable of fully meeting application requirements of a phase change memory.
Description
Technical field
The present invention is specifically related to a kind of phase-change memory cell and preparation method thereof, belongs to semiconductor preparing technical field.
Background technology
Phase transition storage (phase-change memory, PCM) with its excellent characteristic, comprise fast reading and writing speed, excellent size scaling performance, multidigit unit storage capacity, radioresistance, low cost of manufacture etc., be considered to replace the main flow memory of future generation of the conventional memories such as FLASH, SRAM and DRAM.Along with the development of technology, people's Design & preparation has gone out multiple PCM cellular construction, as " mushroom-shaped " structure of classics, sidewall structure, EDGE CONTACT structure, μ-Trench structure etc., be intended to reduce electrode and material contact area, reduce read-write operation electric current to improve memory operation performance.
It is to need one of key issue of solution badly in the application oriented process of PCM that current raising PCM storage density reduces preparation cost simultaneously.The T-shape structure of current main-stream can only be by adopting more advanced photoetching process to obtain less contact size, and this structure can increase significantly process costs in further developing future.
Summary of the invention
The object of the present invention is to provide a kind of phase-change memory cell and preparation method thereof, to overcome the shortcoming of prior art,
For achieving the above object, the present invention has adopted following technical scheme:
A kind of phase-change memory cell, comprise the substrate, bottom electrode, lower thermal insulating layer, phase-change material layers, upper thermal insulating layer and the top electrode that set gradually from bottom to top, described top electrode is also electrically connected with described film of phase-change material, wherein, described lower thermal insulating layer has the periodic structure being mainly made up of a plurality of quadrangular frustum pyramid shapeds unit, described phase-change material layers is covered in described periodic structure continuously, and forms plurality of grooves structure.
Further, the cycle of described periodic structure is 10-100nm.
Further, described quadrangular frustum pyramid shaped unit top margin is of a size of 15-100nm, and base is of a size of 30-150nm.
Further, the thickness of described lower thermal insulating layer is 10-100nm.
Further, the thickness of described upper thermal insulating layer is 10-200nm.
Further, the thickness of described phase-change material layers is 10-100nm.
Further, the width of described top electrode is less than or equal to and is covered in 2/3rds of the phase-change material layers at each top, truncated rectangular pyramids type unit or the width of each groove structure groove bottom.
Further, each top electrode is connected with an extraction electrode one end, and the described extraction electrode other end passes upper thermal insulating layer, and in electrical contact with described phase-change material layers.
Further, described top electrode and extraction electrode are wholely set.
Further, described bottom electrode comprises any in tungsten film and titanium nitride/tungsten duplicature.
Further, aforementioned phase-change material can be selected from but be not limited to Ge
2sb
2te
5, N doped with Ge
2sb
2te
5, O doped with Ge
2sb
2te
5, GeSb
2te
5in any one or more.
Further, the material of aforementioned upper thermal insulating layer can be selected from but be not limited in silicon dioxide, silicon nitride any one or multiple.
Further, the material of aforementioned lower thermal insulating layer can be selected from but be not limited to silicon dioxide, that is described lower thermal insulating layer can have the periodic structure being mainly made up of a plurality of silicon dioxide truncated rectangular pyramids.
Further, the material of aforementioned top electrode can be selected but be not limited to aluminium.
A preparation method for phase-change memory cell, comprising:
(1) successively at substrate surface deposition lower electrode layer and heat-insulating material precursor layer;
(2) adopt photoetching technique at this heat-insulating material precursor layer surface fabrication cycle graphic structure, and utilize wet etching technology to corrode above-mentioned heat-insulating material precursor layer, obtain the periodic structure mainly being formed by a plurality of quadrangular frustum pyramid shapeds unit;
(3) adopt oxidation technology to process aforementioned periodic structure, oxidation forms lower thermal insulating layer;
(4) sediment phase change storage medium (also claiming " phase-change material ") on lower thermal insulating layer, forms and is covered in continuously phase-change material layers in described periodic structure and that have plurality of grooves structure;
(5) on phase-change material layers, deposit upper thermal insulating layer, and open hole at upper thermal insulating layer, then deposits conductive material in through hole, forms the top electrode in electrical contact with phase-change material layers.
Further, described heat-insulating material precursor layer is silicon layer.
In a typical embodiments, the preparation method of aforementioned lower thermal insulating layer comprises: first adopt wet corrosion technique to obtain the aforementioned periodic structure being formed by silicon, then adopt thermal oxidation technology to obtain silicon dioxide heat insulation layer.
Compared with prior art, beneficial effect of the present invention comprises:
(1) in this phase-change memory cell, lower thermal insulating layer structure is easy to preparation, and the etching technics of being combined with conventional lithography is compared the remarkable manufacturing cost that reduced;
(2) in this phase-change memory cell, based on the periodic structure of lower thermal insulating layer, make to deposit by phase-change material the phase-change material layers (rete) forming and have fluted body structure, this rete is continuous, compared with the phase-change storage material region discrete with tradition, photoetching and etching technics step are reduced, thereby further reduce manufacturing cost, and, all can build contact electrode in top and the bottom of groove structure, therefore can improve the storage density of device, meet the application demand of phase transition storage.
Accompanying drawing explanation
Fig. 1 is the structural representation of a kind of phase-change memory cell in the better embodiment of the present invention one;
Fig. 2 is preparation technology's flow chart of phase-change memory cell shown in Fig. 1;
Description of reference numerals: substrate 100, lower electrode layer 200, heat-insulating material precursor layer 300, periodic pattern structure 400, phase-change material layers 500, upper thermal insulating layer 600, top electrode 700, lower thermal insulating layer 800.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearer, below will be further elaborated to technical scheme of the present invention.
Be to be understood that, in this manual, relational terms such as the first and second grades is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply and between these entities or operation, have the relation of any this reality or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thereby the process, method, article or the equipment that make to comprise a series of key elements not only comprise those key elements, but also comprise other key elements of clearly not listing, or be also included as the intrinsic key element of this process, method, article or equipment.The in the situation that of more restrictions not, the key element being limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment that comprises described key element and also have other identical element.
One aspect of the present invention aims to provide a kind of phase-change memory cell, it comprises the substrate, bottom electrode, lower thermal insulating layer, phase-change material layers, upper thermal insulating layer and the top electrode that set gradually from bottom to top, described top electrode is also electrically connected with described film of phase-change material, described lower thermal insulating layer has the periodic structure being mainly made up of a plurality of quadrangular frustum pyramid shapeds unit, described phase-change material layers is covered in described periodic structure continuously, and forms plurality of grooves structure.Further, described quadrangular frustum pyramid shaped unit is preferably silicon dioxide truncated rectangular pyramids.
The cycle of described periodic structure, the size of quadrangular frustum pyramid shaped unit, the thickness of upper thermal insulating layer, lower thermal insulating layer and phase-change material layers, size, the material etc. of top electrode all can as mentioned before, repeat no more herein.
Another aspect of the present invention aims to provide a kind of method of preparing aforementioned phase-change memory cell, it comprises: successively at substrate surface deposition lower electrode layer and heat-insulating material precursor layer, adopt again photoetching technique at this heat-insulating material precursor layer surface fabrication cycle graphic structure, then utilize wet etching technology to corrode above-mentioned heat-insulating material precursor layer, obtain the periodic structure mainly being formed by a plurality of quadrangular frustum pyramid shapeds unit, thereafter, adopt oxidation technology to process aforementioned periodic structure, oxidation forms lower thermal insulating layer, sediment phase change storage medium (also claiming " phase-change material ") on lower thermal insulating layer afterwards, form and be covered in continuously in described periodic structure, and there is the phase-change material layers of plurality of grooves structure, then on phase-change material layers, deposit upper thermal insulating layer, finally open hole and deposits conductive material in through hole at upper thermal insulating layer, form top electrode, and in electrical contact with phase-change material layers.
The structure of aforementioned phase-change memory cell and preparation technology's flow process thereof can be with reference to figure 1-Fig. 2.
In a comparatively preferred embodiment, a kind of step of preparation process of phase-change memory cell is as follows:
Consult Fig. 1, first, at substrate surface deposition lower electrode layer and silicon layer, wherein lower electrode layer is preferably tungsten, titanium nitride/tungsten duplicature; Silicon layer is preferably monocrystalline silicon layer.
Then utilize photoetching technique at this substrate surface fabrication cycle graphic structure.
Further, utilize wet etching technology, use Tetramethylammonium hydroxide to corrode above-mentioned substrate, because Tetramethylammonium hydroxide has anisotropic etching characteristic to silicon, by regulating rightly etching time and corrosion temperature, can obtain the silicon truncated rectangular pyramids structure of different size.Wherein, silicon wet etching, especially wherein each anisotropy etching process is simple and can controllably realize the regulation and control of size by control reaction condition (reaction time, temperature) with its (by suitable corrosive liquid) CMOS compatibility, technique.
In order to obtain lower thermal insulating layer, use oxidation technology to process substrate, silicon truncated rectangular pyramids structure is oxidized to silicon dioxide structure.Preferably, silicon dioxide structure tip size is 15-100nm, and bottom size is 30-150nm; Heat insulation layer thickness is 10-100nm, cycle 10-100nm.
Use Pvd equipment at substrate surface sediment phase change storage medium, phase-change storage material presents groove type.Preferably, phase-change storage material is Ge
2sb
2te
5, N doped with Ge
2sb
2te
5, O doped with Ge
2sb
2te
5, GeSb
2te
5in any, thickness 10-100nm.
Use chemical gaseous phase depositing process deposition upper thermal insulating layer, preferably, upper thermal insulating layer is any one in silicon dioxide, silicon nitride, thickness 10-200nm.
Use photoetching technique, open hole and upper electrode material is deposited to Kong Zhongyu phase-change storage material at upper thermal insulating layer with metal deposition technique in conjunction with lithographic technique and contact, preferably, upper electrode material is aluminium, width be corresponding phase-change material layers top or bottom width 2/3 and following, extraction electrode contacts with the top and bottom of phase-change material layers respectively.
Based on this preparation technology, can make phase-change memory cell effectively obtain less PCM electrode size, thereby improve storage density, reduce manufacturing cost simultaneously.
Further set forth the present invention by some specific embodiments below, these embodiment are only presented for purposes of illustration, do not limit the scope of the invention.
embodiment 1
Select the substrate that deposits tungsten bottom electrode and the thick monocrystalline silicon of 5nm, use photoetching technique deposition spacing 10nm, width is the photoetching offset plate figure of 35nm, with being placed in 75 ℃ of tetramethyl ammonium hydroxide solutions 10 minutes, can obtain top layer 6.5nm, the silicon truncated rectangular pyramids structure of bottom size 13nm, further process this structure by oxidation technology and form silicon dioxide truncated rectangular pyramids structure, owing to being attended by silicon volumetric expansion in oxidizing process, the final silicon dioxide truncated rectangular pyramids structural thickness 10nm obtaining, top layer width is 15nm, and bottom width is 30nm.Utilize the Ge of physical gas-phase deposite method deposition 10nm
2sb
2te
5film, then utilize chemical gaseous phase depositing process to prepare 10nm silicon dioxide upper thermal insulating layer, further utilize photoetching technique, lithographic technique and metal deposition technique to prepare width for 10nm aluminium top electrode, and extraction electrode is positioned respectively the top and bottom of phase-change material layers.
embodiment 2
Select the substrate that deposits tungsten bottom electrode and the thick monocrystalline silicon of 10nm, use photoetching technique deposition spacing 20nm, width is the photoetching offset plate figure of 40nm, with being placed in 75 ℃ of tetramethyl ammonium hydroxide solutions 15 minutes, can obtain top layer 13nm, the silicon truncated rectangular pyramids structure of bottom size 25nm, further process this structure by oxidation technology and form silicon dioxide truncated rectangular pyramids structure, owing to being attended by silicon volumetric expansion in oxidizing process, the final silicon dioxide truncated rectangular pyramids structural thickness 20nm obtaining, top layer width is 30nm, and bottom width is 60nm.Utilize the N doped with Ge of physical gas-phase deposite method deposition 50nm
2sb
2te
5film, then utilize chemical gaseous phase depositing process to prepare 60nm silicon dioxide upper thermal insulating layer, further utilize photoetching technique, lithographic technique and metal deposition technique to prepare width for 15nm aluminium top electrode, and extraction electrode is positioned respectively the top and bottom of phase-change material layers.
embodiment 3
Select the substrate that deposits titanium nitride/tungsten duplicature bottom electrode and the thick monocrystalline silicon of 42nm, use photoetching technique deposition spacing 100nm, width is the photoetching offset plate figure of 40nm, with being placed in 75 ℃ of tetramethyl ammonium hydroxide solutions 15 minutes, can obtain top layer 42nm, the silicon truncated rectangular pyramids structure of bottom size 60nm, further process this structure by oxidation technology and form silicon dioxide truncated rectangular pyramids structure, owing to being attended by silicon volumetric expansion in oxidizing process, the final silicon dioxide truncated rectangular pyramids structural thickness 100nm obtaining, top layer width is 100nm, and bottom width is 150nm.Utilize the O doped with Ge of physical gas-phase deposite method deposition 100nm
2sb
2te
5film, then utilize chemical gaseous phase depositing process to prepare 200nm silicon dioxide upper thermal insulating layer, further utilize photoetching technique, lithographic technique and metal deposition technique to prepare width for 50nm aluminium top electrode, and extraction electrode is positioned respectively the top and bottom of phase-change material layers.
embodiment 4
Select the substrate that deposits tungsten bottom electrode and the thick monocrystalline silicon of 10nm, use photoetching technique deposition spacing 20nm, width is the photoetching offset plate figure of 40nm, with being placed in 75 ℃ of tetramethyl ammonium hydroxide solutions 15 minutes, can obtain top layer 13nm, the silicon truncated rectangular pyramids structure of bottom size 25nm, further process this structure by oxidation technology and form silicon dioxide truncated rectangular pyramids structure, owing to being attended by silicon volumetric expansion in oxidizing process, the final silicon dioxide truncated rectangular pyramids structural thickness 20nm obtaining, top layer width is 30nm, and bottom width is 60nm.Utilize the GeSb of physical gas-phase deposite method deposition 50nm
2te
5film, then utilize chemical gaseous phase depositing process to prepare 60nm silicon dioxide upper thermal insulating layer, further utilize photoetching technique, lithographic technique and metal deposition technique to prepare width for 15nm aluminium top electrode, and extraction electrode is positioned respectively the top and bottom of phase-change material layers.
In addition to the implementation, the present invention can also have other execution modes.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection range of requirement of the present invention.
Claims (10)
1. a phase-change memory cell, comprise the substrate, bottom electrode, lower thermal insulating layer, phase-change material layers, upper thermal insulating layer and the top electrode that set gradually from bottom to top, described top electrode is also electrically connected with described film of phase-change material, it is characterized in that, described lower thermal insulating layer has the periodic structure being mainly made up of a plurality of quadrangular frustum pyramid shapeds unit, described phase-change material layers is covered in described periodic structure continuously, and forms plurality of grooves structure.
2. phase-change memory cell according to claim 1, is characterized in that, described lower thermal insulating layer has the periodic structure being mainly made up of a plurality of silicon dioxide truncated rectangular pyramids, and the cycle of described periodic structure is 10-100nm.
3. phase-change memory cell according to claim 1, is characterized in that, described quadrangular frustum pyramid shaped unit top margin is of a size of 15-100nm, and base is of a size of 30-150nm.
4. phase-change memory cell according to claim 1, is characterized in that, the thickness of described lower thermal insulating layer is 10-100nm, and the thickness of described upper thermal insulating layer is 10-200nm.
5. phase-change memory cell according to claim 1, is characterized in that, the thickness of described phase-change material layers is 10-100nm.
6. phase-change memory cell according to claim 1, is characterized in that, the width of described top electrode is less than or equal to and is covered in 2/3rds of the phase-change material layers at each top, truncated rectangular pyramids type unit or the width of each groove structure groove bottom.
7. phase-change memory cell according to claim 1, is characterized in that, each top electrode is connected with an extraction electrode one end, and the described extraction electrode other end passes upper thermal insulating layer, and in electrical contact with described phase-change material layers.
8. phase-change memory cell according to claim 1, is characterized in that, described bottom electrode comprises any in tungsten film and titanium nitride/tungsten duplicature.
9. a preparation method for phase-change memory cell, is characterized in that comprising:
(1) successively at substrate surface deposition lower electrode layer and heat-insulating material precursor layer;
(2) adopt photoetching technique at this heat-insulating material precursor layer surface fabrication cycle graphic structure, and utilize wet etching technology to corrode above-mentioned heat-insulating material precursor layer, obtain the periodic structure mainly being formed by a plurality of quadrangular frustum pyramid shapeds unit;
(3) adopt oxidation technology to process aforementioned periodic structure, oxidation forms lower thermal insulating layer;
(4) sediment phase change storage medium on lower thermal insulating layer, forms and is covered in continuously phase-change material layers in described periodic structure and that have plurality of grooves structure, and described phase transformation is deposited roughage and comprised Ge
2sb
2te
5, N doped with Ge
2sb
2te
5, O doped with Ge
2sb
2te
5, GeSb
2te
5in any one or more combination;
(5) on phase-change material layers, deposit upper thermal insulating layer, and open hole at upper thermal insulating layer, then deposits conductive material in through hole, forms the top electrode in electrical contact with phase-change material layers.
10. the preparation method of phase-change memory cell according to claim 9, it is characterized in that, described heat-insulating material precursor layer is silicon layer, and described lower thermal insulating layer has the periodic structure being mainly made up of a plurality of silicon dioxide truncated rectangular pyramids, the top margin of arbitrary truncated rectangular pyramids is of a size of 15-100nm, base is of a size of 30-150nm, and the cycle of described periodic structure is 10-100nm.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101572266A (en) * | 2008-04-29 | 2009-11-04 | 财团法人工业技术研究院 | Phase change memory and manufacture method thereof |
| CN102544355A (en) * | 2010-12-09 | 2012-07-04 | 中国科学院上海微系统与信息技术研究所 | Phase-change storage material and preparation method thereof as well as storage device provided therewith and preparation method thereof |
| CN203721775U (en) * | 2014-02-20 | 2014-07-16 | 中国科学院苏州纳米技术与纳米仿生研究所 | Phase change storage unit |
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|---|---|---|---|---|
| CN101572266A (en) * | 2008-04-29 | 2009-11-04 | 财团法人工业技术研究院 | Phase change memory and manufacture method thereof |
| CN102544355A (en) * | 2010-12-09 | 2012-07-04 | 中国科学院上海微系统与信息技术研究所 | Phase-change storage material and preparation method thereof as well as storage device provided therewith and preparation method thereof |
| CN203721775U (en) * | 2014-02-20 | 2014-07-16 | 中国科学院苏州纳米技术与纳米仿生研究所 | Phase change storage unit |
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