CN1251322C - Manufacture of ferroelectric capacitor used in low drive voltage - Google Patents
Manufacture of ferroelectric capacitor used in low drive voltage Download PDFInfo
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- CN1251322C CN1251322C CN 02155770 CN02155770A CN1251322C CN 1251322 C CN1251322 C CN 1251322C CN 02155770 CN02155770 CN 02155770 CN 02155770 A CN02155770 A CN 02155770A CN 1251322 C CN1251322 C CN 1251322C
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- platinum
- ferroelectric
- layer
- zirconium titanate
- lead zirconium
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Abstract
The present invention provides a method for manufacturing a ferroelectric capacitor used for low drive voltage. The manufacturing process of the ferroelectric capacitor comprises the following steps: firstly, a nickel-lanthanum oxide layer (LaNiO3, LNO) used as a buffer layer is formed on a bottom electrode; then, a ferroelectric layer comprising lead titanate zirconium Pb(Zr1-xTix)O3), PZT) and platinum (Pt) is grown by the method which uses sputter deposition on the buffer layer; at last, a layer of top electrode is grown on the ferroelectric layer.
Description
Technical field
The present invention relates to a kind of ferroelectric capacitor, specially refer to a kind of ferroelectric capacitor structure that reduces driving voltage.
Background technology
In the structure of internal memory, the random access memory unit is made of a field-effect transistor (FET) and a capacitor.The storage of data be present in the capacitor two between the electrode the dielectric layers polarization and the electric charge that causes is accumulated and is finished.Yet being stored in two electric charges between the electrode can be because the physical characteristic of dielectric layer and discharge automatically, makes random access memory periodically to charge and just can keep its normal running with upgrading.That is to say that in case dump, the electric charge in the capacitor can discharge, and data can be lost.Therefore, employed capacitor is volatile (volatile) in the general memory.
Past attempts proposes a kind of internal memory that uses ferroelectric condenser, utilizes ferroelectric material to lose to avoid data as dielectric material.Usually, using ferroelectric condenser as storage medium, can store data effectively, do not need to upgrade, mainly is because the characteristic of ferroelectric material, and electric charge is by the ferroelectric material polarization and accumulate, and is not easy to run off because of discharge.
Please refer to Fig. 1, it is traditional ferroelectric capacitor internal memory.Structure with a transistor/capacitor (1T/1C) is an example, its formation method generally is to form after transistorized grid 12, gate dielectric 14 and the source/drain regions 16 on the semiconductor-based end 10 earlier, cover last layer dielectric layer 20 again, in dielectric layer 20, form contact hole connector 22 then and be connected to one of source/drain regions 16, on contact hole connector 22, form ferroelectric capacitor at last.And traditional ferroelectric capacitor storehouse from bottom to top, on bottom electrode 24, form ferroelectric layer film 26, and on ferroelectric layer film 26, form top electrode 28, and this ferroelectric capacitor is coated with an insulating barrier 30, and the constituent material of general ferroelectric layer 26 for example is lead zirconium titanate (PZT) or strontium bismuth titanate (SBT) etc.
Ferroelectric material is selected or is switched polarized state by applying external electrical field, and after removing external electrical field, still can keep its polarized state.Known to the person skilled in the art, ferroelectric condenser can replace tradition employed silicon dioxide capacitor in dynamic random access memory (DRAM) internal memory, it is store charge apace, and after electric power removed, ferroelectric condenser still can be kept its polarized state for a long time.Therefore, ferroelectric material provide development simply, at a low price, the possibility of high density, non-voltile memory.And traditional DRAM internal memory is subjected to the irradiation of ionizing radiation easily and damages, and ferroelectric material has very high resistance to radiation damage, and its polarized state can not change because of radiation.Yet, employed traditionally ferroelectric layer material, lead zirconium titanate (PZT) or strontium bismuth titanate (SBT) etc., the operating voltage that its when polarization is required, usually minimumly only can arrive about 1.5 volts to 2 volts, for will under lower operating voltage, write and read the time, be necessary to develop the ferroelectric structure that makes new advances really to deal with following needs.
In the ferroelectric capacitor memory of the tradition read-write cycle, the polarized state that all can relate to ferroelectric capacitor is switched to another antipodal polarized state, and need apply an applied voltage greater than coercive voltage usually and switch this moment.Generally make the material that is used for constituting ferroelectric layer be generally lead zirconium titanate (PZT) or strontium bismuth titanate (SBT) etc., it switches, and the required applied voltage of polarized state is minimum only to be low to moderate about 1.2 volts, therefore only the assembly of depressing less than 1.2 voltaisms can be operated in for some, traditional ferroelectric capacitor internal memory can not be used.
Summary of the invention
At above-mentioned defective, main purpose of the present invention provides a kind of ferroelectric material manufacture method, to reduce the required voltage swing that adds of whole read-write cycle.
Another object of the present invention provides and a kind ofly can provide the ferroelectric material manufacture method of big polarized state under the situation of low driving voltage.
For achieving the above object, the invention provides a kind of ferroelectric capacitor manufacture method that is used in low driving voltage.The technology of this ferroelectric capacitor at first forms one deck nickel-lanthanum-oxides (LaNiO on bottom electrode
3, LNO) layer is then grown one deck by lead zirconium titanate (Pb (Zr thereon as one deck resilient coating
1-xTi
x) O
3PZT) with the common ferroelectric layer of forming of platinum (Pt), according to preferred embodiment of the present invention, it uses the method for sputtering sedimentation (sputterdeposition) to deposit above-mentioned ferroelectric layer, this kind is by in lead zirconium titanate and the common layer structured ferroelectric of forming of platinum, and lead zirconium titanate belongs to most carriers, and platinum is minority carrier, therefore the present invention can utilize control to put on the radio-frequency (RF) energy of lead zirconium titanate and platinum back face of target, adjusts concentration each other.Growth one deck top electrode on ferroelectric layer is promptly finished ferroelectric capacitor of the present invention at last.
Brief Description Of Drawings
Below in conjunction with accompanying drawing the specific embodiment of the present invention is described in further detail.
In the accompanying drawing,
Fig. 1 is the structural representation of existing general 1T-1C ferroelectric memory unit;
Fig. 2 is the ferroelectric material B-H loop;
Fig. 3 is the ferroelectric capacitor modular construction generalized section of preferred embodiment of the present invention;
Fig. 4 is the ferroelectric capacitor enlarged drawing of preferred embodiment of the present invention;
Fig. 5 is for being used for carrying out the sputtering equipment schematic diagram of lead zirconium titanate (PZT) and platinum (Pt) ferroelectric layer deposition; And
Fig. 6 for the present invention by the common ferroelectric thin film layer that forms of lead zirconium titanate and platinum, with only by the formed ferroelectric thin film layer of lead zirconium titanate between the two the polarized state value difference under same drive voltage apart from size.
Embodiment
Do not limiting under design of the present invention and the range of application, below promptly making embodiment, introducing enforcement of the present invention with a ferroelectric material; Be familiar with the people of this art, after understanding design of the present invention, should use this manufacture method in various ferroelectric internal memory circuit.By ferroelectric material manufacture method of the present invention, reduce ferroelectric capacitor required driving voltage size that adds when the read-write cycle, eliminate traditionally owing to be used for constituting the material of ferroelectric layer, required applied voltage needed greater than 1.2 volts when it switched polarized state, cause traditional ferroelectric capacitor can not be used in operating voltage less than the circuit unit under 1.2 volts, application of the present invention is not limited only to the embodiment of the following stated.
Consult Fig. 2, be the ferroelectric material B-H loop, wherein the abscissa representative puts on the electric field strength on the ferroelectric material, and ordinate is represented the polarized state of ferroelectric material.If use ferroelectric material to be filled between the electric capacity two-plate, can find out by B-H loop, the size of current of electric capacity of flowing through is according to the polarized state that voltage caused that had before put on ferroelectric capacitor, that is to say, if putting on the voltage of ferroelectric capacitor at first is 0 volt, the polarized state of ferroelectric capacitor may be at A point or D point, suppose that polarized state is at the A point, when between the two-plate of ferroelectric capacitor, applying a changing voltage that is higher than coercive voltage (Coercive Voltage) (being B point among Fig. 1), can change the polarized state of ferroelectric capacitor, in this case, ferroelectric capacitor will discharge stored electric charge and be transformed into another kind of polarized state (being C point among Fig. 1), when removing the voltage that puts on ferroelectric capacitor, ferroelectric capacitor can maintain the equipolarization state and be transferred to the D point, and can not get back to the polarized state that A is ordered, if apply positive electricity and be pressed on the ferroelectric capacitor this moment, the ferroelectric capacitor polarized state only can cause small change, be pressed on the ferroelectric capacitor if apply negative electricity, this moment, the ferroelectric capacitor polarized state can be transferred to the E point from the D point, when removing the voltage that puts on ferroelectric capacitor, ferroelectric capacitor can maintain the equipolarization state and be transferred to the A point from the E point, therefore, A point and D point can be represented when the voltage that puts on ferroelectric capacitor is 0 volt, two kinds of different logic states, if and A, 2 of D are far away more apart, just both polarized state value differences are apart from big more (the 2Pr value is big more), and the usefulness that representative stores is good more.Ferroelectric material is exactly to select or switch its polarized state by applying external electrical field, and after removing external electrical field, still can keep its polarized state.Yet, because when switching polarized state, need between two-plate, to apply a changing voltage that is higher than coercive voltage (being B point among Fig. 1), change the polarized state of ferroelectric capacitor, therefore, if can reduce the size of required coercive voltage, can make ferroelectric capacitor also can be applicable in the various circuit units of low driving voltage.
At first the ferroelectric capacitor structure that is used in low driving voltage to preferred embodiment of the present invention describes, yet it should be noted that the present invention only limits to be used for its described preferred embodiment structure down.Please refer to Fig. 3, it illustrates the structural profile schematic diagram of preferred embodiment of the present invention.Semiconductor substrate 100 at first is provided, and for example is to have＜100〉structure P type silicon base.In substrate 100, finished the making of the semiconductor subassembly of part, on the active area of substrate 100, produce transistor, generally include grid 102, grid oxic horizon 104 between grid 102 and substrate 100 is then such as forming source/drain regions 106 in grid 102 both sides with ionic-implantation.Then at transistor upper caldding layer insulating barrier 110, such as being silicon dioxide, spin-on glasses (SOG), low dielectric (Low-k) material or its combination.And formation one contact hole connector 112 is coupled to source/drain regions 106 in insulating barrier 110, contact hole connector 112 employed materials can be tungsten (W), polysilicon (Poly-Si) or doped polycrystalline silicon (Doped poly-Si) etc., are tungsten with this most preferred embodiment.Its manufacture method generally is to utilize photoetching and etching technique, at first forming one deck patterning photoresist layer (not shown) on insulating barrier 110, is mask with this patterning photoresist layer then, etching isolation layer 110, in insulating barrier 110, to form contact window, remove the patterning photoresist layer afterwards.Because mostly being the person skilled in the art, the technology of this structure knows, thus only make simple explanation, but therefore do not limit the manufacture method of structure of the present invention.
Then form the ferroelectric capacitor of tool low driving voltage of the present invention on insulating barrier 110, it comprises from bottom to top bottom electrode 134, resilient coating 140, ferroelectric thin film layer 142 and top electrode 138.Wherein, the constituent material of bottom electrode 134 is such as being platinum (Pt), iridium (Ir) or yttrium oxide (IrO
2) etc., the constituent material of top electrode 138 is then corresponding to bottom electrode 134, such as being platinum (Pt), iridium (Ir) or yttrium oxide (IrO
2) etc., except above-mentioned material of giving an example, other material that is suitable for also can.
Manufacture method as for ferroelectric thin film layer 142 sees also Fig. 4, and it is the enlarged drawing of ferroelectric capacitor of the present invention, and ferroelectric capacitor of the present invention at first forms one deck nickel-lanthanum-oxides (LaNiO on bottom electrode 134
3, LNO) layer 140, wherein this nickel-lanthanum-oxides (LaNiO
3, LNO) layer 140 mainly is as one deck resilient coating, because nickel-lanthanum-oxides (LaNiO
3, LNO) layer 140 is the metal oxide electrode of a kind of perovskite form (perovskite-type), its lattice constant (lattice constant) is about 0.383nm, and its lattice direction is (100), this nickel-lanthanum-oxides (LaNiO
3LNO) layer 140 can help ferroelectric material to be easier to form crystal under the low temperature situation, because in the process that forms ferroelectric thin film layer 142, technological temperature is about 500 to 700 ℃, 134 formed interfacial reactions of ferroelectric thin film layer 142 and bottom electrode will influence the characteristic of ferroelectric thin film layer 142, therefore the present invention is 134 of ferroelectric thin film layer 142 and bottom electrodes, and one deck nickel-lanthanum-oxides (LaNiO grows
3, LNO) layer is 140 as resilient coating, can reduce the required crystallization temperature to 500 of ferroelectric thin film layer 142 ℃, and with this preferred embodiment, the thickness of this layer is about 15 nanometers.
When finishing this nickel-lanthanum-oxides (LaNiO
3, LNO) behind the layer 140, the present invention can grow one deck thereon by lead zirconium titanate (Pb (Zr
1-xTi
x) O
3PZT) with the common ferroelectric thin film layer of forming 142 of platinum (Pt), according to preferred embodiment of the present invention, it uses the method for sputtering sedimentation (sputter deposition) to deposit above-mentioned ferroelectric thin film layer 142, but the mode of chemical vapour deposition (CVD) mode (CVD), MBE or plating also can be used.See also Fig. 5 is used for carrying out lead zirconium titanate (PZT) and platinum (Pt) ferroelectric layer deposition for the present invention makes sputtering equipment skeleton diagram, wherein sputter is to quicken with ion, normally uses Ar
+, through an electric potential gradient, remove to bombard target with ion, and the target back side can apply a radio frequency (RF), to attract Ar
+Sputter takes place in ion, the volatilization of the atom of target material surface, and is plated on the wafer with the form of steam.
With regard to preferred embodiment of the present invention, crystallizing layer 142 of the present invention, it uses lead zirconium titanate 150 (PZT) and platinum 152 (Pt) to be used as target, and when depositing, one finishes above-mentioned technology and its upper surface has nickel-lanthanum-oxides (LaNiO
3, LNO) substrate 154 of layer 140 is placed on the support 156, and wherein this support 156 can be rotated with an angular velocity omega, and this rotation purpose is for obtaining deposition uniformly.Allow substrate 1 54 be positioned at the below of lead zirconium titanate 1 50 and platinum 152 targets in turn, with alternating deposit lead zirconium titanate 150 and platinum 152.When beginning deposition, an Ar at first
+Ion can bombard the target and platinum 152 targets of lead zirconium titanate 150, and the atom on lead zirconium titanate 150 surfaces and platinum 152 surfaces can volatilize, and is plated to nickel-lanthanum-oxides (LaNiO of substrate 154 with the form of atom
3, LNO) on the layer 140, with this preferred embodiment, the thickness of this layer is about 150 nanometers, and the thickness of being grown must not change the structure direction of LNO layer.With this preferred embodiment, the deposition of this lead zirconium titanate 150 and platinum 152 can continue to proceed to total deposit thickness and be about 90 nanometers.
Concerning preferred embodiment of the present invention, in the structure of this kind by lead zirconium titanate and the common ferroelectric thin film layer of forming 142 of platinum, lead zirconium titanate belongs to most carriers, and platinum is minority carrier, therefore the present invention can utilize control to put on the radio-frequency (RF) energy of lead zirconium titanate 150 and platinum 152 back face of target, adjusts concentration each other.Concerning this preferred embodiment, in lead zirconium titanate and the common layer structured ferroelectric of forming of platinum, the content ratio of platinum is less than 10%, and its density therein is approximately less than 5 * 10
13Atom/square centimeter, wherein the size of platinum is 10 to 70 nanometers (nm).
Then annealing (annealing) process quilt puts on this substrate 154 of finishing lead zirconium titanate 150 and platinum 152 depositions, and this annealing temperature is about 550 ℃, and annealing time is about 1 to 10 minute, is used for lead zirconium titanate of the present invention (Pb (Zr
1-xTi
x) O
3, PZT) form crystallization, because lead zirconium titanate of the present invention (Pb (Zr with platinum (Pt)
1-xTi
x) O
3, PZT) crystallizing layer with platinum (Pt) grows in nickel-lanthanum-oxides (LaNiO
3, LNO) on the resilient coating 140, therefore the temperature when carrying out annealing crystallization can be reduced to 550 ℃.Last top electrode 138 grows in promptly finishes ferroelectric capacitor of the present invention on this crystallizing layer.
It should be noted that above-mentioned lead zirconium titanate (Pb (Zr
1-xTi
x) O
3, PZT) crystallizing layer with platinum (Pt) is not limited only to only grow one deck, in another embodiment, and also can be at lead zirconium titanate (Pb (Zr
1-xTi
x) O
3, PZT) with the crystallizing layer of platinum (Pt) on one deck lead zirconium titanate (PZT) layer of growing separately, then form lead zirconium titanate (Pb (Zr thereon
1-xTix) O
3,, and form ferroelectric thin film jointly PZT) with the crystallizing layer of platinum (Pt).In other words, for the present invention, ferroelectric thin film layer wherein is at least by one deck lead zirconium titanate (Pb (Zr
1-xTi
x) O
3, PZT) form, but be not limited in one deck with the crystallizing layer of platinum (Pt).
See also Fig. 6, the ferroelectric thin film layer that forms jointly by lead zirconium titanate and platinum for the present invention, with only by the formed ferroelectric thin film layer of lead zirconium titanate between the two the polarized state value difference under same drive voltage apart from size, i.e. 2Pr value among the figure, by can obviously finding out among the figure at driving voltage only under 1 volt the situation, only by its polarized state value difference of the formed ferroelectric thin film layer of lead zirconium titanate apart from being almost 0 (μ C/cm
2), in other words, it does not almost have storage capacity.And opposite, by the lead zirconium titanate and the common ferroelectric thin film layer that forms of platinum of more excellent specific embodiment of the present invention, it is under 3.4% and 4% platinum ratio, and its polarized state value difference is apart from being about 7 (μ C/cm
2) about, still have suitable storage capacity, therefore clearly, utilize the formed ferroelectric thin film layer of method of the present invention its under 1 volt driving voltage, but operate as normal still.
Comprehensive the above, the present invention discloses a kind of ferroelectric layer film, and ferroelectric capacitor is applied in the low driving voltage, to reduce the required voltage swing that adds of whole read-write cycle.And can under the situation of low driving voltage, provide big polarized state.
Understand as the person skilled in the art, the above only is preferred embodiment of the present invention, is not in order to limit claim of the present invention; All other do not break away from the equivalence of being finished under the disclosed design and changes or modification, all should be included in the following claim.
Claims (13)
1, a kind of ferroelectric capacitor manufacture method that is used under the low driving voltage, this method comprises at least:
Form a bottom electrode;
Form one nickel-lanthanum-oxides resilient coating on this bottom electrode;
Form one by the common ferroelectric layer of forming of lead zirconium titanate and platinum on this resilient coating;
Carry out an annealing process, the common ferroelectric layer of forming of this lead zirconium titanate of crystallization and platinum becomes a crystallizing layer; And
Form a top electrode on this crystallizing layer.
2, method according to claim 1, wherein said buffer layer thickness are 35 nanometer to 150 nanometers.
3, method according to claim 1, the common ferroelectric layer of forming of wherein said lead zirconium titanate and platinum is deposited on the resilient coating in the mode of sputter.
4, method according to claim 1, the common ferroelectric layer thickness of forming of wherein said lead zirconium titanate and platinum is 35 nanometer to 200 nanometers.
5, method according to claim 1, in the common layer structured ferroelectric of forming of wherein said lead zirconium titanate and platinum, wherein the size of platinum is 10 to 70 nanometers.
6, method according to claim 1, in the common layer structured ferroelectric of forming of wherein said lead zirconium titanate and platinum, the content ratio of platinum is 2.5% to 8.5%, the density of platinum is 5 * 10
11To 5 * 10
13Atom/square centimeter.
7, method according to claim 1, wherein said annealing process temperature are 250 to 750 ℃, and the annealing process temperature-time is 1 to 10 minute.
8, method according to claim 1 wherein forms described top electrode and lower electrode material and is selected from platinum (Pt), iridium (Ir) or yttrium oxide (IrO
2).
9, a kind of ferroelectric capacitor structure that is used under the low driving voltage, wherein this ferroelectric capacitor framework has a transistor in this semiconductor-based end in the semiconductor substrate, and the contact hole connector that connects this transistor source or drain electrode, and this structure comprises at least:
First conductor layer was positioned on this semiconductor-based end, and was connected with this contact hole connector, as the bottom electrode of this ferroelectric capacitor;
One nickel-lanthanum-oxides resilient coating is positioned on this first conductor layer;
One by lead zirconium titanate and the common ferroelectric layer of forming of platinum, is positioned on this nickel-lanthanum-oxides resilient coating; And
Second conductor layer is positioned on this ferroelectric layer, as the bottom electrode of this ferroelectric capacitor.
10, structure according to claim 9, wherein said buffer layer thickness are 35 nanometer to 150 nanometers.
11, structure according to claim 9, the common ferroelectric layer of forming of wherein said lead zirconium titanate and platinum is deposited on the resilient coating in the mode of sputter, and thickness is 35 nanometer to 200 nanometers.
12, structure according to claim 9, in the common layer structured ferroelectric of forming of wherein said lead zirconium titanate and platinum, the content ratio of platinum is 2.5% to 8.5%, the density of platinum is 5 * 10
11To 5 * 10
13Atom/square centimeter.
13, structure according to claim 9, wherein said first conductor layer and the second conductor layer material are selected from platinum (Pt), iridium (Ir) or yttrium oxide (IrO
2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02155770 CN1251322C (en) | 2002-12-06 | 2002-12-06 | Manufacture of ferroelectric capacitor used in low drive voltage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02155770 CN1251322C (en) | 2002-12-06 | 2002-12-06 | Manufacture of ferroelectric capacitor used in low drive voltage |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1507030A CN1507030A (en) | 2004-06-23 |
| CN1251322C true CN1251322C (en) | 2006-04-12 |
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|---|---|---|---|
| CN 02155770 Expired - Lifetime CN1251322C (en) | 2002-12-06 | 2002-12-06 | Manufacture of ferroelectric capacitor used in low drive voltage |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4466315B2 (en) * | 2004-10-21 | 2010-05-26 | 株式会社日立製作所 | Phase change memory |
| CN101894843B (en) * | 2010-06-04 | 2012-02-22 | 清华大学 | Ferroelectric dynamic random access memory based on lead zirconate titanate memory medium and preparation method thereof |
| US10818544B2 (en) * | 2017-09-27 | 2020-10-27 | Taiwan Semiconductor Manufacturing Co., Ltd. | Method to enhance electrode adhesion stability |
| RU210435U1 (en) * | 2021-09-15 | 2022-04-15 | Федеральное государственное бюджетное образовательное учреждение высшего образования «МИРЭА Российский технологический университет» | SELF-ADJUSTED FEROELECTRIC CAPACITOR WITH ELECTRODES FROM LaNiO3 |
-
2002
- 2002-12-06 CN CN 02155770 patent/CN1251322C/en not_active Expired - Lifetime
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