CN101891468A - Method for preparing ferroelectric solution and film capacitor thereof - Google Patents
Method for preparing ferroelectric solution and film capacitor thereof Download PDFInfo
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- CN101891468A CN101891468A CN2009100518787A CN200910051878A CN101891468A CN 101891468 A CN101891468 A CN 101891468A CN 2009100518787 A CN2009100518787 A CN 2009100518787A CN 200910051878 A CN200910051878 A CN 200910051878A CN 101891468 A CN101891468 A CN 101891468A
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Abstract
The invention belongs to the technical field of microelectronics, and relates to a method for preparing ferroelectric solution and a film capacitor thereof. When precursor solution is prepared, a certain excessive lead raw material is added, and a certain process flow is matched; and the excessive lead counteracts lead volatilization when a ferroelectric film is prepared so as to improve the electric performance of the ferroelectric film. The precursor solution is Pb1 + xZryTi1-yO3(PZT) solution generated by aggregates of hydrolysis products of Pb, Zr and Ti; and the precursor solution is deposited on a substrate by spin coating and then dried, thermally decomposed and annealed at a high temperature to generate the ferroelectric film with a perovskite crystal structure so as to manufacture the ferroelectric capacitor. The method can overcome the defects that the electric performance of the ferroelectric film declines and the storage performance of the ferroelectric capacitor declines due to lead volatilization of the PZT ferroelectric film during high-temperature crystallization in the prior art, and can obviously improve the storage property of a ferroelectric memory (FERAM).
Description
Technical field
The invention belongs to microelectronics technology, be specifically related to the method for ferroelectric solution and thin-film capacitor thereof preparation.
Background technology
Ferroelectric lead zirconate titanate film (PZT) is because the good characteristic on nonvolatile memory (FERAM), field-effect transistor, pyroelectric detector and micro mechanical system (MEMS) becomes present science and technology area research focus.The particularly application on aspect the ferroelectric memory.Current the market of nonvolatile memory is also increasing along with progressively the popularizing of portable electric appts, and according to investigations, Flash accounts for 90% of nonvolatile memory market at present.But along with the progress of semiconductor technology, Flash has run into increasing technical bottleneck, and tunnel oxide can not be along with the development of integrated circuit technology attenuate unrestrictedly, and according to ITRS 2007, Flash will be difficult to go beyond the 32nm process node.The thinking that addresses this problem is research and development nonvolatile memories of new generation, mainly contain magneticstorage (MRAM), phase transition storage (PCM), Memister (ReRAM) and ferroelectric memory (FeRAM), wherein ferroelectric memory is realized commercialization at first, has very strong commercial potential quality.
The spontaneous polarization that utilizes ferroelectric material to have, and the character that can under External Electrical Field, reverse of spontaneous polarization vector and realize memory function.The principal character of ferroelectric material is to have ferroelectricity, promptly has the relation of ferroelectric hysteresis loop between polarization and the external electric field.This specific character makes it to be suitable for doing storer, two states of its residual polarization corresponding respectively " 0 " and the one state of storer, and can change store status or come its polarized state of sensing by the direction that changes external electric field by peripheral circuit, read information.The PZT ferroelectric material has great saturated polarization and remnant polarization, therefore is one of main ferroelectric material that is applied to the manufacturing of FeRAM storer.
Summary of the invention
The object of the present invention is to provide a kind of ferroelectric solution with and the preparation method of thin-film capacitor, to help improving the performance of ferroelectric memory.
Ferroelectric solution involved in the present invention is Pb-based lanthanumdoped zirconate titanates (PZT) solution, and its corresponding thin-film capacitor is the PZT ferroelectric capacitor.The present invention is when the first liquid solution of preparation, and adding is excessive leady raw materials necessarily, and cooperates certain technical process, by the lead volatilization of excessive lead counteracting when preparing ferroelectric membranc, thus the electric property of raising ferroelectric membranc.
Particularly, the present invention includes following step,
Described Pb-based lanthanumdoped zirconate titanates precursor liquid generates Pb by the aggregation of the hydrolyzate of Pb, Zr, T i
1+xZr
yTi
1-yO
3(PZT) solution, on substrate, the back generates the ferroelectric membranc of perovskite crystal structure, and is made into ferroelectric capacitor on this basis by mummification, pyrolysis, high temperature annealing by spin-on deposition.The inventive method can improve the storage characteristics of ferroelectric memory (FERAM) greatly.Because when the preparation ferroelectric capacitor, plumbous volatilization can take place when high temperature crystallization the PZT ferroelectric membranc, causes the ferroelectric membranc electric property to descend, and then the memory property of ferroelectric capacitor is descended.
Lead zirconate-titanate ferroelectric solution of the present invention is characterized in that,
Press Pb
1+xZr
yTi
1-yO
3(PZT) stoicheiometry: Pb: Zr: Ti=(1+x): y: (1-y), add starting raw materials such as Pb, Zr, Ti, hybrid reaction generates ferroelectric solution, prepares by following step:
(1) claims excessive lead acetate trihydrate to be dissolved in the methanol solvate by stoicheiometry, be heated to 70 ℃ of dehydrations, and stir, obtain plumbic acetate solution;
(2) with required Pb/Zr/Ti stoicheiometry the alkoxide of zirconium and the alkoxide of titanium are mixed in watertight chest, and add acetate subsequently, methanol solvate also at room temperature stirred 2 hours;
(3) above-mentioned binary mixing solutions is added in the plumbic acetate solution, be heated to 80 ℃, and mixed 3 hours, form ternary solution;
(4) with above-mentioned ternary solution adding a small amount of ethylene glycol stablizer, and with acetate or methanol constant volume to certain concentration.
Among the present invention, described stoicheiometry x is 0.3.
Among the present invention, the span of described stoicheiometry y is 0≤y≤0.95.
Among the present invention, the alkoxide of described zirconium is propyl alcohol zirconium, butanols zirconium; The alkoxide of titanium is butyl (tetra) titanate, titanium propanolate.
Among the present invention, described type of heating is the heating method of the condensing reflux of water-bath or oil bath.
Among the present invention, described ethylene glycol stablizer is 1/30 with the volume ratio of total solution.
Among the present invention, described leady raw materials is preferably by 1.3: 1 the excessive interpolation of stoicheiometry, and corresponding to the technology of ensuing preparation ferroelectric capacitor.
Another object of the present invention is to provide the preparation method of ferroelectric capacitor, it is characterized by, and spin coating Pb-based lanthanumdoped zirconate titanates colloidal sol elder generation body is on underlayer electrode, mummification then, pyrolysis, annealing, generate ferroelectric membranc, go up top electrode at last, thereby be prepared into ferroelectric capacitor.Comprise and be prepared as follows step:
(1) with sol evenning machine spin coating Pb-based lanthanumdoped zirconate titanates colloidal sol elder generation body on underlayer electrode;
(2) film of usefulness hot plate mummification spin coating;
(3) with the film after the hot plate pyrolysis mummification;
(4) can repeat (2) (3) according to required thickness requirement after, with the film annealing of annealing furnace after to pyrolysis;
(5) form top electrode, thereby be prepared into ferroelectric capacitor with electron evaporation, physical vapour deposition.
Among the present invention, with sol evenning machine with 3000r/min spin coating Pb-based lanthanumdoped zirconate titanates colloidal sol elder generation body 30 seconds.
Among the present invention, with the film of 175 degrees centigrade hot plate mummification spin coatings 3 minutes.
Among the present invention, with the film after 350 degrees centigrade the hot plate pyrolysis mummification 5 minutes.
Among the present invention, with the film of annealing furnace after to pyrolysis with 650 degrees centigrade of annealing 15 minutes.
Among the present invention, basic conductive substrates electrode comprises platinum, strontium titanate, iridium or chromium au-alloy and iridium oxide; Top electrode comprises platinum, strontium titanate, iridium or chromium au-alloy and iridium oxide.
Ferroelectric solution provided by the invention and thin-film capacitor preparation method thereof through evidence, can obviously improve the ferroelectric memory memory property.
The ferroelectric material of the present invention's preparation has very high slope with respect to other PZT ferroelectric membranc when reversing, i.e. near the rapid reverse-poled of energy coercive voltage, and good fatigue characteristic has very big help to the performance that improves ferroelectric memory.
Description of drawings
Fig. 1 is the ferroelectric membranc XRD figure of preparation.
Figure 22 A-2C is the preparation process diagrammatic cross-section according to embodiments of the invention 2 (ferroelectric capacitor preparation).
The ferroelectric hysteresis loop figure that Fig. 3 is recording for the ferroelectric capacitor for preparing.
The fatigue characteristic figure that Fig. 4 records for the ferroelectric capacitor for preparing.
Embodiment
Further specify the creation of present technique and be confined to embodiment absolutely not below by embodiment.Among the figure, for convenience of description, amplified the thickness in layer and zone, shown in size do not represent physical size.
Example 1
Follow these steps to preparation preparation ferroelectric solution:
(1) claims that by stoicheiometry the lead acetate trihydrate (purity is 99.5%) of 5.942g is dissolved in the methanol solvate at 1.3: 1, in the water-bath condensation reflux unit,, and use magnetic stirrer, obtain plumbic acetate solution 70 ℃ of dehydrations;
(2) in the nitrogen-sealed case, take by weighing 1.682g propyl alcohol zirconium (purity is 70%) and 2.914g butyl (tetra) titanate (purity is 98%) mixes in the 100ml Erlenmeyer flask, and add 10ml acetate subsequently, the 5ml methanol solvate with required Pb/Zr/Ti stoicheiometry.In the nitrogen-sealed case, at room temperature stirred 2 hours with magnetic stirring apparatus;
(3) above-mentioned binary mixing solutions is added just in the plumbic acetate solution of 70 ℃ of heating,, and under magnetic stirring apparatus, stirred 3 hours, form the ternary mixing solutions subsequently 80 ℃ of following water-bath condensing refluxes heating;
(4) with above-mentioned ternary mixing solutions to add 0.5ml ethylene glycol stablizer, at room temperature stirred 5 minutes, pour into subsequently in the 50ml graduated cylinder with the acetate constant volume to 30ml, be prepared into the ferroelectric solution that concentration is 0.4M/ml.
Example 2
Follow these steps to prepare ferroelectric capacitor:
(1) with sol evenning machine with 3000r/min in Pt (111)/Ti/SiO2/Si (100) underlayer electrode Fig. 2 A 101 on spin coating Pb-based lanthanumdoped zirconate titanates colloidal sol elder generation body 30 seconds;
(2) with the film of 175 degrees centigrade hot plate mummification spin coating 3 minutes;
(3) with the film after 350 degrees centigrade the hot plate pyrolysis mummification 5 minutes;
(4) repeat (2) (3) three times after, with 650 degrees centigrade of annealing 15 minutes, obtain the thick ferroelectric membranc of 340nm, i.e. 102 among Fig. 2 B with the film of annealing furnace after to pyrolysis.
(5) form top electrode with electronics evaporation deposition 150nm Cr/Au layer, i.e. 103 among Fig. 2 C, thus be prepared into ferroelectric capacitor.
(6) test this ferroelectric capacitor, as Fig. 3; Test its fatigue characteristic, (whether will point out testing tool, I feel unnecessary) is as Fig. 4.As seen from Figure 4, reversing 10
9After inferior, it is about 17% that remnant polarization has only descended, and it has fabulous memory property.
Shown in Figure 1 when top electrode not being arranged for embodiment 2, the XRD figure that records,
Wherein with " substrate " XRD peak for the underlayer electrode generation; (111) direction peak that the generation of ferroelectric membranc is extremely strong illustrates to have pure perovskite structure.
2A-2C is the ferroelectric capacitor structure iron that embodiment 2 makes among Fig. 2.
The ferroelectric capacitor that among Fig. 3 is embodiment 2 is at 10 volts, the ferroelectric hysteresis loop figure that records under 1000 hertz,
Show that wherein it has great remnant polarization, and near coercive voltage rapid reverse-poled.
Among Fig. 4 positive and negative 5 volts of ferroelectric capacitor of embodiment 2 in pulsed voltage, 10
6The fatigue characteristic that record under hertz,
Show that wherein it is in counter-rotating 10
9Behind the number of times, it is about 17% that its remnant polarization has only descended, and has very great help for the performance boost of ferroelectric memory.
Claims (14)
1. the method for a ferroelectric solution preparation is characterized in that, presses Pb
1+xZr
yTi
1-yO
3(PZT) stoicheiometry: Pb: Zr: Ti=(1+x): y: (1-y), add starting raw materials such as Pb, Zr, Ti, hybrid reaction generates ferroelectric solution, and it comprises the steps:
(1) claims that by stoicheiometry excessive lead acetate trihydrate is dissolved in the methanol solvate at 1.3: 1, be heated to 70 ℃ of dehydrations, and stir, obtain plumbic acetate solution;
(2) with required Pb/Zr/Ti stoicheiometry the alkoxide of zirconium and the alkoxide of titanium are mixed in watertight chest, add acetate subsequently, methanol solvate at room temperature stirred 2 hours;
(3) above-mentioned binary mixing solutions is added in the plumbic acetate solution, is heated to 80 ℃, mixed 3 hours, form ternary solution,
(4) with above-mentioned ternary solution to add the ethylene glycol stablizer, with acetate or methanol constant volume.
2. ferroelectric solution preparation method according to claim 1 is characterized in that: described stoicheiometry x is 0.3.
3. ferroelectric solution preparation method according to claim 1 is characterized in that: the span of described stoicheiometry y is 0≤y≤0.95.
4. ferroelectric solution preparation method according to claim 1, the alkoxide that it is characterized in that described zirconium is propyl alcohol zirconium or butanols zirconium; The alkoxide of titanium is butyl (tetra) titanate or titanium propanolate.
5. ferroelectric solution preparation method according to claim 1 is characterized in that described type of heating is the heating method of the condensing reflux of water-bath or oil bath.
6. ferroelectric solution preparation method according to claim 1 is characterized in that the described ethylene glycol stablizer and the volume ratio of total solution are 1/30.
7. the preparation method of a ferroelectric capacitor, its feature spin coating Pb-based lanthanumdoped zirconate titanates colloidal sol elder generation body is on underlayer electrode, and mummification then, pyrolysis, annealing generate ferroelectric membranc, go up top electrode at last, thereby are prepared into ferroelectric capacitor.
8. the preparation method of ferroelectric capacitor according to claim 7 is characterized in that with sol evenning machine with 3000r/min spin coating Pb-based lanthanumdoped zirconate titanates colloidal sol elder generation body 30 seconds.
9. the preparation method of ferroelectric capacitor according to claim 7 is characterized in that with the film of 175 degrees centigrade hot plate mummification spin coating 3 minutes.
10. the preparation method of ferroelectric capacitor according to claim 7 is characterized in that with the film after 350 degrees centigrade the hot plate pyrolysis mummification 5 minutes.
11. the preparation method of ferroelectric capacitor according to claim 7 is characterized in that with the film of annealing furnace after to pyrolysis with 650 degrees centigrade of annealing 15 minutes.
12. the preparation method of ferroelectric capacitor according to claim 7, it is characterized in that repetition claim 9 and 10 after, obtain the ferroelectric membranc of different thickness, carry out the annealing of claim 11 at last.
13. the preparation method of ferroelectric capacitor according to claim 7 is characterized in that basic conductive substrates electrode is selected from platinum, strontium titanate, iridium or chromium au-alloy and iridium oxide.
14. the preparation method of ferroelectric capacitor according to claim 7 is characterized in that described top electrode is selected from platinum, strontium titanate, iridium or chromium au-alloy and iridium oxide.
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|---|---|---|---|
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102222672A (en) * | 2011-05-13 | 2011-10-19 | 济南大学 | Bismuth ferrite base film layer stacked structure capacitor and preparation method thereof |
| CN103360062A (en) * | 2012-03-30 | 2013-10-23 | 三菱综合材料株式会社 | Ferroelectric thin film-forming sol-gel solution and ferroelectric thin film forming method |
| CN105788864A (en) * | 2016-02-29 | 2016-07-20 | 湘潭大学 | Method for improving negative capacitance of PZT ferroelectric thin film |
| CN109036878A (en) * | 2018-06-06 | 2018-12-18 | 华南师范大学 | A kind of ferroelectric thin-flim materials device and preparation method thereof |
| CN109037218A (en) * | 2018-06-13 | 2018-12-18 | 湘潭大学 | Light erasing and the ferroelectric tunnel junction storage unit and its erasing and read method read |
-
2009
- 2009-05-22 CN CN2009100518787A patent/CN101891468A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 夏冬林等: "PZT铁电薄膜Sol-Gel技术制备和电性能研究", 《无机材料学报》 * |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102222672A (en) * | 2011-05-13 | 2011-10-19 | 济南大学 | Bismuth ferrite base film layer stacked structure capacitor and preparation method thereof |
| CN103360062A (en) * | 2012-03-30 | 2013-10-23 | 三菱综合材料株式会社 | Ferroelectric thin film-forming sol-gel solution and ferroelectric thin film forming method |
| CN103360062B (en) * | 2012-03-30 | 2016-06-08 | 三菱综合材料株式会社 | Ferroelectric thin film forms the forming method with sol-gel liquid and ferroelectric thin film |
| CN105788864A (en) * | 2016-02-29 | 2016-07-20 | 湘潭大学 | Method for improving negative capacitance of PZT ferroelectric thin film |
| CN105788864B (en) * | 2016-02-29 | 2017-12-08 | 湘潭大学 | A kind of method of raising PZT ferroelectric thin film negative capacitances |
| CN109036878A (en) * | 2018-06-06 | 2018-12-18 | 华南师范大学 | A kind of ferroelectric thin-flim materials device and preparation method thereof |
| CN109036878B (en) * | 2018-06-06 | 2020-04-07 | 华南师范大学 | Ferroelectric film material device and preparation method thereof |
| CN109037218A (en) * | 2018-06-13 | 2018-12-18 | 湘潭大学 | Light erasing and the ferroelectric tunnel junction storage unit and its erasing and read method read |
| CN109037218B (en) * | 2018-06-13 | 2020-07-17 | 湘潭大学 | Optically erased and read ferroelectric tunnel junction memory cell and erasing and reading method thereof |
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Application publication date: 20101124 |