CN100483700C - Conductive oxide electrode material and its preparation method - Google Patents
Conductive oxide electrode material and its preparation method Download PDFInfo
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- CN100483700C CN100483700C CNB200510021161XA CN200510021161A CN100483700C CN 100483700 C CN100483700 C CN 100483700C CN B200510021161X A CNB200510021161X A CN B200510021161XA CN 200510021161 A CN200510021161 A CN 200510021161A CN 100483700 C CN100483700 C CN 100483700C
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Abstract
This invention relates to a conductive oxide electrode material and its preparation method. This invention provides a bottom electrode material used in the ferroelectric microwave devices and a preparation method for lanthanum nickelate film of a double crystal epitaxial conductive oxide on the MgO substrate and the microstructure of the electrode material is a double crystal epitaxial structure, in which the film has very good surface smoothness, small grain size and low resistivity to meet the needs of electrode materials integrated on the MgO(100) chips.
Description
Technical field
The invention belongs to the microelectronic material field, particularly conductive oxide electrode material and preparation method thereof.
Background technology
ABO
3The ferroelectric thin film such as the Pb of calcium attitude ore deposit structure
xZr
1-xTiO
3(PZT), Ba
xSr
1-xTiO
3(BST), etc., have character such as ferroelectric, piezoelectricity, pyroelectricity, electric light, acousto-optic and nonlinear optics, have importantly in microelectronics, photoelectron, integrated optics and field such as micro electronmechanical and use.Received great concern in recent years.Ferroelectric thin film is being integrated on the device, and the selection of the hearth electrode material of film is very crucial.The quality quality of electrode greatly affects the performance of integrated ferroelectric device.A good electrode should satisfy three conditions: (1), with the ferroelectric material structure matching; (2), good chemical stability; (3), low resistivity.
Metal platinum (Pt) since its have low-resistivity (8.9 μ Ω .cm) and good chemical stability and be applied in the ferroelectric thin film device as electrode material widely.But Pt is owing to exist structural not matching with the ferroelectric material of perovskite structure, is difficult to that the epitaxial growth ferroelectric thin film obtains the good ferroelectric thin film of structural approach on the Pt electrode.Secondly, in the preparation process of Pt electrode, counterdiffusion takes place between metal electrode meeting and the ferroelectric thin film, form the dipole defective with oxygen on the one hand electricdomain is caused pinning, thereby the ferroelectric fatigability of film is strengthened, can form on the one hand the boundary layer of one deck low-k in addition, the voltage that causes the reality on ferroelectric thin film reduces and causes the polarization reversal difficulty.At last, the Pt electrode surface evenness of preparation is lower usually, and significantly projection hillock is arranged, and can cause leakage current to increase.
Because there are above many shortcomings in metal electrodes such as Pt, a class has ABO
3The conductive oxide of perovskite structure is as (La
0.5Sr
0.5) CoO
3(being abbreviated as LSCO), (La
1/3Sr
1/3Ca
1/3) CoO
3(writing a Chinese character in simplified form LSCCO), SrRuO
3(writing a Chinese character in simplified form SRO), YBa
2Cu
3O
7(writing a Chinese character in simplified form YBCO) and LaNiO
3(writing a Chinese character in simplified form LNO) etc., the electrode material that is used as ferroelectric thin film is broad research in addition.Than metal electrode, the Ca-Ti ore type conductive oxide has the incomparable advantage of metal electrode material as the electrode of ferroelectric thin film.At first, under proper technical conditions, can on Si substrate and oxide substrate, realize epitaxial growth, and the surface of good evenness is arranged, help obtaining the ferroelectric thin film of high-quality subsequent deposition, thereby can reduce its leakage current effectively.Secondly and since with ferroelectric material all be that perovskite structure and lattice constant are close, between them, can form a more smooth interface, boundary defects such as dislocation are less.This helps to improve its ferroelectric properties.
But LSCO, LSCCO etc. is a multivariant oxide, the bad control of composition, and being difficult to obtain composition is stoichiometric film; And contained Ru element is very expensive among the SRO, can increase the cost of sample.LNO is a kind of conductive oxide of pseudo-cubic structure, and lattice constant is
, can both keep metallic conductivity in very wide temperature range, be the Ca-Ti ore type conductive oxide electrode material that has application prospect most.
In the application aspect the microwave device of ferroelectric thin film, magnesium oxide MgO is the most important backing material of using always.Magnesium oxide has the dielectric constant (ε=10) of very little temperature influence and very low dielectric loss (in microwave frequency band tan δ＜10
-5).At present, the conductive oxide LNO film for preparing on the MgO substrate can only obtain polycrystalline structure, and this causes the deterioration of follow-up ferroelectric thin film performance.Therefore, the LNO film that preparation has the epitaxial crystallization structure on the MgO substrate to the application of ferroelectric thin film on microwave device, has very big theory significance and using value.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of hearth electrode material that can be applicable to ferroelectric microwave device, particularly the preparation method of the macle extension conductive oxide lanthanum nickelate thin film on the magnesium oxide substrate.
The technical scheme that the present invention solve the technical problem employing is:
The preparation method of conductive oxide electrode material may further comprise the steps:
1) oxide substrate and target are placed the oxygen atmosphere environment;
2) heated oxide thing substrate;
3) use the laser lift-off target, generation plasma-deposited on the oxide substrate obtains electrode material membrane.
4) rising ambient pressure is with step 2) electrode material membrane that obtains insulation 15-30 minute, cooling then.
Described oxide substrate is the MgO substrate, and described target is LaNiO
3
In step 2-3, keep the O of 10～20Pa
2Atmosphere.Step 2) in, heated oxide thing substrate to 450～750 ℃.Described MgO substrate makes in accordance with the following methods: choose the MgO monocrystal chip of (100) orientation, with substrate annealing in process at high temperature.
The invention has the beneficial effects as follows, electrode material of the present invention, particularly the conductive oxide lanthanum nickelate thin film has good surface smoothness, less crystallite dimension and lower resistivity, can satisfy the requirement as ferroelectric material integrated electrode material on MgO (100) substrate fully.
The present invention is further illustrated below in conjunction with the drawings and specific embodiments.
Description of drawings
Fig. 1: the LaNiO of preparation macle extension
3The structural representation of the PLD film growth system of conductive film.
1-LaNiO
3The ceramic target platform; 2-KrF excimer laser; The lens of 3-laser focusing; The connector of 4-mechanical pump and molecular pump; 5-chip bench; 6-MgO (100) substrate material; 7-heating resistor stove; 8-growth room; 9-blow vent.
Fig. 2: LaNiO
3XRD θ-2 θ the scanning spectra of film.Wherein the x axle is represented 2 θ angles (unit degree of being), and the y axle is represented relative intensity (unit is any).
Fig. 3: the LaNiO of (110) orientation of preparation during 700 ℃ of preferred temperature
3The utmost point figure of (111) XRD of film.
(a) be 3 dimension three-dimensional views, x, y axle are represented ψ angle (unit degree of being), and the z axle is represented relative intensity (unit is any).
(b) be 2 dimensional plane views, three circles are 30 °, 60 ° and 80 ° with respect to the ψ angle respectively.
Fig. 4: LaNiO
3(110) the RHEED diffracting spectrum of film.
(a) be electron beam edge＜01-1〉diffracting spectrum of incident direction;
(b) be electron beam edge＜11-1〉diffracting spectrum of incident direction.
Fig. 5 shows, macle extension LaNiO
3The film schematic diagram of on MgO (100) substrate, growing, LaNiO
3Crystal grain (100) orientation two the mutually perpendicular directions in MgO substrate upper edge on epitaxial growth.
Fig. 6: macle extension LaNiO
3The surface topography map of film.
(a) be scanning spectra in the 1 μ m zone;
(b) amplify the part that is (a).
Embodiment
A kind of preparation method of conductive oxide lanthanum nickelate thin film of macle extension of the hearth electrode that is applied to ferroelectric microwave device is characterized in that adopting pulsed laser deposition (PLD) technology, uses LaNiO
3Ceramic target prepares lanthanum nickelate thin film in oxygen atmosphere, its concrete steps are as follows:
(1) with LaNiO
3Ceramic target is placed on the target platform 1, magnesium oxide substrate 6 is placed on the chip bench 5, resistive heater 7 is placed in the chip bench below, target platform 1, chip bench 5, substrate 6, resistive heater 7 all are placed in the growth room 8, the pore 9 that a logical oxygen is arranged in the left side of growth room, the left upper portion opening is placed lens 3, and lower openings connects vacuum pump 4 (mechanical pump and molecular pump).
(2) with vacuum pump 4 growth room 8 is evacuated to 1 * 10
-2Below the Pa, in growth room 8, charge into high purity oxygen gas (99.9%) from air vent hole 9 then, and make maintenance 20PaO in the growth room
2Atmosphere.
(3) with resistive heater 7 heated substrate platforms 5, make MgO substrate 6 reach 450 ℃-750 ℃ of design temperatures.
(4) the starting impulse laser 2, by condenser lens 3 laser beam focused on LaNiO
3On the ceramic target, with pulse laser stripped ceramic target, the laser plasma of generation is deposited on the MgO substrate and makes LaNiO
3Film.After this, in growth room 8, charge into high purity oxygen gas, make growth indoor oxygen voltage rise, cool to room temperature after then sample being incubated half an hour in position to 0.5atm from air vent hole 9.In film-forming process, target platform 1 and chip bench 5 guarantee the laser beam plasma with constant speed rotation, are deposited on equably on the MgO substrate 6, so that make the uniform film of thickness.
In the above-mentioned steps (2), charge into the oxygen of growth room, preferred 20Pa high purity oxygen gas in thin film growth process.
Resistance furnace in the above-mentioned steps (3) can arbitrary temperature keep constant between 20 ℃-900 ℃, the preferred settings temperature of heating MgO substrate is 700 ℃.
Said pulse laser is KrF (KrF) excimer laser of selecting for use in the above-mentioned steps (4), and wavelength is 248nm, and pulse duration is 30ns, and single pulse energy is 50-600mJ, and energy density is 5J/cm
2
Above-mentioned LaNiO
3Ceramic target, preparation is in two steps finished.At first, prepare LaNiO with citric acid method
3Powder.NiO
2Powder and La
2O
3What the batch mixing of powder and preparation were adopted is little fiery steam seasoning.Promptly use rare nitric acid will be by the Ni (NO of the mixed in molar ratio of 1:1
3)
3And La (NO
3)
3Dissolving places the solution of preparation on the constant temperature oven temperature heating with 120 ℃ then, in the process of heating with the continuous agitating solution of electric mixer.When solution is evaporated to when thick, it is 80 ℃ baking oven that solution is placed temperature, solidifies until it.The material that will solidify is clayed into power with falling into oblivion, and fires with 700 ℃ in the cabinet-type electric furnace then and promptly gets even LaNiO in 2 hours
3Powder.Then, powder is cold-pressed into the disk of Φ 60mm * 3mm under 120MPa, and in cabinet-type electric furnace, with disk 1500 ℃ sintering temperature 6 hours.Finally obtain fine and close LaNiO
3Ceramic target.
MgO choice of substrate and processing: select the MgO monocrystal chip of (100) orientation for use, with substrate in-situ annealing 5 minutes under 800 ℃ high temperature.
With the above LaNiO that makes
3It is as follows that film carries out the instrument of structural analysis and electric performance test:
X-ray diffractometer (XRD), model are Britain BEDE D1; Reflection high energy electron diffraction (RHEED), model are the LMBE-RHEED system that section's instrument company produces in the Shenyang; Atomic force microscope (AFM), model are Japanese SEIKO SPA-300HV; Four point probe tester, model are the digital four point probe tester of SZ82 type.
Below in conjunction with to LaNiO
3Membrane structure and The performance test results further specify beneficial effect of the present invention:
Fig. 2 shows, LaNiO
3XRD θ-2 θ the scanning spectra of film, the LaNiO of preparation when showing 700 ℃ of preferred temperature
3Film has (110) preferred orientation of height.
Fig. 3 shows, the LaNiO of (110) orientation of preparation during 700 ℃ of preferred temperature
3(111) XRD utmost point figure of film.(a) be 3 dimension three-dimensional views; (b) be 2 dimensional plane views.What show among two figure is about 40 ° at ψ and locates to occur peaks such as four, shows the LaNiO of (110) orientation
3Film is the macle extension growth on MgO (100) substrate.Therefore, LaNiO
3(110)/MgO (100) is the macle extension film.
Fig. 4 shows, LaNiO
3(110) the RHEED diffracting spectrum of film.(a) and (b) be respectively electron beam edge＜01-1〉and＜11-1〉diffracting spectrum of incident direction.Substrate rotates a week along normal, just occurs once every 90 ° (a), just occurs once every 180 ° (b), further the LaNiO of proof (110) orientation
3Film is the macle extension growth on MgO (100) substrate.
Fig. 5 shows, macle extension LaNiO
3The film schematic diagram of on MgO (100) substrate, growing, LaNiO
3Crystal grain (100) orientation two the mutually perpendicular directions in MgO substrate upper edge on epitaxial growth.
Fig. 6 shows, macle extension LaNiO
3The surface topography map of film.(a) be scanning spectra in the 1 μ m zone; (b) amplify the part that is (a).(a) LaNiO of demonstration macle extension
3Film has the evenness (1.465nm) of atom level and especially little crystallite dimension (30-50nm).(b) crystal grain that is presented in (a) is arranged by two mutually perpendicular directions.Therefore, the LaNiO of macle extension
3Film has good evenness and crystallite dimension, thereby can be used as the follow-up ferroelectric thin film of template layer growth.
Especially, the LaNiO of the macle extension that in the time of 700 ℃, prepares of the present invention
3Film has the LaNiO than other temperature preparation
3The resistivity that film is lower.The LaNiO of macle extension
3The resistivity of film reaches 300 μ Ω .cm, and this value is enough to satisfy the LaNiO of macle extension
3Film as electrode material in ferroelectric application in integrated.
Claims (6)
1, the preparation method of conductive oxide electrode material may further comprise the steps:
1) magnesium oxide substrate and target are placed the oxygen atmosphere environment;
2) heated oxide magnesium substrate;
3) use the laser lift-off target, generation plasma-deposited on magnesium oxide substrate obtains electrode material membrane.
2, the preparation method of conductive oxide electrode material as claimed in claim 1 is characterized in that, also comprises step 4): the rising ambient pressure, with step 2) the electrode material membrane insulation that obtains 15～30 minutes, cooling then.
3, the preparation method of conductive oxide electrode material as claimed in claim 1 or 2 is characterized in that, described target is LaNiO
3
4, the preparation method of conductive oxide electrode material as claimed in claim 3 is characterized in that, in the step 2-3, keeps the O of 10Pa～20Pa
2Atmosphere.
5, the preparation method of conductive oxide electrode material as claimed in claim 3 is characterized in that step 2) in, heated oxide magnesium substrate to 450～750 ℃.
6, the preparation method of conductive oxide electrode material as claimed in claim 3 is characterized in that, described magnesium oxide substrate makes in accordance with the following methods:
Choose the MgO monocrystal chip of (100) orientation, with substrate annealing in process at high temperature.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200510021161XA CN100483700C (en) | 2005-06-27 | 2005-06-27 | Conductive oxide electrode material and its preparation method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200510021161XA CN100483700C (en) | 2005-06-27 | 2005-06-27 | Conductive oxide electrode material and its preparation method |
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| Publication Number | Publication Date |
|---|---|
| CN1758432A CN1758432A (en) | 2006-04-12 |
| CN100483700C true CN100483700C (en) | 2009-04-29 |
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ID=36703711
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|---|---|---|---|
| CNB200510021161XA Expired - Fee Related CN100483700C (en) | 2005-06-27 | 2005-06-27 | Conductive oxide electrode material and its preparation method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4344942B2 (en) * | 2004-12-28 | 2009-10-14 | セイコーエプソン株式会社 | Inkjet recording head and piezoelectric actuator |
| CN101712549B (en) * | 2008-11-20 | 2012-08-08 | 河南大学 | Method for preparing lanthanum nickel oxide ceramic target |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1487564A (en) * | 2002-09-05 | 2004-04-07 | ������������ʽ���� | Substrate for electronic apparatus, method for producing substrate of electronic apparatus, and electronic apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1487564A (en) * | 2002-09-05 | 2004-04-07 | ������������ʽ���� | Substrate for electronic apparatus, method for producing substrate of electronic apparatus, and electronic apparatus |
Non-Patent Citations (2)
| Title |
|---|
| 异质外延MgO/SrTiO3薄膜中界面应力研究. 郑亮等.真空科学与技术学报，第25卷第1期. 2005 |
| 异质外延MgO/SrTiO3薄膜中界面应力研究. 郑亮等.真空科学与技术学报，第25卷第1期. 2005 * |
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Granted publication date: 20090429 Termination date: 20130627 |