SEMICONDUCTOR SUBSTRATE WITH OXIDE SINGLE CRYSTAL HETEROSTRUCTURES, MANUFACTURING METHOD THEREOF AND ELECTRONIC DEVICE USING THE SAME

Abstract

A semiconductor substrate with oxide single crystal heterostructures, to which a sacrificial layer, an epitaxy functional oxide thin film having a perovskite structure and a metal layer are grown on an oxide single crystal substrate, prepared another metal layer on a semiconductor substrate, and bonded the metal layer of the oxide single crystal substrate to the metal layer of the semiconductor substrate to be face each other, and separated the oxide single crystal substrate by selectively etching and removing only the sacrificial layer after the bonding.

Claims

1. A semiconductor substrate with oxide single crystal heterostructures, comprising: a metal layer formed on a semiconductor substrate and an epitaxy oxide thin film layer having a perovskite structure bonded to the semiconductor substrate via the metal layer.

2. The semiconductor substrate with oxide single crystal heterostructures of claim 1, wherein the metal layer has a single layer structure or a laminated structure composed of one element, or two or more elements selected from a group consisting of Au, Al, W, Ti, Cr, Pt, Cu, Ni, Mo, Ta, Nb, and La.

3. The semiconductor substrate with oxide single crystal heterostructures of claim 2, wherein the laminated structure is a structure (layer A/layer B/layer A′) that layer A, layer B, and layer A′ are laminated in order, the layer A and the layer A′ are able to be identical to or different from each other and are any one selected from a group consisting of Ti, Cr, Cu, Ni, Pt, and Cr, and the layer B is any one selected from a group consisting of Au, Mo, Ta, Nb, La, W, and CuW.

4. The semiconductor substrate with oxide single crystal heterostructures of claim 1, wherein the metal layer has a laminated structure (layer A/layer B/layer A′) which shows that layer A, layer B, and layer A′ are laminated in order, the layer A and the layer A′ are metal adhesion layers having a thickness of 5 to 20 nm, and the layer B is a metal bonding layer having a thickness of 20 nm to 1 μm.

5. The semiconductor substrate with oxide single crystal heterostructures of claim 1, wherein a total thickness of the metal layer is 5 to 1500 nm.

6. The semiconductor substrate with oxide single crystal heterostructures of claim 1, wherein the epitaxy oxide thin film layer has crystallinity, a full width at half maximum (FWHM) of which is 0.1° or below, resulting from measurement of an omega rocking curve aimed at a peak at which diffraction peak intensity is most high, in case that the epitaxy oxide thin film layer is measured in θ-2θ mode of an X-ray diffractometer.

7. The semiconductor substrate with oxide single crystal heterostructures of claim 1, wherein the epitaxy oxide thin film layer is composed of a perovskite piezoelectric oxide whose lattice constant is 0.3 to 0.45 nm.

8. The semiconductor substrate with oxide single crystal heterostructures of claim 7, wherein the perovskite piezoelectric oxide is composed of any one selected from a group consisting of Pb(Mg.sub.1/3,Nb.sub.2/3)O.sub.3, PbZrO.sub.3, PbTiO.sub.3, SrTiO.sub.3, SrRuO.sub.3, BaTiO.sub.3, and BiFeO.sub.3, or a solid solution thereof, or a material to which a dopant is added.

9. The semiconductor substrate with oxide single crystal heterostructures of claim 7, wherein the perovskite piezoelectric oxide comprises a piezoelectric single crystal having a perovskite-type crystal structure (ABO.sub.3) with a compositional formula of Chemical Formula 1 below:
[A.sub.−(a+1.5b)B.sub.aC.sub.b][(MN).sub.1-x-y(L).sub.yTi.sub.x]O.sub.3  Chemical Formula 1 in the formula, A represents Pb or Ba, B represents at least one or more elements selected from a group consisting of Ba, Ca, Co, Fe, Ni, Sn and Sr, C represents at least one or more elements selected from a group consisting of Co, Fe, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, L has a single form composed of one element selected from Zr or Hf, or a mixed form thereof, M represents at least one or more elements selected from a group consisting of Ce, Co, Fe, In, Mg, Mn, Ni, Sc, Yb and Zn, N represents at least one or more elements selected from a group consisting of Nb, Sb, Ta and W, a, b, x, and y satisfy the following requisites:
0<a≤0.10,
0<b≤0.05,
0.05<x≤0.58, and
0.05≤y≤0.62.

10. The semiconductor substrate with oxide single crystal heterostructures of claim 9, wherein in the formula the piezoelectric single crystal satisfies the requites of 0.01≤a≤0.10 and 0.01≤b≤0.05.

11. The semiconductor substrate with oxide single crystal heterostructures of claim 7, wherein the epitaxy oxide thin film layer is a thin film layer that is composed of a perovskite piezoelectric oxide containing Zr grown by a solid-state single crystal growth method and has not a pore.

12. The semiconductor substrate with oxide single crystal heterostructures of claim 1, wherein the epitaxy oxide thin film layer is a thin film formed in a thickness of 10 μm or more.

13. The semiconductor substrate with oxide single crystal heterostructures of claim 1, wherein the epitaxy oxide thin film layer is patterned into a plurality of lattice cells.

14. A method of manufacturing a semiconductor substrate with oxide single crystal heterostructures, comprising: preparing a semiconductor substrate and an oxide single crystal substrate; successively forming a sacrificial layer, an epitaxy oxide thin film layer, and a metal layer to be piled up from the oxide single crystal substrate; forming another metal layer on the semiconductor substrate; bonding the metal layer of the oxide single crystal substrate to second metal layer of the semiconductor substrate to be face each other; and performing separation of the oxide single crystal substrate by etching and removing the sacrificial layer after the bonding.

15. The method of claim 14, further comprising patterning the epitaxial oxide thin film layer and the metal layer formed on the oxide single crystal substrate into a plurality of lattice cells.

16. The method of claim 14, wherein the semiconductor substrate is any one selected from a group consisting of a silicon substrate, a silicon-on-insulator (SOI), a sapphire substrate, GaAs wafer, AlN wafer, Ge wafer, SiGe wafer, GaN wafer, AlGaN wafer, SiC wafer, AlSiC wafer, or Ni plate, Cu plate, Nb plate, Mo plate, Ta plate, La plate, CuW plate, NiW plate, NiCu plate, or a laminated structure composed of the plate materials.

17. The method of claim 14, wherein the oxide single crystal substrate is any one selected from a group consisting of SrTiO.sub.3, DyScO.sub.3, GdScO.sub.3, TbScO.sub.3, EuScO.sub.3, SmScO.sub.3, NdScO.sub.3, PrScO.sub.3, CeScO.sub.3, LaScO.sub.3, LaLuO.sub.3, NdGaO.sub.3, LaGaO.sub.3, SrLaGaO.sub.4, and LaAlO.sub.3.

18. The method of claim 14, wherein the oxide single crystal substrate is subjected to surface treatment to have a surface roughness of 1 nm or below.

19. The method of claim 14, wherein the metal layers are formed in a single layer structure or a laminated structure composed of one element, or two or more elements selected from a group consisting of Au, Al, W, Ti, Cr, Pt, Cu, Ni, Mo, Ta, Nb, and La.

20. The method of claim 19, wherein the laminated structure is a structure (layer A/layer B/layer A′) which shows that layer A, layer B, and layer A′ are laminated in order, the layer A and the layer A′ are able to be identical to or different from each other and are any one selected from a group consisting of Ti, Cr, Cu, Ni, Pt, and Cr, and the layer B is any one selected from a group consisting of Au, Mo, Ta, Nb, La, W, and CuW.

21. The method of claim 19, wherein the metal layers have a laminated structure (layer A/layer B/layer A′) which shows that the layer A, the layer B, and the layer A′ are laminated in order, the layer A and the layer A′ are formed with metal adhesion layers having a thickness of 5 to 20 nm, and the layer B is formed with a metal bonding layer having a thickness of 20 nm to 1 μm.

22. The method of claim 14, wherein the bonding is carried out aligning the metal layers of each substrate to face each other at the same position, mechanical bonding, and then pressing and heating.

23. An electronic device, comprising a semiconductor substrate with oxide single crystal heterostructures of claim 1.

24. The electronic device of claim 23, wherein the semiconductor substrate with oxide single crystal heterostructures is applied to any one selected from a group consisting of an electric and electronic device, an optical device, a sensor, an actuator, a transducer, and a microelectromechanical system (MEMS).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG. 1 is a cross-sectional view showing a semiconductor substrate with oxide single crystal heterostructures according to a first embodiment of the present invention,

[0052] FIG. 2 is an SEM (Scanning Electron Microscope) image concerning a section of the semiconductor substrate with oxide single crystal heterostructures (PMN-PZT/Ti/Au/Ti/Si) shown in FIG. 1,

[0053] FIG. 3 is a cross-sectional view showing a semiconductor substrate with oxide single crystal heterostructures according to a second embodiment of the present invention,

[0054] FIG. 4 is an optical image of the semiconductor substrate with oxide single crystal heterostructures (PMN-PZT/Ti/Au/Ti/Si) shown in FIG. 3,

[0055] FIG. 5 is a cross-sectional schematic diagram showing cutting portions of three patterns of the semiconductor substrate with oxide single crystal heterostructures shown in FIG. 4,

[0056] FIG. 6 is a front view showing a pattern unit of the semiconductor substrate with oxide single crystal heterostructures shown in FIG. 4,

[0057] FIG. 7 is a schematic diagram showing a method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment of the present invention,

[0058] FIG. 8 is a schematic diagram showing a method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the second embodiment of the present invention,

[0059] FIG. 9 is a graph concerning the analysis of X-ray diffraction before transferring according to the semiconductor substrate with oxide single crystal heterostructures of to the present invention,

[0060] FIG. 10 is a graph concerning the analysis of X-ray diffraction after transferring according to the semiconductor substrate with oxide single crystal heterostructures of the present invention,

[0061] FIG. 11 is a graph concerning polarization versus voltage before transferring according to the semiconductor substrate with oxide single crystal heterostructures of the present invention, and

[0062] FIG. 12 is a graph concerning polarization versus voltage after transferring according to the semiconductor substrate with oxide single crystal heterostructures of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0063] Hereinafter, the present invention will be described in detail.

[0064] The present invention provides a semiconductor substrate with oxide single crystal heterostructures to which a high-quality epitaxy functional oxide thin film is bonded using a metal layer formed on a semiconductor substrate.

[0065] FIG. 1 is a cross-sectional view of a semiconductor substrate with oxide single crystal heterostructures according to a first embodiment of the present invention, providing a semiconductor substrate with oxide single crystal heterostructures 1 comprising: a metal layer 20 formed on a semiconductor substrate 10, and an epitaxy oxide thin film layer 30 having a perovskite structure bonded to the semiconductor via the metal layer 20.

[0066] With respect to the semiconductor substrate with oxide single crystal heterostructures, if a substrate has electrically or thermally excellent conductivity, it may be used as the semiconductor substrate 10, and preferably, any one selected from a silicon substrate, a silicon-on-insulator, a sapphire substrate, GaAs wafer, AlN wafer, Ge wafer, SiGe wafer, GaN wafer, AlGaN wafer, SiC wafer, AlSiC wafer, or Ni plate, Cu plate, Nb plate, Mo plate, Ta plate, La plate, CuW plate, NiW plate, NiCu plate, or a laminated structure composed of the plate materials is used. At this time, in case that the semiconductor substrate 10 is a silicon substrate or a silicon-on-insulator, a silicon oxidizing film or a hetero-oxide layer may be provided on the silicon substrate, and the metal layer is formed at an upper part of a second layer.

[0067] With respect to the semiconductor substrate with oxide single crystal heterostructures according to the present invention, the metal layer 20 may be a single layer structure or a laminated structure composed of one element, or two or more elements selected from a group consisting of Au, Al, W, Ti, Cr, Pt, Cu, Ni, Mo, Ta, Nb and La.

[0068] More preferably, the laminated structure is a structure in which an A layer, a B layer and an A′ layer are laminated in order, the A layer and the A′ layer are able to be identical to or different from each other and are any one selected from a group consisting of Ti, Cr, Cu, Ni, Pt and Cr, and the B layer is any one selected from a group consisting of Au, Mo, Ta, Nb, La, W and CuW.

[0069] Furthermore, when the metal layer 20 according to the present invention is the laminated structure (layer A/layer B/layer A′) which shows that the A layer, the B layer, and the A′ layer are laminated in order, it is a structure that the A layer and the A′ layer are formed with metal adhesion layers having a thickness of 5 to 20 nm, and the B layer is formed with a metal bonding layer having a thickness of 20 nm to 1 μm, examples of a bonding structure of the metal layer which is bonded after transferring are Ti/Au/Ti, Cu/Mo/Cu, Ni/Mo/Ni, Cu/Ta/Cu, Ni/Ta/Ni, Cu/Nb/Cu, Ni/Nb/Ni, Cu/La/Cu, Ni/La/Ni, Cu/W/Cu, Ni/W/Ni, Cu/CuW/Cu, Ni/CuW/Ni, Pt/Au/Pt, Cr/Au/Cr, Ti/Au/Pt, and so on, and are not limited to these laminated structures but are able to include a combination thereof, and a symmetrical or asymmetrical structure may also be included upon laminating.

[0070] It is preferable to form a total thickness of the metal layer after transferring in a range of 5 to 1500 nm. At this time, if the metal layer has a very thin thickness of less than 5 nm, it may not be deposited on a whole surface according to surface roughness of the substrate or the epitaxy oxide thin film layer to be transferred, and if the thickness exceeds 1500 μm, it may be problematic in that as the thickness becomes thicker, prices rise because precious metals such as Au and so on are used, and it is not necessary to form the thickness to be excessively thick because the thickness should be set up in such a standard that the metal layer can be used as a lower electrode.

[0071] Accordingly, in the semiconductor substrate with oxide single crystal heterostructures according to the present invention, the metal layer 20 may be used as the lower electrode.

[0072] Furthermore, in the semiconductor substrate with oxide single crystal heterostructures according to the present invention, the epitaxy oxide thin film layer 30 is formed of a functional single crystal oxide of high-quality having crystallinity, a full width at half maximum (FWHM) of which is 0.1° or below, resulting from measurement of an omega rocking curve aimed at a peak at which diffraction peak intensity is most high, in case that functional single crystal oxide is measured in θ-2θ mode of an X-ray diffractometer.

[0073] Specifically, the single crystal oxide is a perovskite piezoelectric oxide whose lattice constant is 0.3 nm to 0.45 nm, and specifically, the perovskite piezoelectric oxide comprises any one selected from a group consisting of Pb(Mg.sub.1/3,Nb.sub.2/3)O.sub.3, PbZrO.sub.3, PbTiO.sub.3, SrTiO.sub.3, SrRuO.sub.3, BaTiO.sub.3, and BiFeO.sub.3, or a solid solution thereof, or a material to which a dopant is added.

[0074] Detailed examples are PMN-PT (Pb(Mg.sub.1/3Nb.sub.2/3)O.sub.3—PbTiO.sub.3) and PMN-PZT (Pb(Mg.sub.1/3Nb.sub.2/3)O.sub.3—Pb(Zr,Ti)O.sub.3), and in particular, in an exemplary embodiment of the present invention, even though PMN-PZT (Pb(Mg.sub.1/3Nb.sub.2/3)O.sub.3—Pb(Zr,Ti)O.sub.3) is used and described, the epitaxy functional oxide thin film 30 of high quality may be formed using a piezoelectric single crystal having a perovskite type crystal structure ABO.sub.3 based on a result which shows that a PMN-PZT thin film, which is the epitaxy oxide thin film layer 30, is smoothly bonded to the semiconductor substrate via the metal layer.

[0075] A perovskite piezoelectric oxide ([A][(MN).sub.1-x-yTi.sub.xZr.sub.y]O.sub.3) including Zr grown by a solid-state single crystal growth method may be used as the piezoelectric single crystal of the perovskite type crystal structure (well-known through Korean Patent No. 0743614).

[0076] In said formula, A represents at least one or more elements selected from a group consisting of Pb, Sr, Ba, and Bi, M represents at least one or more element selected from a group consisting of Ce, Co, Fe, In, Mg, Mn, Ni, Sc, Yb, and Zn, N represents at least one or more element selected from a group consisting of Nb, Sb, Ta, and W, and x and y satisfy the following requisites: 0.05≤x≤0.58 (mole fraction), and 0.05≤y≤0.62 (mole fraction).

[0077] Furthermore, according to the semiconductor substrate with oxide single crystal heterostructures of the present invention, in order to provide the epitaxy oxide thin film layer 30 of high quality, the epitaxy oxide thin film layer 30 is formed of a piezoelectric single crystal of a perovskite type crystal structure (ABO.sub.3) having a compositional formula of Chemical Formula 1 below.

[A1.sub.−(a+1.5b)B.sub.aC.sub.b][(MN).sub.1-x-y(L).sub.yTi.sub.x]O.sub.3  Chemical Formula 1

[0078] In said formula, A represents Pb or Ba,

[0079] B represent at least one or more elements selected from a group consisting of Ba, Ca, Co, Fe, Ni, Sn, and Sr,

[0080] C represents one or more elements selected from a group consisting of Co, Fe, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu,

[0081] L represents a single form composed of any one selected from Zr or Hf, or a mixed form thereof,

[0082] M represents at least one or more element selected from a group consisting of Ce, Co, Fe, In, Mg, Mn, Ni, Sc, Yb and Zn, and

[0083] N represents at least one or more elements selected from a group consisting of Nb, Sb, Ta and W, and

[0084] a, b, x and y satisfy requisites of 0<a≤0.10, 0<b≤0.05, 0.05≤x≤0.58, and 0.05≤y≤0.62.

[0085] Preferably, in the formula, a piezoelectric single crystal satisfies the requisites of 0.01≤a≤0.10 and 0.01≤b≤0.05, and more preferably, satisfying a requisite of a/b≥2. At this time, in the requisites, when a is less than 0.01, it is problematic in that a perovskite phase is unstable, and when a exceeds 0.10, it is not preferable in that it is difficult to use the piezoelectric single crystal really because a phase transition temperature becomes too low.

[0086] Also, if the requisite of a/b≥2 is not satisfied, it will not be preferable because it is problematic in that dielectric and piezoelectric characteristics are not maximized, or growth of the single crystal is limited.

[0087] With respect to the piezoelectric single crystal of the perovskite type crystal structure ABO.sub.3 having the compositional formula of the chemical formula 1, based on a tendency which shows that as chemical composition becomes complex, the more the piezoelectric characteristic increases, in the perovskite type crystal structure (ABO.sub.3), the ions located at the [A] are constituted of mixed composition of [A.sub.1−(a+1.5b)B.sub.aC.sub.b]. The composition of A includes a flexible or inflexible element, and according to the exemplary embodiment of the present invention, even though it is described under the condition that the composition is limited to flexible piezoelectric single crystal which shows that A is Pb, the composition is not be limited thereto.

[0088] In the composite composition of the [A] site ion in the piezoelectric single crystal having the compositional formula of Chemical Formula 1, it is possible to implement an excellent dielectric constant when the composite composition is compared to the case where the metal trivalent element or the metal divalent element is alone.

[0089] The piezoelectric single crystal having the compositional formula of Chemical Formula 1 includes a metal tetravalent element as an ion located at [B] in the perovskite type crystal structure ABO.sub.3, and in particular, composition of L is limited to a single form composed of one element selected from Zr or Hf, or a mixed form thereof.

[0090] Accordingly, according to the present invention, although the composition is complicated chemical composition using a solid-state single crystal growth method, the piezoelectric single crystal of uniform composition is used irrespective of the composition, and based on the mixed composition of the ions located at [A], the epitaxy oxide thin film layer is formed of a piezoelectric single crystal with dielectric characteristics, such as a high dielectric constant K.sub.3T, high piezoelectric constants d.sub.33 and k.sub.33, high phase transition temperatures T.sub.C and T.sub.RT, and a high coercive electric field E.sub.C.

[0091] The epitaxy oxide thin film layer 30 according to the present invention comprises a perovskite piezoelectric oxide containing Zr grown by a solid-state single crystal growth method, and even though the perovskite piezoelectric oxide including a pore occurring in a process of the solid-state single crystal growth method is used, it is characteristic in that the epitaxy oxide thin film layer is formed into a thin film in which no pore exists.

[0092] It is preferable that the thin film of the epitaxy oxide thin film layer 30 has a thickness of 10 μm or more. At this time, the more the thickness of the epitaxy oxide thin film layer is thick the better because the thickness is fixed in such a manner as to cut the bulk single crystal in a wafer shape, and polish after bonding it to the semiconductor substrate. Accordingly, within the scope of the manner in progress, it is possible to form all allowable thicknesses in the light of time and economics, preferably, a thickness of 10 μm or more, and more preferably, a thickness of 10 to 50 μm.

[0093] FIG. 2 is an SEM (Scanning Electron Microscope) image concerning a cross section of the semiconductor substrate with oxide single crystal heterostructures shown in FIG. 1 and shows that according to the exemplary embodiment of the present invention, a silicon substrate is used as the semiconductor substrate 10, and a bonding structure of the semiconductor substrate with oxide single crystal heterostructures (PMN-PZT/Ti/Au/Ti/Si), which shows that the PMN-PZT layer is bonded to the Si substrate via the metal layer including Ti, Au and Ti layers), comprising the metal layer 20 of a metal bonding layer on a metal adhesion layer, and PMN-PZT single crystal of the epitaxy oxide thin film layer 30 of high quality can be confirmed.

[0094] FIG. 3 is a cross-sectional view of a semiconductor substrate with oxide single crystal heterostructures 2 according to a second embodiment of the present invention, comprising a metal layer 21 formed on a semiconductor substrate 11, an epitaxy oxide thin film layer 31 having a perovskite structure bonded to the metal layer, wherein the epitaxy oxide than film layer 31 is a structure of being patterned into a plurality of lattice cells.

[0095] Since raw materials and sizes of the semiconductor substrate, the metal layer, and the epitaxy oxide thin film layer are identical to those of the semiconductor substrate 10, the metal layer 20, and the epitaxy oxide thin film layer 30 as described based on the first embodiment, the detailed description thereof is omitted.

[0096] FIG. 4 is an optical image showing the semiconductor substrate with oxide single crystal heterostructures (PMN-PZT/Ti/Au/Ti/Si) according to the second embodiment, FIG. 5 is a cross-sectional schematic diagram showing three pattern cutting parts shown in the semiconductor substrate with oxide single crystal heterostructures, FIG. 6 represents a front view showing a pattern unit of the semiconductor substrate with oxide single crystal heterostructures shown in FIG. 4, and as a result, smooth bonding of the metal layer 21 formed on the semiconductor substrate 11, and the epitaxy oxide thin film layer 31 patterned into a plurality of lattice cells on the metal layer can be confirmed.

[0097] FIG. 7 is a schematic diagram showing a method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment of the present invention, and provides the method of manufacturing the semiconductor substrate with oxide single crystal heterostructures, comprising:

[0098] step 1) of preparing a semiconductor substrate 10 and an oxide single crystal substrate 50;

[0099] step 2) of successively forming a sacrificial layer 40, an epitaxy oxide thin film layer 30, and a metal layer 20A to be piled up from the oxide single crystal substrate 50;

[0100] step 3) of forming a metal layer 20B on the semiconductor substrate 10;

[0101] step 4) of bonding the metal layer 20A of the oxide single crystal substrate 50 to the metal layer 20B of the semiconductor substrate 10 to be face to each other; and

[0102] step 5) of performing separation of the oxide single crystal substrate 50 by etching and removing the sacrificial layer 40 after the bonding.

[0103] With respect to the method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment of the present invention, in said step 1), the semiconductor substrate 10 is any one selected from a silicon substrate, a silicon-on-insulator, a sapphire substrate, GaAs wafer, AlN wafer, Ge wafer, SiGe wafer, GaN wafer, AlGaN wafer, SiC wafer, AlSiC wafer, or Ni plate, Cu plate, Nb plate, Mo plate, Ta plate, La plate, CuW plate, NiW plate, NiCu plate, or a laminated structure composed of the plate materials, and in the exemplary embodiment of the present invention, although the present invention is described based on the case that a silicon substrate is used, an example of the semiconductor substrate is not limited thereto.

[0104] Furthermore, the oxide single crystal substrate 50 of said step 1) is formed of a material having a perovskite structure, and as one preferable example, any one selected from a group consisting of SrTiO.sub.3, DyScO.sub.3, GdScO.sub.3, TbScO.sub.3, EuScO.sub.3, SmScO.sub.3, NdScO.sub.3, PrScO.sub.3, CeScO.sub.3, LaScO.sub.3, LaLuO.sub.3, NdGaO.sub.3, LaGaO.sub.3, SrLaGaO.sub.4, and LaAlO.sub.3 can be used. At this time, the oxide single crystal substrate 50 is prepared by being subjected to surface treatment to have a surface roughness of 1 nm or below using chemical etching and thermal treatment so that it is favorable to form an epitaxy film at an upper part.

[0105] With respect to the method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment of the present invention, in said step 2), when a functional oxide having a similar crystal structure and physical property grows on the oxide single crystal substrate 50, it is possible to realize the growth of an epitaxy thin film of very high quality. This epitaxy thin film facilitates crystal alignment and domain structure control due to interaction with the substrate, and it is possible to perform evaporation so as to have more improved crystallinity than that of a bulk single crystal.

[0106] Thus, the epitaxy sacrificial layer 40 may be formed on the oxide single crystal substrate 10 using a vacuum deposition process, and the functional epitaxy oxide thin film layer 30 to be transferred may be formed on the epitaxy sacrificial layer 40. At this time, the epitaxy sacrificial layer 40 and the epitaxy oxide thin film layer 30 are formed using a process, such as sputtering, pulsed laser deposition (PLD), molecular beam epitaxy (MBE), chemical vapor deposition (CVD), an evaporator, and so on.

[0107] At this time, it is characteristic in that the epitaxy oxide thin film layer 30 to be transferred onto a silicon substrate has crystallinity, a full width at half maximum (FWHM) of which is 0.1° or below, resulting from measurement of an omega rocking curve aimed at a peak at which diffraction peak intensity is most high, in case that the epitaxy oxide thin film layer is measured in θ-2θ mode of an X-ray diffractometer (for example, in the case of an orientation of (001) plane, a diffraction peak of (002) plane).

[0108] After the epitaxy oxide thin film layer 30 has been formed, chemical mechanical polishing (CMP) treatment may be further carried out for surface polishing.

[0109] After the treatment, the metal layer 20A may be formed on the epitaxy oxide thin film layer 30 using a process, such as sputtering, an evaporator, atomic layer deposition (ALD), chemical vapor deposition (CVD), and so on.

[0110] Specifically, the metal layer 20A may be a single layer structure or a laminated structure composed of one element, or two or more elements selected from a group consisting of Au, Al, W, Ti, Cr, Pt, Cu, Ni, Mo, Ta, Nb, and La.

[0111] The laminated structure is a structure (layer A/layer B/layer A′) which shows that layer A, layer B, and layer A′ are laminated in order, the layer A and the layer A′ may be identical to or different from each other and may be formed of any one selected from a group consisting of Ti, Cr, Cu, Ni, Pt, and Cr, and the layer B may be formed of any one selected from a group consisting of Au, Mo, Ta, Nb, La, W and CuW.

[0112] More particularly, the metal layer 20A is composed of a metal bonding layer which is configured in such a manner that any one selected from a group consisting of Au, Mo, Ta, Nb, La, W, and CuW is deposited on a metal adhesion layer formed of any one selected from a group consisting of Ti, Cr, Cu, Ni, Pt, and Cr.

[0113] With respect to the method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment of the present invention, said step 3) is a step of forming the metal layer 20B on the semiconductor substrate 10.

[0114] At this time, using a similar manner to that of forming the metal layer in said step 2), the metal layer 20B is formed into a metal bonding layer which is configured in such a manner that any one selected from a group consisting of Au, Mo, Ta, Nb, La, W, and CuW is deposited on a metal adhesion layer formed of any one selected from a group consisting of Ti, Cr, Cu, Ni, Pt, and Cr.

[0115] In order to remove oxide layers or other contaminants which can be formed on each surface of the metal layers after evaporation, modifying each surface of the metal layers 20A and 20B may be further performed using Ar or O.sub.2 plasma.

[0116] After this, said step 4) of the method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment of the present invention is to perform a step of bonding the metal layer 20A of the oxide single crystal substrate to the metal layer 20B of the semiconductor substrate to be face to each other.

[0117] Specifically, the metal layers 20A, and 20B are bonded to each other by a pressurization and heating means after being mechanically bonded by being aligned at the same position to be opposite each other, namely, to face each other.

[0118] The bonding means may apply a pressure of 0.1 to 10 MPa for 10 to 20 seconds and heat having a temperature of 400° C. or below to the metal layers, and the heat may be adopted selectively. In order to increase efficiency of the bonding, if necessary, a process of removing impurities through Ar or O.sub.2 plasma treatment intended for each of the metal bonding layers and activating each surface may be performed.

[0119] At this time, a bonding structure of the metal layer 20 bonded after transferring may be formed of any one selected from a group consisting of Ti/Au/Ti, Cu/Mo/Cu, Ni/Mo/Ni, Cu/Ta/Cu, Ni/Ta/Ni, Cu/Nb/Cu, Ni/Nb/Ni, Cu/La/Cu, Ni/La/Ni, Cu/W/Cu, Ni/W/Ni, Cu/CuW/Cu, Ni/CuW/Ni, Pt/Au/Pt, Cr/Au/Cr, and Ti/Au/Pt. These laminated structures are only described as preferable examples without being limited thereto, may be combined with each other and may also include a symmetrical structure or an asymmetrical structure.

[0120] Furthermore, when the metal layer 20 bonded after transferring according to the present invention has a laminated structure (layer A/layer B/layer A′) which shows that layer A, layer B, and layer A′ are laminated in order, the layer A and the layer A′ are formed with metal adhesion layers having a thickness of 5 to 20 nm, and the layer B is formed with a metal bonding layer having a thickness of 20 nm to 1 μm.

[0121] It is preferable that a total thickness of the metal layer 20 after transferring is formed in a range of 5 to 1500 nm.

[0122] Said step 5) of the method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment of the present invention is to produce the semiconductor substrate 10 to which the epitaxy oxide thin layer 30 is bonded via the metal layer 20 in such a manner as to put the bonded two substrates into an etching liquid and perform separation of the oxide single crystal substrate 50 by selectively etching and removing only the sacrificial layer 40.

[0123] At this time, the metal layer 20 may be used as a lower electrode according to a device, and the oxide single crystal substrate 50 which has been separated may be reused.

[0124] FIG. 8 is a schematic diagram showing a method of manufacturing the semiconductor substrate with oxide single crystal heterostructures according to the second embodiment of the present invention, providing the method of manufacturing the semiconductor substrate with oxide single crystal heterostructures, comprising:

[0125] step 1) of preparing a semiconductor substrate 11 and the oxide single crystal substrate 50;

[0126] step 2) of successively forming a sacrificial layer 40, an epitaxy oxide thin film layer 31, and a metal layer 21A to be piled up from the oxide single crystal substrate 50;

[0127] step 3) of patterning the epitaxy oxide thin film layer 31 and the metal layer 21A into a plurality of lattice cells;

[0128] step 4) of forming a metal layer 21B on the semiconductor substrate 11;

[0129] step 5) of bonding the metal layer 21A of the oxide single crystal substrate to the metal layer 21B of the semiconductor substrate to be face to each other; and

[0130] step 6) of performing separation of the oxide single crystal substrate 50 by etching and removing the sacrificial layer 40 after the bonding.

[0131] The manufacturing method of the semiconductor substrate with oxide single crystal heterostructures according to the second embodiment of the present invention is identical to that of the semiconductor substrate with oxide single crystal heterostructures according to the first embodiment except the step of patterning the epitaxy oxide thin film layer 31 and the metal layer 21A formed to be piled up from the oxide single crystal substrate 50 into a plurality of lattice cells.

[0132] At this time, with respect to the manufacturing method of the semiconductor substrate with oxide single crystal heterostructures according to the second embodiment, in the epitaxy oxide thin film layer 31, a functional epitaxy thin film may be produced in a shape like islands separated from each other at a fixed interval using a wet etching method or a dry etching method, and this structure may be used for the purpose of isolation to improve an etching speed of the sacrificial layer in the future or to control each mechanical and electrical reciprocal interference among cells.

[0133] FIG. 9 and FIG. 10 show graphs concerning each analysis of X-ray diffraction before and after transferring of the bonding substrate with respect to the manufacturing method of the semiconductor substrate with oxide single crystal heterostructures according to the second embodiment of the present invention, and as each peak corresponding to the structure before transferring of the bonding substrate (PMN-PZT/LSMO (sacrificial layer)/STO (oxide single crystal substrate)), and the structure after transferring of the bonding substrate (PMN-PZT/Au&Ti (metal layer)/Si (semiconductor substrate)), is confirmed, manufacturing of the semiconductor substrate 11 to which the epitaxy oxide thin film layer 31 is bonded via the metal layer 21 may be confirmed.

[0134] Furthermore, FIG. 11 and FIG. 12 show graphs of polarization versus voltage before and after transfer of the semiconductor substrate with oxide single crystal heterostructures of the present invention, and it can be confirmed that the PMN-PZT layer, which is the epitaxy oxide thin film layer 30, shows an imprint characteristic of being horizontally transferred in a negative direction before transferring, whereas the PMN-PZT layer after transferring is horizontally transferred in a positive direction.

[0135] These results are caused by the fact that an upper part and a lower part of the PMN-PZT layer during imprinting are changed, and are favorable results with respect to improvement of high-quality piezoelectric capability and stability.

[0136] Accordingly, the present invention provides an electronic device comprising a semiconductor substrate with oxide single crystal heterostructures in which an epitaxy oxide thin film layer is bonded to a semiconductor substrate via a metal layer.

[0137] Specifically, the semiconductor substrate with oxide single crystal heterostructures may be applied to a sensor, an actuator, a transducer, or a microelectromechanical system (MEMS) as well as an electrical and electronic device or an optical device.

[0138] The present invention is described below in more detail with reference to the examples.

[0139] The examples are intended for more specifically describing the present invention, and a scope of the present invention should not be limited to these examples.

<Example 1> Production of a Specimen (PMN-PZT Single Crystal Piezoelectric-Layer/Metal Layer/Si)

[0140] A sacrificial layer, (La.sub.0.67, Sr.sub.0.33)MnO.sub.3 (LSMO, 40) of 50 nm grew into an epitaxy thin film on a single crystal substrate 50 of SrTiO.sub.3 through a PLD process. PMN-PZT layer of 1.2 μm grew into an epitaxy oxide thin film layer 30 on LSMO layer through a sputtering process, and a chemical mechanical polishing (CMP) process was performed in order to reduce surface roughness. After this, a metal layer including Ti layer of 10 nm as a metal bonding layer, and Au layer of 120 nm as a metal transferring layer successively grew through a thermal evaporation process.

[0141] A metal layer (Au/Ti) was also formed on a silicon substrate 10 to be transferred using a vacuum deposition process. The silicon substrate and Au surface formed on the PMZ-PZT layer were bonded to each other after oxygen plasma treatment. 5 MPa of a pressure was applied thereto using pressing for 15 minutes, and after completion of metal bonding, the specimen was put into a solution, the sacrificial layer of LSMO was selectively etched so that the PMN-PZT layer could be separated from the SrTiO.sub.3 substrate and could be transferred onto the silicon substrate, and as a result, the semiconductor substrate with oxide single crystal heterostructures was manufactured.

<Example 2> Production of a Specimen (PMN-PZT Single Crystal Piezoelectric-Layer/Metal Layer/Si)

[0142] A semiconductor substrate with oxide single crystal heterostructures was manufactured in the same manner as that shown in said Example 1 except the fact that a photo lithography process was performed with respect to an epitaxy oxide thin film layer 31 and a metal layer (Au/Ti) formed to be piled up from a single crystal substrate of SrTiO.sub.3 50 so that a photo resist pattern of 100×100 μm could be formed, and a process of etching the metal layer (Au/Ti) and the PMN-PZT layer through a wet etching process was further performed.

<Experimental Example 1> Analysis of X-Ray Diffraction Before and After Transferring According to the Semiconductor Substrate with Oxide Single Crystal Heterostructures

[0143] With respect to the specimen (PMN-PZT/Ti/Au/Ti/Si) which is the semiconductor substrate with oxide single crystal heterostructures manufactured in said Example 1, the analysis of high-resolution X-ray diffraction using a wavelength (λ=1.540562 Å) of Cu K.sub.α1 radiation was performed under Bragg-Brentano's condition.

[0144] As a result thereof, as presented in FIG. 9 and FIG. 10, from the structure before transferring (PMN-PZT/LSMO (sacrificial layer)/STO (oxide single crystal substrate)), it could be confirmed that the PMZ-PZT layer and the sacrificial layer of LSMO had grew into a single crystal having an orientation of (001) plane on the substrate of SrTiO.sub.3. Also, from the structure after transferring (PMN-PZT/Au&Ti (metal layer)/Si(semiconductor substrate), it was confirmed that the epitaxy oxide thin film layer of PMN PZT having an orientation of (001) plane as well as the metal layer preferentially oriented in a direction of (111) plane had been formed on the silicon substrate. Accordingly, it was confirmed that the semiconductor substrate 10 to which the epitaxy oxide thin film layer 30 had been bonded via the metal layer 20 had been produced.

<Experimental Example 2> Valuation on Ferroelectric Capability of the Semiconductor Substrate with Oxide Single Crystal Heterostructures

[0145] With respect to the specimen (PMN-PZT/Ti/Au/Ti/Si) which is the semiconductor substrate with oxide single crystal heterostructures manufactured in said Example 1, ferroelectric capability of the materials was valued using machinery, Precision Premier II (by RADIANT TECHNOLOGIES. INC.).

[0146] As a result, through the graphs shown in FIG. 11 and FIG. 12 concerning voltage versus polarization before and after transferring according to the semiconductor substrate with oxide single crystal heterostructures according to the present invention, it was confirmed that a ferroelectric property of the epitaxy oxide thin film layer of PMN-PZT had been well maintained even after transferring.

[0147] The PMN-PZT epitaxial oxide thin film layer shows imprint characteristics horizontally shifted in the negative direction before transfer, whereas it shows a tendency to horizontal shift in the positive direction after transfer. This result is caused by the fact that an upper part and a lower part of the epitaxy oxide thin film layer of PMN-PZT are changed during transferring. Therefore, since the imprint phenomenon is maintained, it can be expected to improve the stability of the piezoelectric performance when manufacturing devices such as piezoelectric MEMS devices, actuators, sensors, or transducers in the future.

[0148] As described above, although the embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will obviously appreciate that various variations and modifications are possible, within the scope of the technical spirit of the present invention.

EXPLANATION OF NUMBERS

[0149] 1, 2: semiconductor substrate with oxide single crystal heterostructures [0150] 10, 11: semiconductor substrate [0151] 20, 20A, 20B, 21, 21A, 21B: metal layer [0152] 30, 31: epitaxy oxide thin film layer [0153] 40: sacrificial layer [0154] 50: oxide single crystal substrate